adrenomedullin and Disease-Models--Animal

Adrenomedullin (AM) is a 52-amino acid peptide with anti-inflammatory, anti-apoptotic, and anti-oxidative properties discovered in a human pheochromocytoma. It is a member of the calcitonin peptide superfamily, and its signal is mediated by calcitonin receptor-like receptor (CLR). CLR interacts with receptor activity-modifying proteins (RAMPs), among which RAMP-2 and RAMP-3 carry CLR from the endoplasmic reticulum to the cellular membrane to confer high affinity for AM. In addition to being implicated in a variety of systemic diseases, AM is a critical contributor to the pathogenesis of retinochoroidal disease. It is robustly upregulated in retinochoroidal disease models of oxygen-induced retinopathy (OIR) and laser-induced choroidal neovascularisation (CNV) as well as in human patients with retinochoroidal diseases. In this review, we discuss the most salient recent findings that strongly illustrate the role of AM in retinochoroidal disease. In the OIR model, AM was identified as a key angiogenic mediator of retinal vascularisation, and AM inhibition suppressed only pathological angiogenesis, not physiological angiogenesis. On the contrary, lesion size was larger in AM(+/-) CNV model mice, presumably due to the anti-inflammatory function of AM. Despite the success of anti-vascular endothelial growth factor agents for the treatment of retinochoroidal disease, therapeutic shortcomings remain. Finding ways to modulate AM activity will provide new treatment avenues. Potential treatment strategies modulating the action of AM and its signaling pathway have been studied extensively. AM and its signaling molecules are intriguing future treatment targets for retinochoroidal disease.

Topics: Adrenomedullin; Animals; Calcitonin Receptor-Like Protein; Choroid Diseases; Disease Models, Animal; Humans; Signal Transduction

Complement factor H has been extensively studied since its discovery 50 years ago, and its role in the complement system is quite well established. It has another role, however, as a binding protein for the regulatory peptide adrenomedullin. Part of this role appears to be protection of adrenomedullin from proteolytic degradation. The binding interaction is unusual and merits further investigation. Adrenomedullin has potential therapeutic uses in diseases affecting the vasculature, and factor H has been administered with adrenomedullin in some animal models of disease.

Topics: Adrenomedullin; Animals; Binding Sites; Complement Factor H; Disease Models, Animal; Gene Expression; Hemorrhage; Humans; Protein Binding; Protein Stability; Protein Structure, Tertiary; Proteolysis; Reperfusion Injury; Sepsis

The immunology of pregnancy is complex and incompletely understood. Aberrant immune activity in the decidua and in the placenta is believed to play a role in diseases of pregnancy, such as infertility, miscarriage, fetal growth restriction and preeclampsia. Here, we briefly review the endocrine control of uterine natural killer cell populations and their functions by the peptide hormone adrenomedullin. Studies in genetic animal models have revealed the critical importance of adrenomedullin dosage at the maternal-fetal interface, with cells from both the maternal and fetal compartments contributing to essential aspects underlying appropriate uterine receptivity, implantation and vascular remodeling of spiral arteries. These basic insights into the crosstalk between the endocrine and immune systems within the maternal-fetal interface may ultimately translate to a better understanding of the functions and consequences of dysregulated adrenomedullin levels in clinically complicated pregnancies.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Embryo Implantation; Endocrine System; Female; Humans; Immunity, Cellular; Killer Cells, Natural; Neovascularization, Physiologic; Pre-Eclampsia; Pregnancy

Adrenomedullin (AM) was originally isolated from human pheochromocytoma as a biologically active peptide with potent vasodilating action but is now known to exert a wide range of physiological effects, including cardiovascular protection, neovascularization, and apoptosis suppression. A variety of tissues, including the gastrointestinal tract, have been shown to constitutively produce AM. Pro-inflammatory cytokines, such as tumor necrosis factor-α and interleukin-1, and lipopolysaccharides, induce the production and secretion of AM. Conversely, AM induces the downregulation of inflammatory cytokines in cultured cells. Furthermore, AM downregulates inflammatory processes in a variety of different colitis models, including acetic acid-induced colitis and dextran sulfate sodium-induced colitis. AM exerts antiinflammatory and antibacterial effects and stimulates mucosal regeneration for the maintenance of the colonic epithelial barrier. Here, we describe the first use of AM to treat patients with refractory ulcerative colitis. The results strongly suggest that AM has potential as a new therapeutic agent for the treatment of refractory ulcerative colitis.

Topics: Adrenomedullin; Animals; Anti-Inflammatory Agents; Colitis, Ulcerative; Disease Models, Animal; Humans; Inflammatory Bowel Diseases; Translational Research, Biomedical; Treatment Outcome

Adrenomedullin (AM) is a potent, long-lasting vasoactive peptide originally isolated from human pheochromocytoma. Since its discovery, serum and tissue AM expression have been shown to be increased in experimental models and in patients with cardiac hypertrophy, myocardial infarction and end-stage heart failure with several beneficial effects. Considerable evidence exists for a wide range of autocrine, paracrine and endocrine mechanisms for AM which include vasodilatory, anti-apoptotic, angiogenic, anti-fibrotic, natriuretic, diuretic and positive inotropic. Thus, through regulation of body fluid or direct cardiac mechanisms, AM has additive and beneficial effects in the context of heart disease. Notable molecular mechanisms of AM include cyclic adenosine monophosphate, guanosine-3',5'-monophosphate, PI3K/Akt and MAPK-ERK-mediated cascades. Given the endogenous and multifunctional nature of AM, we consider this molecule to have great potential in the treatment of cardiovascular diseases. In agreement, early experimental and preliminary clinical studies suggest that AM is a new and promising therapy for cardiovascular diseases.

Topics: Adrenomedullin; Animals; Cardiotonic Agents; Cell Communication; Disease Models, Animal; Extracellular Signal-Regulated MAP Kinases; Heart Diseases; Humans; Nucleotides; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt

The angiogenic activity of peptide adrenomedullin (AM) was first shown in 1998 . Since then, a number of reports have confirmed the ability of AM to induce the growth and migration of isolated vascular endothelial and smooth muscle cells in vitro and to promote angiogenesis in xenografted tumours in vivo. In addition, knockout murine models point to an essential role for AM in embryonic vasculogenesis and ischaemic revascularisation. AM expression is upregulated by hypoxia (a typical feature of solid tumours) and a potential role as a regulator of carcinogenesis and tumour progression has been proposed based on studies in vitro and in animal models. Nevertheless, translational research on AM, and in particular, confirmation of its importance in the vascularisation of human tumours has lagged behind. In this commentary, we review current progress and potential directions for future research into the role of AM in tumour angiogenesis.

Topics: Adrenomedullin; Animals; Cell Hypoxia; Cell Transformation, Neoplastic; Disease Models, Animal; Gene Expression Regulation; Humans; Neoplasms; Neovascularization, Pathologic; Peptides; Signal Transduction; Transplantation, Heterologous

The hyperdynamic circulatory syndrome observed in chronic liver diseases is a great example of research that originated from clinical observations and progressed in the last 50 years from the patient to the experimental laboratory. Our knowledge has evolved from the patient to the molecule, using experimental models that serve as a source for understanding the complex pathophysiological mechanisms that govern this complex syndrome. We now know that progressive vasodilatation is central to the detrimental effects observed in multiple organs. Although nitric oxide has been shown to be the primary vasodilator molecule in these effects, other molecules also participate in the complex mechanisms of vasodilatation. This review summarizes three major areas: first, clinical observation in patients; second, experimental models used to study the hyperdynamic circulatory syndrome; and third, the vasodilator molecules that play roles in vascular abnormalities observed in portal hypertension.

Topics: Adrenomedullin; Animals; Biological Factors; Blood Pressure; Cannabinoid Receptor Modulators; Carbon Monoxide; Chronic Disease; Disease Models, Animal; Endothelium, Vascular; Humans; Hydrogen Sulfide; Hypertension, Portal; Liver; Liver Diseases; Nitric Oxide; Peptides; Splanchnic Circulation; Tumor Necrosis Factor-alpha; Vasodilation

Topics: Adrenomedullin; Animals; Aspartic Acid Endopeptidases; Atrial Natriuretic Factor; Disease Models, Animal; Endothelin-Converting Enzymes; Endothelins; Heart Failure; Intracellular Signaling Peptides and Proteins; Metalloendopeptidases; Natriuretic Peptide, Brain; Nitric Oxide; Oxidative Stress; Peptides; Protein Serine-Threonine Kinases; Rats; Rats, Inbred Dahl; Renin-Angiotensin System; rho-Associated Kinases

The role of central nervous system (CNS) in regulation of gastric function has long been known. The dorsal vagal complex (DVC) has an important role in regulation of gastric mucosal integrity; it is involved both in mucosal protection and in ulcer formation. Neuropeptides have been identified in DVC, the origin of these peptides are both intrinsic and extrinsic. Neuropeptides are localized also in the periphery, in afferent neurons. The afferent neurons also have efferent-like function in the gastroinetestinal tract, and neuropeptides released from the peripheral nerve endings of primary afferent neurons can induce gastric mucosal protection. Centrally and /or peripherally injected neuropeptides, such as amylin, adrenomedullin, bombesin, cholecystokinin, neurotensin, opioid peptides, thyreotropin releasing hormone and vasoactive intestinal peptide, influence both the acid secretion and the gastric mucosal lesions induced by different ulcerogens. The centrally induced gastroprotective effect of neuropeptides may be partly due to a vagal dependent increase of gastric mucosal resistance to injury; activation of vagal cholinergic pathway is resulted in stimulation of the release of mucosal prostaglandin and nitric oxide. Furthermore, release of sensory neuropeptides (calcitonin gene-related peptide, tachykinins) from capsaicin sensitive afferent fibers are also involved in the centrally induced gastroprotective effect of neuropeptides.

Topics: Adrenomedullin; Amyloid; Animals; Bombesin; Calcitonin Gene-Related Peptide; Disease Models, Animal; Gastric Acid; Gastric Mucosa; Homeostasis; Humans; Islet Amyloid Polypeptide; Neurons, Afferent; Neuropeptides; Neuroprotective Agents; Peptides; Stomach Ulcer; Tachykinins; Vagus Nerve

Topics: Adrenomedullin; Animals; Antioxidants; Cardiovascular Diseases; Disease Models, Animal; Homozygote; Humans; Insulin Resistance; Kidney Diseases; Mice; Mice, Knockout; Oxidative Stress; Peptides

Evidence suggests that adrenomedullin (AM) plays a role in the pathophysiology of heart failure. Circulating concentrations of AM are elevated in cardiovascular disease in proportion to the severity of cardiac and hemodynamic impairment. Raised plasma AM levels following acute cardiac injury and in heart failure provide prognostic information on adverse outcomes. In heart failure, elevated circulating AM also identifies patients likely to receive long-term benefit from inclusion of additional anti-failure therapy (carvedilol). Administration of AM in experimental and human heart failure induces reductions in arterial pressure and cardiac filling pressures, and improves cardiac output, in association with inhibition of plasma aldosterone (despite increased renin release) and sustained (or augmented) renal glomerular filtration and sodium excretion. Furthermore, AM in combination with other therapies (angiotensin-converting enzyme inhibition and augmentation of the natriuretic peptides) results in hemodynamic and renal benefits greater than those achieved by the agents separately. Manipulation of the AM system holds promise as a therapeutic strategy in cardiac disease.

Topics: Adrenomedullin; Amino Acid Sequence; Angiotensin-Converting Enzyme Inhibitors; Animals; Disease Models, Animal; Heart Failure; Humans; Molecular Sequence Data; Natriuretic Peptide, Brain; Peptides; Sequence Alignment; Sheep

Adrenomedullin (AM) is a recently discovered regulatory peptide involved in many functions including vasodilatation, electrolyte balance, neurotransmission, growth, and hormone secretion regulation, among others. This 52-amino acid peptide is expressed by specific cell types in many organs throughout the body. A complex receptor system has been described for AM; it requires at least the presence of a seven-transmembrane-domain G-protein-coupled receptor, a single-transmembrane-domain receptor activity modifying protein, and a receptor component protein needed to establish the connection with the downstream signal transduction pathway, which usually involves cyclicAMP. In addition, a serum-binding protein regulates the biological actions of AM, frequently by increasing AM functional attributes. Changes in levels of circulating AM correlate with several critical diseases, including cardiovascular and renal disorders, sepsis, cancer, and diabetes. Whether AM is a causal agent, a protective reaction, or just a marker for these diseases is currently under investigation. New technologies seeking to elevate and/or reduce AM levels are being investigated as potential therapeutic avenues.

Topics: Adrenomedullin; Animals; Diabetes Mellitus; Disease Models, Animal; GTP-Binding Proteins; Humans; Neoplasms; Peptides; Receptors, Cell Surface; Signal Transduction; Viscera

Hypertension is a debilitating disease with significant socioeconomic and emotional impact. Despite recent success in the development of traditional pharmacotherapy for the management of hypertension, the incidence of this disease is on the rise and has reached epidemic proportions by all estimates. This has led many to conclude that traditional pharmacotherapy has reached an intellectual plateau, and novel approaches for the treatment and control of hypertension must be explored. We have begun to investigate the possibility of treating and/or curing hypertension by using genetic means. In this review, we will provide evidence in favor of targeting of the renin-angiotensin system by antisense gene therapy as an effective strategy for the lifelong prevention of hypertension in the spontaneously hypertensive rat model. In addition, we will discuss the properties of an ideal vector for the systemic delivery of genes and the potential experimental hurdles that must be overcome to take this innovative approach to the next level of evaluation.

Topics: Adenoviridae; Adrenomedullin; Angiotensin II; Animals; Atrial Natriuretic Factor; Blood Pressure; Disease Models, Animal; DNA, Antisense; Genetic Therapy; Genetic Vectors; Green Fluorescent Proteins; HIV; Humans; Hypertension; Kallikreins; Luminescent Proteins; Mutation; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Peptides; Rats; Rats, Inbred SHR; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Receptors, Angiotensin; Renin-Angiotensin System; Retroviridae; Transfection

Topics: Adrenomedullin; Animals; Brain; Disease Models, Animal; Heart Failure; Humans; Injections, Intraventricular; Male; Myocardial Infarction; Peptides; Radioimmunoassay; Sheep; Vasodilator Agents

Topics: Adaptation, Physiological; Adrenomedullin; Animals; Animals, Newborn; Cats; Disease Models, Animal; Fetal Blood; Fetus; Humans; Infant, Newborn; Peptides; Perinatal Care; Pulmonary Circulation; Rats; Sensitivity and Specificity; Sheep; Vasodilator Agents

Topics: Adrenomedullin; Animals; Digestive System; Disease Models, Animal; Gene Expression; Humans; Immunohistochemistry; Inflammation; Mice; Peptides; Rats; Reference Values; RNA, Messenger

Lung inflammation interrupts alveolarization and causes bronchopulmonary dysplasia (BPD). Besides mechanical ventilation and hyperoxia, sepsis contributes to BPD pathogenesis. Adrenomedullin (Adm) is a multifunctional peptide that exerts anti-inflammatory effects in the lungs of adult rodents. Whether Adm mitigates sepsis-induced neonatal lung injury is unknown. The lung phenotype of mice exposed to early postnatal lipopolysaccharide (LPS) was recently shown to be similar to that in human BPD. This model was used to test the hypothesis that Adm-deficient neonatal mice will display increased LPS-induced lung injury than their wild-type (WT) littermates. Adm-deficient mice or their WT littermates were intraperitoneally administered 6 mg/kg of LPS or vehicle daily on postnatal days (PNDs) 3 to 5. The lungs were harvested at several time points to quantify inflammation, alveolarization, and vascularization. The extent of LPS-induced lung inflammation in Adm-deficient mice was 1.6-fold to 10-fold higher than their WT littermates. Strikingly, Adm deficiency induced STAT1 activation and potentiated STAT3 activation in LPS-exposed lungs. The severity of LPS-induced interruption of lung development was also greater in Adm-deficient mice at PND7. At PND14, LPS-exposed WT littermates displayed substantial improvement in lung development, whereas LPS-exposed Adm-deficient mice continued to have decreased lung development. These data indicate that Adm is necessary to decrease lung inflammation and injury and promote repair of the injured lungs in LPS-exposed neonatal mice.

Topics: Adrenomedullin; Animals; Animals, Newborn; Bronchopulmonary Dysplasia; Disease Models, Animal; Female; Gene Dosage; Lipopolysaccharides; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Transgenic; Pregnancy

Age-related macular degeneration (AMD) is a leading cause of visual impairment. Anti-vascular endothelial growth factor drugs used to treat AMD carry the risk of inducing subretinal fibrosis. We investigated the use of adrenomedullin (AM), a vasoactive peptide, and its receptor activity-modifying protein 2, RAMP2, which regulate vascular homeostasis and suppress fibrosis. The therapeutic potential of the AM-RAMP2 system was evaluated after laser-induced choroidal neovascularization (LI-CNV), a mouse model of AMD. Neovascular formation, subretinal fibrosis, and macrophage invasion were all enhanced in both AM and RAMP2 knockout mice compared with those in wild-type mice. These pathologic changes were suppressed by intravitreal injection of AM. Comprehensive gene expression analysis of the choroid after LI-CNV with or without AM administration revealed that fibrosis-related molecules, including Tgfb, Cxcr4, Ccn2, and Thbs1, were all down-regulated by AM. In retinal pigment epithelial cells, co-administration of transforming growth factor-β and tumor necrosis factor-α induced epithelial-mesenchymal transition, which was also prevented by AM. Finally, transforming growth factor-β and C-X-C chemokine receptor type 4 (CXCR4) inhibitors eliminated the difference in subretinal fibrosis between RAMP2 knockout and wild-type mice. These findings suggest the AM-RAMP2 system suppresses subretinal fibrosis in LI-CNV by suppressing epithelial-mesenchymal transition.

Topics: Adrenomedullin; Animals; Choroidal Neovascularization; Disease Models, Animal; Epithelial-Mesenchymal Transition; Fibrosis; Humans; Intravitreal Injections; Macular Degeneration; Mice, Knockout; Receptor Activity-Modifying Protein 2; Retinal Pigment Epithelium

The main disadvantage of doxorubicin (DOX) is that it has cardiotoxic side effects. Our aim is to evaluate the cardioprotective effects of adrenomedullin (ADM) and to compare these effects with melatonin (MEL), it's cardioprotective effects are well known. Rats were divided into four groups: Control group (0.9% NaCl solution, intravenously), Doxorubicin group (45 mg/kg DOX, intravenously), Doxorubicin + Melatonin group (DOX + MEL, 10 mg/kg melatonin, intraperitoneally), Doxorubicin + Adrenomedullin group (DOX + ADM, 12 µg/kg adrenomedullin, intraperitoneally). A single dose of DOX was injected to the experimental groups on day 5, and a single dose of 0.9% NaCl solution was injected to the control group through the tail vein. The animals were anesthetized and ECG recordings were obtained on day 8. For the purpose of biochemical and histological analysis, cardiac tissue biopsy was obtained after ECG recordings. Compared to the control group, the DOX group had significantly increased duration of QRS complex, PR interval, QT interval and QTc interval. QRS complex, QT interval and QTc interval were prolonged with the administration of DOX and shortened with the administration of ADM. MEL weakened the toxic effects of DOX on the cardiac tissue and it is shown histologically. DOX increased interleukins (IL-1α, IL-6, IL-18), tumor necrosis factor-α (TNF-α), hypoxia-inducible factor 1-alpha (HIF-1α), malondialdehyde (MDA), nitric oxide (NO), creatine kinase myocardial band (CK-MB), and total oxidant status (TOS) levels in cardiac tissue, while reducing total antioxidant status (TAS), superoxide dismutase (SOD) and catalase (CAT) levels. MEL administration decreased the levels of CK-MB, MDA, IL-1α, IL-6, IL-18, NO, and TNF-α, whereas ADM only decreased IL-1α, IL-18, MDA and TNF-α levels. In summary, these results show that DOX has toxic effects on rat cardiac tissue which is documented histologically, electrocardiographically and biochemically. MEL alleviated histological damage and showed improvement on the several biochemical parameters of cardiac tissue. ADM brought several electrocardiographic and biochemical parameters closer to normal values.

Topics: Action Potentials; Adrenomedullin; Animals; Anti-Inflammatory Agents; Antioxidants; Cardiotoxicity; Cytokines; Disease Models, Animal; Doxorubicin; Heart Diseases; Heart Rate; Hypoxia-Inducible Factor 1, alpha Subunit; Inflammation Mediators; Male; Melatonin; Myocytes, Cardiac; Nitric Oxide; Oxidative Stress; Rats, Wistar

This study investigated the potential effect of adrenomedullin (ADM) on metabolic and endocrinal dysfunctions in experimentally induced polycystic ovary. Twenty-four female Wistar rats were allocated into three groups: control; polycystic ovary syndrome (PCOS) in which PCOS was induced by letrozole, orally in a dose of 1 mg/kg once daily for 3 weeks; and ADM group in which ADM was injected intraperitonally in a dose of 3.5/μg/twice daily for 4 weeks. At the end of the experimental period, the serum sex hormone profile, ADM, fasting glucose, insulin, homeostatic model assessment of insulin resistance, and lipid parameters were determined. Ovarian tissue homogenates were used to determine malondialdehyde, total antioxidant capacity, glutathione peroxidase activity, tumor necrosis factor α, interleukin 6, B cell lymphoma-2 (Bcl-2), and Bcl-2 associated X protein. The profibrotic growth factors, including transforming growth factor β1 and connective tissue growth factor, were determined; and also, the relative gene expression of endoplasmic reticulum (ER) stress, including (Xbox-binding protein-1 [XBP-1], activating transcription factor 6 [ATF6], and homologous protein [CHOP]), serine/threonine kinase 1 (Akt1), phosphatidylinositol 3-kinase (PI3K), and peroxisome proliferator-activated receptor γ (PPAR-γ) were determined. Finally, histopathological analysis of the ovaries was evaluated. PCOS group exhibited increased ER stress, suppressing of PI3K/Akt1 and PPAR-γ pathways, imbalance of sex hormonal profile, hyperglycemia, insulin resistance, dyslipidemia, increased profibrotic factors, and abnormal ovarian histopathological picture, while ADM treatment alleviated these disturbances occurring in the PCOS model. We concluded that ADM mitigated PCOS via attenuating the ER stress, in addition to activation of PI3K/Akt1 and PPAR-γ pathways, its antioxidant, anti-inflammatory, antiapoptotic, and antifibrotic properties.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Endoplasmic Reticulum Stress; Female; Gene Expression Regulation; Letrozole; Polycystic Ovary Syndrome; Rats; Rats, Wistar; Signal Transduction

Intermedin(IMD) is a novel member of the calcitonin/calcitonin gene-related peptide (CT/CGRP) family that has anti-inflammatory, antioxidant and anti-apoptosis properties. This study aimed to evaluate the renoprotective effects of IMD on podocyte apoptotic loss and slit diaphragm protein deficiency the kidneys of rats with in streptozotocin (STZ) induced diabetes in high glucose-exposed podocytes. Our results showed that IMD significantly attenuated proteinuria, and alleviated the abnormal alterations in glomerular ultrastructure in vivo. IMD also improved the induction of slit diaphragm proteins, and restored the decreased Bcl-2 expression and suppressed Bax and caspase-3 induction in the diabetic glomeruli. In addition, IMD attenuated podocyte apoptosis and filamentous actin (F-actin) rearrangement in high glucose-exposed podocytes. Exposure to high glucose elevated the unfolded protein response (UPR) to endoplasmic reticulum (ER) stress in renal podocytes, and IMD treatment blocked such ER stress responses pertinent to podocyte apoptosis and reduced synthesis of slit diaphragm proteins in vivo and in vitro. These observations demonstrate that targeting ER stress is an underlying mechanism of IMD-mediated amelioration of diabetes-associated podocyte injury and dysfunction.

Topics: Adrenomedullin; Animals; bcl-2-Associated X Protein; Caspase 3; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Disease Models, Animal; Endoplasmic Reticulum Stress; Glucose; Male; Podocytes; Proto-Oncogene Proteins c-bcl-2; Random Allocation; Rats; Streptozocin; Unfolded Protein Response

Pulmonary fibrosis is an irreversible, potentially fatal disease. Adrenomedullin (AM) is a multifunctional peptide whose activity is regulated by receptor activity-modifying protein 2 (RAMP2). In the present study, we used the bleomycin (BLM)-induced mouse pulmonary fibrosis model to investigate the pathophysiological significance of the AM-RAMP2 system in the lung. In heterozygous AM knockout mice (AM+/-), hydroxyproline content and Ashcroft scores reflecting the fibrosis severity were significantly higher than in wild-type mice (WT). During the acute phase after BLM administration, FACS analysis showed significant increases in eosinophil, monocyte, and neutrophil infiltration into the lungs of AM+/-. During the chronic phase, fibrosis-related molecules were upregulated in AM+/-. Notably, nearly identical changes were observed in RAMP2+/-. AM administration reduced fibrosis severity. In the lungs of BLM-administered AM+/-, the activation level of Smad3, a receptor-activated Smad, was higher than in WT. In addition, Smad7, an antagonistic Smad, was downregulated and microRNA-21, which targets Smad7, was upregulated compared to WT. Isolated AM+/- lung fibroblasts showed less proliferation and migration capacity than WT fibroblasts. Stimulation with TGF-β increased the numbers of α-SMA-positive myofibroblasts, which were more prominent among AM+/- cells. TGF-β-stimulated AM+/- myofibroblasts were larger and exhibited greater contractility and extracellular matrix production than WT cells. These cells were α-SMA (+), F-actin (+), and Ki-67(-) and appeared to be nonproliferating myofibroblasts (non-p-MyoFbs), which contribute to the severity of fibrosis. Our findings suggest that in addition to suppressing inflammation, the AM-RAMP2 system ameliorates pulmonary fibrosis by suppressing TGF-β-Smad3 signaling, microRNA-21 activity and differentiation into non-p-MyoFbs.

Topics: Adrenomedullin; Animals; Bleomycin; Cell Differentiation; Disease Models, Animal; Drug Evaluation, Preclinical; Infusions, Intravenous; Male; Mice, Inbred C57BL; Mice, Knockout; MicroRNAs; Myofibroblasts; Pulmonary Fibrosis; Receptor Activity-Modifying Protein 2; Smad7 Protein; Transforming Growth Factor beta

Adrenomedullin is a vasoactive peptide that improves endothelial barrier function in sepsis, but may also cause hypotension and organ failure. Treatment with a non-neutralizing monoclonal anti-adrenomedullin antibody showed improvement in murine sepsis models. We tested the effects of the humanized monoclonal anti-adrenomedullin antibody Adrecizumab in a porcine two-hit model of hemorrhagic and septic shock.In this randomized, blinded study 12 German Landrace pigs were bled to half of baseline mean arterial pressure for 45 min. Sepsis was induced using an Escherichia coli clot placed into the abdominal cavity 6 h after hemorrhagic shock. Animals received either 2 mg/kg BW anti-adrenomedullin antibody or vehicle solution immediately after sepsis induction. After 4 h, resuscitation was initiated using balanced crystalloids and noradrenalin to maintain a central venous pressure of 8 to 12 mm Hg, a mean arterial pressure ≥ 65 mm Hg, and a ScvO2 ≥70% for another 8 h. Hemodynamic parameters, laboratory parameters, and kidney histology were assessed.The amount of volume resuscitation was significantly lower and significantly less animals developed a septic shock in the antibody-treated group, compared with the vehicle group. Kidney histology showed significantly lower granulocytes in both cortex and medulla in antibody-treated animals, while the remaining four kidney measures (serum creatinine and urine output and cortical and medullary injury in histopathology) did not reach the significance levels. After induction of sepsis, plasma adrenomedullin increased immediately in both the groups, but increased quicker and more pronounced in the antibody group.In this two-hit shock model, treatment with an anti-adrenomedullin antibody significantly increased plasma adrenomedullin levels, while significantly less animals developed septic shock and renal granulocyte extravasation was significantly reduced. Thus, therapy with Adrecizumab may provide benefit in sepsis, and clinical investigation of this drug candidate is warranted.

Topics: Adrenomedullin; Animals; Antibodies, Monoclonal, Humanized; Disease Models, Animal; Kidney; Models, Biological; Sepsis; Swine; Swine Diseases

Adrenomedullin (AM) is a multifunctional bioactive peptide. Recent studies have shown that AM has protective effects against ischemic brain damage. We recently prepared a long-acting human AM derivative that was conjugated with a 60 kDa polyethylene glycol (PEG-AM), which had an effect similar to that of native AM. In this study, we examined the effect of PEG-AM on four-vessel occlusion model rats, which exhibit vascular dementia. From day 10 to day 14 after surgery, the learning and memory abilities of the rats were examined using a Morris water maze. The rats were treated with a single subcutaneous injection of 1.0 or 10.0 nmol/kg of PEG-AM. PEG-AM treatment reduced the escape latency in the hidden platform test. Furthermore, the treatment increased the time spent in the platform quadrant in the probe test. The data showed that PEG-AM injection prevented memory loss and learning disorders in dose-dependent manner. On day 14, the immunoreactive AM concentration in plasma was 9.749 ± 2.167 pM in the high-dose group (10.0 nmol/kg) and 0.334 ± 0.073 pM in the low-dose group (1.0 nmol/kg). However, even in the low-dose group, a significant effect was observed in both tests. The present data indicate that PEG-AM is a possible therapeutic agent for the treatment of ischemic brain injury or vascular dementia.

