vasoactive-intestinal-peptide and Brain-Ischemia

Nowadays, stroke is the most frequent cause of adult disability and death of the elderly. In most cases, the etiology of stroke involves cerebral ischemia. Ischemia-induced changes in the brain tissue lead not only to its degeneration, but also to significant activation of cellular mechanisms which protect the affected cells from damage. One such mechanism is the expression of endogenous neuroprotective substances, for example pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intenstinal peptide (VIP), whose properties were investigated recently. PACAP and VIP are neuropeptides widely distributed in both the central nervous system and peripheral organs of various vertebrates. They display pleiotropic biological activity. An extremely strong neuroprotective potential of these peptides has been observed and confirmed in numerous animal models. The protective mechanism of PACAP and VIP involves many intracellular pathways, which can be generally classified into four categories of action: antiapoptotic, anti-inflammatory, metabolic, and modulation of gene expression. Numerous data provided by many research centers suggest that endo- and exogenous PACAP and VIP, as well as their synthetic derivatives, reveal considerable neuroprotective and anti-inflammatory potential, suggesting a possibility of their use as new therapeutic strategies in stroke treatment.

Topics: Adult; Anti-Inflammatory Agents; Brain Ischemia; Central Nervous System; Gene Expression Regulation; Humans; Nerve Tissue Proteins; Neuroprotective Agents; Pituitary Adenylate Cyclase-Activating Polypeptide; Vasoactive Intestinal Peptide

More than 30 neurotrophins have been identified, and many of them have neuroprotective effects in brain ischemia or injury. However, all the clinical trials with several neurotrophins for the treatment of acute ischemic stroke or neurodegenerative diseases have failed so far, primarily because of their poor blood-brain barrier (BBB) permeability. This article is an overview of recent progress in the research focused on BBB targeted neurotrophins using a chimeric peptide approach, in which antitransferrin receptor antibody was used as a BBB delivery vector, and neurotrophin peptide was conjugated to the antibody via the avidin/biotin technology. Vasoactive intestinal peptide was the first model chimeric peptide to show an enhanced CNS effect after noninvasive peripheral administration. Brain-derived neurotrophic factor (BDNF) chimeric peptide was neuroprotective in rats subjected to transient forebrain ischemia, permanent focal ischemia, or transient focal ischemia. Delayed treatments with the BDNF chimeric peptide showed an effective time window of 1-2 h after ischemia. Basic FGF chimeric peptide was highly effective in the reduction of infarct volume in the rat model of permanent focal ischemia, with lowest effective dose of 1 mug per rat. Future studies in this exciting area include genetically engineered fusion proteins or humanized antibodies for BBB drug targeting with less immunogenicity and reduced working burden in the chemical conjugation, the use of antihuman insulin receptor antibody for higher BBB delivery efficiency, and combination therapies using chimeric neurotrophins plus other neuroprotectants to achieve additive or synergistic effects.

Topics: Animals; Blood-Brain Barrier; Brain Ischemia; Brain-Derived Neurotrophic Factor; Clinical Trials as Topic; Fibroblast Growth Factor 2; Humans; Nerve Growth Factors; Neuroprotective Agents; Receptors, Transferrin; Recombinant Fusion Proteins; Stroke; Thrombolytic Therapy; Vasoactive Intestinal Peptide

Vasoactive intestinal peptide (VIP) appears to play an important role as a neurotransmitter or neuromediater in ischemic cerebrovascular diseases (ICVD). The effect of acupuncture, which is used in treatment of ICVD with good efficiency, on VIP has not been known. For finding the mechanism of acupuncture in treatment of ICVD and the effect of electro-acupuncture on VIP, the present study was performed.. 59 patients with acute ICVD were randomly divided into two groups. Electro-acupuncture and routine treatment were given in Group 1 (n = 29), and routine treatment was used alone in Group 2 (n = 30). The cerebrospinal fluid (CSF) and blood were taken before the beginning of treatment and after a course of treatment in both groups. The control group consisted of 38 cases of non-ICVD. VIP was measured by radioimmunoassay.. The level of CSF VIP in patients with acute ICVD was significantly lower than that in the controls, while the levels of plamsa VIP showed no significant difference between the ICVD and control groups, and the level of CSF VIP was not significantly correlated with the level of plasma VIP. After acupuncture treatment, the level of CSF VIP was increased and showed no significant difference as compared with the control group.. Acupuncture might alleviate the disturbance of metabolism of VIP in CNS.

