hexarelin and Disease-Models--Animal

Amyotrophic lateral sclerosis (ALS) is an incurable motor neuron disease whose etiology remains unresolved; nonetheless, mutations of superoxide dismutase 1 (SOD1) have been associated with several variants of ALS. Currently available pharmacologic interventions are only symptomatic and palliative in effect; therefore, there is a pressing demand for more effective drugs. This study examined potential therapeutic effects of growth hormone secretagogues (GHSs), a large family of synthetic compounds, as possible candidates for the treatment of ALS. Human neuroblastoma cells expressing the SOD1-G93A mutated protein (SH-SY5Y SOD1

Topics: Amyotrophic Lateral Sclerosis; Animals; Cell Line; Disease Models, Animal; Humans; Hydrogen Peroxide; Mice; Mice, Transgenic; Neuroblastoma; Superoxide Dismutase; Superoxide Dismutase-1

Hexarelin, a synthetic growth hormone-releasing peptide, is shown to be protective in cardiovascular diseases such as myocardial infraction and atherosclerosis. However, the functional role of hexarelin in abdominal aortic aneurysm (AAA) remains undefined. The present study determined the effect of hexarelin administration (200 μg/kg twice per day) in a mouse model of elastase-induced abdominal aortic aneurysm. Echocardiography and in situ pictures showed hexarelin decreased infrarenal aorta diameter. Histology staining showed elastin degradation was improved in hexarelin-treated group. Hexarelin rescued smooth muscle cell contractile phenotype with increased α-SMA and decreased MMP2. Furthermore, hexarelin inhibited inflammatory cell infiltration, NLRP3 inflammasome activation and IL-18 production. Particularly, hexarelin suppressed NF-κB signaling pathway which is a key initiator of inflammatory response. These results demonstrated that hexarelin attenuated AAA development by inhibiting SMC phenotype switch and NF-κB signaling mediated inflammatory response.

Topics: Animals; Anti-Inflammatory Agents; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Cell Plasticity; Cytokines; Disease Models, Animal; Inflammasomes; Male; Mice, Inbred C57BL; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; NF-kappa B; NLR Family, Pyrin Domain-Containing 3 Protein; Oligopeptides; Phenotype; Signal Transduction; Vascular Remodeling

Obese individuals often show low growth hormone (GH) secretion, which leads to reduced lipid mobilization and further fat accumulation. Pharmacological approaches to increase GH levels in obese individuals by GH injection or GH-releasing hormone receptor agonist showed promising effects on fat reduction. However, side effects on glucose metabolism and the heavy costs on making large peptides hindered their clinical application. Here, we tested whether stimulation of endogenous GH secretion by a synthetic GH secretagogue receptor (GHSR) agonist, hexarelin, improved the metabolism in a hyperphagic obese mouse model. Male melanocortin 4 receptor knockout mice (MC4RKO) were pair-fed and received continuous hexarelin (10.56 μg/day) or vehicle infusion by an osmotic pump for 3-4 weeks. Hexarelin treatment significantly increased the pulsatile GH secretion without detectable alteration on basal GH secretion in MC4RKO mice. The treated mice showed increased lipolysis and lipid oxidation in the adipose tissue, and reduced de novo lipogenesis in the liver, leading to reduced visceral fat mass, reduced triglyceride content in liver, and unchanged circulating free fatty acid levels. Importantly, hexarelin treatment improved the whole-body insulin sensitivity but did not alter glucose tolerance, insulin levels, or insulin-like growth factor 1 (IGF-1) levels. The metabolic effects of hexarelin were likely through the direct action of GH, as indicated by the increased expression level of genes involved in GH signaling pathways in visceral adipose tissues and liver. In conclusion, hexarelin treatment stimulated the pulsatile GH secretion and reduced the fat accumulation in visceral depots and liver in obese MC4RKO mice with improved insulin sensitivity without altered levels of insulin or IGF-1. It provides evidence for managing obesity by enhancing pulsatile GH secretion through activation of GHSR in the pituitary gland.