Topics: Adrenomedullin; Animals; Brain Injuries; Dementia, Vascular; Disease Models, Animal; Drug Administration Schedule; Glycoconjugates; Humans; Injections, Subcutaneous; Male; Maze Learning; Memory; Nootropic Agents; Polyethylene Glycols; Rats; Rats, Wistar; Reperfusion Injury; Treatment Outcome; Vasodilator Agents; Vertebrobasilar Insufficiency

Adrenomedullin (AM) exerts a potent anti-inflammatory effect. Intrarectal or consecutive intravenous administrations of AM reduce pathological manifestations in rodent colitis models. However, in clinical applications, a safer administration route that provides stronger alleviation of patient burden is preferred. We investigated whether subcutaneously administered AM is effective against dextran sulfate sodium (DSS)-induced colitis. C57BL/6J mice were administered 1% DSS in drinking water and received AM at 8, 40 or 80 nmol/kg subcutaneously once a day for 7 consecutive days. Subcutaneously administered AM significantly and dose-dependently ameliorated body weight loss, diarrhea, and histological severity of colonic inflammation in DSS-treated mice. The AM therapeutic effect was associated with the upregulation of the production of autocrine AM, and expression of cAMP, c-fos, KLF4, and downregulation of STAT3 and NF-κB p65 phosphorylation, as well as a decrease in proinflammatory cytokine expression in the colon. Subcutaneous AM treatment potently attenuated DSS-induced colitis, which suggests that AM administered subcutaneously in ulcerative colitis (UC) patients may decrease diseases burden and improve quality of life.

Topics: Adrenomedullin; Animals; Anti-Inflammatory Agents; Cell Differentiation; Colitis, Ulcerative; Cyclic AMP; Cytokines; Dextran Sulfate; Disease Models, Animal; Dose-Response Relationship, Drug; Goblet Cells; Inflammation Mediators; Injections, Subcutaneous; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Male; Mice, Inbred C57BL; NF-kappa B; Proto-Oncogene Proteins c-fos; STAT3 Transcription Factor; Stimulation, Chemical

Renal fibrosis promotes the progression of chronic renal disease to end-stage renal disease. Microvascular damage and loss play an important role in renal fibrosis. Intermedin (IMD) is expressed mainly in the heart and kidney. IMD has been shown to increase renal blood flow and reduce the loss of glomerular and surrounding renal tubules, but its role in mediating microvascular damage in renal fibrosis remains to be elucidated. Here, we investigated the effects of IMD on microvascular damage in a renal fibrosis model.. We created a rat model of unilateral ureteral obstruction (UUO) to clarify the effect of microvascular damage on renal fibrosis and the effect of intermedin on reversing renal vascular injury and promoting angiogenesis. Rats were divided randomly into three groups: sham, UUO, and UUO + IMD. The sham group underwent free ureteral ligation but not occlusion. Rats in the latter two groups underwent UUO, and rats in the IMD group were additionally administered intermedin (100 ng/kg/h) daily. On the 7th, 14th, 21st, and 28th days after surgery, abdominal aortic blood and the obstructed kidneys were harvested from the rats (n = 6) for analysis.. IMD was found to protect against renal vascular injury and to increase microvessel density. Molecularly, IMD upregulated vascular endothelial growth factor-vascular endothelial growth factor receptor (VEGF-VEGFR2) pathway activity. The VEGF-VEGFR2 pathway might be the underlying mechanism mediating the protective activities of IMD in promoting angiogenesis, delaying renal fibrosis, and improving renal function.. IMD could be a potential candidate treatment for renal fibrosis.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Fibrosis; Kidney; Kidney Diseases; Kidney Tubules; Male; Neovascularization, Pathologic; Neuropeptides; Rats; Rats, Wistar; Up-Regulation; Ureteral Obstruction; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2

Cardiac lymphangiogenesis contributes to the reparative process post-myocardial infarction, but the factors and mechanisms regulating it are not well understood.. To determine if epicardial-secreted factor AM (adrenomedullin; Adm=gene) improves cardiac lymphangiogenesis post-myocardial infarction via lateralization of Cx43 (connexin 43) in cardiac lymphatic vasculature.. Firstly, we identified sex-dependent differences in cardiac lymphatic numbers in uninjured mice using light-sheet microscopy. Using a mouse model of Adm. AM is an endogenous, epicardial-derived factor that drives reparative cardiac lymphangiogenesis and function via Cx43, and this represents a new therapeutic pathway for improving myocardial edema after injury.

Topics: Adrenomedullin; Animals; Cells, Cultured; Connexin 43; Disease Models, Animal; Edema, Cardiac; Female; Gap Junctions; Humans; Lymphangiogenesis; Lymphatic Vessels; Male; Mice, Inbred C57BL; Mice, Transgenic; Myocardial Infarction; Myocardium; Pericardium; Signal Transduction; Ventricular Function, Left

Central retinal vein occlusion (CRVO) is an intractable disease that causes visual acuity loss with retinal ischemia, hemorrhage, and edema. In this study, we developed an experimental CRVO model in mice and evaluated the therapeutic potential of the pleiotropic peptide adrenomedullin (ADM) and its receptor activity-modifying protein 2 (RAMP2). The CRVO model, which had phenotypes resembling those seen in the clinic, was produced by combining i.p. injection of Rose bengal, a photoactivator dye enhancing thrombus formation, with laser photocoagulation. Retinal vascular area, analyzed using fluorescein angiography and fluorescein isothiocyanate-perfused retinal flat mounts, was decreased after induction of CRVO but gradually recovered from day 1 to 7. Measurements of retinal thickness using optical coherence tomography and histology revealed prominent edema early after CRVO, followed by gradual atrophy. Reperfusion after CRVO was diminished in Adm and Ramp2 knockout (KO) mice but was increased by exogenous ADM administration. CRVO also increased expression of a coagulation factor, oxidative stress markers, and a leukocyte adhesion molecule in both wild-type and Adm KO mice, and the effect was more pronounced in Adm KO mice. Using retinal capillary endothelial cells, ADM was found to directly suppress retinal endothelial injury. The retinoprotective effects of the Adm-Ramp2 system make it a novel therapeutic target for the treatment of CRVO.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Fluorescein Angiography; Humans; Mice; Mice, Knockout; Receptor Activity-Modifying Protein 2; Retinal Vein Occlusion; Tomography, Optical Coherence

Human adrenomedullin (hAM) is a hypotensive peptide hormone that exerts powerful anti-inflammatory effects. However, treatment required continuous administration of hAM, as the half-life of native hAM is quite short in blood. To resolve this problem, we designed two kinds of human IgG1 Fc fusion proteins containing either full-length hAM (IgG1-AM) or hAM residues 6-52 [IgG1-AM (6-52)]. A DNA construct was constructed by connecting DNA sequences encoding hAM and the IgG1 Fc region with a DNA sequence encoding a (GGGGS)3 linker. The molecular weights of IgG1-AM and IgG1-AM (6-52) were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography. By protein sequencing, the N-terminal sequence of both recombinant AM-Fc fusions showed the expected human IgG1 sequence. Sufficient concentrations of both AM-Fc fusions were observed in blood 2 days after a single subcutaneous administration. IgG1-AM and IgG1-AM (6-52) stimulated cAMP production in human embryonic kidney-293 cells stably expressing the AM1 receptor. The activity of IgG1-AM (6-52) was higher than that of IgG1-AM. Treatment with IgG1-AM (6-52) inhibited blood pressure increase in spontaneously hypertensive rats. In addition, IgG1-AM (6-52) reduced total inflammation scores in the dextran sulfate sodium colitis model. Therefore, AM-IgG1 Fc fusions represent potential novel therapeutic agents.

Topics: Adrenomedullin; Animals; Cells, Cultured; Colitis; Dextran Sulfate; Disease Models, Animal; HEK293 Cells; Humans; Immunoglobulin Fc Fragments; Immunoglobulin G; Inflammation; Male; Protein Folding; Rats; Rats, Inbred SHR; Rats, Wistar; Recombinant Proteins

Remote ischemic preconditioning (RIPC) is a minimally invasive method that provides protection by reducing injury to the heart, kidneys, brain and other tissues or organs. RIPC may improve the outcome in patients undergoing surgery. Although the role of RIPC has been studied, the results remain controversial. It is difficult to confirm whether RIPC has a kidney protective effect and the understanding of the preconditioning signal pathway involved remains unclear. In the present study, the effect of RIPC in urology was evaluated. The protection against renal damage was assessed by investigating the potential mediator, hypoxia‑inducible factor‑1α (HIF‑1α), and the functional adrenomedullin (ADM) pathway. Male Sprague‑Dawley (SD) rats were used in the present study. The animal model of kidney damage induced by ischemia reperfusion (IR) was used to investigate the protective effect of the acute and delayed phase RIPC. Furthermore, the protective effects of RIPC mediated by a HIF‑1α‑ADM pathway were assessed. The indexes of renal function and oxidative damage indicators were measured by Cr, BUN, mALB, β2‑MG, MPO, MDA and SOD assays, and the expression of HIF‑1α and ADM were detected by western blot analysis, immunohistochemistry and ELISA assays. Tubular score, determined using hematoxylin and eosin staining, was used to evaluate renal tissue damage. Applying RIPC prevented IR‑induced renal dysfunction and oxidative damage by decreasing Cr, BUN, mALB, β2‑MG, MPO, MDA levels and increasing SOD activity. Findings showed that delayed RIPC had an improved effect compared with acute treatment. Delayed RIPC also upregulated the expression of HIF‑1α and ADM, indicating that the protective effect of the delayed RIPC may be associated with a HIF‑1α‑ADM‑mediated mechanism. The effect of the delayed RIPC to reduce IR‑induced renal damage and increase ADM expression was enhanced by HIF‑1α agonists DMOG and BAY 85‑3934, whereas the effect was whittled by HIF‑1α antagonists YC‑1 and 2‑MeOE2. Furthermore, receiving ADM also offered protection to the kidney in comparison with the IR+Vehicle group. These findings suggest that RIPC prevents IR‑mediated renal damage by HIF‑1α via an ADM humoral pathway. In the present study, RIPC provided an effective renal protection. ADM could also offer protection regulated by HIF‑1α in renal tissue. However, the mechanism of ADM as a protective factor in RIPC requires further research.

Topics: Adrenomedullin; Animals; Blood Urea Nitrogen; Creatinine; Disease Models, Animal; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Indazoles; Ischemic Preconditioning; Kidney; Male; Malondialdehyde; Pyrazoles; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxide Dismutase; Triazoles; Up-Regulation

Cotransfer of angiogenic and antiapoptotic genes could be the basis of new gene therapy strategies for myocardial infarction. In this study, rAAV-PR39-ADM, coexpressing antimicrobial peptide (PR39) and adrenomedullin (ADM), was designed with the mediation of recombinant adeno-associated virus. In vitro, CRL-1730 cells were divided into four groups, namely, the sham group, the AAV-null group, the NS (normal saline) group, and the PR39-ADM group. Immunocytochemistry analysis, CCK-8 assays, Matrigel assays, and apoptotic analysis were performed; in vivo, myocardial infarction model was established through ligation of the left coronary artery on rats, and treatment groups corresponded to those used in vitro. Myocardial injury, cardiac performance, and the extent of myocardial apoptosis were assessed. Results suggested that rAAV-PR39-ADM administration after myocardial infarction improved cell viability and cardiac function, attenuated apoptosis and myocardial injury, and promoted angiogenesis. Subsequently, levels of 6×His, HIF-1

Topics: Adrenomedullin; Animals; Antimicrobial Cationic Peptides; Apoptosis; bcl-2-Associated X Protein; Cell Line; Dependovirus; Disease Models, Animal; Genetic Vectors; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Male; Myocardial Infarction; Myocardium; Neovascularization, Physiologic; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Vascular Endothelial Growth Factor A

Flap necrosis in the distal area due to the deficiency of blood circulation is a major complication in flap treatment. In many previous studies, some natural substances such as chlorogenic acid, adrenomedullin (ADM), and glucagon-like peptide-1 (GLP-1) have been used to improve flap viability via their vasodilator, angiogenic, and antioxidant effects. The aim of this study is to clarify the mechanism through the use of selective antagonists for calcitonin gene-related peptide (CGRP) receptors and GLP-1 receptors such as CGRP-(8-37), exendin-(9-39), respectively, in the flap healing effects of ADM and GLP-1. The role of nitric oxide (NO) was investigated in the mechanism as well.. Seventy adult female Wistar rats (200 g-250 g) were used in the study. The cutaneous skin flap (8 cm x 3 cm) on the abdominal wall was raised based on the superficial inferior epigastric artery (SIEA). Single-dose substance injections were administered into the SIEA. Necrosis in the flap area was evaluated on postoperative day 7. The proportion of the necrosis area (necrosis area % = [necrosis area/flap area] x 100) and vascularity (vascular number/cm2) in the distal area were calculated.. The administrations of ADM or GLP-1 increased the vascularity and decreased the necrosis area in the distal flap region. The ADM receptor antagonist, CGRP-(8-37), did not prevent the positive effects of ADM on flap healing and vascularity. A GLP-1 receptor antagonist, exendin-(9-39), prevented the effect of GLP-1 on flap healing and vascularity. Nitric oxide mediated the beneficial effects of both peptides on flap healing.. The CGRP receptors have no direct role, but NO acts as a mediator in the beneficial effect of ADM on flap healing. The GLP-1 specific receptors and NO act as important interagents for the effects of GLP-1 on flap healing.

Topics: Adrenomedullin; Animals; Antioxidants; Calcitonin Gene-Related Peptide; Disease Models, Animal; Epigastric Arteries; Female; Glucagon-Like Peptide Receptors; Glucagon-Like Peptides; Graft Survival; Immunohistochemistry; Necrosis; Nitric Oxide; Rats; Rats, Wistar; Receptors, Calcitonin Gene-Related Peptide; Surgical Flaps; Wound Healing; Wounds and Injuries

Preclinical Research Human adrenomedullin (hAM), a hypotensive peptide, also has anti-inflammatory effects. hAM can reduce the severity of the dextran sulphate sodium (DSS)- and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in animal models. Furthermore, in a clinical study, hAM treatment reduced the Disease Activity Index in ulcerative colitis. However, these therapeutic effects required continuous administration of hAM as the half-life of native hAM is quite short in blood. To resolve this problem, hAM N-terminal was conjugated with two kinds of polyethylene glycol (PEG); 5 kDa PEG or 60 kDa PEG (5 kDa PEG-hAM and 60 kDa PEG-hAM respectively). In a previous study, 5 kDa PEG-hAM stimulated cAMP production and prolonged the plasma half-life compared with native hAM. Herein we examine the effect of PEG-hAM in the DSS colitis model. Treatment with both PEG-hAM preparations reduced the total inflammation score. In addition, the plasma half-life of 60 kDa PEG-hAM was much longer than 5 kDa PEG-hAM. In summary, a single subcutaneous administration of 60 kDa PEG-hAM reduced the total inflammation score in mice with DSS-induced colitis. Therefore, these results suggest that 60 kDa PEG-hAM is a possible therapeutic agent for the treatment of inflammatory bowel disease. Drug Dev Res 78 : 129-134, 2017. © 2017 Wiley Periodicals, Inc.

Topics: Adrenomedullin; Animals; Anti-Inflammatory Agents; Colitis, Ulcerative; Cyclic AMP; Dextran Sulfate; Disease Models, Animal; Half-Life; Humans; Injections, Subcutaneous; Male; Mice; Polyethylene Glycols

To investigate the contribution of adrenomedullin (AM) and its gene-related peptide, proadrenomedullin N-terminal 20 peptide (PAMP), to the progression and potential treatment of colon cancer we studied the effects of four small molecules (SM) related to AM and PAMP on a mouse model of colon cancer. For each SM, four experimental groups of male mice were used: (i) Control group; (ii) SM group; (iii) DSS group (injected with azoxymethane [AOM] and drank dextran sulfate sodium [DSS]); and (iv) DSS + SM group (treated with AOM, DSS, and the SM). None of the mice in groups i and ii developed tumors, whereas all mice in groups iii and iv developed colon neoplasias. No significant differences were found among mice treated with PAMP modulators (87877 and 106221). Mice that received the AM negative modulator, 16311, had worse colitis symptoms than their control counterparts, whereas mice injected with the AM positive modulator, 145425, had a lower number of tumors than their controls. SM 145425 regulated the expression of proliferation marker Lgr5 and had an impact on microbiota, preventing the DSS-elicited increase of the Bacteroides/Prevotella ratio. These results suggest that treatment with AM or with positive modulator SMs may represent a novel strategy for colon cancer.

Topics: Adrenomedullin; Animals; Antineoplastic Agents; Azoxymethane; Cluster Analysis; Colitis; Colon; Colonic Neoplasms; Disease Models, Animal; Disease Progression; Gastrointestinal Agents; Mice

Adrenomedullin (AM) and its receptors components, calcitonin-receptor-like receptor (CRLR), and receptor activity-modifying protein (RAMP1, RAMP2, and RAMP3) are expressed in cerebellum. Cerebellar AM, AM binding sites and receptor components are altered during hypertension, suggesting a role for cerebellar AM in blood pressure regulation. Thus, we assessed the effect of valsartan, on AM and its receptor components expression in the cerebellar vermis of Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Additionally, we evaluated AM action on superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activity, and thiobarbituric acid reactive substances (TBARS) production in cerebellar vermis. Animals were treated with valsartan or vehicle for 11 days. Rats were sacrificed by decapitation; cerebellar vermis was dissected; and AM, CRLR, RAMP1, RAMP2, and RAMP3 expression was quantified by Western blot analysis. CAT, SOD, and GPx activity was determined spectrophotometrically and blood pressure by non-invasive plethysmography. We demonstrate that AM and RAMP2 expression was lower in cerebellum of SHR rats, while CRLR, RAMP1, and RAMP3 expression was higher than those of WKY rats. AM reduced cerebellar CAT, SOD, GPx activities, and TBARS production in WKY rats, but not in SHR rats. Valsartan reduced blood pressure and reversed the altered expression of AM and its receptors components, as well the loss of AM capacity to reduce antioxidant enzyme activity and TBARS production in SHR rats. These findings demonstrate that valsartan is able to reverse the dysregulation of cerebellar adrenomedullinergic system; and they suggest that altered AM system in the cerebellum could represent the primary abnormality leading to hypertension.

Topics: Adrenomedullin; Angiotensin II Type 1 Receptor Blockers; Animals; Antihypertensive Agents; Catalase; Cerebellum; Disease Models, Animal; Glutathione Peroxidase; Hypertension; Male; Random Allocation; Rats, Inbred SHR; Rats, Inbred WKY; Receptor Activity-Modifying Protein 1; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances; Valsartan

The recruitment of vascular endothelial cells from the tumor microenvironment (TME) to promote angiogenesis plays key roles in the progression of renal cell carcinoma (RCC). The potential impact of immune cells in the TME on RCC angiogenesis, however, remains unclear. Here, we found that recruitment of mast cells resulted in increased RCC angiogenesis in both in vitro cell lines and in vivo mouse models. Mechanistic analyses revealed that RCC recruited mast cells by modulating PI3K→︀AKT→︀GSK3β→︀AM signaling. A clinical survey of human RCC samples also showed that higher expression of the PI3K→︀AKT→︀GSK3β→︀AM signaling pathway correlated with increased angiogenesis. Interruption of PI3K→︀AKT→︀GSK3β→︀AM signaling via specific inhibitors led to decreased recruitment of mast cells, and targeting this infiltrating mast cell-related signaling via an AKT-specific inhibitor suppressed RCC angiogenesis in xenograft mouse models. Together, these results identified a novel role of infiltrating mast cells in RCC angiogenesis and metastasis and suggest a new strategy for treating RCC by targeting this newly identified signaling pathway.

Topics: Adrenomedullin; Animals; Biomarkers; Carcinoma, Renal Cell; Cell Line, Tumor; Chemotaxis, Leukocyte; Disease Models, Animal; Endothelial Cells; Glycogen Synthase Kinase 3 beta; Heterografts; Humans; Immunohistochemistry; Kidney Neoplasms; Male; Mast Cells; Mice; Neovascularization, Pathologic; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction

The equilibrium between lung epithelium damage and recovery in the context of chronic injury is at the basis of numerous lung diseases, including lung cancer and COPD. Understanding the contribution of growth factors and other molecular intermediates to this crosstalk may help in devising new therapeutic approaches. To better understand the contribution of adrenomedullin (AM) to lung homeostasis, we built club cell-specific conditional knockout (KO) mice for AM and subjected them to naphthalene injury. Untreated KO mice had lower levels of club cell 10 KDa protein (CC10) immunoreactivity than their wild type (WT) littermates in both terminal and regular bronchioles. Naphthalene injury resulted in a rapid necrosis of club cells followed by a progressive recovery of the epithelium. Club cells proliferated at higher rates in the KO mice and at 21 days post-injury the club cell coverage of the main bronchioles was higher and more homogeneous than in the WT animals. In conclusion, the paracrine/autocrine influence of AM in club cells subtly modulates their proliferation and spreading kinetics during lung epithelium recovery.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Lung Injury; Mice; Mice, Inbred C57BL; Mice, Knockout; Naphthalenes; Real-Time Polymerase Chain Reaction; Respiratory Mucosa

Natriuretic peptide receptor 3 (NPR3) is the clearance receptor for the cardiac natriuretic peptides (NPs). By modulating the level of NPs, NPR3 plays an important role in cardiovascular homeostasis. Although the physiological functions of NPR3 have been explored, little is known about its regulation in health or disease. MicroRNAs play an essential role in the post-transcriptional expression of many genes. Our aim was to investigate potential microRNA-based regulation of NPR3 in multiple models. Hypoxic challenge elevated levels of NPPB and ADM mRNA, as well as NT-proBNP and MR-proADM in human left ventricle derived cardiac cells (HCMa), and in the corresponding conditioned medium, as revealed by qRT-PCR and ELISA. NPR3 was decreased while NPR1 was increased by hypoxia at mRNA and protein levels in HCMa. Down-regulation of NPR3 mRNA was also observed in infarct and peri-infarct cardiac tissue from rats undergoing myocardial infarction. From microRNA microarray analyses and microRNA target predictive databases, miR-100 was selected as a candidate regulator of NPR3 expression. Further analyses confirmed up-regulation of miR-100 in hypoxic cells and associated conditioned media. Antagomir-based silencing of miR-100 enhanced NPR3 expression in HCMa. Furthermore, miR-100 levels were markedly up-regulated in rat hearts and in peripheral blood after myocardial infarction and in the blood from heart failure patients. Results from this study point to a role for miR-100 in the regulation of NPR3 expression, and suggest a possible therapeutic target for modulation of NP bioactivity in heart disease.

Topics: 3' Untranslated Regions; Adrenomedullin; Aged; Animals; Base Sequence; Binding Sites; Case-Control Studies; Culture Media, Conditioned; Disease Models, Animal; Down-Regulation; Female; Gene Expression Profiling; Gene Expression Regulation; Heart Failure; Humans; Hypoxia; Male; MicroRNAs; Middle Aged; Myocardial Infarction; Myocytes, Cardiac; Natriuretic Peptide, Brain; Peptide Fragments; Protein Precursors; Rats; Receptors, Atrial Natriuretic Factor; RNA Interference; RNA, Messenger; Time Factors

The present study was designed to investigate the effect of Agaricus brasiliensis extract (ABE) on phenylhydrazine-induced neonatal jaundice in rats. Administration of ABE dose-dependently reduced the elevated bilirubin level induced by phenylhydrazine. It can be somewhat supported from the results of in vitro bilirubin degradation experiment. ABE treatment also reduced the total antioxidant status (TAOS), cascade O2(-)/SOD, level of NF-κB protein, and adrenomedullin (AM). Overall, the results of this study demonstrated that Agaricus brasiliensis extract may be beneficial to reducing bilirubin level without causing hepatotoxicity in neonatal jaundice.

Topics: Adrenomedullin; Agaricus; Animals; Antioxidants; Complex Mixtures; Disease Models, Animal; Jaundice, Neonatal; NF-kappa B; Phenylhydrazines; Rats; Rats, Wistar; Superoxide Dismutase; Superoxides

Transforming growth factor-β1 (TGF-β1) plays a pivotal role in the progression of renal fibrosis. Reactive oxygen species mediate profibrotic action of TGF-β1. Intermedin (IMD) has been shown to inhibit oxidative stress, but its role in renal fibrosis remains unclear. Here, we investigated the effects of IMD on renal fibrosis in a rat model of unilateral ureteral obstruction (UUO).. The expression of IMD and its receptors, calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMP1/2/3), in the obstructed kidney was detected by real-time polymerase chain reaction (PCR), western blotting and immunohistochemistry. To evaluate the effects of IMD on renal fibrosis, we locally overexpressed exogenous IMD in the obstructed kidney using an ultrasound-microbubble-mediated delivery system. Renal fibrosis was determined by Masson trichrome staining. The expression of TGF-β1, connective tissue growth factor (CTGF), α-smooth muscle actin (α-SMA) and fibronectin was measured. Smad2/3 activation and macrophage infiltration were evaluated. We also studied oxidative stress by measuring superoxide dismutase (SOD) activity and malondialdehyde (MDA) content.. mRNA and protein expression of IMD increased after UUO. CRLR, RAMP1, RAMP2 and RAMP3 were also induced by ureteral obstruction. IMD overexpression remarkably attenuated UUO-induced tubular injury and blunted fibrotic response as shown by decreased interstitial collagen deposition and downregulation of fibronectin. Macrophage infiltration, α-SMA and CTGF upregulation caused by UUO were all relieved by IMD, whereas TGF-β1 upregulation and Smad2/3 activation were not affected. Meanwhile, we noted increased oxidative stress in obstruction, which was also attenuated by IMD gene delivery.. Our results indicate that IMD is upregulated after UUO. IMD plays a protective role in renal fibrosis via its antioxidant effects.

Topics: Adrenomedullin; Animals; Calcitonin Receptor-Like Protein; Collagen; Disease Models, Animal; Fibronectins; Fibrosis; Genetic Therapy; Kidney; Kidney Diseases; Male; Microbubbles; Neuropeptides; Oxidative Stress; Rats, Wistar; Receptor Activity-Modifying Protein 1; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; RNA, Messenger; Signal Transduction; Smad2 Protein; Smad3 Protein; Time Factors; Transfection; Transforming Growth Factor beta1; Ultrasonics; Up-Regulation; Ureteral Obstruction

The pulmonary vasodilation induced by adrenomedullin may be beneficial in the acute pulmonary embolism (APE) setting. This study examined effects of adrenomedullin in sheep with microsphere-induced APE.. Twenty four anesthetized, mechanically ventilated sheep were randomly assigned into 3 groups (n=8 per group): animals not subjected to any intervention (Sham), animals with APE induced by microspheres (500 mg, intravenously) treated 30 min later by intravenous physiological saline (Emb group) or intravenous adrenomedullin (50 ng/kg/min) during 30 min (Emb+Adm group). Plasma concentrations of cyclic adenosine (cAMP) and guanosine monophosphate (cGMP) were determined by enzyme immunoassay.. Variables did not change over time in sham animals. In both embolized groups, microsphere injection significantly (P<0.05) increased pulmonary vascular resistance index (PVRI) and mean pulmonary artery pressure (MPAP) from baseline by 181% and 111-142%, respectively (% change in mean values). Adrenomedullin significantly decreased PVRI (18%-25%) and significantly increased cardiac index (22%-25%) from values recorded 30 min after APE (E30), without modifying MPAP. Adrenomedullin decreased mean arterial pressure (18%-24%) and systemic vascular resistance index (32%-40%). Embolization significantly increased arterial-to-end tidal CO2 gradient, alveolar-to-arterial O2 gradient, and pulmonary shunt fraction from baseline, but these variables were unaffected by adrenomedullin. While adrenomedullin significantly increased plasma cAMP, cGMP levels were unaltered.. Adrenomedullin induces systemic and pulmonary vasodilation, possibly via a cAMP mediated mechanism, without modifying the gas exchange impairment associated with APE. The pulmonary anti-hypertensive effect of adrenomedullin may be offset by increases in cardiac index.

Topics: Acute Disease; Adrenomedullin; Animals; Cyclic AMP; Cyclic GMP; Disease Models, Animal; Hypertension, Pulmonary; Lung; Male; Pulmonary Embolism; Sheep; Vasodilation; Vasodilator Agents

Intermedin is a proopiomelanocortin-derived peptide before opioid promoting cortical hormone, its main function embodies in mononuclear macrophages and neutrophilic granulocytes to inhibit the proinflammatory cytokines. The aim of this study is to determine intermedin attenuates myocardial infarction and its related mechanisms in a rat model of ischemic heart failure. After rat model of ischemic heart failure was set up, myocardial infarction, blood levels of activities of creatine kinase (CK), the MB isoenzyme of creatine kinase (CK-MB), lactate dehydrogenase (LDH) and cardiac troponin T (cTnT) were effectively reduced by treatment with intermedin. Tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) in a rat model of ischemic heart failure were recovered by pretreatment with intermedin. Administrate of intermedin availably promoted cAMP contents and suppressed caspase-3 protein in ischemic heart failure rat. ERK1/2 and LC3 protein expression were significantly activated and autophagy was significantly promoted by intermedin in a rat model of ischemic heart failure. These results indicate that intermedin protected rat heart, attenuates myocardial infarction from ischemic heart failure in the rat model. The underlying mechanisms may include upregulation of cAMP, ERK1/2 and LC3 protein expression and activating of autophagy.