Topics: Acupuncture Therapy; Adult; Aged; Brain Ischemia; Electroacupuncture; Female; Humans; Male; Middle Aged; Vasoactive Intestinal Peptide

To investigate the effects of vasoactive intestinal peptide on the blood brain barrier function after focal cerebral ischemia in rats.. Rats were intracerebroventricular injected with vasoactive intestinal peptide after a two hours middle cerebral artery occlusion. Functional outcome was studied with the neurological severity score. The brain edema and the infarction were evaluated via histology. The blood brain barrier permeability was assessed using Evans Blue dye injection method. We also measure the apoptosis of brain microvascular endothelial cells and brain levels of B-cell leukemia-2 protein by immunohistochemical analysis and western blotting, respectively.. In contrast to the cases treated with vehicle at 72 h after middle cerebral artery occlusion, the treatment with vasoactive intestinal peptide significantly (P < 0.05) reduced the neurological severity score, the brain edema and infarct volume. The Evans Blue leakage and brain water content were obviously reduced (P < 0.05) in vasoactive intestinal peptide-treated rats compared with those of control rats at 72 and 96 h after stroke. In addition, vasoactive intestinal peptide decreased the numbers of terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling positive endothelial cells and increased the protein levels of B-cell leukemia-2 in the ischemic hemisphere at 72 h after ischemia.. Our data suggest that treatment with vasoactive intestinal peptide ameliorates the blood brain barrier function, contributing to reduce in brain damage both morphologically and functionally in the ischemic rat. This amelioration may be associated with attenuation in apoptosis of brain microvascular endothelial cells by increased B-cell leukemia-2 expression.

Topics: Animals; Blood-Brain Barrier; Brain Edema; Brain Ischemia; Endothelial Cells; Humans; Infarction, Middle Cerebral Artery; Rats; Rats, Sprague-Dawley; Vasoactive Intestinal Peptide

Background Shengui Sansheng Pulvis (SSP) has about 300 years history used for stroke treatment, and evidences suggest it has beneficial effects on neuro-angiogenesis and cerebral energy metabolic amelioration post-stroke. However, its protective action and mechanisms on blood-brain barrier (BBB) is still unknown. Purpose Based on multiple neuroprotective properties of vasoactive intestinal peptide (VIP) in neurological disorders, we investigate if SSP maintaining BBB integrity is associated with VIP pathway in rat permanent middle cerebral artery occlusion (MCAo) model. Methods Three doses of SSP extraction were administered orally. Evaluations of motor and balance abilities and detection of brain edema were performed, and BBB permeability were assessed by Evans blue (EB) staining. Primary brain microvascular endothelial cells (BMECs) were subjected to oxygen-glucose deprivation, and incubated with high dose SSP drug-containing serum and VIP-antagonist respectively. Transendothelial electrical resistance (TEER) assay and Tetramethylrhodamine isothiocyanate (TRITC)-dextran (4.4 kDa) and fluorescein isothiocyanate (FITC)-dextran (70 kDa) were used to evaluate the features of paracellular junction. Western blot detected the expressions of Claudin-5, ZO-1, Occludin and VE-cadherin, matrix metalloproteinase (MMP) 2/9 and VIP receptors 1/2, and immunofluorescence staining tested VIP and Claudin-5 expressions. Results Our results show that SSP significantly reduces EB infiltration in dose-dependent manner in vivo and attenuates TRITC- dextran and FITC-dextran diffusion in vitro, and strengthens endothelial junctional complexes as represented by decreasing Claudin-5, ZO-1, Occludin and VE-cadherin degradations and MMP 2/9 expression, as well as promoting TEER in BMECs after ischemia. Moreover, it suggests that SSP notably enhances VIP and its receptors 1/2 expressions. VIP-antagonist exacerbates paracellular barrier of BMECs, while the result is reversed after incubation with high dose SSP drug-containing serum. Additionally, SSP also improve brain edema and motor and balance abilities after ischemic stroke. Conclusions we firstly demonstrate that the ameliorated efficacy of SSP on BBB permeability is related to the enhancements of VIP and its receptors, suggesting SSP might be an effective therapeutic agent on maintaining BBB integrity post-stroke.