Topics: Animals; Disease Models, Animal; Growth Hormone; Growth Hormone-Releasing Hormone; Intra-Abdominal Fat; Lipid Metabolism; Liver; Mice; Mice, Obese; Obesity; Oligopeptides; Receptors, Ghrelin

Acute myocardial ischemia and reperfusion injury (IRI) underly the detrimental effects of coronary heart disease on the myocardium. Despite the ongoing advances in reperfusion therapies, there remains a lack of effective therapeutic strategies for preventing IRI. Growth hormone secretagogues (GHS) have been demonstrated to improve cardiac function, attenuate inflammation and modulate the autonomic nervous system (ANS) in models of cardiovascular disease. Recently, we demonstrated a reduction in infarct size after administration of hexarelin (HEX), in a murine model of myocardial infarction. In the present study we employed a reperfused ischemic (IR) model, to determine whether HEX would continue to have a cardioprotective influence in a model of higher clinical relevance. Myocardial ischemia was induced by transient ligation of the left descending coronary artery (tLAD) in C57BL/6 J mice followed by HEX (0.3 mg/kg/day; n = 20) or vehicle (VEH) (n = 18) administration for 21 days, first administered immediately prior-to reperfusion. IR-injured and sham mice were subjected to high-field magnetic resonance imaging to assess left ventricular (LV) function, with HEX-treated mice demonstrating a significant improvement in LV function compared with VEH-treated mice. A significant decrease in interstitial collagen, TGF-β1 expression and myofibroblast differentiation was also seen in the HEX-treated mice after 21 days. HEX treatment shifted the ANS balance towards a parasympathetic predominance; combined with a significant decrease in cardiac troponin-I and TNF-α levels, these findings were suggestive of an anti-inflammatory action on the myocardium mediated via HEX. In this model of IR, HEX appeared to rebalance the deregulated ANS and activate vagal anti-inflammatory pathways to prevent adverse remodelling and LV dysfunction. There are limited interventions focusing on IRI that have been successful in improving clinical outcome in acute myocardial infarction (AMI) patients, this study provides compelling evidence towards the translational potential of HEX where all others have largely failed.

Topics: Animals; Anti-Inflammatory Agents; Disease Models, Animal; Inflammation; Male; Mice; Mice, Inbred C57BL; Myocardial Infarction; Myocardial Reperfusion Injury; Oligopeptides; Troponin I; Ventricular Dysfunction, Left; Ventricular Function, Left

Hexarelin is a synthetic growth hormone-releasing peptide that exerts cardioprotective effects. However, its cardioprotective effect against heart failure (HF) is yet to be explained. This study investigated the therapeutic role of hexarelin and the mechanisms underlying its cardioprotective effects against coronary artery ligation (CAL)-induced HF in rats.. Rats with four weeks of permanent CAL, induced myocardial infarction, and HF were randomly separated into four groups: the control group (Ctrl), sham group (Sham), hexarelin treatment group (HF + Hx), and heart failure group (HF). The rats were treated with subcutaneous injection of hexarelin (100 μg/kg) in the treatment group or saline in the other groups twice a day for 30 days. Left ventricular (LV) function, oxidative stress, apoptosis, molecular analyses, and cardiac structural and pathological changes in rats were assessed.. The treatment of HF rats with hexarelin significantly induced the upregulation of phosphatase and tensin homologue (PTEN) expression and inhibited the phosphorylation of protein kinase B (Akt) and mammalian target of rapamycin (mTOR) to significantly improve LV function, ameliorate myocardial remodeling, and reduce oxidative stress.. These findings indicate that hexarelin attenuates CAL-induced HF in rats by ameliorating myocardial remodeling, LV dysfunction, and oxidative stress via the upmodulation of PTEN signaling and downregulation of the Akt/mTOR signaling pathway.

Topics: Animals; Coronary Vessels; Disease Models, Animal; Heart Failure; Heart Ventricles; Male; Oligopeptides; PTEN Phosphohydrolase; Rats; Rats, Sprague-Dawley; Up-Regulation

Ischemic heart disease (IHD) is a leading cause of morbidity and mortality worldwide. Growth hormone secretagogues (GHS) have been shown to improve cardiac function in models of IHD. This study determined whether hexarelin (HEX), a synthetic GHS, preserves cardiac function and morphology in a mouse model of myocardial infarction (MI). MI was induced by ligation of the left descending coronary artery in C57BL/6J mice followed by vehicle (VEH; n = 10) or HEX (0.3 mg/kg/day; n = 11) administration for 21 days. MI-injured and sham mice (treated with VEH; n = 6 or HEX; n = 5) underwent magnetic resonance imaging for measurement of left ventricular (LV) function, mass and infarct size at 24 h and 14 days post-MI. MI-HEX mice displayed a significant improvement (P < 0.05) in LV function compared with MI-VEH mice after 14 days treatment. A significant decrease in LV mass, interstitial collagen and collagen concentration was demonstrated with chronic HEX treatment (for 21 days), accompanied by a decrease in TGF-β1 expression, myofibroblast differentiation and an increase in collagen-degrading MMP-13 expression levels. Furthermore, heart rate variability analysis demonstrated that HEX treatment shifted the balance of autonomic nervous activity toward a parasympathetic predominance and sympathetic downregulation. This was combined with a HEX-dependent decrease in troponin-I, IL-1β and TNF-α levels suggestive of amelioration of cardiomyocyte injury. These results demonstrate that GHS may preserve ventricular function, reduce inflammation and favorably remodel the process of fibrotic healing in a mouse model of MI and hold the potential for translational application to patients suffering from MI.