Topics: Adrenomedullin; Animals; Autophagy; Blotting, Western; Cyclic AMP; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Heart Failure; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase Kinases; Myocardial Infarction; Neuropeptides; Rats; Rats, Sprague-Dawley

Calcitonin Gene-Related Peptide (CGRP) inhibits microglia inflammatory activation in vitro. We here analyzed the involvement of CGRP and Receptor Component Protein (RCP) in experimental autoimmune encephalomyelitis (EAE). Alpha-CGRP deficiency increased EAE scores which followed the scale alpha-CGRP null>heterozygote>wild type. In wild type mice, CGRP delivery into the cerebrospinal fluid (CSF) 1) reduced chronic EAE (C-EAE) signs, 2) inhibited microglia activation (revealed by quantitative shape analysis), and 3) did not alter GFAP expression, cell density, lymphocyte infiltration, and peripheral lymphocyte production of IFN-gamma, TNF-alpha, IL-17, IL-2, and IL-4. RCP (probe for receptor involvement) was expressed in white matter microglia, astrocytes, oligodendrocytes, and vascular-endothelial cells: in EAE, also in infiltrating lymphocytes. In relapsing-remitting EAE (R-EAE) RCP increased during relapse, without correlation with lymphocyte density. RCP nuclear localization (stimulated by CGRP in vitro) was I) increased in microglia and decreased in astrocytes (R-EAE), and II) increased in microglia by CGRP CSF delivery (C-EAE). Calcitonin like receptor was rarely localized in nuclei of control and relapse mice. CGRP increased in motoneurons. In conclusion, CGRP can inhibit microglia activation in vivo in EAE. CGRP and its receptor may represent novel protective factors in EAE, apparently acting through the differential cell-specific intracellular translocation of RCP.

Topics: Adrenomedullin; Animals; Calcitonin Gene-Related Peptide; Cells, Cultured; Cytokines; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Enzyme Inhibitors; Freund's Adjuvant; Gene Expression Regulation; Lymphocytes; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Myelin-Oligodendrocyte Glycoprotein; Nerve Tissue Proteins; Peptide Fragments; Receptors, Calcitonin Gene-Related Peptide

Although drug-eluting stents (DES) have been widely used for the treatment of coronary artery disease, they potentially increase the risk of late thrombosis. It is, therefore, desirable to establish a strategy to stimulate reendothelialization. Endothelial injury models have been widely used to analyze the mechanisms of coronary restenosis. However, animal models deployed with coronary stents in the blood vessels are necessary to accurately analyze the mechanisms of coronary restenosis and late thrombosis because persistent inflammation occurs around the coronary stents.. Coronary stents were implanted into rat abdominal aorta and adipose tissue-derived stem cells (ASC) were administered from the adventitial side. Reendothelialization was then visualized by Evans blue staining, and neointimal formation was analyzed histologically. ASC significantly stimulated reendothelialization and inhibited neointimal formation in bare metal stents (BMS)-implanted aorta. In addition, ASC promoted reendothelialization in DES-implanted aorta; however, the effects were weaker than in BMS-implanted aorta. Among the cytokines that ASC produce, adrenomedullin (AM) significantly stimulated reendothelialization and inhibited neointimal formation in BMS-implanted aorta, when an adenovirus expressing AM was administered from the adventitial side.. These results suggest that ASC produce several cytokines that stimulate reendothelialization and inhibit neointimal formation in stent-deployed vessels, and that AM could mediate these effects.

Topics: Adipose Tissue; Adrenomedullin; Animals; Aorta, Abdominal; Cells, Cultured; Coronary Restenosis; Disease Models, Animal; Male; Neointima; Rats; Rats, Wistar; Stem Cell Transplantation; Stem Cells; Stents

Traumatic brain injury (TBI) is a common cause of death and disability throughout the world. A multifunctional peptide adrenomedullin (AM) has protective effects in the central nervous system. We evaluated AM in an animal model as a therapeutic agent that reduces brain damage after traumatic brain injury. A total of 36 rats was divided into 3 groups as sham, head trauma plus intraperitoneal (ip) saline, and head trauma plus adrenomedullin ip. The diffuse brain injury model of Marmarou et al. was used. Blood samples were taken from all groups at the 1st, 6th and 24th hours for analysis of TNF-α (tumor necrosis factor-α), IL-1β (interleukin-1β) and IL-6 (interleukin-6) levels. At the end of the study (at the 24th hour) a neurological examination was performed and half of the rats were decapitated to obtain blood and tissue samples, the other half were perfused transcardiacally for studying the histopathology of the brain tissue. There were no statistically significant changes in plasma levels of IL-1β, IL-6 and TNF-α relative to the sham group. Also, changes in tissue levels of malonedialdehyde, myeloperoxidase and glutathione were not statistically significant. However, neurological scores and histopathological examinations revealed healing. AM individually exerts neuroprotective effects in animal models of acute brain injury. But the mechanisms of action remain to be assessed.

Topics: Adrenomedullin; Animals; Brain Injuries; Disease Models, Animal; Interleukin-1beta; Interleukin-6; Rats; Tumor Necrosis Factor-alpha

Adrenomedullin (ADM) has been shown to take part in physiological and pathological angiogenesis. The purpose of this study was to investigate whether ADM signaling is involved in choroidal neovascularization (CNV) using a mouse model.. CNV was induced by laser photocoagulation in 8-week-old C57BL/6 mice. ADM mRNA expression significantly increased following treatment, peaking 4 days thereafter. The expression of ADM receptor (ADM-R) components (CRLR, RAMP2 and RAMP 3) was higher in CD31(+)CD45(-) endothelial cells (ECs) than CD31(-)CD45(-) non-ECs. Inflammatory stimulation upregulated the expression of ADM not only in cell lines but also in cells in primary cultures of the choroid/retinal pigment epithelium complex. Supernatants from TNFα-treated macrophage cell lines potentiated the proliferation of ECs and this was partially suppressed by an ADM antagonist, ADM (22-52). Intravitreous injection of ADM (22-52) or ADM neutralizing monoclonal antibody (mAb) after laser treatment significantly reduced the size of CNV compared with vehicle-treated controls (p<0.01).. ADM signaling is involved in laser-induced CNV formation, because both an ADM antagonist and ADM mAb significantly inhibited it. Suppression of ADM signaling might be a valuable alternative treatment for CNV associated with age-related macular degeneration.

Topics: Adrenomedullin; Animals; Antibodies, Neutralizing; Cell Line; Cell Proliferation; Choroidal Neovascularization; Culture Media, Conditioned; Disease Models, Animal; Epithelial Cells; Gene Expression Regulation; Lasers; Leukocyte Common Antigens; Macrophages; Macular Degeneration; Mice; Platelet Endothelial Cell Adhesion Molecule-1; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; Signal Transduction; Tumor Necrosis Factor-alpha

In this study we investigated the effects of adrenomedullin (AM) and vascular endothelial growth factor (VEGF) on skeletal muscle ischemia/reperfusion (I/R) injury in a rat model.. Thirty-six Wistar rats were randomized into six groups (n = 6). Laparotomy was performed in all groups under general anesthesia. Nothing else was done in Group S (Sham). The Group I/R underwent I/R performed by clamping and declamping of the infrarenal abdominal aorta for 120 min, respectively. Group VEGF and Group AM received intravenous infusion of VEGF (0.8 μg/kg) or AM (12 μg/kg) respectively, without I/R. Group I/R + VEGF and Group I/R + AM received intravenous infusion of VEGF (0.8 μg/kg) or AM (12 μg/kg) immediately after 2 h period of ischemia, respectively. At the end of reperfusion period, skeletal muscle samples of lower extremity were taken from all groups for biochemical and histopathologic examinations.. Tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), nitric oxide (NO), and hypoxia inducible factor 1 alpha (HIF 1α) were found to be significantly higher in Group I/R than the levels in Group S (P < 0.05). Tissue levels of MDA, SOD, NO, and HIF 1α were significantly lower in Group I/R + AM compared with the levels in Group I/R (P < 0.05). In Group I/R + VEGF, tissue levels of MDA and NO were significantly lower than the levels in Group I/R (P < 0.05). No statistically significant difference was found in the tissue levels of catalase among the groups. Histologic examination revealed a larger central muscular necrosis than the peripheral necrosis, red blood cells in the lumens of capillary vessels, and a stronger atrophy and elliptical or round shape in muscle fibers in Group I/R. Terminal deoxynucleotidyl transferase mediated dUPT nick end labeling (TUNEL)-positive cell count was significantly lower in groups I/R + AM and I/R + VEGF than Group I/R (P < 0.0001, P < 0.0001, respectively).. These results indicate that AM and VEGF have protective effects on I/R injury in skeletal muscle in a rat model.

Topics: Adrenomedullin; Animals; Catalase; Cytoprotection; Disease Models, Animal; Hypoxia-Inducible Factor 1, alpha Subunit; Malondialdehyde; Muscle, Skeletal; Nitric Oxide; Oxidative Stress; Random Allocation; Rats; Rats, Wistar; Reperfusion Injury; Superoxide Dismutase; Vascular Endothelial Growth Factor A

Revealing the mechanisms underlying the functional integrity of the vascular system could make available novel therapeutic approaches. We previously showed that knocking out the widely expressed peptide adrenomedullin (AM) or receptor activity-modifying protein 2 (RAMP2), an AM-receptor accessory protein, causes vascular abnormalities and is embryonically lethal. Our aim was to investigate the function of the vascular AM-RAMP2 system directly.. We generated endothelial cell-specific RAMP2 and AM knockout mice (E-RAMP2(-/-) and E-AM(-/-)). Most E-RAMP2(-/-) mice died perinatally. In surviving adults, vasculitis occurred spontaneously. With aging, E-RAMP2(-/-) mice showed severe organ fibrosis with marked oxidative stress and accelerated vascular senescence. Later, liver cirrhosis, cardiac fibrosis, and hydronephrosis developed. We next used a line of drug-inducible E-RAMP2(-/-) mice (DI-E-RAMP2(-/-)) to induce RAMP2 deletion in adults, which enabled us to analyze the initial causes of the aforementioned vascular and organ damage. Early after the induction, pronounced edema with enhanced vascular leakage occurred. In vitro analysis revealed the vascular leakage to be caused by actin disarrangement and detachment of endothelial cells. We found that the AM-RAMP2 system regulates the Rac1-GTP/RhoA-GTP ratio and cortical actin formation and that a defect in this system causes the disruption of actin formation, leading to vascular and organ damage at the chronic stage after the gene deletion.. Our findings show that the AM-RAMP2 system is a key determinant of vascular integrity and homeostasis from prenatal stages through adulthood. Furthermore, our models demonstrate how endothelial cells regulate vascular integrity and how their dysregulation leads to organ damage.

Topics: Adrenomedullin; Age Factors; Aging; Animals; Antigens, CD; Arteriosclerosis; Cadherins; Disease Models, Animal; Edema; Endothelium, Vascular; Fibrosis; Glomerulosclerosis, Focal Segmental; Homeostasis; Kidney; Leukocytes; Mice; Mice, Knockout; Oxidative Stress; Receptor Activity-Modifying Protein 2; Vasculitis

AM5 (adrenomedullin 5), a newly described member of the CGRP (calcitonin gene-related peptide) family, is reported to play a role in normal cardiovascular physiology. The effects of AM5 in HF (heart failure), however, have not been investigated. In the present study, we intravenously infused two incremental doses of AM5 (10 and 100 ng/min per kg of body weight each for 90 min) into eight sheep with pacing-induced HF. Compared with time-matched vehicle control infusions, AM5 produced progressive and dose-dependent increases in left ventricular dP/dt(max) [LD (low dose), +56 mmHg/s and HD (high dose), +152 mmHg/s] and cardiac output (+0.83 l/min and +1.81 l/min), together with decrements in calculated total peripheral resistance (-9.4 mmHg/min per litre and -14.7 mmHg/min per litre), mean arterial pressure (-2.8 mmHg and -8.4 mmHg) and LAP (left atrial pressure; -2.6 mmHg and -5.6 mmHg) (all P<0.001). HD AM5 significantly raised PRA (plasma renin activity) (3.5-fold increment, P<0.001), whereas plasma aldosterone levels were unchanged over the intra-infusion period and actually fell in the post-infusion period (70% decrement, P<0.01), resulting in a marked decrease in the aldosterone/PRA ratio (P<0.01). Despite falls in LAP, plasma atrial natriuretic peptide and B-type natriuretic peptide concentrations were maintained relative to controls. AM5 infusion also induced significant increases in urine volume (HD 2-fold increment, P<0.05) and urine sodium (2.7-fold increment, P<0.01), potassium (1.7-fold increment, P<0.05) and creatinine (1.4-fold increment, P<0.05) excretion and creatinine clearance (60% increment, P<0.05). In conclusion, AM5 has significant haemodynamic, endocrine and renal actions in experimental HF likely to be protective and compensatory in this setting. These results suggest that AM5 may have potential as a therapeutic agent in human HF.

Topics: Adrenomedullin; Aldosterone; Animals; Atrial Natriuretic Factor; Cyclic AMP; Disease Models, Animal; Female; Heart Failure; Hemodynamics; Humans; Infusions, Intravenous; Kidney; Natriuretic Peptide, Brain; Renin; Renin-Angiotensin System; Second Messenger Systems; Sheep, Domestic

Renal injury induced by aortic ischemia-reperfusion (IR) is an important factor in the development of postoperative acute renal failure following abdominal aortic surgery. The aim of this study was to examine the effect of adrenomedullin (AM) on kidney injury induced by infrarenal abdominal aortic IR in rats. Thirty-two Wistar Albino rats were randomized into four groups (eight per group) as follows: Control group, IR group (120-minute ischemia and 120-minute reperfusion), IR + AM group (a bolus intravenously of 0.05 µg/kg/min AM), and control + AM group. At the end of the experiment, blood and kidney tissue specimens were obtained for biochemical analysis. Immunohistological evaluation of the rat kidney tissues was also done. IR significantly increased (p < 0.05 vs control group) and AM significantly decreased (p < 0.05 vs. IR group) all of the biochemical parameters. Immunohistological evaluation showed that AM attenuated morphological changes as apoptosis associated with kidney injury. The results of this study indicate that AM attenuates both biochemically and immunohistopathologically kidney injury induced by aortic IR in rats.

Topics: Acute Kidney Injury; Adrenomedullin; Animals; Anti-Inflammatory Agents; Antioxidants; Aorta, Abdominal; Apoptosis; Biomarkers; Constriction; Cytoprotection; Disease Models, Animal; Immunohistochemistry; Inflammation Mediators; Kidney; Lipid Peroxidation; Male; Oxidative Stress; Rats; Rats, Wistar; Reperfusion Injury; Time Factors; Vascular Surgical Procedures

The anti-inflammatory peptide, adrenomedullin (AM), and its cognate receptor are expressed in lung tissue, but its pathophysiological significance in airway inflammation is unknown.. This study investigated whether allergen-induced airway inflammation involves an impaired local AM response.. Airway AM expression was measured in acute and chronically sensitized mice following allergen inhalation and in airway epithelial cells of asthmatic and nonasthmatic patients. The effects of AM on experimental allergen-induced airway inflammation and of AM on lung epithelial repair in vitro were investigated.. Adrenomedullin mRNA levels were significantly (P < 0.05) reduced in acute ovalbumin (OVA)-sensitized mice after OVA challenge, by over 60% at 24 h and for up to 6 days. Similarly, reduced AM expression was observed in two models of chronic allergen-induced inflammation, OVA- and house dust mite-sensitized mice. The reduced AM expression was restricted to airway epithelial and endothelial cells, while AM expression in alveolar macrophages was unaltered. Intranasal AM completely attenuated the OVA-induced airway hyperresponsiveness and mucosal plasma leakage but had no effect on inflammatory cells or cytokines. The effects of inhaled AM were reversed by pre-inhalation of the putative AM receptor antagonist, AM ((22-52)) . AM mRNA levels were significantly (P < 0.05) lower in human asthmatic airway epithelial samples than in nonasthmatic controls. In vitro, AM dose-dependently (10(-11) -10(-7) M) accelerated experimental wound healing in human and mouse lung epithelial cell monolayers and stimulated epithelial cell migration.. Adrenomedullin suppression in T(H) 2-related inflammation is of pathophysiological significance and represents loss of a factor that maintains tissue integrity during inflammation.

Topics: Administration, Intranasal; Adrenomedullin; Allergens; Animals; Asthma; Capillary Permeability; Cytokines; Disease Models, Animal; Endothelial Cells; Epithelial Cells; Gene Expression Regulation; Humans; Inflammation; Macrophages, Alveolar; Mice; Mice, Inbred BALB C

Endothelin-1 (ET-1) has been suggested to be involved in different types of pain due to its neuromodulatory nature. However, its role in inflammatory pain processing, specifically the origin-specific effect, has not yet been clearly defined. Therefore, the aim of this study is to determine the role of cell-type specific ET-1 induction in the modulation of inflammatory pain processing.. The current study assesses the effects of ET-1 over-expression specifically targeted to astrocytes (GET-1) or endothelial cells (TET-1) on the expression of pain-like behaviors induced by a model of inflammatory pain, consisting of a formalin injection into the hind paw.. The baseline sensitivity thresholds of GET-1 and TET-1 mice to the response elicited by tactile and radiant heat stimulation were similar to those observed in age-matched non-transgenic (NTg) controls. Relative to the NTg controls, GET-1 mice displayed a marked decrease in pain-like behavioral responses during the second phase of formalin-induced pain (i.e., 15-20 min after injection), whereas the responses elicited in TET-1 mice were unaltered. The levels of mRNA encoding adrenomedullin, calcitonin gene-related peptide and calcitonin-like receptor were elevated in the spinal cord of saline-injected GET-1 mice compared to those of NTg mice.. The current results support a suppressor role for astrocyte-derived ET-1 in inflammatory pain and suggest that the study of GET-1 mice might provide mechanistic insights for improving the treatment of inflammatory pain.

Topics: Adrenomedullin; Animals; Astrocytes; Behavior, Animal; Calcitonin Gene-Related Peptide; Calcitonin Receptor-Like Protein; Disease Models, Animal; Endothelial Cells; Endothelin-1; Formaldehyde; Gene Expression Regulation; Inflammation; Mice; Mice, Inbred C57BL; Mice, Transgenic; Pain; RNA, Messenger; Spinal Cord

Pressure ulcers are one of the most common complications in elderly, incontinent or paralyzed patients. For the healing of pressure ulcers, the development of granulation tissue and reepithelialization is required. Adrenomedullin (AM), an endogenous vasodilator peptide, is reported to stimulate the proliferation and migration of various cells including endothelial cells, fibroblasts and keratinocytes. Therefore, we hypothesized that AM might accelerate the healing process of pressure ulcers in which these cells were involved. We developed a sustained-release ointment containing human recombinant AM, and applied it in a mouse model of pressure ulcer twice a day for 14 days. Human AM was efficiently absorbed in wound area, but its blood concentration was negligible. AM ointment significantly reduced the wound area on day 5 to 7 after injury. In addition, AM ointment accelerated the formation of granulation tissue and angiogenesis as well as lymphangiogenesis after 7 days of treatment. Immunological analysis revealed that Ki-67-positive proliferating cells in granulation tissue expressed AM receptors. In summary, sustained-release AM significantly improved wound healing of pressure ulcers through acceleration of granulation and induction of angiogenesis and lymphangiogenesis. Therefore, sustained-release AM ointment may be a novel therapeutic agent for pressure ulcers.

Topics: Adrenomedullin; Animals; Calcitonin Receptor-Like Protein; Cell Proliferation; Disease Models, Animal; Humans; Male; Mice; Mice, Inbred ICR; Ointments; Pressure Ulcer; Receptor Activity-Modifying Protein 1; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; Reverse Transcriptase Polymerase Chain Reaction; Wound Healing

Although subcortical vascular dementia, the major subtype of vascular dementia, is caused by a disruption in white matter integrity after cerebrovascular insufficiency, no therapy has been discovered that will restore cerebral perfusion or functional cerebral vessels. Because adrenomedullin (AM) has been shown to be angiogenic and vasoprotective, the purpose of the study was to investigate whether AM may be used as a putative treatment for subcortical vascular dementia.. A model of subcortical vascular dementia was reproduced in mice by placing microcoils bilaterally on the common carotid arteries. Using mice overexpressing circulating AM, we assessed the effect of AM on cerebral perfusion, cerebral angioarchitecture, oxidative stress, white matter change, cognitive function, and brain levels of cAMP, vascular endothelial growth factor, and basic fibroblast growth factor.. After bilateral common carotid artery stenosis, mice overexpressing circulating AM showed significantly faster cerebral perfusion recovery due to substantial growth of the capillaries, the circle of Willis, and the leptomeningeal anastomoses and reduced oxidative damage in vascular endothelial cells compared with wild-type mice. Vascular changes were preceded by upregulation of cAMP, vascular endothelial growth factor, and basic fibroblast growth factor. White matter damage and working memory deficits induced by bilateral common carotid artery stenosis were subsequently restored in mice overexpressing circulating AM.. These data indicate that AM promotes arteriogenesis and angiogenesis, inhibits oxidative stress, preserves white matter integrity, and prevents cognitive decline after chronic cerebral hypoperfusion. Thus, AM may serve as a strategy to tackle subcortical vascular dementia.

Topics: Adrenomedullin; Animals; Brain Infarction; Cerebral Arteries; Cognition Disorders; Disease Models, Animal; Hypoxia-Ischemia, Brain; Mice; Neovascularization, Physiologic

Adrenomedullin (AM), a 52-amino acid ringed-structure peptide with C-terminal amidation, was originally isolated from human pheochromocytoma. AM are widely distributed in various tissues and acts as a local vasoactive hormone in various conditions.. In the present study, we investigated the efficacy of AM on the animal model of bleomycin (BLM)-induced lung injury. Mice were subjected to intratracheal administration of BLM and were assigned to receive AM daily by an intraperitoneal injection of 200 ngr/kg.. Myeloperoxidase activity, lung histology, immunohistochemical analyses for cytokines and adhesion molecules expression, inducible nitric oxide synthase (iNOS), nitrotyrosine, and poly (ADP-ribose) polymerase (PARP) were performed one week after fibrosis induction. Lung histology and transforming growth factor beta (TGF-β) were performed 14 and 21 days after treatments. After bleomycin administration, AM-treated mice exhibited a reduced degree of lung damage and inflammation compared with BLM-treated mice, as shown by the reduction of (1) myeloperoxidase activity (MPO), (2) cytokines and adhesion molecules expression, (3) nitric oxide synthase expression, (4) the nitration of tyrosine residues, (5) poly (ADP-ribose) (PAR) formation, a product of the nuclear enzyme poly (ADP-ribose) polymerase (PARP) (6) transforming growth factor beta (TGF-β) (7)and the degree of lung injury.. Our results indicate that AM administration is able to prevent bleomycin induced lung injury through the down regulation of proinflammatory factors.

Topics: Adrenomedullin; Animals; Anti-Inflammatory Agents; Bleomycin; Cell Adhesion Molecules; Cytokines; Disease Models, Animal; Inflammation Mediators; Injections, Intraperitoneal; Lung; Male; Mice; Mice, Inbred ICR; Nitric Oxide Synthase Type II; Peroxidase; Pneumonia; Poly(ADP-ribose) Polymerases; Pulmonary Fibrosis; Severity of Illness Index; Time Factors; Transforming Growth Factor beta; Tyrosine

In subtotal nephrectomy (SN)- and salt-induced hypertension, calcitonin gene-related peptide (CGRP) plays a compensatory role to attenuate the blood pressure increase in the absence of an increase in the neuronal synthesis and release of this peptide. Therefore, the purpose of this study was to determine whether the mechanism of this antihypertensive activity is through enhanced sensitivity of the vasculature to the dilator actions of this neuropeptide. Hypertension was induced in Sprague-Dawley rats by SN and 1% saline drinking water. Control rats were sham-operated and given tap water to drink. After 11 days, rats had intravenous (drug administration) and arterial (continuous mean arterial pressure recording) catheters surgically placed and were studied in a conscious unrestrained state. Baseline mean arterial pressure was higher in the SN-salt rats (157 ± 5 mmHg) compared with controls (128 ± 3 mmHg). Administration of CGRP (and adrenomedullin) produced a significantly greater dose-dependent decrease in mean arterial pressure in SN-salt rats compared with controls (∼2.0-fold for both the low and high doses). Interestingly, isolated superior mesenteric arterioles from SN-salt rats were significantly more responsive to the dilator effects of CGRP (but not adenomedullin) than the controls (pEC(50), SN-salt, 14.0 ± 0.1 vs. control, 12.0 ± 0.1). Analysis of the CGRP receptor proteins showed that only the receptor component protein was increased significantly in arterioles from SN-salt rats. These data indicate that the compensatory antihypertensive effects of CGRP result from an increased sensitivity of the vasculature to dilator activity of this peptide. The mechanism may be via the upregulation of receptor component protein, thereby providing a more efficient coupling of the receptor to the signal transduction pathways.

Topics: Adrenomedullin; Analysis of Variance; Animals; Antihypertensive Agents; Arterioles; Blood Pressure; Blotting, Western; Calcitonin Gene-Related Peptide; Disease Models, Animal; Dose-Response Relationship, Drug; Hypertension; Infusions, Intravenous; Male; Mesentery; Nephrectomy; Rats; Rats, Sprague-Dawley; Receptors, Calcitonin Gene-Related Peptide; Sodium Chloride, Dietary; Time Factors; Vasodilation; Vasodilator Agents

Daikenchuto (TU-100), a traditional Japanese medicine, has been reported to up-regulate the adrenomedullin (ADM)/calcitonin gene-related peptide (CGRP) system, which is involved in intestinal vasodilatation. The microvascular dysfunction of the intestine in Crohn's disease (CD), due to down-regulation of the ADM/CGRP system, is etiologically related to the recurrence of CD. Therefore, we investigated the vasodilatory effect of TU-100 in a CD rat model.. Colitis was induced by the rectal instillation of 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats. Laser Doppler blood flowmetry was used to measure colonic blood flow. ADM, CGRP, and their receptors in the ischemic colon were measured by reverse transcription polymerase chain reaction (RT-PCR) and enzyme immunoassays. Additionally, we determined whether the intestinal epithelial cell line IEC-6 released ADM in response to TU-100.. TU-100 increased blood flow in ischemic segments of the colon but not in hyperemic segments. Pretreatment with an antibody to ADM abolished the vasodilatory effect of TU-100. CGRP levels and βCGRP mRNA expression were decreased in the ischemic colon, while protein and mRNA levels of ADM were unchanged. Hydroxy α-sanshool, the main constituent of TU-100, was the most active component in improving blood flow. Additionally, both TU-100 and hydroxy α-sanshool enhanced the release of ADM from IEC-6 cells.. In the ischemic colon, endogenous βCGRP, but not ADM, was decreased. Thus, it was concluded that TU-100 ameliorated microvascular dysfunction by the up-regulation of endogenous ADM in the CD rat model. TU-100 may be a possible therapeutic agent for gastrointestinal ischemia-related diseases including CD.

Topics: Adrenomedullin; Amides; Animals; Calcitonin Gene-Related Peptide; Cell Line; Colitis; Colon; Crohn Disease; Disease Models, Animal; Intestinal Mucosa; Male; Microvessels; Panax; Plant Extracts; Rats; Rats, Sprague-Dawley; RNA, Messenger; Trinitrobenzenesulfonic Acid; Up-Regulation; Vasodilation; Zanthoxylum; Zingiberaceae

To investigate the effect and potential mechanism of intermedin (IMD) in acute cardiac ischemic injury and to provide a new approach for exploring mechanism of sudden cardiac death.. Seventy-two healthy male rats were randomly divided into 3 groups: control, ischemic and the IMD-treated group. The activity of lactate dehydrogenase (LDH), malondialdehyde (MDA) and superoxide dismutase (SOD) in heart blood were tested by enzyme chemistry method. The mRNA changes of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs) in cardiac were measured by real-time PCR analysis. Myocardial cyclic adenosine monophosphate (cAMP) content was determined by enzyme linked immunosorbent assay (ELISA). Apoptosis related factors Bcl-2 and Bax were detected by immunohistochemistry.. Comparing with the control group, LDH and MDA activity of ischemic group in heart blood increased and SOD activity decreased. The concentration of cAMP increased in ventricular muscle, Bcl-2 and Bax proteins expression ratio level decreased. The intravenation of IMD decreased the level of increased activity of LDH and MDA, and lessened the level of decreased activity of SOD. The mRNA expression of CRLR and RAMPs obviously increased in ventricular muscle.. The protective effect of IMD against myocardial ischemic injury could be caused by decreasing the oxidative stress of ischemia and inhibiting the myocardial apoptosis.