Topics: Animals; Blood-Brain Barrier; Brain Ischemia; Claudin-5; Drugs, Chinese Herbal; Endothelial Cells; Endothelium, Vascular; Infarction, Middle Cerebral Artery; Male; Permeability; Rats, Inbred Strains; Receptors, Vasoactive Intestinal Peptide, Type II; Receptors, Vasoactive Intestinal Polypeptide, Type I; Stroke; Vasoactive Intestinal Peptide

Reduced blood flow to the brain induces cerebral ischaemia, potentially causing central injury and peripheral complications including gastrointestinal (GI) dysfunction. The pathophysiology behind GI symptoms is suspected to be neuropathy in the enteric nervous system (ENS), which is essential in regulating GI function. This study investigates if enteric neuropathy occurs after cerebral ischaemia, by analysing neuronal survival and relative numbers of vasoactive intestinal peptide (VIP) and neuronal nitric oxide synthase (nNOS) expressing neurons in mouse ileum after three types of cerebral ischaemia. Focal cerebral ischaemia, modelled by permanent middle cerebral artery occlusion (pMCAO) and global cerebral ischaemia, modelled with either transient occlusion of both common carotid arteries followed by reperfusion (GCIR) or chronic cerebral hypoperfusion (CCH) was performed on C56BL/6 mice. Sham-operated mice for each ischaemia model served as control. Ileum was collected after 1-17 weeks, depending on model, and analysed using morphometry and immunocytochemistry. For each group, intestinal mucosa and muscle layer thicknesses, neuronal numbers and relative proportions of neurons immunoreactive (IR) for nNOS or VIP were estimated. No alterations in mucosa or muscle layer thicknesses were noted in any of the groups. Loss of myenteric neurons and an increased number of VIP-IR submucous neurons were found in mouse ileum 7 days after pMCAO. None of the global ischaemia models showed any alterations in neuronal survival or relative numbers of VIP- and nNOS-IR neurons. We conclude that focal cerebral ischaemia and global cerebral ischaemia influence enteric neuronal survival differently. This is suggested to reflect differences in peripheral neuro-immune responses.

Topics: Animals; Brain Ischemia; Carotid Stenosis; Cell Death; Cerebrovascular Circulation; Disease Models, Animal; Ileum; Infarction, Middle Cerebral Artery; Male; Mice, Inbred C57BL; Myenteric Plexus; Neurons; Nitric Oxide Synthase Type I; Time Factors; Up-Regulation; Vasoactive Intestinal Peptide

Vasoactive intestinal peptide (VIP) enhances angiogenesis in rats with focal cerebral ischemia. In the present study, we investigated the molecular mechanism of the proangiogenic action of VIP using an in vitro ischemic model, in which rat brain microvascular endothelial cells (RBMECs) are subjected to oxygen and glucose deprivation (OGD). Western blotting and immunocytochemistry were carried out to examine the expression of VIP receptors and vascular endothelial growth factor (VEGF) in cultured RBMECs. The cell proliferation was assessed by the MTT assay. Cyclic adenosine monophosphate (cAMP) and VEGF levels were measured by using the enzyme-linked immunosorbent assay. The cultured RBMECs expressed VPAC1, VPAC2 and PAC1 receptors. Treatment with VIP significantly promoted the proliferation of RBMECs and increased OGD-induced expression of VEGF, and this effect was antagonized by the VPAC receptor antagonist VIP6-28 and VEGF antibody. VIP significantly increased contents of cAMP in RBMECs and VEGF in the culture medium. The VIP-induced VEGF production was blocked by H89, a protein kinase A (PKA) inhibitor. These data suggest that treatment with VIP promotes VEGF-mediated endothelial cell proliferation after ischemic insult in vitro, and this effect appears to be initiated by the VPAC receptors leading to activation of the cAMP/PKA pathway.

Topics: Animals; Brain; Brain Ischemia; Cell Proliferation; Cells, Cultured; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Endothelial Cells; Glucose; Oxygen; Rats; Rats, Sprague-Dawley; Receptors, Vasoactive Intestinal Peptide; Receptors, Vasoactive Intestinal Peptide, Type II; Receptors, Vasoactive Intestinal Polypeptide, Type I; Vascular Endothelial Growth Factor A; Vasoactive Intestinal Peptide

Vasoactive intestinal peptide (VIP) exerts neuroprotective effects under various neurotoxic conditions in vitro. In the present study, we investigated the effects of VIP on transient ischemic brain damage. Focal cerebral ischemia was induced using middle cerebral artery occlusion (MCAO) for 120 min in the adult rat brain. Either a single intracerebroventricular injection of VIP or saline was given at the beginning of reperfusion. Forty-eight hours after MCAO, the rats were sacrificed for evaluation of the infarct volume and histological analysis. ELISA was performed to assay levels of serum S100B before being sacrificed. We also evaluated the blood-brain barrier (BBB) permeability using Evans blue dye injection method. In contrast to the cases treated with vehicle, the infarct volume was significantly (P<0.05) reduced, and terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) staining and immunoreactivity for S100B were also significantly (P<0.05) decreased in the ischemic hemisphere with VIP treatment. In addition, the elevations of serum S100B were significantly (P<0.01) attenuated in VIP-treated rats compared with those of control rats. Treatment with VIP did not result in a significant reduction of Evans blue leakage, although it tended to be lower than that in the control rats. Our data suggest that treatment with VIP reduces brain damage in ischemic rats, and this effect may be associated with the attenuation of apoptosis and S100B expression.