Topics: Animals; Blood Pressure; Disease Models, Animal; Fibrosis; Heart; Inflammation; Male; Mice, Inbred C57BL; Myocardial Infarction; Myocardium; Oligopeptides; Ventricular Remodeling

Hexarelin, a synthetic growth hormone-releasing peptide, has been proven to possess cardioprotective actions through its binding to the growth hormone secretagogue receptor (GHSR) 1a and the non-GHSR receptor CD36. However, its effect on myocardial ischemia/reperfusion (I/R) injury has not been fully clarified in vivo. We aimed to determine whether hexarelin treatment could protect cardiomyocytes from I/R injury and to examine the underlying mechanisms. In vivo hearts of male SD rats underwent 30 minutes of ischemia by left coronary artery ligation followed by reperfusion. The rats were then treated subcutaneously twice daily with hexarelin [100 μg/kg·day], ghrelin [400 μg/ kg·day], or saline for 7 days. Echocardiography, malondialdehyde detection, and histochemical staining were performed after treatment. In addition, Western blot was used to examine the expression levels of IL-1β, IL-1Ra, and IL-1RI. Our study showed that hexarelin treatment improved cardiac systolic function, decreased malondialdehyde production, and increased the number of surviving cardiomyocytes. The beneficial effects of hexarelin treatment were slightly superior to those of equimolar ghrelin treatment. We meanwhile confirmed that hexarelin induced down-regulation of IL-1β expression and up-regulation of IL-1Ra expression in I/R myocardium, which could be neutralized by the GHSR antagonist [D-Lys3]-growth hormone releasing peptide-6 ([D-Lys3]-GHRP-6). These findings suggest that hexarelin protects in vivo cardiomyocytes from I/R injury partly by modification of the IL-1 signaling pathway through the activation of cardiac GHSR1a receptors.

Topics: Animals; Disease Models, Animal; Growth Substances; Heart; Interleukin-1; Male; Malondialdehyde; Myocardial Reperfusion Injury; Myocardium; Myocytes, Cardiac; Oligopeptides; Rats; Rats, Sprague-Dawley; Receptors, Ghrelin; Signal Transduction

Chemotherapy can cause cachexia, which consists of weight loss associated with muscle atrophy. The exact mechanisms underlying this skeletal muscle toxicity are largely unknown and co-therapies to attenuate chemotherapy-induced side effects are lacking. By using a rat model of cisplatin-induced cachexia, we here characterized the mitochondrial homeostasis in tibialis anterior cachectic muscle and evaluated the potential beneficial effects of the growth hormone secretagogues (GHS) hexarelin and JMV2894 in this setting. We found that cisplatin treatment caused a decrease in mitochondrial biogenesis (PGC-1α, NRF-1, TFAM, mtDNA, ND1), mitochondrial mass (Porin and Citrate synthase activity) and fusion index (MFN2, Drp1), together with changes in the expression of autophagy-related genes (AKT/FoxO pathway, Atg1, Beclin1, LC3AII, p62) and enhanced ROS production (PRX III, MnSOD). Importantly, JMV2894 and hexarelin are capable to antagonize this chemotherapy-induced mitochondrial dysfunction. Thus, our findings reveal a key-role played by mitochondria in the mechanism responsible for GHS beneficial effects in skeletal muscle, strongly indicating that targeting mitochondrial dysfunction might be a promising area of research in developing therapeutic strategies to prevent or limit muscle wasting in cachexia.