Topics: Adrenomedullin; Animals; Apoptosis; Calcitonin Receptor-Like Protein; Cardiotonic Agents; Cyclic AMP; Disease Models, Animal; L-Lactate Dehydrogenase; Male; Malondialdehyde; Myocardial Ischemia; Myocardium; Neuropeptides; Proto-Oncogene Proteins c-bcl-2; Random Allocation; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Receptor Activity-Modifying Proteins; RNA, Messenger; Superoxide Dismutase

The effect of adrenomedullin (AM), a peptide that has demonstrated vasodilatory activity, was studied in the colon and small mesenteric arteries of rats in a chronic model of inflammatory bowel disease. AM (50 ng/kg/day) was administered i.p. daily, starting 24h after trinitrobenzensulfonic acid (TNBS, 30 mg) instillation. After 14 days, rats were sacrificed, colons were macroscopically analyzed and biochemical parameters (myeloperoxidase activity, cytokines, cyclooxygenase-2 (COX-2) as well as inducible nitric oxide synthase (iNOS) expression) were determined. Vascular function of small mesenteric arteries was assessed by addition of phenylephrine (10⁻⁸ to 10⁻⁴ mol/L) and participation of COX and NOS pathways was also evaluated by using different inhibitors: indomethacin, NS-398, L-NNA, and 1400 w. Chronic AM treatment significantly reduced colonic macroscopic damage and inflammation markers. TNBS instillation induced COX-2 and iNOS expressions in colon and small mesenteric arteries; AM treatment decreased COX-2 expression only in microvessels from rats with colitis. An attenuation of phenylephrine-induced contraction was detected in small mesenteric arteries from both TNBS and AM-treated rats. COX and NOS inhibitors altered the contractile ability of phenylephrine in small mesenteric arteries from TNBS rats, suggesting the involvement of COX-2 and iNOS derived factors in the deleterious effect of TNBS on vascular reactivity; AM administration was able to reduce such alteration. Finally, treatment with the peptide significantly reduced colonic nitric oxide (NO) levels, without affecting plasma concentration. In conclusion, AM showed beneficial effects in the restoration of vascular function through the regulation of vasoactive products derived from COX-2 and iNOS.

Topics: Adrenomedullin; Animals; Biomarkers; Colitis; Cyclooxygenase 2; Disease Models, Animal; Gene Expression Regulation, Enzymologic; In Vitro Techniques; Inflammatory Bowel Diseases; Male; Mesenteric Arteries; Microcirculation; Nitrates; Nitric Oxide; Nitric Oxide Synthase Type II; Nitrites; Phenylephrine; Rats; Rats, Wistar; Vasoconstriction

Leakage from colonic anastomosis is a major complication causing increased mortality and morbidity. Ischemia is a well-known cause of this event. This study was designed to investigate the effects of adrenomedullin on the healing of ischemic colon anastomosis in a rat model.. Standardized left colon resection 3 cm above the peritoneal reflection and colonic anastomosis were performed in 40 Wistar rats that were divided into four groups. To mimic ischemia, the mesocolon was ligated 2 cm from either side of the anastomosis in all of the groups. The control groups (1 and 2) received no further treatment. The experimental groups (3 and 4) received adrenomedullin treatment. Adrenomedullin therapy was started in the perioperative period in group 3 and 4 rats (the therapeutic groups). Group 1 and group 3 rats were sacrificed on postoperative day 3. Group 2 and group 4 rats were sacrificed on postoperative day 7. After careful relaparotomy, bursting pressure, hydroxyproline, malondialdehyde, interleukin 6, nitric oxide, vascular endothelial growth factor, and tumor necrosis factor alpha levels were measured. Histopathological characteristics of the anastomosis were analyzed.. The group 3 animals had a significantly higher bursting pressure than group 1 (p<0.05). Hydroxyproline levels in group 1 were significantly lower than in group 3 (p<0.05). The mean bursting pressure was significantly different between group 2 and group 4 (p<0.05). Hydroxyproline levels in groups 3 and 4 were significantly increased by adrenomedullin therapy relative to the control groups (p<0.05). When all groups were compared, malondialdehyde and nitric oxide were significantly lower in the control groups (p<0.05). When vascular endothelial growth factor levels were compared, no statistically significant difference between groups was observed. Interleukin 6 and tumor necrosis factor alpha were significantly decreased by adrenomedullin therapy (p<0.05). The healing parameters and inflammatory changes (e.g., granulocytic cell infiltration, necrosis, and exudate) were significantly different among all groups (p<0.05).. Adrenomedullin had positive effects on histopathologic anastomotic healing in this experimental model of ischemic colon anastomosis.

Topics: Adrenomedullin; Anastomosis, Surgical; Anastomotic Leak; Animals; Colon; Disease Models, Animal; Female; Ischemia; Postoperative Complications; Postoperative Period; Rats; Rats, Wistar; Time Factors; Vasodilator Agents; Wound Healing

Vascular calcification (VC) is highly associated with increased morbidity and mortality in patients with advanced chronic kidney disease. Paracrine/autocrine factors such as vasoactive peptides are involved in VC development. Here, we investigated the expression of the novel peptide intermedin (IMD) in the vasculature, tested its ability to prevent VC in vivo and in vitro, and examined the mechanism involved.. Rat VC was induced by administration of vitamin D3 plus nicotine (VDN). IMD (100 ng kg(-1) h(-1)) was systemically administered by a mini-osmotic pump. VDN-treated rat aortas showed lower IMD content and increased expression of its receptors, along with increased vascular calcium deposition and alkaline phosphatase (ALP) activity. Low IMD levels were accompanied by increased calcium deposition in human atherosclerotic plaques. In vivo administration of IMD greatly reduced vascular calcium deposition and ALP activity in VDN-treated rats when compared with vehicle treatment, which was further confirmed in cultured vascular smooth muscle cells. Concurrently, the loss of smooth-muscle lineage markers and matrix gamma-carboxyglutamic acid (Gla) protein (cMGP) in aortas was ameliorated by administering IMD to rats with VC, and the increased phosphor-Smad(1/5/8) and core binding factor alpha-1 levels in calcified vasculature were also reduced. However, the inhibitory effects of IMD on VC were eliminated upon pre-treatment with warfarin or small interfering RNA to reduce cMGP.. Reduced endogenous IMD levels are associated with increased mineralization in vivo, and administration of IMD inhibits VC development by increasing cMGP levels. IMD may be an endogenous vasoprotective factor for VC.

Topics: Adrenomedullin; Animals; Aorta; Atherosclerosis; Calcinosis; Calcium-Binding Proteins; Cell Differentiation; Cell Lineage; Disease Models, Animal; Extracellular Matrix Proteins; Humans; Matrix Gla Protein; Muscle, Smooth, Vascular; Neuropeptides; Nicotine; Nicotinic Agonists; Peptide Hormones; Phenotype; Rats; Signal Transduction; Smad Proteins; Vascular Diseases; Vitamin D; Vitamins

Extravasation of vesicant drugs such as vinca alkaloids causes severe injury, which may range from erythema to skin necrosis or ulceration. The skin necrosis may not be fully evident until several weeks or months after the initial damage, and may require surgical intervention. The main treatments for vincristine extravasation are hyaluronidase injection and topical warming, and the aim of treatment is to increase the clearance of the drug from the extravasation site.. To investigate the effect of adrenomedullin, a potent vasodilatory peptide, in rats subjected to vincristine-induced extravasation.. In total, 36 Wistar albino rats were given intradermal injection of vincristine and saline. The rats were assigned to one of three treatment groups (adrenomedullin, adrenomedullin + hyaluronidase, or hyaluronidase), a control group given vincristine only, or a sham group (saline). Tissue superoxide dismutase (SOD), glutathione peroxidase, malondialdehyde (MDA) and protein content were evaluated in skin biopsies taken on day 22. The ulcer size and histopathological grading scores were also recorded.. SOD levels were significantly increased by adrenomedullin and increased by hyaluronidase. Glutathione peroxidase levels were significantly decreased in all four vincristine groups. Tissue MDA levels were highest in the adrenomedullin group. In all four vincristine groups, MDA levels were reduced, indicating preservation from tissue injury. Protein carbonyl (PCO) content levels in the adrenomedullin group were significantly greater than in the other three study groups (P < 0.05). In contrast, PCO levels in the hyaluronidase group were significantly lower than in the other three groups.. In this animal model of vincristine-induced extravasation, antioxidant status and histology were preserved by hyaluronidase but worsened by adrenomedullin.

Topics: Adrenomedullin; Albinism; Animals; Antineoplastic Agents, Phytogenic; Disease Models, Animal; Glutathione Peroxidase; Hyaluronoglucosaminidase; Male; Malondialdehyde; Necrosis; Rats; Rats, Wistar; Skin; Skin Ulcer; Superoxide Dismutase; Treatment Outcome; Vasodilator Agents; Vincristine

Adrenomedullin 2/intermedin (AM2/IMD) is a potent vasodilator peptide with organ-protective effects and is abundantly expressed in the kidney. We examined the expression of AM2/IMD in the kidneys of rats with hypertension or chronic renal impairment using quantitative RT-PCR, radioimmunoassay, and immunohistochemistry. Kidneys of 8-wk-old male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were dissected into inner medulla, outer medulla, cortex, and glomerulus fractions. A rat renal impairment model was prepared by 5/6 nephrectomy in WKY rats. AM2/IMD mRNA levels were the highest in the cortex among four renal portions, and significantly lower in SHR than WKY rats in all renal portions. In the remnant kidneys of 5/6 nephrectomized rats, AM2/IMD mRNA levels were significantly decreased on days 3 and 56, whereas mRNA levels of calcitonin receptor-like receptor, receptor activity-modifying proteins-1 and -2, which form receptor for AM and AM2/IMD, were increased, compared with that in sham-operated rats. AM mRNA levels were decreased on day 3, but increased on day 56, after nephrectomy. Decreased immunoreactive AM2/IMD levels in the remnant kidneys of 5/6 nephrectomized rats on day 56 were confirmed by radioimmunoassay. The renal tubules were immunostained with anti-AM2/IMD antibody, with a decreased AM2/IMD immunostaining found in proximal tubular cells of 5/6 nephrectomized rats compared with sham-operated rats. In conclusion, intrarenal AM2/IMD expression is decreased in SHR and 5/6 nephrectomized rats. Given the organ-protective effects of AM2/IMD, the downregulation of AM2/IMD as an endogenous regulatory peptide may have a role in the progression of renal impairment.

Topics: Adrenomedullin; Animals; Calcitonin Receptor-Like Protein; Disease Models, Animal; Down-Regulation; Hypertension; Immunohistochemistry; Intracellular Signaling Peptides and Proteins; Kidney; Male; Membrane Proteins; Nephrectomy; Neuropeptides; Radioimmunoassay; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptor Activity-Modifying Proteins; Receptors, Calcitonin; Renal Insufficiency; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors

Chronic inhibition of nitric oxide (NO) synthesis is associated with hypertension, myocardial ischemia, oxidative stress and hypertrophy; expression of the vasodilator peptide, adrenomedullin (AM) and its receptors is augmented in cardiomyocytes, indicating that the myocardial AM system may be activated in response to pressure loading and ischemic insult to serve a counter-regulatory, cardio-protective role. The study examined the hypothesis that oxidative stress and hypertrophic remodeling in NO-deficient cardiomyocytes are attenuated by adenoviral vector-mediated delivery of the human adrenomedullin (hAM) gene in vivo.. The NO synthesis inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 15mg . kg(-1) . day(-1)) was given to rats for 4 weeks following systemic administration via the tail vein of a single injection of either adenovirus harbouring hAM cDNA under the control of the cytomegalovirus promoter-enhancer (Ad.CMV-hAM-4F2), or for comparison, adenovirus alone (Ad.Null) or saline. Cardiomyocytes were subsequently isolated for assessment of the influence of each intervention on parameters of oxidative stress and hypertrophic remodelling.. Cardiomyocyte expression of the transgene persisted for > or =4 weeks following systemic administration of adenoviral vector. In L-NAME treated rats, relative to Ad.Null or saline administration, Ad.CMV-hAM-4F2 (i) reduced augmented cardiomyocyte membrane protein oxidation and mRNA expression of pro-oxidant (p22phox) and anti-oxidant (SOD-3, GPx) genes; (ii) attenuated increased cardiomyocyte width and mRNA expression of hypertrophic (sk-alpha-actin) and cardio-endocrine (ANP) genes; (iii) did not attenuate hypertension.. Adenoviral vector mediated delivery of hAM resulted in attenuation of myocardial oxidative stress and hypertrophic remodelling in the absence of blood pressure reduction in this model of chronic NO-deficiency. These findings are consistent with a direct cardio-protective action in the myocardium of locally-derived hAM which is not dependant on NO generation.

Topics: Adrenomedullin; Animals; Atrial Natriuretic Factor; Cardiomegaly; Disease Models, Animal; Gene Transfer Techniques; Genetic Vectors; Humans; Myocytes, Cardiac; NADPH Oxidases; NG-Nitroarginine Methyl Ester; Nitric Oxide; Oxidative Stress; Pressure; Rats; Superoxide Dismutase

Adrenomedullin (AM) belongs to calcitonin gene-related peptide (CGRP) family and is a pronociceptive mediator. This study investigated whether AM plays a role in the development of tolerance to morphine-induced analgesia. Repetitive intrathecal injection of morphine increased the expression of AM-like immunoreactivity (AM-IR) in the spinal dorsal horn and dorsal root ganglion (DRG) neurons. Ganglion explant culture study showed that this upregulation of AM-IR was μ-opioid receptor dependent through the use of another agonist, fentanyl, and a selective antagonist, CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH(2)). The coadministration of the selective AM receptor antagonist AM(22-52) markedly attenuated the development of morphine tolerance, associated thermal hyperalgesia, and increase in AM-IR. A likely autocrine mechanism is supported by the finding that AM-IR is colocalized with AM receptor components in DRG neurons. Furthermore, opiate-induced increase in AM content was blocked by protein kinase C (PKC) inhibitors, whereas a PKC activator increased AM synthesis and release. A treatment with AM(22-52) also inhibited increases in the expression of CGRP-IR in the spinal cord and DRGs as well as in culture ganglion explants, whereas exposure to CGRP failed to alter AM content. Together, these results reveal that a sustained opiate treatment induces an upregulation of AM through the activation of μ-opioid receptors and the PKC signaling pathway. This phenomenon contributes to the development of tolerance to the antinociceptive effects of opiates at least partially via the upregulation of CGRP. Targeting AM and its receptors should be considered as a novel approach to preserve the analgesic potency of opiates during their chronic use.

Topics: Adrenomedullin; Analgesics, Opioid; Animals; Calcitonin Receptor-Like Protein; Cells, Cultured; Disease Models, Animal; Drug Tolerance; Enzyme Activation; Ganglia, Spinal; Injections, Spinal; Male; Morphine; Narcotics; Organ Culture Techniques; Protein Kinase C; Rats; Rats, Sprague-Dawley; Receptors, Adrenomedullin; Receptors, Calcitonin; Receptors, Peptide; Up-Regulation

Adrenomedullin (AM) and its binding protein, complement factor H (FH), are expressed throughout the brain. In this study we used a brain-specific conditional knockout for AM and a complete knockout for FH to investigate the effect of these molecules on the pathophysiology of stroke. Following 48 h of middle cerebral artery permanent occlusion, there was a statistically significant infarct size increase in animals lacking AM when compared to their wild type littermates. In contrast, lack of FH did not affect infarct volume. To investigate some of the mechanisms by which lack of AM may augment brain damage, markers of nitrosative stress, apoptosis, and autophagy were studied at the mRNA and protein levels. There was a significant increase of inducible nitric oxide synthase (iNOS), matrix metalloproteinase-9 (MMP9), fractin, and Beclin-1 in the peri-infarct area of AM-deficient mice when compared to their wild type counterparts and to contralateral and sham-operated controls. These data suggest that AM exerts a neuroprotective action in the brain and that this protection may be mediated by regulation of iNOS, matrix metalloproteases, and inflammatory mediators. In the future, substances that increase AM actions in the central nervous system may be used as potential neuroprotective agents in stroke.

Topics: Adrenomedullin; Animals; Brain Infarction; Brain Ischemia; Complement Factor H; Disease Models, Animal; Disease Progression; Infarction, Middle Cerebral Artery; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic

The liver is a major organ that is susceptible to injury after blunt or penetrating trauma to the abdomen. No specific nonoperative treatment exists for traumatic hepatic injury (THI). Adrenomedullin (AM), a vasoactive peptide, combined with its binding protein, AM protein (AMBP-1), is beneficial in various disease conditions. In this study, we propose to analyze whether human AM combined with human AMBP-1 provides benefit in a model of THI in the rat.. Male adult rats were subjected to trauma hemorrhage by resection of ∼50% of total liver tissues and allowed bleeding for 15 minutes. Immediately thereafter, human AM (48 μg/kg birth weight) plus human AMBP-1 (160 μg/kg birth weight) were given intravenously over 30 minutes in 1-mL normal saline. After 4 hours, the rats were killed, blood was collected, and tissue injury indicators were assessed. A 10-day survival study was also conducted.. At 4 hours after THI, plasma AMBP-1 levels were markedly decreased. Plasma levels of liver injury indicators (i.e., aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase) were significantly increased after THI. Similarly, lactate, creatinine, and tumor necrosis factor-α levels were significantly increased after THI. Administration of human AM/AMBP-1 after THI produced significant decreases of 64%, 23%, and 19% of plasma aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase levels, respectively. Similarly, plasma levels of lactate, creatinine, and tumor necrosis factor-α were also decreased by 42%, 28%, and 46% after human AM/AMBP-1 treatment, respectively. In a 10-day survival study, although vehicle treatment produced 41% survival, human AM/AMBP-1 treatment improved the survival rate to 81%.. Administration of human AM/AMBP-1 significantly attenuated tissue injury and inflammation and improved survival after THI. Thus, human AM/AMBP-1 can be developed as a novel treatment for victims with uncontrolled traumatic hemorrhage.

Topics: Adrenomedullin; Analysis of Variance; Animals; Complement Factor H; Creatinine; Disease Models, Animal; Hemorrhage; Immunoenzyme Techniques; Lactates; Liver; Male; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Resuscitation; Survival Rate; Tumor Necrosis Factor-alpha

Adrenomedullin (ADM) is a member of the calcitonin family of regulatory peptides, and is reported to have anti-inflammatory effects in animal models of Crohn's disease (CD). We investigated the therapeutic effects of daikenchuto (DKT), an extracted Japanese herbal medicine, on the regulation of endogenous ADM in the gastrointestinal tract in a CD mouse model.. Colitis was induced in mice by intrarectal instillation of 2,4,6-trinitrobenzenesulfonic acid (TNBS); afterwards, DKT was given orally. Colonic damage was assessed on day 3 by macroscopic and microscopic observation, enzyme immunoassays of proinflammatory cytokines in the colonic mucosa, and serum amyloid A (SAA), a hepatic acute-phase protein. To determine the involvement of ADM, an ADM antagonist was instilled intrarectally before DKT administration. The effect of DKT on ADM production by intestinal epithelial cells was evaluated by enzyme immunoassay and real-time PCR.. DKT significantly attenuated mucosal damage and colonic inflammatory adhesions, and inhibited elevations of SAA in plasma and the proinflammatory cytokines TNFα and IFNγ in the colon. Small and large intestinal epithelial cells produced higher levels of ADM after DKT stimulation. A DKT-treated IEC-6 cell line also showed enhanced ADM production at protein and mRNA levels. Abolition of this effect by pretreatment with an ADM antagonist shows that DKT appears to exert its anti-colitis effect via up-regulation of endogenous ADM in the intestinal tract.. DKT exerts beneficial effects in a CD mouse model through endogenous release and production of ADM. Endogenous ADM may be a therapeutic target for CD.

Topics: Adrenomedullin; Animals; Anti-Inflammatory Agents, Non-Steroidal; Cell Adhesion; Cell Line; Colitis; Colon; Crohn Disease; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Flow Cytometry; Gene Expression; Immunohistochemistry; Interferon-gamma; Intestinal Mucosa; Male; Mice; Mice, Inbred BALB C; Panax; Phytotherapy; Plant Extracts; Rats; Serum Amyloid A Protein; Treatment Outcome; Trinitrobenzenesulfonic Acid; Tumor Necrosis Factor-alpha; Up-Regulation; Zanthoxylum; Zingiberaceae

Ureteral obstruction is characterized by decreased renal blood flow that is associated with hypoxia within the kidney. Adrenomedullin (AM) is a peptide hormone with tissue-protective capacity that is stimulated through hypoxia. We tested the hypothesis that ureteral obstruction stimulates expression of AM and hypoxia-inducible factor-1 (HIF-1alpha) in kidneys. Rats were exposed to bilateral ureteral obstruction (BUO) for 2, 6, 12, and 24 h or sham operation and compared with unilateral obstruction (UUO). AM mRNA expression was measured by quantitative PCR in cortex and outer medulla (C+OM) and inner medulla (IM). AM and HIF-1alpha protein abundance and localization were determined in rats subjected to 24-h BUO. AM mRNA expression in C+OM increased significantly after 12-h BUO and further increased after 24 h. In IM, AM mRNA expression increased significantly in response to BUO for 6 h and further increased after 24 h. AM peptide abundance was enhanced in C+OM and IM after 24-h BUO. Immunohistochemical labeling of kidneys showed a wider distribution and more intense AM signal in 24-h BUO compared with Sham. In UUO rats, AM mRNA expression increased significantly in IM of the obstructed kidney compared with nonobstructed and Sham kidney whereas AM peptide increased in IM compared with Sham. HIF-1alpha protein abundance increased significantly in IM after 24-h BUO compared with Sham and HIF-1alpha immunoreactive protein colocalized with AM. In summary, AM and HIF-1alpha expression increases in response to ureteral obstruction in agreement with expected oxygen gradients. Hypoxia acting through HIF-1alpha accumulation may be an important pathway for the renal response to ureteral obstruction.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Kidney; Male; Oxygen; Rats; Rats, Wistar; RNA, Messenger; Time Factors; Tumor Necrosis Factor-alpha; Up-Regulation; Ureteral Obstruction

To determine whether administration of a vasoactive peptide, human adrenomedullin (AM), in combination with its binding protein (ie, AMBP-1), prevents or minimizes hepatic ischemia-reperfusion (I/R) injury.. Hepatic I/R injury results from tissue hypoxia and subsequent inflammatory responses. Even though numerous pharmacological modalities and substances have been studied to reduce I/R-induced mortality, none have been entirely successful. We have shown that administration of AM/AMBP-1 produces significant beneficial effects under various pathophysiological conditions. However, it remains unknown if human AM/AMBP-1 has any protective effects on hepatic I/R-induced tissue damage and mortality.. Seventy percent hepatic ischemia was induced in male adult rats by placing a microvascular clip across the hilum of the left and median lobes for 90 minutes. After removing the clip, human AM alone, human AMBP-1 alone, human AM in combination with human AMBP-1 or vehicle was administered intravenously over a period of 30 minutes. Blood and tissue samples were collected 4 hours after reperfusion for various measurements. In additional groups of animals, the nonischemic liver lobes were resected at the end of 90-minute ischemia. The animals were monitored for 7 days and survival was recorded.. After hepatic I/R, plasma levels of AM were significantly increased, whereas AMBP-1 levels were markedly decreased. Likewise, gene expression of AM in the liver was increased significantly, whereas AMBP-1 expression was markedly decreased. Administration of AM in combination with AMBP-1 immediately after the onset of reperfusion down-regulated inflammatory cytokines, decreased hepatic neutrophil infiltration, inhibited liver cell apoptosis and necrosis, and reduced liver injury and mortality in a rat model of hepatic I/R. On the other hand, administration of human AM alone or human AMBP-1 alone after hepatic I/R failed to produce significant protection.. Human AM/AMBP-1 may be a novel treatment to attenuate tissue injury after an episode of hepatic ischemia.

Topics: Adrenomedullin; Animals; Complement Factor H; Disease Models, Animal; Liver; Liver Diseases; Male; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Vasodilator Agents

Leakage of the gut mucosal barrier in the critically ill patient may allow translocation of bacteria and their virulence factors, thereby perpetuating sepsis and inflammation. Present evidence suggests that adrenomedullin (AM) improves endothelial barrier function and stabilizes circulatory function in systemic inflammation. We tested the hypothesis that exogenously applied AM stabilizes gut epithelial barrier function. Infusion of Staphylococcus aureus alpha-toxin induced septic shock in rats. AM infusion in a therapeutic setting reduced translocation of labeled dextran from the gut into the systemic circulation in this model. AM also reduced alpha-toxin and hydrogen peroxide (H2O2)-related barrier disruption in Caco-2 cells in vitro and reduced H2O2-related rat colon barrier malfunction in Ussing chamber experiments. AM was shown to protect endothelial barrier function via cAMP elevation, but AM failed to induce cAMP accumulation in Caco-2 cells. cAMP is degraded via phosphodiesterases (PDE), and Caco-2 cells showed high activity of cAMP-degrading PDE3 and 4. However, AM failed to induce cAMP accumulation in Caco-2 cells even in the presence of sufficient PDE3/4 inhibition, whereas adenylyl cyclase activator forskolin induced strong cAMP elevation. Furthermore, PDE3/4 inhibition neither amplified AM-induced epithelial barrier stabilization nor affected AM cAMP-related rat colon short-circuit current, furthermore indicating that AM may act independently of cAMP in Caco-2 cells. Finally, experiments using chemical inhibitors indicated that PKC, phosphatidylinositide 3-kinase, p38, and ERK did not contribute to AM-related stabilization of barrier function in Caco-2 cells. In summary, during severe inflammation, elevated AM levels may substantially contribute to the stabilization of gut barrier function.

Topics: Adrenomedullin; Animals; Bacterial Toxins; Bacterial Translocation; Caco-2 Cells; Colon; Cyclic AMP; Cyclic Nucleotide Phosphodiesterases, Type 3; Cyclic Nucleotide Phosphodiesterases, Type 4; Dextrans; Disease Models, Animal; Enzyme Activators; Extracellular Signal-Regulated MAP Kinases; Fluorescein-5-isothiocyanate; Fluorescent Dyes; Hemolysin Proteins; Humans; Hydrogen Peroxide; Ileum; Infusions, Intravenous; Intestinal Mucosa; Male; p38 Mitogen-Activated Protein Kinases; Permeability; Phosphatidylinositol 3-Kinases; Phosphodiesterase Inhibitors; Protein Kinase C; Protein Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Shock, Septic; Signal Transduction; Time Factors

This study was designed to examine the effect of adrenomedullin deficiency on cerebral infarction and the relationship between adrenomedullin and cyclic AMP-protein kinase A pathway in regulating reactive oxygen species (ROS). Adrenomedullin heterozygous and wild-type mice were subjected to 60-mins focal ischemia. We used adrenomedullin heterozygous mice because adrenomedullin homozygotes die in utero. Infarct volume, neurologic deficit scores, and immunohistochemical analyses were evaluated at several time points after ischemia. The infarct volume and neurologic deficit scores were significantly worse in adrenomedullin heterozygous mice. Significant accumulation of inducible nitric oxide, oxidative DNA damage, and lipid peroxidation was noted after reperfusion in adrenomedullin heterozygous mice. Treatment of wild-type mice with H89, a protein kinase A inhibitor, resulted in increased infarct size, and worsening of neurologic deficit score and other parameters to levels comparable to those of adrenomedullin heterozygous mice. In contrast, cilostazol, which increases cyclic AMP, rescued neurologic deficit and ROS accumulation in adrenomedullin heterozygous mice. This study showed that adrenomedullin downregulation results in increase in ROS after transient focal ischemia in mice. The results also indicated that adrenomedullin has an important function against ischemic injury through the cyclic AMP-protein kinase A pathway.

Topics: Adrenomedullin; Animals; Cilostazol; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic Nucleotide Phosphodiesterases, Type 3; Cyclic Nucleotide Phosphodiesterases, Type 4; Disease Models, Animal; Down-Regulation; Electrophoresis, Polyacrylamide Gel; Heterozygote; Immunoblotting; Immunohistochemistry; Ischemic Attack, Transient; Isoquinolines; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Phosphodiesterase Inhibitors; Reactive Oxygen Species; Sulfonamides; Tetrazoles

Inspired from preconditioning studies, ischemic postconditioning, consisting of the application of intermittent interruptions of blood flow shortly after reperfusion, has been described in cardiac ischemia and recently in stroke. It is well known that ischemic tolerance can be achieved in the brain not only by ischemic preconditioning, but also by hypoxic preconditioning. However, the existence of hypoxic postconditioning has never been reported in cerebral ischemia.. Adult mice subjected to transient middle cerebral artery occlusion underwent chronic intermittent hypoxia starting either 1 or 5 days after ischemia and brain damage was assessed by T2-weighted MRI at 43 days. In addition, we investigated the potential neuroprotective effect of hypoxia applied after oxygen glucose deprivation in primary neuronal cultures.. The present study shows for the first time that a late application of hypoxia (5 days) after ischemia reduced delayed thalamic atrophy. Furthermore, hypoxia performed 14 hours after oxygen glucose deprivation induced neuroprotection in primary neuronal cultures. We found that hypoxia-inducible factor-1alpha expression as well as those of its target genes erythropoietin and adrenomedullin is increased by hypoxic postconditioning. Further studies with pharmacological inhibitors or recombinant proteins for erythropoietin and adrenomedullin revealed that these molecules participate in this hypoxia postconditioning-induced neuroprotection.. Altogether, this study demonstrates for the first time the existence of a delayed hypoxic postconditioning in cerebral ischemia and in vitro studies highlight hypoxia-inducible factor-1alpha and its target genes, erythropoietin and adrenomedullin, as potential effectors of postconditioning.