Topics: Animals; Apoptosis; Brain Infarction; Brain Ischemia; Disease Models, Animal; Male; Nerve Degeneration; Nerve Growth Factors; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; S100 Calcium Binding Protein beta Subunit; S100 Proteins; Vasoactive Intestinal Peptide

It has been proposed that the immune system is activated during ischemic cerebral events and that brain damage caused by ischemia is increased by this immune activity. Neutrophils (PMNs) are one of the first factors in the chain of reactions of the immune system during focal cerebral ischemia. Experimental and clinical studies have emphasized the important role of proinflammatory cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor (TNFalpha), in addition to vasoactive peptide and endothelin-1 (ET-1), in the formation of cerebral ischemia.. The experiments were carried out using Wistar rats that were divided into four groups: three experimental groups (acute and prolonged focal cerebral ischemia and following reperfusion) and one control group (sham). Focal cerebral ischemia was induced by the intraluminal surgical suture method. The oxidative activity of PMNs was measured after stimulation with phorbol myristate acetate, a protein kinase C activator (luminol enhanced chemiluminescence). The concentration of IL-1beta and TNFalpha in rat lymphocyte culture after stimulation with CSF was determined using commercial ELISA kits. The plasma concentration of ET-1 was determined using commercial kits with the RIA method.. We confirmed a statistically significant increase in the oxidative activity of PMNs in rats with acute focal cerebral ischemia (p < 0.00001), prolonged ischemia (p < 0.001) and reperfusion (p < 0.05). An increase in IL-1beta and TNFalpha in lymphocytes following CSF stimulation was observed in the group with prolonged ischemia and in the group with reperfusion after transient ischemia (p < 0.05 for both). An increase in plasma ET-1 concentration was observed with acute and prolonged focal cerebral ischemia (p < 0.05 and p < 0.01, respectively).. Our results show that acute and prolonged focal cerebral ischemia and reperfusion induce statistically significant increases in the oxidative activity of PMNs. The concentration of proinflammatory mediators (IL-1beta, TNFalpha) as well as ET-1 is also increased, indicating the important role of immune reactions in the development of damage to the brain following ischemia.

Topics: Animals; Brain Ischemia; Cells, Cultured; Disease Models, Animal; Endothelin-1; Enzyme Activators; Interleukin-1beta; Male; Neutrophils; Radioimmunoassay; Rats; Rats, Wistar; Reperfusion; Statistics, Nonparametric; Tetradecanoylphorbol Acetate; Time Factors; Tumor Necrosis Factor-alpha; Vasoactive Intestinal Peptide

To investigate the effect of vasoactive intestinal peptide (VIP) on angiogenesis after focal cerebral ischemia.. Focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 120 min in adult SD rats with intracerebroventricular VIP administration at the beginning of reperfusion. Immunohistochemistry was performed to assay BrdU immunoreactive endothelial cells, expressions of VEGF, flt-1 and flk-1 in the ischemic zone, and the protein expressions of vascular endothelial growth factor (VEGF) in the brain was measured using Western blotting.. Immunohistochemical staining revealed significantly increased BrdU immunoreactive endothelial cells on the margins of the ischemic lesion in rats treated with VIP as compared with that in the control rats (P<0.05). VIP significantly increased the number of VEGF immunoreactive cells and flt-1- and flk-1-positive endothelial cells in comparison with the control group (P<0.01). Western blotting showed that VIP treatment resulted in significantly increased VEGF protein level in the ipsilateral hemisphere (P<0.05).. VIP enhances angiogenesis in the ischemic brain by increasing the expressions of VEGF in the brain tissue and its receptors flt-1 and flk-1 in the endothelial cells.