Topics: Animals; Autophagy; Biomarkers; Body Weight; Cachexia; Cisplatin; Disease Models, Animal; Forkhead Box Protein O3; Growth Hormone; Indoles; Male; Mitochondria; Mitochondrial Dynamics; Muscle, Skeletal; Oligopeptides; Organ Size; Organelle Biogenesis; Oxidative Stress; Phosphorylation; Piperidines; Proto-Oncogene Proteins c-akt; Rats; Secretagogues; Triazoles

Cardiac fibrosis is a hallmark of heart disease and plays a vital role in cardiac remodeling during heart diseases, including hypertensive heart disease. Hexarelin is one of a series of synthetic growth hormone secretagogues (GHSs) possessing a variety of cardiovascular effects via action on GHS receptors (GHS-Rs). However, the role of hexarelin in cardiac fibrosis in vivo has not yet been investigated. In the present study, spontaneously hypertensive rats (SHRs) were treated with hexarelin alone or in combination with a GHS-R antagonist for 5 wk from an age of 16 wk. Hexarelin treatment significantly reduced cardiac fibrosis in SHRs by decreasing interstitial and perivascular myocardial collagen deposition and myocardial hydroxyproline content and reducing mRNA and protein expression of collagen I and III in SHR hearts. Hexarelin treatment also increased matrix metalloproteinase (MMP)-2 and MMP-9 activities and decreased myocardial mRNA expression of tissue inhibitor of metalloproteinase (TIMP)-1 in SHRs. In addition, hexarelin treatment significantly attenuated left ventricular (LV) hypertrophy, LV diastolic dysfunction, and high blood pressure in SHRs. The effect of hexarelin on cardiac fibrosis, blood pressure, and cardiac function was mediated by its receptor, GHS-R, since a selective GHS-R antagonist abolished these effects and expression of GHS-Rs was upregulated by hexarelin treatment. In summary, our data demonstrate that hexarelin reduces cardiac fibrosis in SHRs, perhaps by decreasing collagen synthesis and accelerating collagen degradation via regulation of MMPs/TIMP. Hexarelin-reduced systolic blood pressure may also contribute to this reduced cardiac fibrosis in SHRs. The present findings provided novel insights and underscore the therapeutic potential of hexarelin as an antifibrotic agent for the treatment of cardiac fibrosis.

Topics: Animals; Blood Pressure; Cardiovascular Agents; Collagen Type I; Collagen Type III; Disease Models, Animal; Fibrosis; Gene Expression Regulation; Heart Diseases; Hydroxyproline; Hypertension; Hypertrophy, Left Ventricular; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Myocardium; Oligopeptides; Rats; Rats, Inbred SHR; Rats, Wistar; Receptors, Ghrelin; RNA, Messenger; Time Factors; Tissue Inhibitor of Metalloproteinase-1; Ventricular Dysfunction, Left; Ventricular Function, Left

It has been reported that ghrelin exerts anticonvulsive effects in models of epilepsy. In this study we aimed to characterize the anticonvulsive activity of ghrelin and other growth hormone secretagogue receptor 1a (GHSR(1a)) ligands in rats exposed to status epilepticus induced by pilocarpine or kainate. Firstly, in three independent experiments, before receiving pilocarpine (380 mg/kg, i.p.), rats were pretreated with one among ghrelin (1.5mg/kg), desacyl-ghrelin (1.5mg/kg), hexarelin (330 μg/kg), EP-80317 (330 μg/kg), JMV-1843 (330 μg/kg), JMV-2959 (330 μg/kg) or saline. Secondly, in the fourth experiment, rats were pretreated with i.p. ghrelin, desacyl-ghrelin, hexarelin, EP-80317 or saline, followed by kainate (15 mg/kg, i.p.). We evaluated: induction of generalized seizures, latency to generalized seizures, status epilepticus, latency to status epilepticus (the time lag between the first tonic-clonic convulsion and the switch to continuous seizures) and mortality. In the pilocarpine model, 60% of rats pretreated with EP-80317 (P<0.05) showed no seizure. Hexarelin and EP-80317 were both able to prevent progression to status epilepticus in pilocarpine-treated rats (P<0.05). When status epilepticus was induced by kainate, seizures developed with few exceptions. However, latency to status epilepticus was significantly (P<0.01) longer in rats pretreated with desacyl-ghrelin, whereas hexarelin and EP-80317 did not display any effect. Almost all GHSR(1a) ligands prevented pilocarpine-induced mortality, which was observed only in rats pretreated with saline or JMV-2959. After kainate administration, all rats survived to status epilepticus. These findings demonstrate that desacyl-ghrelin, hexarelin and EP-80317 but not other GHSR(1a) ligands display relevant anticonvulsive properties in models of limbic seizures.

Topics: Animals; Disease Models, Animal; Ghrelin; Kainic Acid; Male; Oligopeptides; Peptides; Pilocarpine; Rats; Rats, Sprague-Dawley; Seizures; Status Epilepticus