Topics: Adrenomedullin; Animals; Atrophy; Brain; Cells, Cultured; Cytoprotection; Disease Models, Animal; Energy Metabolism; Erythropoietin; Hypoxia-Inducible Factor 1, alpha Subunit; Hypoxia-Ischemia, Brain; Hypoxia, Brain; Infarction, Middle Cerebral Artery; Male; Mice; Nerve Degeneration; Oxidative Stress; Time Factors

The vasodilator and vascular regulatory peptide adrenomedullin (AM), a member of the calcitonin gene-related peptide family of peptides, is predicted to play a pivotal protective role in cardiovascular dysfunction. The principle AM (AM1) receptor is composed of a G protein-linked calcitonin receptor-like receptor and a receptor activity-modifying protein (receptor activity-modifying protein 2). There is little knowledge of the receptors via which AM acts in diseases. Using smooth muscle-targeted receptor activity-modifying protein 2 transgenic mice with increased vascular density of functional AM1 receptors, we demonstrate that receptor activity-modifying protein 2 transgenic mice are not protected against angiotensin II-induced hypertension or cardiac hypertrophy. However, vascular hypertrophy, together with vascular cell adhesion molecule 1 and monocyte chemotactic protein 1 expression, is significantly reduced in the aortic walls of transgenic mice, as determined by histological techniques. This indicates that the AM1 vascular smooth muscle receptor can mediate local protection in vivo. This is supported by proliferation studies in cultured smooth muscle cells. By comparison, levels of hypotension and inflammation in a shock model were similar to those in wild-type mice. Thus, a role of the AM1 receptor in the vasoactive component could not be detected, and evidence is provided to show that the hypotensive response to AM is subject to desensitization in vivo. The finding that the vascular smooth muscle AM1 receptor acts at a local level to protect against hypertension-induced vascular hypertrophy and inflammation provides evidence that targeting this receptor may be a beneficial therapeutic approach.

Topics: Adrenomedullin; Angiotensin II; Animals; Blood Pressure; Cardiomegaly; Cells, Cultured; Disease Models, Animal; Female; Hypertension; Hypertrophy; Hypotension; Intracellular Signaling Peptides and Proteins; Lipopolysaccharides; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Transgenic; Muscle, Smooth, Vascular; Receptor Activity-Modifying Proteins; Receptors, Adrenomedullin; Receptors, Peptide; Vasculitis

To investigate the effects of TNF-alpha, TNF-beta and the acceptor expression about mechanical renal trauma with extraneous ADM.. There were 104 healthy adult plain grade Wistar rat, randomly divided into four groups:8 in the group of control, 32 in the group of trauma, 32 in the group injected ADM before trauma, 32 in the group injected ADM post trauma. The experimental model of rat kidney with mechanical trauma was prepared by striking the area of rat skin reflecting by kidney with free dropping ferrous hammer in the last three groups. ADM (0.1 nmol/kg) administrated by intraperitoneal injection at 10 minutes before trauma or post trauma respectively in injected groups. All rats were executed by drawing-out all the blood in their hearts. Renal tissue was investigated to study positive expression of TNF-alpha, TNF-beta, TNFR after SABC stained.. TNF-alpha expression:the TNF-alpha expression of trauma group was more positive than it of control group in the wound early time. The expression of group injected post trauma was less than it of trauma group at 1 h (P < 0.01). The expression of group injected before trauma was less than it of trauma group at 6 h (P < 0.05) TNF-beta expression: the TNF-beta expression of trauma group was less than it of control group at 1 h and 6 h (P < 0.05). The TNF-beta expression of group injected post trauma was more positive than it of trauma group at the same time of 1 h and 6 h (P < 0.01). TNFR expression: the TNFR expression of trauma group was less than it of control group at 6 h (P < 0.01). The TNFR expression of group injected before trauma was more positive than it of trauma group in the at the same time of 1 h and 6 h (P < 0.01).. The TNFR can regulate the TNF-alpha and the TNF-beta in dynamic balancing. The regulation of TNFR is main to TNF-alpha. What the TNF-beta participated in renal trauma mainly is the anti-damage process. ADM can reduce the expression of TNF-alpha. ADM increases the expression of TNF-beta and TNFR.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Female; Kidney; Lymphotoxin-alpha; Male; Rats; Rats, Wistar; Receptors, Tumor Necrosis Factor; Tumor Necrosis Factor-alpha

We aimed to investigate the mechanism mediating the antifibrotic effects of mesenchymal stem cells (MSCs) via in vitro and in vivo study.. In vitro, cardiac fibroblasts (CFs) from passage 2 were cultured and incubated with DMEM/F12 supplemented with 10% fetal bovine serum (DM-10), DM-10 containing angiotensin II (Ang II, 1 x 10(-6) M) or a combination of MSC-conditioned medium (MSC-CM) and Ang II (1 x 10(-6) M) for 48 h. CFs proliferation and gene expression of collagen I and III were analyzed by MTT and reverse transcription-polymerase chain reaction (RT-PCR). In vivo, global heart failure was induced in Wistar rats by isoproterenol (ISO) injection. Four weeks later, MSCs or culture medium were transplanted by intramyocardial injection. Four weeks after transplantation, heart function was assessed, and histological analysis conducted. In addition, the expression of adrenomedullin (ADM), an antifibrotic factor, in MSCs and myocardium were also examined.. In vitro, MSCs expressed ADM. MSC-CM obviously inhibited CFs proliferation and expression of collagen I and III mRNA. In vivo, compared with medium transplantation, MSC transplantation significantly improved heart function, decreased collagen volume fraction and increased expression of ADM in myocardium.. MSC transplantation can inhibit function of CFs by secreting antifibrotic factors such as ADM, resulting in decrease of myocardial fibrosis.

Topics: Adrenomedullin; Animals; Apoptosis; Cell Shape; Cells, Cultured; Disease Models, Animal; Fibrosis; Gene Expression Regulation; Heart Failure; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Paracrine Communication; Rats; Rats, Wistar

Hypoxia-inducible transcription factor-1 (HIF-1) is the most important component of cellular and molecular adaptive responses to hypoxia. We aimed to analyze effects of systemic hypoxia and CO exposure on the oxygen-regulated alpha-subunit of HIF-1 and HIF-1-dependent vasoactive target genes in rat brain. Brains of adult Sprague-Dawley rats were investigated after incubation for 3 and 12 h under normoxia, hypoxia (8% O(2)) and CO 0.1% (n = 10 per group). Upon 3 h of exposure, hypoxia and CO-induced accumulation of HIF-1alpha protein in brain homogenates assessed by Western blot analysis. In contrast to hypoxia HIF-1alpha signals decreased markedly during 12 h-exposure to CO. By immunohistochemistry, intensive HIF-1alpha-positive staining was found in neurons of the cortex and hippocampus. Cerebral expression of vasoactive target genes adrenomedullin (ADM) and vascular endothelial growth factor (VEGF) showed up-regulation during both hypoxia and CO exposure indicating functional activation of HIF-1. Hypoxia increased ADM (P < 0.05) and VEGF mRNA levels within 3 h (P < 0.01) which persisted up to 12 h of exposure (ADM, P < 0.05; VEGF, P < 0.001). Similarly, CO inhalation led to early up-regulation of VEGF (3 h: P < 0.05; 12 h: P < 0.01), but a more delayed increase of ADM mRNA levels (3 h: n.s., 12 h: P < 0.01). We suggest that CO-induced oxygen deprivation is a potent stimulus to cerebral HIF-1-regulated hypoxic stress responses even though its effects are more transient than exposure to hypoxia.

Topics: Adrenomedullin; Animals; Blotting, Western; Brain; Carbon Monoxide; Cerebrovascular Circulation; Disease Models, Animal; Hypoxia-Inducible Factor 1, alpha Subunit; Hypoxia, Brain; Immunohistochemistry; Male; Rats; Rats, Sprague-Dawley; RNA, Messenger; Stress, Physiological; Time Factors; Up-Regulation; Vascular Endothelial Growth Factor A

Adrenomedullin (AM) is a multifunctional peptide hormone that plays a significant role in vasodilation and angiogenesis. Lymphoedema is a common but refractory disorder that is difficult to be treated with conventional therapy. We therefore investigated whether AM promotes lymphangiogenesis and improves lymphoedema.. The effects of AM on lymphatic endothelial cells (LEC) were investigated. AM promoted proliferation, migration, and network formation of cultured human lymphatic microvascular endothelial cells (HLMVEC). AM increased intracellular cyclic adenosine monophosphate (cAMP) level in HLMVEC. The cell proliferation induced by AM was inhibited by a cAMP antagonist and mitogen-activated protein kinase kinase (MEK) inhibitors. Phosphorylated extracellular signal-regulated kinase (ERK) in HLMVEC was increased by AM. Continuous administration of AM (0.05 microg/kg/min) to BALB/c mice with tail lymphoedema resulted in a decrease in lymphoedema thickness. AM treatment increased the number of lymphatic vessels and blood vessels in the injury site.. AM promoted LEC proliferation at least in part through the cAMP/MEK/ERK pathway, and infusion of AM induced lymphangiogenesis and improved lymphoedema in mice.

Topics: Adrenomedullin; Animals; Cell Movement; Cell Proliferation; Cells, Cultured; Cyclic AMP; Disease Models, Animal; Endothelium, Lymphatic; Extracellular Signal-Regulated MAP Kinases; Humans; Lymphangiogenesis; Lymphedema; Male; Mice; Mice, Inbred BALB C; Mitogen-Activated Protein Kinase Kinases; Neovascularization, Physiologic; Signal Transduction; Vasodilation

To establish a nude mouse model of nasopharyngeal carcinoma (NPC) lymph node metastasis and screen the signature genes associated with the metastasis.. The NPC 5-8F-EGFP cells were inoculated into nude mice, from which a 5-8F-LN cell line with lymph node metastasis potential was obtained. The lymphatic metastasis-related signature genes of breast cancer and head and neck squamous cell carcinoma were screened by data mining method.. The NPC cell lines 5-8F and 6-10B showed 307 differentially expressed genes by microarray analysis, from which 20 overlapping genes were identified, and 3 overexpressed genes were found with probable metastasis potential, namely the ADM, IRF1, and CAV1 genes. Quantitative RT-PCR validated the data mining results in the 5-8F-EGFP, 6-10B-EGFP, NP69, and 5-8F-LN cell lines. The 3 NPC cell lines 5-8F-EGFP, 6-10B-EGFP and 5-8F-LN showed significantly higher expressions of IRF1 than NP69 cells (P=0.008, 0.022, and 0.006, respectively. The expression level of CAV1 in 5-8F-EGFP cells was significantly higher than that in 6-10B-EGFP cells (P=0.014), but ADM expression showed no significant difference between the 4 cell lines.. IRF1 may play an important role in the progression of NPC. The overexpression of CAV1 in 5-8F-EGFP cells can be associated with the high metastatic potential of the cells.

Topics: Adrenomedullin; Animals; Caveolin 1; Cell Line, Tumor; Disease Models, Animal; Gene Expression Profiling; Humans; Interferon Regulatory Factor-1; Lymphatic Metastasis; Mice; Mice, Inbred BALB C; Mice, Nude; Nasopharyngeal Neoplasms; Neoplasm Transplantation; Reverse Transcriptase Polymerase Chain Reaction; Transplantation, Heterologous

Topics: Adrenomedullin; Animals; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Endothelium, Lymphatic; Humans; Lymphangiogenesis; Lymphedema; Mice; Vasodilator Agents; Wound Healing

Adrenomedullin (AdM) was originally discovered as a vasorelaxant peptide. The antioxidative properties of AdM have been reported recently. Through its antioxidative effect, adrenomedullin can protect organs from damage induced by stressors. Lead, commonly detected in air, soil, water and food, is a major source of oxidative stress. The effect of AdM in the liver of rats exposed to lead was investigated. Twenty-four female Wistar rats were divided into four groups: a control group (C), adrenomedullin group (AdM), lead (Pb) group and lead + adrenomedullin (Pb + AdM) group. In the Pb-treated groups, the animals were exposed to lead in drinking water containing 250 ppm PbCl2 for 4 weeks. In the AdM-treated group, the animals received an i.p. injection of AdM (3000 ng kg(-1) body weight) in the third week of lead treatment for 1 week. The activities of catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) and the level of malondialdehyde (MDA) were determined in the liver of rats. Histological changes in the liver were examined by light and electron microscopy as well. The MDA levels were increased significantly in the Pb-treated groups, but in the Pb + AdM group the MDA levels were decreased significantly when compared with the Pb group. AdM reduced hepatic damage in the Pb + AdM group, but the difference in the total histopathological scores between the Pb and Pb + AdM groups was not significant. When the results are taken together, it can be concluded that AdM may have protective or compensating effects in lead toxicity.

Topics: Adrenomedullin; Animals; Antioxidants; Catalase; Disease Models, Animal; Female; Glutathione Peroxidase; Injections, Intraperitoneal; Lead; Lead Poisoning; Lipid Peroxidation; Liver; Malondialdehyde; Microscopy, Electron, Transmission; Oxidative Stress; Rats; Rats, Wistar; Superoxide Dismutase; Time Factors

Clinical and experimental research findings suggest that a local burn insult produces oxidant-induced organ changes as evidenced by increased lipid peroxidation in lung, liver and gut. Adrenomedullin (AM), a potent vasodilator, was originally isolated from pheochromocytoma cells, and has been identified in other tissues. In this study, we investigated the potential role of AM in burn-induced remote organ damage in rats. Sprague-Dawley rats (250-300 g) were treated with either AM (100 ng/kg, subcutaneously) or saline 10 min before burn insult which covers 30% of total body surface area and were decapitated 24 h after the burn insult. Trunk blood was collected and analyzed for liver and kidney functions and for determination of TNF-alpha levels. The liver, lung and kidney samples were taken for histologic evaluation and for measurement of malondialdehyde (MDA) level, myeloperoxidase (MPO) activity and chemiluminescence levels. The data revealed that AM treatment resulted in a significant protection in tissues tested against burn injury via suppression of lipid peroxidation, tissue neutrophil infiltration, oxidant generation and via decreasing circulating levels of the pro-inflammatory cytokine TNF-alpha. AM treatment was also effective in attenuating hepatic and kidney dysfunction due to burn injury, suggesting that peripherally AM administration may protect the tissues against burn-induced injury.

Topics: Adrenomedullin; Animals; Burns; Disease Models, Animal; Kidney; Liver; Lung; Malondialdehyde; Peroxidase; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha

Pulmonary hypertension (PHT) is a common complication of congenital heart disease and the pulmonary vascular structural remodeling because of the high pulmonary blood flow is considered to be the key pathologic process. In the present study the change and distribution of peptides derived from proadrenomedullin in a rat model of PHT caused by a left-to-right shunt were measured to elucidate the mechanism.. Twelve weeks after a cervical shunt was established by a cuff technique in an experimental group of rats, the systolic pulmonary artery pressure (sPAP) was measured by catheterization. Morphologic assessment included the measurement of the weight ratio of the right ventricle (RV) to the left ventricle plus septum (LV+SP) and the mean percentage of media wall thickness (MT%) in moderate-sized pulmonary arteries. The distribution of adrenomedullin (ADM), adrenotensin (ADT) and proadrenomedullin N-terminal 20 peptide (PAMP) were measured by immunohistochemical staining. The mRNA expressions of ADM, ADT, PAMP and proADM45-92 were investigated by reverse transcription polymerase chain reaction. The sPAP and the ratios of RV/(LV+SP) and MT% were significantly increased in the experimental rats (p<0.01, and p<0.05). Positive signals (brown granules) of ADM, ADT and PAMP were mainly located in the smooth muscle cells, but the brown granules of PAMP were also located in the tunica adventitia. The levels of ADM and PAMP were significantly increased, while that of ADT was markedly decreased in the Experimental group compared with the Control group (p<0.05 and p<0.01 respectively). The mRNA expression levels of ADM and preADM45-92 were significantly increased in the experimental rats (p<0.01); however, the expression of ADT mRNA was statistically deceased in the Experimental group compared with the Control group (p<0.01). The mRNA expression of PAMP showed no statistical difference between the 2 groups of rats (p>0.05).. The change and distribution of peptides derived from proadrenomedullin in PHT caused by a left-to-right shunt in rats is powerful evidence for intramolecular regulation.

Topics: Adrenomedullin; Animals; Arteriovenous Shunt, Surgical; Carotid Arteries; Disease Models, Animal; Hypertension, Pulmonary; Jugular Veins; Lung; Male; Peptide Fragments; Protein Precursors; Rats; Rats, Wistar; RNA, Messenger

Adrenomedullin (AM) is a multifunctional peptide with a putative beneficial role after an ischaemic insult. The aim of this study was to evaluate the effect of AM on partial hepatic ischaemia reperfusion (I/R) injury.. Rats were subjected to 1 h of 70% hepatic ischaemia, followed by reperfusion or sham. At the end of ischaemia, vehicle (phosphate-buffered saline solution), N-nitro-L-arginine methyl ester (L-NAME) and AM with or without L-NAME were infused via the portal vein. Analysis was performed at pre-ischaemia, ischaemia onset and 1, 2 and 4 h after reperfusion. Hepatic tissue blood flow (HTBF) was evaluated by laser Doppler.. Plasma AM levels in the I/R groups were significantly lower than the levels in the sham group. AM treatment significantly reduced levels of aspartate transaminase and tissue arginase (P<0.05). Significant decreases of tumour necrosis factor-alpha, interleukin-1beta and endothelin-1 levels were also found in the serum. Endothelin-1, malondialdehyde and necrosis were observed more frequently in liver tissue in the AM group than the control (P<0.05). Tissue nitric oxide, energy charge and HTBF were significantly increased in AM treatment experiments (P<0.05).. The improved HTBF, energy charge and nitric oxide and the reduction of hepatic necrosis, oxidative stress, liver enzymes, endotelin-1 and pro-inflammatory cytokines demonstrate that treatment with AM attenuates liver I/R injury.

Topics: Adrenomedullin; Animals; Arginase; Aspartate Aminotransferases; Blood Flow Velocity; Disease Models, Animal; Drug Therapy, Combination; Endothelin-1; Enzyme Inhibitors; Interleukin-1beta; Liver Diseases; Male; Malondialdehyde; NG-Nitroarginine Methyl Ester; Nitric Oxide; Oxidative Stress; Rats; Rats, Wistar; Reperfusion Injury; Tumor Necrosis Factor-alpha; Vasodilator Agents

Male rats aged 3 months, 12 months and 20 months were subjected to breathing 8% oxygen for 6 hours. Lung preproadrenomedullin (AM) messenger RNA (mRNA) levels were measured by solution hybridization-RNase protection assay while AM was measured by radioimmunoassay. The binding of hypoxia-inducible factor-1alpha (HIF-1alpha) to DNA was determined by electrophoretic mobility shift. There was an age-related increase in basal levels of preproAM mRNA and AM and of the binding of hypoxia-inducible factor (HIF) to DNA. Upon hypoxic stimulation, HIF binding to DNA increased in the young and middle-aged rats, but not in the old rats. AM gene expression increased in response to hypoxia in rats of all ages, but the increase was much less in the old rats. AM peptide levels in the lung decreased with age in hypoxia. In a separate experiment, male rats aged 3 months and 20 months were subjected to hypoxia as described above. PreproAM, calcitonin receptor-like receptor (CRLR), receptor activity modifying protein (RAMP) mRNA, HIF-1 and peptidyl-glycine-amidating monooxygenase (PAM) mRNA levels were measured by reverse transcription-polymerase chain reaction. All except PAM showed a decrease in basal levels and a diminished response to hypoxia in the old rats. Polysome profiling demonstrated decreases in the percentages of translatable preproAM mRNA in response to hypoxia, with a greater decrease in the old than the young rats. It is concluded that an age-dependent decrease in the hypoxic response of the AM system in the lung was associated with high basal levels of HIF activity and AM expression in the old rats, and a lower proportion of translatable preproAM mRNA in the old rats in response to hypoxia. Thus, the HIF-AM pathway may be impaired in the aged lung, and other mechanisms may be present to maintain an AM response to hypoxia.

Topics: Adrenomedullin; Aging; Animals; Calcitonin Receptor-Like Protein; Disease Models, Animal; Electrophoresis; Gene Expression Regulation, Developmental; Hypoxia; Hypoxia-Inducible Factor 1; Lung; Male; Mixed Function Oxygenases; Multienzyme Complexes; Polyribosomes; Protein Precursors; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Receptors, Calcitonin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Xenopus Proteins

In this work we aimed to observe (1) the changes in adrenomedullin (AM) and its receptor system - calcitonin receptor-like receptor (CRLR) and receptor activity modifying proteins (RAMPs) - in myocardial ischemic injury and (2) the response of injuried myocardia to AM and the phosphorylation of Akt to illustrate the protective mechanism of AM in ischemic myocardia. Male SD rats were subcutaneously injected with isoproterenol (ISO) to induce myocardial ischemia. The mRNA levels of AM, CRLR, RAMP1, RAMP2 and RAMP3 were determined by RT-PCR. Protein levels of Akt, phosphor-Akt, CRLR, RAMP1, RAMP2 and RAMP3 were assayed by Western blot. Results showed that, compared with that of the controls, ISO-treated rats showed lower cardiac function and myocardial injury. The mRNA relative amount of AM, CRLR, RAMP1, RAMP2 and RAMP3 in the myocardia of ISO-treated rats was increased. The elevated mRNA levels of CRLR, RAMP1, RAMP2 and RAMP3 were positively correlated with AM content in injured myocardia. The protein levels of CRLR, RAMP1, RAMP2 and RAMP3 in injured myocardia were increased compared with that of control myocardia. AM-stimulated cAMP generation in myocardia was elevated in the ISO group, and was antagonized by AM(22-52) and CGRP(8-37). Western blot analyses revealed that AM significantly enhanced Akt phosphorylation in injured myocardia, which was blocked by pretreatment with AM(22-52) or CGRP(8-37). Ischemia-injured myocardia hyper-expressed AM and its receptors - CRLR, RAMP1, RAMP2 and RAMP3 - and the response of ischemic myocardia to AM was potentiated, and the level of Akt phosphorylation was also increased, which suggests that changes in cardiac AM/AM receptor might play an important role in the pathogenesis of myocardial ischemic injury.

Topics: Adrenomedullin; Animals; Blotting, Western; Calcitonin Receptor-Like Protein; Cardiotonic Agents; Cyclic AMP; Disease Models, Animal; Gene Expression Regulation; Heart; Intracellular Signaling Peptides and Proteins; Isoproterenol; Lipid Peroxides; Male; Membrane Proteins; Myocardial Ischemia; Myocardium; Natriuretic Peptide, Brain; Nerve Tissue Proteins; Phosphorylation; Proto-Oncogene Proteins c-akt; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Receptor Activity-Modifying Proteins; Receptors, Calcitonin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

To explore the influence of adrenomedullin (ADM) on apoptosis of neuron, volume of infarction and the expression of early growth response gene-1 (Egr-1) mRNA in the rat with focal ischemia/reperfusion (I/R) injury.. Fifty-four SD rats were randomly divided into sham operation group, ADM femoral vein group, internal carotid artery group and lateral cerebral ventricle group. The model was reproduced by ligating the middle cerebral artery (MCA) with a ligature for 2 hours followed by injection of ADM through femoral artery, internal carotid artery and lateral cerebral ventricle before reperfusion for 22 hours. The volume of infarction was estimated with tetrazolium chloride (TTC) staining, apoptosis of the neuron was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method, the positive expression of Egr-1 mRNA was detected by in-situ hybridization.. The volume of infarction were smaller after the injection of ADM through different ways than that of I/R group. The result was better when the internal carotid artery and the lateral cerebral ventricle were used than that after injection by the way of the femoral vein (both P<0.05). There were few positive cells with TUNEL staining in the cerebral cortex and hippocampus CA1 zone in the sham operation group, and more apoptotic cells were seen in the group with focal brain I/R injury (both P<0.01). After the administration of ADM, especially through the internal carotid artery and the lateral cerebral ventricle, the number of the positive cells with TUNEL staining was decreased obviously compared with I/R group (both P<0.01). There was a little positive expression of Egr-1 mRNA in the cerebral cortex and hippocampus CA1 zone in sham operation group. The expression was enhanced in the group with focal brain I/R injury (both P<0.01). With the injection of ADM, the expression was much more enhanced, especially when internal carotid artery and the lateral cerebral ventricle were used for injection compared with those in I/R group (both P<0.01).. The injection of ADM through different ways can reduce the neural injury, decrease the apoptosis of the neurons and the volume of the infarction, and increase the expression of Egr-1 mRNA. Therefore, it is efficacious in the treatment of cerebral ischemia.

Topics: Adrenomedullin; Animals; Apoptosis; Brain; Disease Models, Animal; Early Growth Response Protein 1; Infarction, Middle Cerebral Artery; Male; Neurons; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; RNA, Messenger

1. The present study was designed to examine the cardiovascular effects of intravenously administered pcDNA3.1AM, a recombinant non-virus vector carrying a rat adrenomedullin (AM) gene translation fragment, in rats with chronic cardiac dysfunction induced by ligation of the left descending coronary artery. 2. Haemodynamic parameters were recorded by intraventricular catheterization. In situ hybridization and polymerase chain reaction (PCR) were performed to identify the distribution of the introduced vector. The concentration of AM was determined by radioimmunoassay. 3. Progressive cardiac dysfunction was observed following coronary artery ligation, as indicated by a significant reduction in mean arterial pressure (MAP) and increases in both central venous pressure (CVP) and end-diastolic pressure of the left ventricle (LVEDP; P < 0.01). Administration of pcDNA3.1AM significantly attenuated the progressive cardiac dysfunction and lowered the elevated CVP and LVEDP. The introduced vector was widely distributed in different organs, including the lungs, kidney, heart, liver, spleen and brain. However, intense staining of pcDNA3.1 AM was observed in the lungs and kidneys. The introduced vector was localized mainly in the endothelial cells of blood vessels. Radioimmunoassay showed elevated levels of AM in the plasma and lung and heart after surgery, but there was no significant further increase in the concentration of AM after pcDNA3.1AM delivery. 4. The present study has provided some novel findings on the potential beneficial effects of AM gene delivery on chronic cardiac function in rats. Expression of AM by a non-virus vector may also have therapeutic value against cardiac dysfunction in vivo.

Topics: Adrenomedullin; Animals; Blood Pressure; Central Venous Pressure; Chronic Disease; Coronary Vessels; Disease Models, Animal; Endothelial Cells; Genetic Therapy; Genetic Vectors; Heart Failure; Kidney; Ligation; Lung; Male; Myocardial Infarction; Rats; Rats, Sprague-Dawley; Time Factors; Ventricular Function, Left; Ventricular Pressure

Our aim was to evaluate if the combined inhalation of both nitric oxide (iNO) and aerosolized prostacyclin or iNO and adrenomedullin (ADM) is more effective in lowering pulmonary arterial pressure (PAP) and improving oxygenation than nitric oxide alone in an animal model with pulmonary hypertension (PH). Moreover, we studied the effect on pulmonary mechanics, surfactant activity, and pulmonary oxidative stress of the different treatments. Twenty-eight piglets with acute lung injury induced by lung lavages with saline were randomized to receive nitric oxide, nitric oxide plus prostacyclin, nitric oxide plus ADM or saline, after. Dynamic compliance, tidal volume, and airway resistance were measured. Lung tissue oxidation was evaluated by measuring total hydroperoxide and advanced oxidation protein products in bronchial aspirate samples. Surface surfactant activity was studied using Capillary Surfactometer. Inhaled nitric oxide combined with prostacyclin or ADM was more effective than nitric oxide alone in lowering PAP and improving oxygenation. Nitric oxide alone or combined increased lung compliance and tidal volume, and decreased airway resistance. No effects on surfactant surface activity and lung tissue oxidation were observed. The treatment with nitric oxide alone or combined with prostacyclin or ADM were effective in decreasing mean PAP and improving oxygenation in a piglet model of PH. However, nitric oxide plus prostacyclin and nitric oxide plus ADM were more effective than nitric oxide alone. The combination of aerosolized prostacyclin and ADM with nitric oxide might have a role in the treatment of infants with PH refractory to nitric oxide alone.

Topics: Administration, Inhalation; Adrenomedullin; Animals; Disease Models, Animal; Drug Therapy, Combination; Epoprostenol; Female; Hypertension, Pulmonary; Male; Nitric Oxide; Pulmonary Artery; Pulmonary Surfactants; Respiratory Distress Syndrome; Respiratory Function Tests; Sus scrofa; Vasodilator Agents

Adrenomedullin (AM) is a peptide hormone widely distributed in the central nervous system. Our previous study showed that AM gene delivery immediately after middle cerebral artery occlusion (MCAO) protected against cerebral ischemia/reperfusion (I/R) injury by promoting glial cell survival and migration. In the present study, we investigated the effect of delayed AM peptide infusion on ischemic brain injury at 24 h after MCAO. AM infusion significantly reduced neurological deficit scores at days 2, 4, and 8 after cerebral I/R. AM reduced cerebral infarct size at 8 and 15 days after surgery as determined by quantitative analysis. Double staining showed that AM infusion reduced TUNEL-positive apoptotic cells in both neurons and glial cells, as well as reduced caspase-3 activity in the ischemic area of the brain. In addition, AM treatment increased capillary density in the ischemic region at 15 days after I/R injury. Parallel studies revealed that AM treatment enhanced the proliferation of cultured endothelial cells as measured by both (3)H-thymidine incorporation and in situ BrdU labeling. Both in vitro and in vivo AM effects were blocked by calcitonin gene-related peptide (8-37), an AM receptor antagonist. Moreover, AM's effects were associated with increased cerebral nitric oxide (NO) levels, as well as decreased NAD(P)H oxidase activities and superoxide anion production. These results indicate that a continuous supply of exogenous AM peptide protects against I/R injury by improving the survival of neuronal and glial cells, and promoting angiogenesis through elevated NO formation and suppression of oxidative stress.

Topics: Adrenomedullin; Analysis of Variance; Animals; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Brain Infarction; Brain Ischemia; Calcitonin Gene-Related Peptide; Caspase 3; Caspases; Cell Proliferation; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Endothelial Cells; Gene Expression Regulation, Enzymologic; Glial Fibrillary Acidic Protein; Immunohistochemistry; In Situ Nick-End Labeling; Male; NADPH Oxidases; Neovascularization, Physiologic; Neurologic Examination; Nitrates; Nitrites; Peptides; Rats; Rats, Sprague-Dawley; Stroke; Time Factors

Urocortin 1 (UCN) and adrenomedullin (AM) are two recently discovered neuropeptides that, due to their distribution and binding to receptors in immune cells, have emerged as potential endogenous anti-inflammatory factors. Crohn's disease is a chronic debilitating disease characterised by a Th1 driven severe inflammation of the gastrointestinal tract. This study investigated the therapeutic effect of UCN and AM in a murine model of colitis.. Treatment with UCN or AM ameliorated significantly the clinical and histopathological severity of the inflammatory colitis, abrogating body weight loss, diarrhoea, and inflammation, and increased the survival rate of colitic mice. The therapeutic effect was associated with downregulation of both inflammatory and Th1 driven autoimmune responses, including regulation of a wide spectrum of inflammatory mediators. In addition, partial involvement of interleukin 10 secreting regulatory cells in this therapeutic effect was demonstrated. Importantly, UCN or AM treatments were therapeutically effective in established colitis and avoided recurrence of the disease.. This work identifies UCN and AM as two potent anti-inflammatory factors with the capacity to deactivate the intestinal inflammatory response and restore mucosal immune tolerance at multiple levels. Consequently, both peptides represent novel multistep therapeutic approaches for the treatment of Crohn's disease and other Th1 mediated inflammatory diseases.

Topics: Adrenomedullin; Animals; Anti-Inflammatory Agents, Non-Steroidal; Cells, Cultured; Chemokines; Corticotropin-Releasing Hormone; Crohn Disease; Cytokines; Disease Models, Animal; Interleukin-10; Mice; Mice, Inbred BALB C; Mice, Inbred Strains; Peptides; Proteins; Th1 Cells; Trinitrobenzenesulfonic Acid; Urocortins

We investigated the pathophysiological role of the renal adrenomedullin (AM) system, including the ligand, receptor, and amidating activity, in severe hypertensive rats.. We studied three groups: control Wistar Kyoto rats (WKY), spontaneously hypertensive stroke-prone rats (SHR-SP), and diuretic-treated SHR-SP. We measured AM-mature, active form, and AM-total (active form+inactive form) in plasma and renal tissues, and mRNA levels of AM and AM receptor system components such as calcitonin receptor-like receptor (CRLR), receptor activity-modifying protein (RAMP) 2, and RAMP3 in renal tissues.. SHR-SP had higher blood pressure, plasma neurohumoral factors, and lower renal function than WKY. SHR-SP had higher AM-mature and AM-total levels in plasma and renal tissues than WKY. Although the plasma AM-mature/AM-total ratio was similar in the two groups, AM-mature/AM-total ratio in renal tissues was higher in SHR-SP than in WKY. In addition, mRNA levels of AM in the renal cortex and medulla and the mRNA levels of CRLR, RAMP2, and RAMP3 in the renal cortex were higher in SHR-SP than in WKY. Chronic diuretic treatment decreased blood pressure and improved kidney function and neurohumoral factors, with reductions in plasma and renal AM system.. Upregulation of circulating and renal AM system may modulate pathophysiology in SHR-SP.

Topics: Adrenomedullin; Aldosterone; Animals; Collagen Type I; Disease Models, Animal; Diuretics; Gene Expression Regulation; Hypertension; Kidney; Lymphotoxin-alpha; Male; Peptides; Rats; Receptors, Adrenomedullin; Receptors, Calcitonin; Receptors, Peptide; RNA, Messenger

Adrenomedullin (AM) induces angiogenesis and inhibits cell apoptosis through the phosphatidylinositol 3-kinase/Akt pathway. Transplantation of mesenchymal stem cells (MSCs) has been shown to improve neurological deficits after stroke in rats. We investigated whether AM enhances the therapeutic potency of MSC transplantation.. Male Lewis rats (n=100) were subjected to 2-hour middle cerebral artery occlusion. Immediately after reperfusion, rats were assigned randomly to receive intravenous transplantation of MSCs plus subcutaneous infusion of AM for 7 days (MSC+AM group), AM infusion alone (AM group), MSC transplantation alone (MSC group), or vehicle infusion (control group). Neurological and immunohistological assessments were performed to examine the effects of these treatments.. Some engrafted MSCs were positive for neuronal and endothelial cell markers, although the number of differentiated MSCs did not differ significantly between the MSC and MSC+AM groups. The neurological score significantly improved in the MSC, AM, and MSC+AM groups compared with the control group. Importantly, improvement in the MSC+AM group was significantly greater than that in the MSC and AM groups. There was marked induction of angiogenesis in the ischemic penumbra in the MSC+AM group, followed by the AM, MSC, and control groups. AM infusion significantly inhibited apoptosis of transplanted MSCs. As a result, the number of engrafted MSCs in the MSC+AM group was significantly higher than that in the MSC group.. AM enhanced the therapeutic potency of MSCs, including neurological improvement, possibly through inhibition of MSC apoptosis and induction of angiogenesis.

Topics: Adrenomedullin; Animals; Apoptosis; Body Weight; Cell Transplantation; Disease Models, Animal; Immunohistochemistry; In Situ Nick-End Labeling; Infarction, Middle Cerebral Artery; Ischemia; Male; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Neovascularization, Pathologic; Neurons; Peptides; Phosphatidylinositol 3-Kinases; Rats; Rats, Inbred Lew; Stem Cells; Stroke; Time Factors

Increased microvascular permeability and perfusion mismatch are hallmarks of sepsis or septic shock. The intestinal mucosa is very sensitive to tissue hypoxia. Intestinal mucosa dysfunction may allow translocation of bacteria and their products, thereby perpetuating sepsis and inflammation. Staphylococcus aureus alpha-toxin is a major pathogenicity determinant of this bacterium, provoking cardiovascular collapse. Current evidence suggests that the endogenous peptide adrenomedullin stabilizes circulatory homeostasis in systemic inflammatory response. Using alpha-toxin as a well-defined strong initiator of an inflammatory reaction, we tested the hypothesis that exogenously applied adrenomedullin stabilizes gut microcirculation.. Prospective, experimental study.. Research laboratory at a university hospital.. Isolated, perfused ileum from male Sprague-Dawley rats and human umbilical vein endothelial cells.. Administration of S. aureus alpha-toxin before or after infusion of adrenomedullin.. Injection of a bolus of 1 microg of alpha-toxin in the superior mesenteric artery in a constant-flow, blood-perfused preparation of rat ileum increased perfusion pressure and relative hemoglobin concentration and decreased mucosal hemoglobin oxygen saturation. Continuous infusion of adrenomedullin (0.1 micromol/L) significantly reduced these alpha-toxin-related effects. Severe microvascular hyperpermeability observed in alpha-toxin-exposed ileum was abolished by adrenomedullin pretreatment. In addition, adrenomedullin blocked alpha-toxin-induced endothelial myosin light chain phosphorylation, endothelial cell contraction, and subsequent loss of endothelial barrier function in vitro. Treatment of alpha-toxin (infusion of 0.05 microg/mL)-exposed ileum with adrenomedullin (0.1 micromol/L) started 10 mins after onset of toxin application also significantly reduced superior mesenteric artery pressure and permeability increase.. In summary, these data suggest that exogenous adrenomedullin protects ileum by reducing alpha-toxin-induced microcirculatory disturbances and by stabilizing endothelial barrier function.

Topics: Actin Cytoskeleton; Adrenomedullin; Animals; Anti-Infective Agents; Bacterial Toxins; Capillary Permeability; Disease Models, Animal; Ileum; Infusions, Intravenous; Intestinal Mucosa; Male; Microcirculation; Myosin Light Chains; Peptides; Phosphorylation; Prospective Studies; Rats; Rats, Sprague-Dawley; Staphylococcus aureus; Treatment Outcome

Intermedin/Adrenomedullin-2 (IMD), a newly described peptide with structural homology to adrenomedullin (AM), is present in brain and pituitary gland and binds to the same receptors as AM and calcitonin gene-related peptide (CGRP). We hypothesized that IMD would exert actions similar to AM and CGRP and previously have demonstrated that indeed IMD, like AM and CGRP, increases sympathetic tone and inhibits feeding and drinking when administered centrally. Here, we extend those observations by demonstrating that like AM, IMD acts in brain to stimulate the secretions of prolactin (PRL) and adrenocorticotropin (ACTH) and to inhibit the secretion of growth hormone (GH) in conscious rats. In addition, in conscious rats, central administration of IMD results in increased plasma levels of oxytocin (OT) and vasopressin (AVP). The ability of IMD to activate the hypothalamo-pituitary-adrenal (HPA) axis can be blocked by intravenous pretreatment with the corticotropin releasing factor (CRF) antagonist, astressin. These results suggest that multiple members of the AM family of peptides may be involved in the cardiovascular, behavioral and neuroendocrine responses to stress.

Topics: Adrenocorticotropic Hormone; Adrenomedullin; Animals; Corticotropin-Releasing Hormone; Disease Models, Animal; Growth Hormone; Hypothalamo-Hypophyseal System; Male; Neuropeptides; Neurosecretory Systems; Oxytocin; Peptide Fragments; Pituitary Hormones; Prolactin; Rats; Rats, Sprague-Dawley; Stress, Physiological; Vasopressins

Irreversible hypovolemia remains a major clinical problem. Preliminary studies indicate that administration of adrenomedullin and adrenomedullin binding protein-1 in combination (AM/AMBP-1) after hemorrhage, improves cardiovascular function despite the increased levels of AM. Our aim was to determine whether vascular responsiveness to AM is reduced after hemorrhage and, if so, to elucidate the possible mechanism responsible for such hyporesponsiveness.. Male rats were bled to and maintained at a mean arterial pressure of 40 mm Hg for 90 minutes. The animals were then resuscitated with 4 times the volume of shed blood with lactated Ringer's solution over 60 minutes. At 1.5 hours postresuscitation, vascular responses to AM and AMBP-1, plasma levels of AM and AMBP-1, AMBP-1 and AM receptor gene expression were measured. In additional animals, AM and AMBP-1 were administered intravenously at 15 minutes after resuscitation over 45 minutes. Serum levels of liver enzymes, lactate, creatinine, TNF-alpha, IL-6, and IL-10 were measured at 1.5 hours postresuscitation.. AM-induced vascular relaxation decreased significantly after hemorrhage and resuscitation, which was markedly improved by AMBP-1. However, AM receptor gene expression did not change under such conditions. Hemorrhage-induced AM hyporesponsiveness was accompanied by the decreased expression and release of AMBP-1. Moreover, AM/AMBP-1 treatment down-regulated TNF-alpha and IL-6, up-regulated IL-10, and attenuated organ injury.. The decreased AMBP-1 levels rather than alterations in AM receptors are responsible for producing AM hyporesponsiveness after hemorrhage. Thus, administration of AMBP-1 in combination with AM can be useful to reduce organ injury after severe hypovolemia.

Topics: Adrenomedullin; Alanine Transaminase; Animals; Base Sequence; Biomarkers; Blotting, Western; Complement Factor H; Creatinine; Cytokines; Disease Models, Animal; Hemorrhage; Intestine, Small; Lactates; Male; Molecular Sequence Data; Peptides; Polymerase Chain Reaction; Probability; Random Allocation; Rats; Rats, Sprague-Dawley; Reference Values; Resuscitation; RNA, Messenger; Sensitivity and Specificity; Shock, Hemorrhagic; Vasodilation; Vasodilator Agents

To investigate the changes in adrenomedullin release in bronchial alveolar lavage fluid (BALF) from different lung areas in acute respiratory distress syndrome (ARDS) of produced dogs, by pulmonary and extra-pulmonary causes, with low tidal volume and positive end expiratory pressure (PEEP) treatment under supine and prone position.. Twenty-four male mongrel dogs were randomly divided into ARDSp (ARDS caused by pulmonary causes) supine group, ARDSp prone group, ARDSexp (ARDS caused by extra-pulmonary causes) supine group, and ARDSexp prone group. A detergent to cause lung injury in ARDSp dogs, and intravenous oleic acid was given in ARDSexp dogs. The results of adrenomedullin in different areas of dog's lung (upper lobe, middle lobe, and lower lobe) and arterial blood gas under lung protective ventilation treatment were measured.. After lung injury, the arterial oxygenation index was lowered, and the levels of adrenomedullin in the upper lobe and middle lobe of ARDSp dogs were higher than that of ARDSexp dogs. After receiving low tidal volume and PEEP ventilation, the conditions of all the dogs were gradually getting ameliorated, and prone position ventilation gave better effects on lung injury dogs by inhibiting adrenomedullin release.. There are statistical differences in adrenomedullin release in different lung areas between ARDSp dogs and ARDSexp dogs, and in both ARDSexp dogs and ARDSp dogs low tidal volume and PEEP treatment under prone position ventilation give better results compared to supine position.

Topics: Adrenomedullin; Animals; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Dogs; Lung; Male; Positive-Pressure Respiration; Posture; Random Allocation; Respiratory Distress Syndrome; Tidal Volume

In this work, we aimed to observe the changes in adrenomedullin (ADM) and its receptor-calcitonin receptor-like receptor (CL), receptor activity-modifying protein (RAMP) 1, RAMP2 and RAMP3-in cardiac ventricles and aortas of hypertensive rats, and the responsiveness of injured cardiovascular tissue to ADM, then to illustrate the protective mechanism of ADM on the cardiovascular system. Male SD rats were subjected to treatment with chronic N(G)-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase. The ADM contents and cAMP production in myocardia and aortas were measured by RIA. The mRNA levels of ADM, CL, and RAMP1-3 were determined by RT-PCR. L-NNA induced severe hypertension and cardiomegaly. The ir-ADM content in plasma, ventricles and aortas in L-NNA-treated animals increased by 80%, 72% and 57% (all p<0.01), respectively. Furthermore, mRNA levels of ADM, CL, RAMP2 and RAMP3 were elevated by 91%, 33%, 50% and 72.5% (all p<0.01), respectively, in ventricles and by 95%, 177%, 74.7% and 85% (all p<0.01), respectively, in aortas. mRNA level of RAMP1 was elevated by 129% (p<0.01) in aortas but no significant difference in ventricles. The elevated mRNA levels of RAMP2 and RAMP3 were positively correlated with that of ADM in hypertrophic ventricles (r=0.633 and 0.828, p<0.01, respectively) and the elevated mRNA levels of CL, RAMP2 and RAMP3 were positively correlated with that of ADM in aortas (r=0.941, 0.943 and 0.736, all p<0.01, respectively). The response of ventricular myocardia and aortas to ADM administration potentiated, and the production of cAMP was increased by 41% and 68% (both p<0.01), respectively. ADM-stimulated cAMP generation in ventricular myocardia and aortas was blocked by administration of both ADM22-52, the specific antagonist of ADM receptor, and CGRP8-37, the antagonist of the CGRP1 receptor. The results showed an increased in cardiovascular ADM generation and an up-regulation of the gene expression of ADM and its receptor-CL, RAMP1-3 during hypertension, augmented responsiveness of ventricular myocardia and aortas of hypertensive rats to ADM, suggesting that these receptors may play a role in the cardiovascular adaptation in response to sub-chronic NO-inhibition.

Topics: Adrenomedullin; Animals; Antihypertensive Agents; Aorta; Cyclic AMP; Disease Models, Animal; Enzyme Inhibitors; Heart; Heart Ventricles; Hypertension; Intracellular Signaling Peptides and Proteins; Male; Myocardium; Nitroarginine; Peptides; Rats; Rats, Sprague-Dawley; Receptors, Calcitonin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

To investigate the expression of endothelin-1 (ET-1) and adrenomedullin (ADM) in the renal pelvis, stenotic ureteropelvic junction, and ureter of 20 male Wistar rats with congenital unilateral ureteropelvic junction obstruction; the normal contralateral kidneys served as controls. The molecular pathophysiology of congenital ureteropelvic junction obstruction is still unclear. The implication of altered peptidergic innervation is under discussion. Our study group has recently been able to demonstrate a significant increase in ET-1 and a significant decrease in ADM in prestenotic and stenotic tissue, but not in the remainder of the ureter, compared with controls.. Twenty animals were killed, and samples of the renal pelvis, ureteropelvic junction, upper ureter, middle part of the ureter, and lower ureter were immediately snap-frozen and stored in liquid nitrogen. Total RNA was extracted, and subsequently 1 microg of RNA was reversely transcribed. mRNA expression of ET-1 and ADM was determined semiquantitatively using on-line polymerase chain reaction. The expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was determined to relate the specific mRNA expression to the expression of a housekeeping gene.. We found a significant increase in the expression of ET-1 in the obstructed junctions related to GAPDH (P <0.001). The expression of ADM, however, revealed no statistically significant differences. No differences at all could be detected in the tissue samples from the rest of the ureter.. Alterations in the local production of peptidergic neurotransmitters, especially ET-1, may contribute to the molecular pathogenesis of ureteropelvic junction obstruction. Results previously obtained in the stenotic tissue from children were confirmed in the stenotic tissue from the rat model. We hypothesize that the alterations are disease-, but not age-specific.

Topics: Abnormalities, Multiple; Adrenomedullin; Animals; Atrophy; Computer Systems; Constriction, Pathologic; Disease Models, Animal; Endothelin-1; Gene Expression Profiling; Hydronephrosis; Kidney Pelvis; Male; Peptides; Polymerase Chain Reaction; Rats; Rats, Mutant Strains; Rats, Wistar; RNA, Messenger; Ureter; Ureteral Obstruction

To determine whether vascular endothelial cell apoptosis occurs in the late stage of sepsis and, if so, whether administration of a potent vasodilatory peptide adrenomedullin and its newly reported specific binding protein (AM/AMBP-1) prevents sepsis-induced endothelial cell apoptosis.. Polymicrobial sepsis is characterized by an early, hyperdynamic phase followed by a late, hypodynamic phase. Our recent studies have shown that administration of AM/AMBP-1 delays or even prevents the transition from the hyperdynamic phase to the hypodynamic phase of sepsis, attenuates tissue injury, and decreases sepsis-induced mortality. However, the mechanisms responsible for the beneficial effects of AM/AMBP-1 in sepsis remain unknown.. Polymicrobial sepsis was induced by cecal ligation and puncture in adult male rats. Human AMBP-1 (40 microg/kg body weight) was infused intravenously at the beginning of sepsis for 20 minutes and synthetic AM (12 microg/kg body weight) was continuously administered for the entire study period using an Alzert micro-osmotic pump, beginning 3 hours prior to the induction of sepsis. The thoracic aorta and pulmonary tissues were harvested at 20 hours after cecal ligation and puncture (ie, the late stage of sepsis). Apoptosis was determined using TUNEL assay, M30 Cytodeath immunostaining, and electromicroscopy. In addition, anti-apoptotic Bcl-2 and pro-apoptotic Bax gene expression and protein levels were assessed by RT-PCR and Western blot analysis, respectively.. Vascular endothelial cells underwent apoptosis formation at 20 hours after cecal ligation and puncture as determined by three different methods. Moreover, partial detached endothelial cell in the aorta was observed. Bcl-2 mRNA and protein levels decreased significantly at 20 hours after the onset of sepsis while Bax was not altered. Administration of AM/AMBP-1 early after sepsis, however, significantly reduced the number of apoptotic endothelial cells. This was associated with significantly increased Bcl-2 protein levels and decreased Bax gene expression in the aortic and pulmonary tissues.. The above results suggest that vascular endothelial cell apoptosis occurs in late sepsis and the anti-apoptotic effects of AM/AMBP-1 appear to be in part responsible for their beneficial effects observed under such conditions.

Topics: Adrenomedullin; Animals; Apoptosis; Cells, Cultured; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Endothelium, Vascular; In Situ Nick-End Labeling; Infusions, Intravenous; Male; Microscopy, Electron; Peptides; Polymerase Chain Reaction; Rats; Rats, Sprague-Dawley; Receptors, Adrenomedullin; Receptors, Peptide; Reference Values; Sensitivity and Specificity; Sepsis; Vasodilator Agents

The purpose of this study was to test for the presence of liver hypoxia and recovery after reperfusion when blood alcohol levels (BAL) are high. Male rats were fed ethanol intragastrically at a constant rate for 1 month. The pO(2) levels were then measured on the liver surface of these rats, in vivo during laparatomy under isoflurane anesthesia. To measure the response to acute hypoxia, the hepatic blood flow was clamped off at the porta hepatis. When the clamp was released, recovery from hypoxia was measured. A number of hypoxic-inducible genes in the liver were analyzed by means of quantitative RT-PCR as a measure of increased activation of hypoxia initiated transcription. The mRNA levels of genes for adrenomedullin, adrenergic receptor alpha, 1a and 1d, CDK inhibitor 1a, and erythropoietin were all significantly higher at the peaks than troughs. Expression of these same genes in the livers of control rats fed dextrose was lower than at the troughs. Although the mRNA level of the hypoxia-inducible factor (HIF-1alpha) was higher at the trough than at the peak, its protein concentration in the nuclear fraction was not increased at the troughs compared with the peaks. In fact, the nuclear protein level of HIF-1alpha at the peak was significantly higher than in control samples, which is consistent with the presence of hypoxia at the peaks. Further analysis of the HIF-alpha degradation regulation revealed that prolyl 4-hydroxylase (P4ha1) and von Hippel-Lindau syndrome homolog (Vhl) were both up-regulated at the troughs compared with the peaks. The liver surface oxygen levels at the peaks were reduced compared with the control samples. The pO(2) levels fell abruptly when the vessels at the porta hepatis were clamped. When the clamp was removed, allowing reperfusion of the liver, pO(2) returned to baseline levels in the control, and at the troughs but not at the peaks. These results support the hypothesis that hypoxia occurs at the peaks of the BAL cycle and recovery from ischemia is impaired at the peaks.

Topics: Administration, Oral; Adrenomedullin; Animals; Cell Cycle Proteins; Cyclin-Dependent Kinase Inhibitor p21; Disease Models, Animal; Erythropoietin; Ethanol; Hypoxia; Liver; Liver Diseases, Alcoholic; Male; Oligonucleotide Array Sequence Analysis; Oxygen; Peptides; Rats; Rats, Wistar; Receptors, Adrenergic; Reperfusion Injury; RNA, Messenger

We hypothesize that administration of adrenomedullin (AM), an endogenous vasodilator, will ameliorate the hypertension and growth restriction associated with chronic nitric oxide inhibition induced by L-omega nitro-L-arginine methyl ester (L-NAME) infusion in pregnant rats.. Osmotic minipumps were inserted on day 14 of gestation to deliver continuously either AM, L-NAME, AM+L-NAME, or vehicle control. Systolic blood pressure was recorded daily in pregnant rats. Pregnant rats were either sacrificed on gestational days 15, 16, 17, 18, or 22, or they were allowed to deliver at term. The placentas from all of the treated groups were fixed for 24 hr in Bouin solution, sectioned, processed, embedded in paraffin, and stained with hematoxylin and eosin. The placentas were graded for the quality of fetal vessel development in the labyrinth.. Systolic blood pressure was increased in AM+L-NAME-treated rats. The animals that delivered in the AM+L-NAME group exhibited decreased pup weight (L-NAME and AM+L-NAME, 5.2+/-0.1 compared with 6.4+/-0.1 g for both AM and controls, p<0.001) and increased pup mortality (AM+L-NAME, 44.4% compared with 16.7% in L-NAME, 0% in AM and 3.1% in controls, p<0.001 AM+L-NAME compared with controls). Increased decidual necrosis, necrosis in the labyrinth, and deficient fetal vessel development in the labyrinth was identified in the placentas treated with AM+L-NAME.. Addition of the endogenous vasodilator AM to an L-NAME-induced state of chronic NO inhibition did not ameliorate hypertension and growth restriction.

Topics: Adrenomedullin; Animals; Blood Pressure; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Female; Fetal Growth Retardation; Fetal Weight; Infusions, Intravenous; Litter Size; NG-Nitroarginine Methyl Ester; Nitric Oxide; Peptides; Placenta; Pre-Eclampsia; Pregnancy; Rats; Rats, Sprague-Dawley; Systole; Vasodilator Agents

Adrenomedullin is a potent vasodilator peptide originally isolated from a pheochromocytoma. Recently, a novel adrenomedullin receptor has been identified as a complex of calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 2 (RAMP2). To explore the pathophysiological roles of adrenomedullin and its receptor component RAMP2 in ischemic cardiovascular diseases, we studied the changes of adrenomedullin and RAMP2 mRNA in myocardium and aorta in rats with isoproterenol (ISO)-induced myocardial impairment. In ISO-treated rats, heart became enlarged markedly, the ratio of heart to body weight was increased by 54% (P<0.01), and myocardial malondialdehyde content and plasma lactate dehydrogenase activity was elevated by 43% (P<0.01) and 138% (P<0.01), respectively. Immunoreactive adrenomedullin (ADM) in plasma, myocardium and aorta was augmented by 116.7% (P<0.01), 50.8% (P<0.01) and 12.5% (P>0.05), respectively. ADM mRNA in myocardium and aorta was increased by 96.8% (P<0.01) and 38.5% (P<0.01), respectively. RAMP2 mRNA in myocardium and aorta was increased by 19.6% (P<0.05) and 15.8% (P<0.01), respectively. These results suggest that the increase of ADM level and the up-regulation of ADM and RAMP2 gene in myocardium and aorta may be significant in the pathogenesis of ischemic myocardiopathy.

Topics: Adrenomedullin; Animals; Aorta; Disease Models, Animal; Heart; Intracellular Signaling Peptides and Proteins; Isoproterenol; Male; Membrane Proteins; Myocardial Ischemia; Myocardium; Peptides; Rats; Rats, Wistar; Receptor Activity-Modifying Proteins; RNA, Messenger

In pulmonary hypertension, systemic infusion of adrenomedullin (ADM), a potent vasodilator peptide, leads to pulmonary vasodilatation. However, systemic blood pressure declines alike. The present study investigated the effect of aerosolized ADM on pulmonary arterial pressure in surfactant-depleted newborn piglets with pulmonary hypertension. Animals randomly received aerosolized ADM (ADM, n = 6), aerosolized ADM combined with intravenous application of NG-nitro-l-arginine methylester to inhibit nitric-oxide (NO) synthases (ADM + l-NAME, n = 5), or aerosolized normal saline solution (control, n = 6). Aerosol therapy was performed in 30-min intervals for 5 h. After a total experimental period of 8 h, mRNA expression of endothelial and inducible NO synthase and endothelin-1 (ET-1) in lung tissue was quantified using TaqMan real-time polymerase chain reaction. Aerosolized ADM reduced mean pulmonary artery pressure (MPAP) compared with control (p < 0.001; at the end of the study, Delta-MPAP -13.5 +/- 1.4 versus -6.2 +/- 2.4 mm Hg). PaO2 significantly increased in the ADM (DeltaPaO2 243.3 mm Hg) and the ADM + l-NAME group (DeltaPaO2 217.4 mm Hg) compared with the control group (DeltaPaO2 82.9 mm Hg; p < 0.001). Aerosolized ADM did not influence mean systemic arterial pressure (baseline 63.2 +/- 2.7 versus end of the study 66.3 +/- 6.5 mm Hg; not significant). NO synthases gene expressions were 20 to 30% lower with ADM compared with control. ET-1 gene expression was significantly reduced (>50%) after ADM aerosol therapy (p < 0.001). Aerosolized adrenomedullin significantly reduced MPAP without lowering the systemic arterial pressure and improved profoundly the arterial oxygen tension. This effect seems to be mediated at least in part by the reduction of ET-1.

Topics: Adrenomedullin; Aerosols; Animals; Antihypertensive Agents; Blood Pressure; Disease Models, Animal; Endothelin-1; Hypertension, Pulmonary; Nitric Oxide Synthase; Oxygen; Peptides; Swine

Circulating endothelial progenitor cells (EPCs) migrate to injured vascular endothelium and differentiate into mature endothelial cells. We investigated whether transplantation of vasodilator gene-transduced EPCs ameliorates monocrotaline (MCT)-induced pulmonary hypertension in rats.. We obtained EPCs from cultured human umbilical cord blood mononuclear cells and constructed plasmid DNA of adrenomedullin (AM), a potent vasodilator peptide. We used cationic gelatin to produce ionically linked DNA-gelatin complexes. Interestingly, EPCs phagocytosed plasmid DNA-gelatin complexes, which allowed nonviral, highly efficient gene transfer into EPCs. Intravenously administered EPCs were incorporated into the pulmonary vasculature of immunodeficient nude rats given MCT. Transplantation of EPCs alone modestly attenuated MCT-induced pulmonary hypertension (16% decrease in pulmonary vascular resistance). Furthermore, transplantation of AM DNA-transduced EPCs markedly ameliorated pulmonary hypertension in MCT rats (39% decrease in pulmonary vascular resistance). MCT rats transplanted with AM-expressing EPCs had a significantly higher survival rate than those given culture medium or EPCs alone.. Umbilical cord blood-derived EPCs had a phagocytosing action that allowed nonviral, highly efficient gene transfer into EPCs. Transplantation of AM gene-transduced EPCs caused significantly greater improvement in pulmonary hypertension in MCT rats than transplantation of EPCs alone. Thus, a novel hybrid cell-gene therapy based on the phagocytosing action of EPCs may be a new therapeutic strategy for the treatment of pulmonary hypertension.

Topics: Adrenomedullin; Animals; Cells, Cultured; Disease Models, Animal; DNA; Drug Carriers; Endothelium, Vascular; Fetal Blood; Gelatin; Gene Transfer Techniques; Genetic Therapy; Green Fluorescent Proteins; Humans; Hybrid Cells; Hypertension, Pulmonary; Luminescent Proteins; Male; Monocrotaline; Peptides; Phagocytosis; Pulmonary Circulation; Rats; Rats, Nude; Stem Cell Transplantation; Stem Cells; Survival Rate; Vascular Resistance

To evaluate the effect of adrenomedullin (ADM) on pulmonary circulation and the change of ADM in plasma and lung tissue from rats with hypoxic pulmonary hypertension.. Fifty Wistar rats were divided into the control group (10 rats) and the hypoxic group (40 rats). The animal model of pulmonary hypertension was established by exposing the rats to normobaric hypoxic conditions for 3 weeks; Mean pulmonary arterial pressure (mPAP) was measured by right cardiac catheterization, and mean systemic blood pressure (mSBP) was measured by left femoral catheterization. The thickness of pulmonary arterioles was measured by a computerized image analyser. The level of ADM in plasma and lung tissue was measured by radioimmunoassay. We ADM was administered in doses of 0.5, 1.0, 2.0 nmol/kg respectively to 30 hypoxic rats and the changes in mPAP and mSBP to ADM was evaluated.. Rats exposed to hypoxia developed pulmonary hypertension, the mPAP in the control group being (16 +/- 3) mm Hg and in hypoxic group being (30 +/- 4) mm Hg, and the difference was significant (P < 0.01). The hypoxic rats developed significantly thickened pulmonary arterioles. The plasma level of ADM was (288 +/- 24) pg/ml in the hypoxic rats and (168 +/- 25) pg/ml in the control group the difference being significant (P < 0.01). The level of ADM in the lung homogenates from the hypoxic group was (2 319 +/- 238) pg/g and that from the control group was (1 153 +/- 127) pg/g and the difference was significant (P < 0.01). The ADM levels had a positive correlation with the mPAP (gamma = 0.567 and 0.612 P < 0.01, respectively). Administration of exogenous ADM reduced the mPAP in a dose-dependent manner in hypoxic rats, and the effect lasted 5 approximately 15 minutes.. ADM has a relaxing effect on pulmonary circulation. The change of ADM in plasma and lung tissue may serve as a compensatory mechanism in maintaining the stability of pulmonary circulation in hypoxic condition.

Topics: Adrenomedullin; Animals; Blood Pressure; Disease Models, Animal; Hypertension, Pulmonary; Hypoxia; Male; Oxygen; Peptides; Pulmonary Artery; Pulmonary Circulation; Rats; Rats, Wistar

To investigate the effects of the dual angiotensin-converting enzyme (ACE) + neutral endopeptidase (NEP) inhibitor, MDL-100,240 (MDL), on hypertension and cardiovascular damage in male heterozygous transgenic Ren2 rats.. Blood-pressure-matched 5-week-old transgenic rats were allocated to receive a placebo, MDL (40 mg/kg body weight) or ramipril (5 mg/kg body weight) for 8 weeks. During the last 4 weeks, the bradykinin B2 receptor antagonist, icatibant (0.5 mg/kg body weight), was also administered subcutaneously via osmotic minipumps to 50% of the transgenic rats receiving MDL or ramipril. We measured blood pressure, heart weight, structural changes in the aorta and small resistance mesenteric arteries, and the plasma concentrations of adrenomedullin, aldosterone, atrial natriuretic peptide and cGMP. To verify if MDL could regress long-standing hypertension and full-blown cardiovascular damage, 3-month-old transgenic rats received MDL subcutaneously (3 and 10 mg/kg body weight, osmotic minipumps) for 4 weeks.. Compared with placebo, MDL decreased blood pressure (P < 0.001) and prevented left ventricular hypertrophy (P < 0.001), being as effective as ramipril. Hypertrophy and dilatation of the aorta and hypertrophy of the resistance arterioles were all prevented by MDL. Plasma aldosterone was decreased by MDL (P < 0.001), but not by ramipril. Icatibant blunted the decrease in blood pressure (P < 0.001), decreased cGMP concentrations and blunted the decrease in cross-sectional area of the resistance arteries in MDL-treated, but not in ramipril-treated, transgenic rats. In 3-month-old transgenic rats, MDL normalized blood pressure, regressed left ventricular hypertrophy and decreased adrenomedullin concentrations.. The dual ACE+NEP inhibitor MDL prevented and regressed severe hypertension and cardiovascular damage, even in this model of severe angiotensin II-dependent hypertension with pronounced cardiovascular damage. Enhancement of the effects of bradykinin has a role in such favourable outcomes.

Topics: Adrenomedullin; Aldosterone; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Animals, Genetically Modified; Antihypertensive Agents; Benzazepines; Biomarkers; Blood Pressure; Body Weight; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Enzyme Inhibitors; Heart; Hypertension; Male; Models, Cardiovascular; Neprilysin; Organ Size; Peptides; Pyridines; Ramipril; Rats; Rats, Sprague-Dawley; Receptor, Bradykinin B2; Receptors, Bradykinin; Severity of Illness Index; Systole; Treatment Outcome; Vasoconstrictor Agents

The aim of the present study was to investigate the effect of adrenomedullin (ADM) on vascular calcification.. The vascular calcification model was established in rats (VND group) by using vitamin D3 (300,000 IU/kg) and nicotine (25 mg/kg, two doses). The effect of liposome-encapsulated ADM was observed. Vascular calcium content, alkaline phosphatase (ALP) activity, ADM in aortic tissue and plasma, binding ability of 125I-ADM for ADM receptor on vascular plasma membrane and content of cAMP in vessels were measured.. Compared with control rats, the aortic calcium content and vascular ALP activity in rats of the VDN group was obviously increased; in addition ADM concentrations in plasma and vessels of rats in VDN group were increased. But the maximum binding sites of 125I-ADM for ADM receptor (Bmax) on vascular plasma membrane in rats of VDN group were significantly decreased compared with control rats. The affinity of 125I-ADM for the ADM receptor was reduced, as shown by the Kd value and vascular cAMP content being reduced in rats of the VDN group compared to the control group. The in vitro response of isolated vessels to ADM incubation was weakened. Administration of empty liposome had no effect on vascular calcification. But administration of ADM significantly decreased vascular calcium content and ALP activity. The Bmax of 125I-ADM for ADM receptors on vascular plasma membrane increased by 17.7% (p < 0.01), and the value of Kd decreased by 36.2% (P < 0.01) in rats treated with ADM as compared with rats of the VDN group. In addition, the vascular cAMP content and the response to ADM in isolated aorta were markedly increased.. Vascular calcification induced an alteration of the vascular ADM-ADM receptor-cAMP pathway. Treatment with exogenous ADM inhibited vascular calcification by improving the vascular ADM-ADM receptor-cAMP pathway.

Topics: Adrenomedullin; Alkaline Phosphatase; Animals; Aorta, Thoracic; Aortic Diseases; Arteriosclerosis; Calcinosis; Calcium; Culture Techniques; Cyclic AMP; Disease Models, Animal; Liposomes; Male; Myocardium; Peptides; Rats; Rats, Wistar; Receptors, Adrenomedullin; Receptors, Peptide

Short-term administration of adrenomedullin, a recently discovered peptide with potent vasodilator, natriuretic, and aldosterone-inhibitory actions, has beneficial effects in experimental and clinical heart failure. The effects of prolonged adrenomedullin administration have not previously been assessed in this setting. Consequently, in 16 sheep with pacing-induced heart failure, we infused either adrenomedullin (10 ng/kg per minute; n=8) or a vehicle control (Hemaccel; n=8) for 4 days. Compared with control data, infusion of adrenomedullin persistently increased circulating levels of the peptide (by approximately 9.5 pmol/L; P<0.001), in association with prompt (15 minutes) and sustained (4 days) increases in cardiac output (day 4, 27%), and reductions in peripheral resistance (30%), mean arterial pressure (13%), and left atrial pressure (24%; all, P<0.001). Adrenomedullin also significantly enhanced urinary sodium excretion (day 4, 3-fold; P<0.05), creatinine excretion (1.2-fold; P<0.001), and creatinine clearance (1.4-fold; P<0.001) over the 4 days of treatment, whereas urine volume and cAMP excretion tended to be elevated (both, 0.1>P>0.05). Plasma renin activity was increased (P<0.05), whereas aldosterone levels were reduced in a sustained fashion (P<0.01). Plasma endothelin rose transiently (hours 1 to 6) after initiation of treatment (P<0.05). Despite substantial cardiac unloading, plasma concentrations of the natriuretic peptides were not significantly different from control. In conclusion, long-term administration of adrenomedullin induces pronounced and sustained cardiovascular and renal effects in experimental heart failure, including reductions in cardiac preload and afterload, as well as augmentation of cardiac output, sodium excretion, and glomerular filtration. These findings support the concept of adrenomedullin as a protective hormone during hemodynamic compromise with therapeutic potential in heart failure.

Topics: Adrenomedullin; Aldosterone; Animals; Atrial Natriuretic Factor; Blood Pressure; Cardiac Output; Cardiac Pacing, Artificial; Cyclic AMP; Disease Models, Animal; Endothelins; Female; Heart Failure; Hemodynamics; Hydrocortisone; Infusions, Intravenous; Kidney; Natriuretic Peptide, Brain; Peptides; Renin; Sheep; Time; Treatment Outcome; Vascular Resistance

Adrenomedullin (AM) is a potent vasodilating peptide and is involved in cardiovascular and renal disease. In the present study, we investigated the role of AM in cardiac and renal function in streptozotocin (STZ)-induced diabetic rats. A single tail-vein injection of adenoviral vectors harboring the human AM gene (Ad.CMV-AM) was administered to the rats 1-wk post-STZ treatment (65 mg/kg iv). Immunoreactive human AM was detected in the plasma and urine of STZ-diabetic rats treated with Ad.CMV-AM. Morphological and chemical examination showed that AM gene delivery significantly reduced glycogen accumulation within the hearts of STZ-diabetic rats. AM gene delivery improved cardiac function compared with STZ-diabetic rats injected with control virus, as observed by decreased left ventricular end-diastolic pressure, increased cardiac output, cardiac index, and heart rate. AM gene transfer significantly increased left ventricular long axis (11.69 +/- 0.46 vs. 10.31 +/- 0.70 mm, n = 10, P < 0.05) and rate of pressure rise and fall (+6,090.1 +/- 597.3 vs. +4,648.5 +/- 807.1 mmHg/s), (-4,902.6 +/- 644.2 vs. -3,915.5 +/- 805.8 mmHg/s, n = 11, P < 0.05). AM also significantly attenuated renal glycogen accumulation and tubular damage in STZ-diabetic rats as well as increased urinary cAMP and cGMP levels, along with increased cardiac cAMP and Akt phosphorylation. We also observed that delivery of the AM gene caused an increase in body weight along with phospho-Akt and membrane-bound GLUT4 levels in skeletal muscle. These results suggest that AM plays a protective role in hyperglycemia-induced glycogen accumulation and cardiac and renal dysfunction via Akt signal transduction pathways.

Topics: Adenoviridae; Adrenomedullin; Animals; Blood Glucose; Body Weight; Cyclic AMP; Cyclic GMP; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Disease Models, Animal; Gene Expression; Genetic Therapy; Genetic Vectors; Glucose Transporter Type 4; Glycogen; Heart; Heart Function Tests; Humans; Kidney; Male; Monosaccharide Transport Proteins; Muscle Proteins; Muscle, Skeletal; Myocardium; Peptides; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Streptozocin; Ventricular Function, Left

Topics: Adrenomedullin; Animals; Blood Pressure; Disease Models, Animal; Genetic Markers; Mice; Models, Cardiovascular; Peptides; Vascular Diseases

In this study, we used the animal model of preeclampsia. The blood pressure in animals receiving L-NAME at 25 mg/day were significantly higher compared to that of rats receiving saline solution only. In addition, L-NAME treated rats showed a high fetal mortality as compared with intact rats. Also, we demonstrated infusion of AM reverse the hypertension and decrease in pup mortality induced by L-NAME during pregnancy. We showed that the AM mRNA levels predominantly exists in a high level in the placenta, uterus and ovary as compared with other tissues. These evidences suggest that AM may have a possible important role during pregnancy. In conclusion, the present study suggest that L-NAME-induced elevated blood pressure and increased fetal mortality can be reversed by low dose of AM. Thus AM may play an important role in the regulation of blood pressure, the blood supply to the utero-placental unit and fetal development.

Topics: Adrenomedullin; Animals; Blood Pressure; Disease Models, Animal; Female; Genitalia, Female; Peptides; Placental Circulation; Pre-Eclampsia; Pregnancy; Rats; Rats, Wistar; RNA, Messenger

Omapatrilat (OMA), a vasopeptidase inhibitor, simultaneously inhibits angiotensin-converting enzyme (ACE) and neutral endopeptidase, which degrades vasodilatory factors (eg, ADM) and natriuretic peptides. Based on the beneficial cardiorenal and humoral properties of the natriuretic peptides, we hypothesized that an acute vasopeptidase inhibitor with or without diuretic would result in more favorable cardiorenal and hormonal actions than ACE inhibition plus diuretic (ACEI+D) in congestive heart failure.. We compared the actions of OMA alone and with diuretic (OMA+D) to ACEI+D in a model of pacing-induced congestive heart failure. OMA+D decreased pulmonary arterial and pulmonary capillary wedge pressures to a greater level than OMA alone or ACEI+D. Glomerular filtration rate was lower with ACEI+D than with either OMA group. Plasma renin activity and aldosterone immediately increased with ACEI+D, whereas OMA+D resulted in higher plasma renin activity and a delayed increase in aldosterone. OMA alone did not increase plasma renin activity and aldosterone, but resulted in a sustained increase in plasma adrenomedullin, with higher urinary atrial natriuretic peptide, adrenomedullin, and cGMP excretions than with ACEI+D.. Acute administration of OMA with or without diuretic results in more favorable cardiorenal and humoral responses in experimental congestive heart failure than does ACEI+D. There is no acute activation of renin and aldosterone with OMA alone such as occurs with ACEI+D and OMA+D. Thus, OMA with or without a diuretic possesses beneficial cardiorenal and humoral actions comparable to those observed with ACEI+D that can be explained by potentiation of natriuretic peptides.

Topics: Adrenomedullin; Aldosterone; Angiotensin-Converting Enzyme Inhibitors; Animals; Atrial Natriuretic Factor; Cardiac Pacing, Artificial; Cyclic GMP; Disease Models, Animal; Diuretics; Dogs; Drug Therapy, Combination; Glomerular Filtration Rate; Heart Failure; Heart Function Tests; Hemodynamics; Kidney Function Tests; Male; Neprilysin; Peptides; Peptidyl-Dipeptidase A; Protease Inhibitors; Pulmonary Wedge Pressure; Pyridines; Renin; Thiazepines; Treatment Outcome

The angiogenic peptide adrenomedullin (ADM) has been implicated as a mediator of the increased risk of endometrial hyperplasia and cancer resulting from the use of tamoxifen for the treatment and prevention of breast cancer. ADM has been shown to be induced by tamoxifen in the endometrium and to be a growth factor for endometrial endothelial cells in vitro. We have now shown ADM to be strongly angiogenic in the mouse subcutaneous sponge angiogenesis assay. To examine the role of ADM in tumor growth, the ADM cDNA was transfected into endometrial carcinoma cells followed by xenografting into athymic mice. Two endometrial cancer cell lines were employed, those in which transfection and expression of ADM resulted in no effect on growthin vitro (Ishikawa cells) and those in which expressionof exogenous ADM stimulated in vitro growth (RL95.2 cells). A clear enhancement of tumor growth was seen with both cell lines but the effect was far greater with the RL95.2 cells. We conclude that ADM is pro-tumorigenic by stimulating either angiogenesis alone or by stimulating angiogenesis and carcinoma cell growth directly. The combined activities lead to a striking increase in tumor growth. These results provide the first direct evidence of tumorigenic activity of ADM and provide further support for ADMs involvement in tamoxifen induced endometrial neoplasia.

Topics: Adrenomedullin; Angiogenesis Inducing Agents; Animals; Calcitonin Gene-Related Peptide; Disease Models, Animal; Endometrial Neoplasms; Female; Humans; Mice; Mice, Inbred C57BL; Neoplasm Transplantation; Neovascularization, Pathologic; Peptide Fragments; Peptides; Transfection; Transplantation, Heterologous

Advances in the treatment of heart failure may require manipulation of neurohumoral responses to cardiac impairment in addition to the established strategy of angiotensin-converting enzyme (ACE) inhibition. Importantly, since new treatments are likely to be used in conjunction with ACE inhibition therapy, the effects of the combination of agents need to be assessed. Adrenomedullin (ADM) is a peptide with potent vasodilator and natriuretic actions. ADM and an ACE inhibitor (captopril) were administered for 3 h both separately and together in eight sheep with heart failure. Both ADM and captopril alone reduced arterial pressure, left atrial pressure (greater with captopril) and peripheral resistance, and increased cardiac output (greater with ADM). Compared with either treatment separately, combined ADM+captopril produced directionally similar but significantly greater changes in all haemodynamic variables (particularly falls in blood pressure). ADM increased renal sodium and creatinine excretion and creatinine clearance, and maintained urine output. Captopril and ADM+captopril reduced creatinine excretion and creatinine clearance, while urine volume and sodium excretion were not significantly altered. Plasma renin activity rose with all active treatments, whereas angiotensin II levels rose during ADM, but fell during captopril and ADM+captopril. Aldosterone was reduced by all active treatments. ADM+captopril reduced plasma noradrenaline (norepinephrine). In conclusion, short-term co-treatment with ADM and an ACE inhibitor produced significantly greater decreases in ventricular filling pressures and cardiac afterload, and increases in cardiac output, compared with either treatment alone. Despite the greater falls in blood pressure (and presumably renal perfusion pressure), renal function was maintained at a level similar to that observed with captopril alone.

Topics: Adrenomedullin; Angiotensin-Converting Enzyme Inhibitors; Animals; Captopril; Cardiotonic Agents; Creatinine; Disease Models, Animal; Drug Therapy, Combination; Female; Heart Failure; Hemodynamics; Kidney; Peptides; Potassium; Sheep; Sodium; Vasodilator Agents

Calcitonin gene-related peptide (CGRP) and adrenomedullin (ADM) are potent vasodilators in humans and improved myocardial ischemia is observed after CGRP administration. Receptors for CGRP and ADM were already identified in heart. Receptor activity-modifying proteins (RAMPs) determine the ligand specificity of the calcitonin receptor-like receptor (CRLR); co-expression of RAMP1 and CRLR results in a CGRP receptor, whereas the association of RAMP2 or RAMP3 with CRLR gives an ADM receptor. As CGRP and ADM may play a beneficial role in heart failure, we investigated whether the CGRP and ADM receptors are upregulated in chronic heart failure. We have used semi-quantitative RT-PCR and Western-blot analysis to detect and quantify the mRNA and the protein of RAMP1 and RAMP3 in both atria and ventricles of failing hearts 6 months after aortic banding in rats. Our results showed for the first time an up-regulation of RAMP1 and RAMP3 mRNAs and proteins in this model of cardiac failure. No change was observed in mRNAs coding for CRLR, RAMP2, RDC1 (canine orphan receptor), and ADM. The present results suggested after congestive heart failure in adult rats, an up-regulation of the CGRP receptor (by an increase in RAMP1 that is associated with CRLR) in atria and ventricles and of ADM receptor (by increased RAMP3 expression that is associated with CRLR) in atria. These findings support a functional role for CGRP and ADM receptors to compensate the chronic heart failure in rats.

Topics: Adrenomedullin; Animals; Aortic Valve Stenosis; Calcitonin Gene-Related Peptide; Calcitonin Receptor-Like Protein; Chronic Disease; Disease Models, Animal; Heart Atria; Heart Failure; Heart Ventricles; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Myocardium; Peptides; Rats; Rats, Wistar; Receptor Activity-Modifying Protein 1; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; Receptor Activity-Modifying Proteins; Receptors, Calcitonin; Receptors, Cell Surface; Receptors, Chemokine; Receptors, CXCR; Receptors, G-Protein-Coupled; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Up-Regulation

The recently discovered vasodilating and positive inotropic peptide, adrenomedullin (ADM), has strong natriuretic actions. ADM-induced natriuresis is caused by an increase in glomerular filtration rate and a decrease in distal tubular sodium reabsorption. Although ADM is activated in human and experimental heart failure, the role of ADM in the kidney in heart failure remains undefined.. The present study was performed to determine the renal hemodynamic and urinary excretory actions of exogenously administered ADM in a canine model of acute heart failure produced by rapid ventricular pacing. Experimental acute heart failure was characterized by a decrease in cardiac output and an increase in pulmonary capillary wedge pressure with an increase in plasma ADM concentration. Intrarenal infusion of ADM (1 and 25 ng/kg/min) induced an increase in urinary sodium excretion in the normal control dogs (change in urinary sodium excretion [Delta UNaV], +94.5 microEq/min during 1 ng/kg/min ADM infusion and +128.1 microEq/min during 25 ng/kg/min ADM infusion). In the acute heart failure dogs, intrarenal ADM infusion resulted in an attenuated increase in urinary sodium excretion (Delta UNaV, +44.8 microEq/min during 1 ng/kg/min ADM infusion and +51.8 microEq/min during 25 ng/kg/min ADM infusion). Both glomerular and tubular actions of ADM were attenuated in the acute heart failure group compared with responses in the normal control group.. The present study shows that the renal natriuretic responses to ADM are markedly attenuated in experimental acute heart failure. This study provides insight into humoral mechanisms that may promote sodium retention in heart failure via a renal hyporesponsiveness to natriuretic actions of ADM.

Topics: Adrenomedullin; Animals; Attention; Disease Models, Animal; Dogs; Heart Failure; Hemodynamics; Infusions, Intravenous; Kidney; Natriuresis; Natriuretic Agents; Peptides

Adrenomedullin (AM) is a potent vasodilator and natriuretic peptide that plays an important role in cardiovascular function. In this study, we employed a somatic gene delivery approach to explore its potential protective role in renovascular hypertension. A single tail vein injection of adenovirus harboring the human AM gene significantly blunted a blood pressure increase that lasted for more than 3 wk in two-kidney one-clip (2K1C) hypertensive rats. The expression of human AM mRNA was detected in the kidney, adrenal gland, heart, lung, and liver, and immunoreactive human AM was detected in the plasma and urine of 2K1C rats after human AM gene delivery. A maximal blood pressure difference of 28 mmHg was observed 10 days after AM gene delivery, compared with that in rats injected with the control virus carrying the LacZ gene. Human AM gene delivery significantly attenuated increases in the ratio of left ventricular weight to heart weight, cardiomyocyte diameter, and fibrosis in the heart, as well as glomerular sclerosis, tubular injuries, and protein casts in the kidney. The beneficial effects of AM gene delivery were accompanied by increased urinary cAMP levels, indicating activation of AM receptors. These findings provide new insights into the role of AM in renovascular hypertension and may have significance in therapeutic applications in cardiovascular diseases.

Topics: Adenoviridae; Adrenomedullin; Animals; Blood Pressure; Cardiomegaly; Disease Models, Animal; Fibrosis; Gene Expression; Gene Transfer Techniques; Genetic Therapy; Glomerulosclerosis, Focal Segmental; Humans; Hypertension, Renovascular; Male; Organ Size; Peptides; Radioimmunoassay; Rats; Rats, Wistar; RNA, Messenger

We examined the effects of TCV-116, an angiotensin II type 1 receptor antagonist, on endothelial-cell nitric oxide synthase (eNOS), inducible NOS (iNOS), and adrenomedullin (ADM) expression in the left ventricle (LV) and evaluated these relation to myocardial remodeling in failing heart of Dahl salt-sensitive hypertensive rats (DS) fed a high-salt diet. TCV-116 (DSHF-T, 5 mg/kg/day, subdepressor dose) or vehicle (DSHF-V) were given from left ventricular hypertrophy to heart failure stage for 7 weeks. Markedly increased left ventricular end-diastolic diameter and reduced fractional shortening in DSHF-V was significantly ameliorated in DSHF-T. The eNOS mRNA and protein in the LV was significantly suppressed in DSHF-V compared with control rats (DR-C), and significantly increased in DSHF-T compared with DSHF-V. The iNOS mRNA and protein, ADM mRNA and immunoreactive ADM contents, and type I collagen mRNA in the LV were significantly increased in DSHF-V compared with DR-C, and significantly decreased in DSHF-T compared with DSHF-V. DSHF-V showed a significant increase of the wall-to-lumen ratio, perivascular fibrosis, and myocardial fibrosis, with all these parameters being significantly improved by TCV-116. In conclusion, myocardial remodeling and heart failure in DS rats fed a high-salt diet were significantly ameliorated by a subdepressor dose of TCV-116, which may be due to a increased in eNOS and a decreased in iNOS mRNA and protein expression in the LV. Moreover, the ADM mRNA and immunoreactive ADM contents are upregulated in failing heart of DS rats fed a high-salt diet, and increased ADM expression may have a role in the defense mechanism against further cardiac dysfunction and impaired myocardial remodeling.

Topics: Adrenomedullin; Angiotensin Receptor Antagonists; Animals; Benzimidazoles; Biphenyl Compounds; Disease Models, Animal; Endothelium, Vascular; Heart Failure; Hypertrophy, Left Ventricular; Immunohistochemistry; Male; Myocardial Reperfusion; Myocardium; Nitric Oxide; Organ Size; Peptides; Rats; Rats, Inbred Dahl; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Receptors, Angiotensin; Tetrazoles; Ventricular Dysfunction, Left; Ventricular Remodeling

Adrenomedullin (AM), a potent vasodilatory peptide, has recently been reported to be involved in the altered cardiovascular responses under various pathophysiological conditions. Although the increase in plasma AM levels is associated with upregulation of AM gene expression in various tissues, it remains unknown whether the gut is an important source of AM release under such conditions. To determine this, adult male rats were subjected to sepsis by cecal ligation and puncture (CLP) followed by fluid resuscitation. Systemic and portal blood samples were collected simultaneously at 10 and 20 h after CLP or sham operation. A portion of the jejunum was also harvested. Plasma and tissue levels of AM were then determined by RIA. The localization of AM in the intestinal tissue was examined using immunohistochemistry. In an additional group of normal rats, synthetic rat AM (8.5 microg/kg body wt) was infused for 15 min at a constant rate via the portal vein (which produces a similar level of AM as observed during sepsis). Cardiac output, stroke volume, total peripheral resistance, and microvascular blood flow in various organs were determined before and 30 min after AM administration. The results indicate that AM levels in portal blood were significantly higher than in systemic blood at 10 and 20 h after CLP. Intestinal AM was also markedly elevated. Immunohistochemical visualization shows that AM immunostainings were localized in the mucosa, submucosa, and intestinal nerve fibers, and they were increased at 10-20 h post-CLP. Because AM-immunopositive nerve fibers increase in the gut during sepsis, a nerve pathway may be involved in the regulation of vascular reactivity by this peptide. Moreover, intraportal administration of AM increased cardiac output, stroke volume, and microvascular blood flow in the liver, kidney, small intestine, and spleen. In contrast, total peripheral resistance was significantly reduced. Thus the gut plays an important role in increasing the levels of circulating AM during the progression of sepsis. Gut-derived AM appears to be a major factor in initiating the hyperdynamic response after the onset of sepsis.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Hemodynamics; Immunohistochemistry; Intestine, Small; Male; Peptides; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Sepsis; Vasodilator Agents

To study the biosyntheses and pathophysiological roles of adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) in septic shock, we compared the time course of plasma concentrations of these peptides and blood pressure in rats injected with either 0.9% saline (control group) or lipopolysaccharide (LPS group). The plasma AM concentration in the LPS group did not increase 30 and 60 min after LPS injection, at which time points the blood pressure remained low. Thereafter, AM rapidly increased, and it amounted to 35 times the basal value 4 h after injection, when the blood pressure returned to the basal level. The increment of plasma PAMP in the LPS group was lower than that of AM. We also examined the tissue concentration of AM and PAMP--as well as the tissue expression of proadrenomedullin (proAM) mRNA--in the LPS and control groups. LPS significantly increased the tissue concentrations of AM and PAMP in the lung, but decreased them in the adrenal gland and cardiac atrium. The LPS injection augmented proAM gene transcription in the lung, adrenal gland and aorta. In an immunohistochemical examination, AM staining was intense in alveolar endothelial cells of the lung in the LPS group. Thus, this septic shock model had high plasma levels of PAMP as well as AM, while the biosynthesis and secretion of the two peptides may have been differentially regulated in various tissues of rats injected with LPS. The present results suggest that these two bioactive peptides may play different roles in the pathophysiology of septic shock.

Topics: Adrenomedullin; Animals; Blood Pressure; Disease Models, Animal; Gene Expression; Lipopolysaccharides; Lung; Male; Peptide Fragments; Peptides; Proteins; Rats; Rats, Wistar; RNA, Messenger; Shock, Septic

Pressure overload, such as hypertension, to the heart causes pathological cardiac hypertrophy, whereas chronic exercise causes physiological cardiac hypertrophy, which is defined as athletic heart. There are differences in cardiac properties between these two types of hypertrophy. We investigated whether mRNA expression of various cardiovascular regulating factors differs in rat hearts that are physiologically and pathologically hypertrophied, because we hypothesized that these two types of cardiac hypertrophy induce different molecular phenotypes. We used the spontaneously hypertensive rat (SHR group; 19 wk old) as a model of pathological hypertrophy and swim-trained rats (trained group; 19 wk old, swim training for 15 wk) as a model of physiological hypertrophy. We also used sedentary Wistar-Kyoto rats as the control group (19 wk old). Left ventricular mass index for body weight was significantly higher in SHR and trained groups than in the control group. Expression of brain natriuretic peptide, angiotensin-converting enzyme, and endothelin-1 mRNA in the heart was significantly higher in the SHR group than in control and trained groups. Expression of adrenomedullin mRNA in the heart was significantly lower in the trained group than in control and SHR groups. Expression of beta(1)-adrenergic receptor mRNA in the heart was significantly higher in SHR and trained groups than in the control group. Expression of beta(1)-adrenergic receptor kinase mRNA, which inhibits beta(1)-adrenergic receptor activity, in the heart was markedly higher in the SHR group than in control and trained groups. We demonstrated for the first time that the manner of mRNA expression of various cardiovascular regulating factors in the heart differs between physiological and pathological cardiac hypertrophy.

Topics: Actins; Adrenomedullin; Animals; Blood Pressure; Body Weight; Cardiomegaly; Disease Models, Animal; Gene Expression Regulation; Hemodynamics; Natriuretic Peptide, Brain; Peptides; Peptidyl-Dipeptidase A; Phenotype; Physical Conditioning, Animal; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptor, Muscarinic M2; Receptors, Adrenergic, beta-1; Receptors, Muscarinic; Reference Values; Swimming; Transcription, Genetic

The effect of adrenomedullin, a vasodilatory peptide on transient middle cerebral artery (MCA) occlusion was investigated in rats.. Transient MCA occlusion for 2 hours was made by using the intra-arterial suture method, followed by reperfusion.. An intravenous infusion of adrenomedullin (1 microg/kg/min) from one hour before ischemia to one hour after ischemia significantly reduced the infarct size and improved neurological deficits (p<0.05), without affecting systemic blood pressure or other physiological parameters. The infarct size was reduced with adrenomedullin by 25.4+/-12.7%, 31.3+/-5.8%, 31.6+/-6.1% respectively at the coronal level 6, 8 and 10 mm posterior from the frontal pole. Adrenomedullin also significantly inhibited the increase in myeloperoxidase (MPO) activity in the MCA area of the ischemic hemisphere after 22-hour reperfusion (control: 0.205+/-0.054 unit/g wet tissue, adrenomedullin group: 0.047+/-0.009 unit/g wet tissue, p<0.0001).. These data suggest that adrenomedullin reduces acute ischemic brain injury and one of is neuroprotective mechanisms may be derived from inhibition of the infiltration of neutrophils into the ischemic tissue.

Topics: Adrenomedullin; Animals; Brain Ischemia; Disease Models, Animal; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Male; Neutrophils; Peptides; Peroxidase; Rats; Rats, Wistar; Reperfusion Injury; Vasodilator Agents

We investigated the potential roles of adrenomedullin (AM) in cardiovascular and renal function by somatic gene delivery. We showed that a single intravenous injection of the human AM gene under the control of cytomegalovirus promoter/enhancer induces a prolonged delay in blood pressure rise for several weeks in spontaneously hypertensive rats, Dahl salt-sensitive, DOCA-salt, and two-kidney one-clip hypertensive rats as compared to their respective controls injected with a reporter gene. Expression of the human AM transcript was identified in the heart, kidney, lung, liver and aorta of the rat after adenovirus-mediated AM gene delivery by RT-PCR followed by Southern blot analysis. Immunoreactive human AM levels were measured in rat plasma and urine following AM gene delivery. AM gene delivery induced significant reduction of left ventricular mass in these hypertensive animal models. It also reduces urinary protein excretion and increases glomerular filtration rate, renal blood flow and urinary cAMP levels. AM gene transfer attenuated cardiomyocyte diameter and interstitial fibrosis in the heart, and reduced glomerular sclerosis, tubular disruption, protein cast accumulation and renal cell proliferation in the kidney. In the rat model with myocardial ischemia/reperfusion injury, AM gene delivery significantly reduced myocardial infarction, apoptosis, and superoxide production. Furthermore, local AM gene delivery significantly inhibited arterial thickening, promoted re-endothelialization and increased vascular cGMP levels in rat artery after balloon angioplasty. Collectively, these results indicate that human AM gene delivery attenuates hypertension, myocardial infarction, renal injury and cardiovascular remodeling in animal models via cAMP and cGMP signaling pathways. These findings provide new insights into the role of AM in cardiovascular and renal function.

Topics: Adenoviridae; Adrenomedullin; Animals; Cardiomegaly; Cardiomyopathies; Disease Models, Animal; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Humans; Hypertension; Kidney Diseases; Male; Myocardial Infarction; Peptides; Rats; Rats, Inbred Dahl; Rats, Inbred SHR; Streptozocin; Tunica Intima; Ventricular Remodeling

We have reported that adrenomedullin (AM)-induced vasodilation is at least in part nitric oxide (NO)-cGMP-dependent in the rat. Although it is well known that NO is much involved in the erectile function, it is controversial as to whether AM influences the erectile function. Thus, we examined the effects of AM on intracavernous pressure (ICP) during penile erection. The left carotid artery of rats was cannulated to monitor of mean arterial pressure (MAP). Bipolar electrodes were positioned on the cavernous nerve. The right cavernous body was cannulated with a needle connected to a pressure transducer to monitor ICP. Electrical stimulation (ES) increased ICP in a voltage-dependent manner. Elevation of ICP continued during ES. The intracavernous injection of 0.5 nmol AM significantly potentiated ES-induced increases in both maximal developed ICP/MAP and area under the curve (ICP trace; AUC). Since AM slightly lowered MAP, ICP was normalized by MAP. i.v. administration of N(omega)-nitro-L-arginine, a NO synthase inhibitor, markedly decreased AM/ES-induced ICP elevation. However, in the presence of E-4021, a cGMP-specific phosphodiesterase inhibitor, AM further increased both ICP/MAP and AUC. These results suggest that a NO-cGMP pathway is involved in the regulation of AM-induced rat cavernous vasorelaxation.

Topics: Adrenomedullin; Animals; Arginine; Cyclic GMP; Disease Models, Animal; Enzyme Inhibitors; Erectile Dysfunction; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Penile Erection; Peptides; Phosphodiesterase Inhibitors; Piperidines; Quinazolines; Rats; Rats, Wistar

Adrenomedullin (AM) has vasodilator and diuretic actions, similarly to natriuretic peptides. AM receptor complexes are composed of calcitonin receptor-like receptor (CRLR) and receptor-activity modifying protein-2 (RAMP2), or CRLR and RAMP3. We aimed to know whether gene expression of AM and AM receptor complexes are regulated in kidneys under pathophysiological conditions. Expression of AM, RAMP2, RAMP3 and CRLR mRNA was studied in the remnant kidney of rats with renal mass ablation using competitive quantitative RT-PCR techniques. Partial cloning was performed to determine the rat RAMP3 nucleotide sequence. In normal rat kidneys, expression levels of RAMP2, RAMP3, CRLR and AM mRNAs were 26.5 +/- 1.9 mmol/mole of GAPDH, 7.7 +/- 0.9 mmol/mole of GAPDH, 3.6 +/- 0.2 mmol/mole of GAPDH and 0.57 +/- 0.03 mmol/mole of GAPDH (mean +/- SE, n = 6), respectively. RAMP3 mRNA levels decreased significantly to about 50% and about 70% of control (sham-operated rats) 4 days and 14 days after 5/6 nephrectomy, respectively. CRLR mRNA levels also decreased significantly to about 30% and about 43% of control. Sodium intake restriction had no significant effects on the RAMP3 and CRLR gene expression. On the other hand, RAMP2 mRNA expression in the kidney was suppressed by sodium intake restriction regardless of nephrectomy, while RAMP2 levels in the remnant kidney were not significantly changed by 5/6 nephrectomy. Neither 5/6 nephrectomy or sodium intake restriction had any significant effects on the AM gene expression in the kidney. The present study showed that expression of mRNAs encoding AM, RAMP2, RAMP3 and CRLR were differentially regulated in remnant kidneys of rats with renal mass ablation.

Topics: Adrenomedullin; Analysis of Variance; Animals; Calcitonin Receptor-Like Protein; Disease Models, Animal; Gene Expression; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Nephrectomy; Peptides; Rats; Rats, Wistar; Receptor Activity-Modifying Protein 2; Receptor Activity-Modifying Protein 3; Receptor Activity-Modifying Proteins; Receptors, Adrenomedullin; Receptors, Calcitonin; Receptors, Peptide; Renal Insufficiency; RNA, Messenger

To investigate the synthesis and release of adrenomedullin (AM) of lung tissue in rats on hypoxic pulmonary hypertension (HPH) and study its mechanism and significance in the pathogenesis process of HPH.. 54 Wistar rats were divided into hypoxia 10 d (n = 12), 20 d (n = 12), 30 d (n = 12) groups and control group (n = 18). The rats of hypoxia groups were exposed to chronic hypobaric hypoxia environment at high 5 km to establish HPH models. The expression of pulmonary cell AM protein, the content of plasma AM and bronchial alveolar lavage fluid (BALF) AM were determined by optical microscopy, immunohistochemistry and radio-immunoassay.. AM was widely distributed in lung tissue. There was positive of AM in intraplasma of vascular endothelial cells (EC), vascular and bronchial smooth muscular cells (SMC), bronchial epithelial cells, macrophages (M phi) and type II alveolar epithelial cells in every groups. After hypoxia, the expression of AM in above cells, especially EC, SMC and M phi, increased more than control group. Plasma AM contents of hypoxia groups were higher than control group(P < 0.01). 20 d after hypoxia, the AM content was twice as control group. At 10 d to 20 d after hypoxia, BALF AM content was increased more than control group (P < 0.01). But at 30 d the content was decreased near to normal.. Hypoxia is effective in promoting AM synthesis and release in pulmonary tissue and suggestes that AM as a peptide plays an important regulating role on pulmonary circulation, exchange of air and pulmonary vascular structural remodeling in the pathophysiological process of HPH.

Topics: Adrenomedullin; Altitude Sickness; Animals; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Hypertension, Pulmonary; Lung; Male; Peptides; Pulmonary Wedge Pressure; Rats; Rats, Wistar

Myocardial actions of the vasodilator peptide adrenomedullin (ADM) in the intact animal are unknown. Negative and positive inotropic actions have been reported in ex vivo experiments. Myocardial and load-altering actions of ADM in dogs before and after development of heart failure were studied. With controlled heart rate (atrial pacing) and after beta-blockade, ADM was administered to five normal dogs in doses of 20 ng. kg(-1). min(-1) iv, 100 ng. kg(-1). min(-1) iv, and 200 ng. kg(-1). min(-1) into the left ventricle (LV). LV peak systolic pressure and end-systolic volume decreased with each dose of ADM. End-systolic pressure decreased with the two higher doses. At the highest dose, arterial elastance and the time constant of LV isovolumic relaxation (tau) decreased, and LV end-systolic elastance (E(es)) increased. LV end-diastolic pressure and volume were unchanged. In five additional normal dogs receiving only the highest dose of ADM (200 ng. kg(-1). min(-1) intra-LV), to control for increased heart rate and sympathetic activation observed with the cumulative infusion, ADM produced arterial vasodilation but no change in E(es) or tau. In four dogs with pacing-induced heart failure, ADM (200 ng. kg(-1). min(-1) intra-LV) was without effect on tau, E(es), and systolic or diastolic pressure and volume. In vivo, ADM appears to be a selective arterial dilator without inotropic or lusitropic effects. The vasodilatory actions are attenuated in heart failure.

Topics: Adrenomedullin; Animals; Blood Pressure; Cardiac Pacing, Artificial; Cyclic AMP; Disease Models, Animal; Dogs; Dose-Response Relationship, Drug; Epinephrine; Heart; Heart Failure; Heart Rate; Infusions, Intravenous; Male; Myocardial Contraction; Norepinephrine; Peptides; Vasodilation; Vasodilator Agents; Ventricular Function, Left

Adrenomedullin (AM) is a potent vasodilator and natriuretic peptide that plays an important role in cardiorenal function. In this study, we explored the potential protective role of AM in volume-dependent hypertension by somatic gene delivery. Adenovirus containing the human AM cDNA under the control of the cytomegalovirus promoter/enhancer was administered into deoxycorticosterone acetate (DOCA)-salt hypertensive rats via tail vein injection. A single injection of the human AM gene resulted in a prolonged reduction of blood pressure with a maximal reduction of 41 mm Hg 9 days after gene delivery. Human AM gene delivery enhanced renal function, as indicated by a 3-fold increase in renal blood flow and a 2-fold increase in glomerular filtration rate (n=5, P<0.05). Histological examination of the kidney revealed a significant reduction in glomerular sclerosis, tubular injury, luminol protein cast accumulation, and interstitial fibrosis as well as urinary protein. Human AM gene delivery caused significant decreases in left ventricular weight and cardiomyocyte diameter, which were accompanied by reduced interstitial fibrosis and extracellular matrix formation within the heart. Expression of human AM mRNA was detected in the kidney, adrenal gland, heart, aorta, lung, and liver; immunoreactive human AM levels were measured in urine and plasma. Significant increases in urinary and cardiac cAMP levels were observed in DOCA-salt rats receiving the human AM gene, indicating activation of the AM receptor. These findings showed that AM gene delivery attenuates hypertension, protects against cardiac remodeling and renal damage in volume-overload hypertension, and may have significance in therapeutic applications in cardiovascular and renal diseases.

Topics: Adenoviridae; Adrenomedullin; Animals; Cardiomegaly; Cyclic AMP; Cyclic GMP; Desoxycorticosterone; Disease Models, Animal; Fibrosis; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Humans; Hypertension; Kidney Diseases; Male; Peptides; Rats; Rats, Sprague-Dawley; Systole

Heart failure is characterized by increased vascular resistance and water retention. Adrenomedullin is a peptide hormone with vasodilating and diuretic properties whose efficacy in heart failure has not been well established. We used an aortocaval shunt model of moderate heart failure in rats and infused increasing doses of adrenomedullin, both as bolus injections and 20-min infusions. In controls, a clear dose-dependent 4.8+/-1.0 to 13.6+/-2.3 mm Hg decrease in arterial blood pressure was observed after injection of 1 microg to 30 microg of adrenomedullin. In rats with aortocaval shunt, the hypotensive responses were significantly diminished. The urine flow rate, which was diminished at baseline in rats with aortocaval shunt, was increased and normalized by adrenomedullin administration. The glomerular filtration rate increased after infusion of adrenomedullin (0.5 microg/kg min(-1)) from 2.37+/-0.25 to 3.47+/-0.43 ml/min (P<0.01) in controls and from 1.79+/-0.33 to 2.58+/-0.49 (P<0.05) in rats with aortocaval shunt. Similarly, renal blood flow was significantly increased by adrenomedullin in both groups. Our results indicate a beneficial effect of adrenomedullin on renal function in rats with aortocaval shunt. These data suggest that adrenomedullin might be of potential therapeutic value in heart failure, without inordinately decreasing blood pressure.

Topics: Adrenomedullin; Animals; Arteriovenous Shunt, Surgical; Cardiotonic Agents; Cyclic AMP; Cyclic GMP; Disease Models, Animal; Diuresis; Glomerular Filtration Rate; Heart Failure; Hemodynamics; Kidney; Male; Natriuresis; Peptides; Rats; Rats, Wistar; Renal Circulation

We examined the effect of adrenomedullin on the cardiovascular system of an animal model for preeclampsia. An inhibitor of nitric oxide synthase, N(G)-nitro-L-arginine methyl ester (L-NAME), was infused subcutaneously into rats at a constant rate from day 14 of pregnancy to make an animal model for preeclampsia. Adrenomedullin was continuously infused intravenously at a dose of 3 or 10 pmol/h from day 17 of pregnancy. The basal systolic blood pressure was significantly higher in the L-NAME treated rats than in the control rats. The adrenomedullin administration at day 19 of pregnancy showed a significant decrease in the blood pressure in the L-NAME treated rats than in vehicle rats during infusion. The blood pressure of normal pregnant rats did not significantly decrease by adrenomedullin infusion. The adrenomedullin decreased pup mortality of the L-NAME treated rats. Adrenomedullin attenuated the L-NAME induced hypertension and pup mortality. On the other hand, adrenomedullin administration in both pregnant rats in early gestation (5-11 days of pregnancy) and in non-pregnant rats did not show any significant effect on L-NAME-induced hypertension. The adrenomedullin mRNA level was predominantly expressed at high levels in the ovary, uterus and placenta, but at low levels in other tissues in pregnant rats in late gestation. The adrenomedullin mRNA level of the L-NAME treated rats in placenta decreased more than in the normal pregnant rats in late gestation (P < 0.05). These findings suggest that the adrenomedullin might play an important role in the regulation of the cardiovascular system of the mother and fetoplacental unit in rats.

Topics: Adrenomedullin; Animals; Antihypertensive Agents; Blood Pressure; Blotting, Northern; Body Weight; Disease Models, Animal; Enzyme Inhibitors; Female; Fetus; Hypertension; Infusions, Intravenous; NG-Nitroarginine Methyl Ester; Peptides; Pre-Eclampsia; Pregnancy; Pregnancy, Animal; Rats; Rats, Wistar; RNA, Messenger; Time Factors

The antiinflammatory effect of ADM was studied in different models of inflammation and compared to the one of CGRP. Peptides were active against acetic acid-induced peritonitis in the rats. ADM and CGRP exerted the antiinflammatory effect at different doses, 400 and 20 ng/kg respectively, but with different efficacy (ADM >CGRP). This effect was blocked by pretreatment with CGRP (8-37) fragment or with L-NAME. No antiinflammatory activity was evidenced against serotonin- or carrageenin-induced rat paw edema. Our data suggest that ADM exerts antiinflammatory activity in the model characterized by a vascular component. This effect involves CGRP receptors and appears to be mediated by nitric oxide system.

Topics: Acetic Acid; Adrenomedullin; Animals; Anti-Inflammatory Agents, Non-Steroidal; Calcitonin Gene-Related Peptide; Disease Models, Animal; Dose-Response Relationship, Drug; Edema; Enzyme Inhibitors; Humans; Mice; NG-Nitroarginine Methyl Ester; Peptides; Peritonitis; Rats; Rats, Sprague-Dawley

The study of two populations with a recent onset of type 2 diabetes showed that a subset of the patients had higher levels of adrenomedullin (AM) than the rest of the diabetics. In this subset, physiological elevations of AM might have triggered the disease in predisposed individuals. Diabetics showed higher levels of AM than healthy controls. In addition, glycemia was measured in diabetic rats after injection of saline, AM, or antiAM antibody. AM elevated glycemia, whereas the antibody reduced circulating glucose to normal. These results suggest that manipulation of AM levels could represent a new approach in the management of diabetes for the appropriate individuals.

Topics: Adolescent; Adrenomedullin; Adult; Animals; Antibodies; Blood Glucose; Case-Control Studies; Diabetes Mellitus, Type 2; Diabetes, Gestational; Disease Models, Animal; Female; Humans; Male; Middle Aged; Peptides; Phenotype; Prediabetic State; Pregnancy; Rats; Rats, Inbred SHR

Wistar rats were injected intravenously with bacterial lipopolysaccharide (LPS) and developed endotoxic shock with severe hypotension. This was accompanied by significantly elevated concentrations of adrenomedullin (AM) in the plasma and expression of high levels of AM mRNA in the lung. Pretreatment of the rats with dexamethasone (DEX) prevented hypotension caused by LPS administration, but plasma AM concentrations and AM mRNA levels in the lung remained elevated. Adrenalectomized (ADX) rats developed a more severe form of circulatory shock in response to a low-dose of LPS. This was accompanied by only a slight increase in circulating AM in the plasma. However, pretreatment of ADX rats with DEX caused substantial elevations of plasma AM concentrations and expression of AM mRNA in the lung. Our studies demonstrate that glucocorticoid upregulates the expression and secretion of AM in vivo, and endogenous glucocorticoid is required for increased AM secretion under certain conditions such as endotoxic shock.

Topics: Adrenal Glands; Adrenalectomy; Adrenomedullin; Animals; Dexamethasone; Disease Models, Animal; Dose-Response Relationship, Drug; Glucocorticoids; Lipopolysaccharides; Lung; Male; Peptides; Rats; Rats, Wistar; RNA, Messenger; Shock, Septic

The intravenous infusion of rat adrenomedullin, at concentrations ranging from 0.1 to 1.0 microgram/kg/min, for 60 min increased the regional cerebral blood flow (rCBF) in a dose-dependent manner in rats. rCBF was measured using a laser Doppler flowmetry device placed on the surface of the parietal cortex. The increase in rCBF induced by 1.0 microgram/kg/min of adrenomedullin was up to 145 +/- 10.8% of controls at 60 min (n = 5, p < 0.001). These concentrations of adrenomedullin did not affect systemic blood pressure or other physiologic parameters, including pH, PaCO2, PaO2, hemoglobin, and blood glucose. Repeated infusion of 1.0 microgram/kg/min of adrenomedullin at 2-h intervals caused tachyphylaxis (n = 5, p < 0.01). Rat adrenomedullin (1.0 microgram/kg/min) demonstrated a more potent effect than the same dose of human adrenomedullin. The C-terminal fragment of human adrenomedullin (0.5 and 5.0 micrograms/kg/min), adrenomedullin22-52, which did not affect rCBF alone, inhibited the effect of rat adrenomedullin (0.5 microgram/kg/min) as a receptor antagonist in a dose-dependent manner. In a model of middle cerebral artery (MCA) occlusion in spontaneously hypertensive rats, pre- and postinfusion of 1.0 microgram/kg/min of adrenomedullin suppressed the reduction in rCBF following MCA occlusion (control, 29 +/- 15.1%; adrenomedullin group, 45 +/- 14.4%; not significant) and decreased the volume of ischemic brain injury (control, 288 +/- 35 mm3; adrenomedullin group, 232 +/- 35 mm3; p < 0.05). These results suggest that adrenomedullin increases rCBF and prevents ischemic brain injury, partly by increasing the collateral circulation.

Topics: Adrenomedullin; Animals; Arterial Occlusive Diseases; Brain Ischemia; Cerebral Arteries; Cerebrovascular Circulation; Disease Models, Animal; Humans; Infusions, Intravenous; Male; Peptides; Rats; Rats, Inbred SHR; Rats, Sprague-Dawley; Regional Blood Flow; Vasodilator Agents

The hypotensive effect of chronically infused adrenomedullin, a potent vasodilator peptide, was examined in conscious two-kidney, one-clip (2K-1C) hypertensive and sham-operated rats. They were infused with 1.0 microgram/h of synthetic human adrenomedullin for 14 days by means of osmotic minipumps. Control groups were infused on the same schedule with 0.9% saline. Systolic blood pressure was measured before and during the infusion. Plasma renin activity, aldosterone and human adrenomedullin concentrations were determined at day 14 of the infusion. A significant reduction of systolic blood pressure was observed in the adrenomedullin-infused 2K-1C rats at day 4, and systolic blood pressure remained significantly lower throughout the experiment compared to that of the control 2K-1C. A similar hypotensive effect was seen in the adrenomedullin-infused sham-operated rats. Both the plasma renin activity and aldosterone concentrations of the adrenomedullin-infused 2K-1C and sham groups were significantly reduced compared to those of the respective control, whereas, the plasma human adrenomedullin concentration in the adrenomedullin-infused groups was found to be within the physiological range. These findings demonstrated that chronically infused adrenomedullin had a hypotensive effect accompanied by significant reductions of plasma renin activity and plasma aldosterone concentration in 2K-1C hypertensive and sham-operated rats.

Topics: Adrenomedullin; Aldosterone; Animals; Antihypertensive Agents; Blood Pressure; Disease Models, Animal; Hypertension, Renovascular; Infusions, Intravenous; Kidney; Linear Models; Male; Peptides; Rats; Rats, Wistar; Renin; Vasodilator Agents

Adrenomedullin is a recently discovered endogenous peptide with hypotensive and natriuretic actions in normal animals. Circulating and ventricular adrenomedullin are elevated in congestive heart failure, suggesting a possible role in the pathophysiology of this disease. No studies have previously examined the effects of adrenomedullin in heart failure.. Eight sheep with pacing-induced heart failure received human adrenomedullin(1-52) at 10 and 100 ng x kg(-1) x min(-1) I.V. for 90 minutes each. Compared with vehicle control data, adrenomedullin increased plasma cAMP (high dose, P<.05) in association with dose-dependent falls in calculated peripheral resistance (13 mm Hg x L(-1) x min(-1), P<.001), mean arterial pressure (9 mm Hg, P<.001), and left atrial pressure (5 mm Hg, P<.001) and increases in cardiac output (0.5 L/min, P<.001). Adrenomedullin increased urine sodium (threefold, P<.05), creatinine (P<.05) and cAMP excretion (P<.01), creatinine clearance (P<.05), and renal production of cAMP (P<.05), whereas urine output was maintained during infusion and raised after infusion (P<.05). Adrenomedullin reduced plasma aldosterone levels (P<.05), whereas plasma atrial and brain natriuretic peptide concentrations were unchanged during infusion and rose after infusion (P<.01 and P<.05, respectively). Plasma catecholamine, cortisol, renin, calcium, and glucose concentrations were not significantly altered.. Adrenomedullin reduced ventricular preload and afterload and improved cardiac output in sheep with congestive heart failure. Despite the clear fall in arterial pressure, adrenomedullin increased creatinine clearance and sodium excretion and maintained urine output. These results imply an important pathophysiological role for adrenomedullin in the regulation of pressure and volume in heart failure and raise the possibility of a new therapeutic approach to this disease.

Topics: Adrenomedullin; Animals; Blood Glucose; Blood Pressure; Calcium; Cardiac Output; Creatinine; Cyclic AMP; Disease Models, Animal; Dose-Response Relationship, Drug; Drinking; Epinephrine; Female; Heart Failure; Hemodynamics; Hydrocortisone; Norepinephrine; Pacemaker, Artificial; Peptides; Potassium; Renal Circulation; Sheep; Vasodilator Agents; Ventricular Dysfunction, Left

Adrenomedullin is a strong vasorelaxing peptide discovered in pheochromocytoma tissue. Monocrotaline, a pyrrolizidine alkaloid derived from Crotalaria spectabilis, is known to cause pulmonary hypertension. To test the hypothesis that adrenomedullin plays a role similar to that of atrial natriuretic peptide or brain natriuretic peptide in modulating right ventricular responses to pulmonary hypertension, we have compared concentrations of immunoreactive rat adrenomedullin and adrenomedullin messenger RNA levels in tissues of monocrotaline treated rats with those of control rats. We also measured the effect of pulmonary hypertension on plasma level of the peptide. The concentrations of adrenomedullin immunoreactivity in right ventricle and plasma were significantly higher in monocrotaline treated rats than in control rats. The messenger RNA level of adrenomedullin in right ventricle was also higher in monocrotaline treated rats than in control rats. These results suggest that adrenomedullin participates in the mechanism to counteract the high blood pressure in pulmonary circulation.

Topics: Adrenomedullin; Animals; Disease Models, Animal; Heart Ventricles; Hypertension, Pulmonary; Immunoblotting; Lung; Male; Monocrotaline; Myocardium; Peptides; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Reference Values; RNA; RNA, Messenger; Ventricular Function, Right

Responses to adrenomedullin, a newly discovered hypotensive peptide isolated from human pheochromocytoma cells, and the carboxy terminal 15-52 (adrenomedullin-(15-52)) and 22-52 (adrenomedullin-(22-52)) amino acid fragments of adrenomedullin were investigated in the mesenteric vascular bed of the cat. Under constant flow conditions, injections of adrenomedullin, adrenomedullin-(15-52), and calcitonin gene-related peptide (CGRP) in doses of 0.003-1 nmol into the perfused superior mesenteric artery caused significant dose-related decreases in mesenteric arterial perfusion pressure. Mesenteric vasodilator responses to adrenomedullin and adrenomedullin-(15-52) were similar in magnitude and duration, while vasodilator responses to CGRP were greater in magnitude and longer in duration than those produced by adrenomedullin or adrenomedullin-(15-52) when these agents were injected in doses of 0.1-1 nmol. Adrenomedullin-(22-52) caused no significant change in mesenteric arterial perfusion pressure when injected in doses up to 10 nmol. These results suggest that amino acids 15-52 and the six-membered ring structure of adrenomedullin are important for the expression of vasodilator activity in the mesenteric vascular bed of the cat.

Topics: Adrenomedullin; Amino Acid Sequence; Animals; Antihypertensive Agents; Blood Pressure; Calcitonin Gene-Related Peptide; Cats; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Humans; Hypertension; Injections, Intra-Arterial; Male; Mesenteric Arteries; Molecular Sequence Data; Peptide Fragments; Peptides; Recombinant Proteins; Structure-Activity Relationship; Vasodilation