Topics: Animals; Brain; Brain Ischemia; Endothelial Cells; Gene Expression Regulation; Male; Neovascularization, Physiologic; Rats; Rats, Sprague-Dawley; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-1; Vascular Endothelial Growth Factor Receptor-2; Vasoactive Intestinal Peptide

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are neuroprotective in numerous models. Impairment of cerebrovascular reactivity (CR) contributes to ischemia/reperfusion (I/R)-induced neuronal damage. We tested whether PACAP and/or VIP preserve CR to I/R-sensitive dilator responses dependent on endothelial and/or neuronal function. Accordingly, changes in pial arteriolar diameters in response to hypercapnia (5-10% CO(2) ventilation) or topical N-methyl-d-aspartate (NMDA, 10(-4) M) were determined before and after I/R via intravital microscopy in anesthetized/ventilated piglets. Local pretreatment with non-vasoactive doses of PACAP (10(-8) M) and VIP (10(-9) M) prevented the attenuation of postischemic CR to hypercapnia; to 10% CO(2), the CR values were 27+/-8% vs 92+/-5% vs 88+/-13% (vehicle vs PACAP38 vs VIP, CR expressed as a percentage of the response before I/R, mean+/-SEM, n=8-8, p<0.05). PACAP, but not VIP, preserved CR to NMDA after I/R, with CR values of 31+/-10% vs 87+/-8% vs 35+/-12% (vehicle vs PACAP38 vs VIP, n=6-6). Unlike PACAP, VIP-induced vasodilation has not yet been investigated in the piglet. We tested whether VIP-induced arteriolar dilation was sensitive to inhibitors of cyclooxygenase (COX)-1 (SC-560, 1 mg/kg), COX-2 (NS-398, 1 mg/kg), indomethacin (5 mg/kg), and nitric oxide synthase (L-NAME, 15 mg/kg). VIP (10(-8)-10(-7)-10(-6) M, n=8) induced reproducible, dose-dependent vasodilation of 16+/-3%, 33+/-6%, and 70+/-8%. The response was unaffected by all drugs, except that the vasodilation to 10(-8) M VIP was abolished by SC-560 and indomethacin. In conclusion, PACAP and VIP differentially preserve postischemic CR; independent of their vasodilatory effect.

Topics: Animals; Animals, Newborn; Anti-Inflammatory Agents, Non-Steroidal; Arterioles; Brain Ischemia; Cerebral Arteries; Cerebrovascular Circulation; Cyclooxygenase Inhibitors; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelial Cells; Excitatory Amino Acid Agonists; Female; Hypercapnia; Indomethacin; Male; Neuroprotective Agents; Nitric Oxide Synthase Type I; Pituitary Adenylate Cyclase-Activating Polypeptide; Sus scrofa; Vasoactive Intestinal Peptide; Vasodilation

To explore the neuroprotective effect of vasoactive intestinal peptide (VIP) in rat ischemic brain injury.. VIP was administered via intracerebroventricular injection in SD rats prior to focal cerebral ischemia by intraluminal occlusion of the middle cerebral artery. The infarct volume was assessed with TTC staining, and immunohistochemistry was performed to analyze the S100beta expression in the cerebral tissue, with the serum concentrations of S100beta detected by double-antibody sandwich enzyme-linked immunosorbent assay.. After VIP injection, the relative infarct volume in the rats with cerebral ischemia was significantly reduced by 32.3% as compared with the volume in the control group on day 1 (P<0.05), and the number of S100beta-positive cells was significantly decreased in the cerebral tissue (P<0.05). The injection also resulted in significantly decreased serum S100beta concentrations in the rats (P<0.05).. VIP injection can reduce the infarct volume in rats with focal cerebral ischemia, suggesting the neuroprotective effect of VIP in brain ischemia possibly by reducing S100beta overexpression.

Topics: Animals; Brain Ischemia; Cerebral Infarction; Nerve Growth Factors; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; S100 Calcium Binding Protein beta Subunit; S100 Proteins; Vasoactive Intestinal Peptide

Vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating peptide (PACAP), are members of a VIP/secretin/glucagon family. These peptides were demonstrated to possess the neuroprotective properties. However, these peptides are not suited to be developed as a medicine for brain ischemia because of their susceptibilities to endopeptidases.. We examined the effects of IK 312548 (IK), VIP derivative, and Ac-PACAP, PACAP derivative, on the 10 min two-vessel occlusion (2 VO) model in C 57 BL/6 N mice lacking a part of the posterior communicating artery, and the 30 min middle cerebral artery occlusion (MCAO) model in ICR mice. A 10 ml x kg(-1) dose of each derivative (final concentration; 1 fmol x kg(-1) and 100 pmol x kg(-1)) was injected intraperitoneally (i.p.) to each animal just after the preparation of brain ischemia.. In 2 VO experiments, the number of neuronal cells in hippocampus was significantly reduced. However IK and Ac-PACAP treatments inhibited such reductions of neuronal cells in a dose-dependent manner. Particularly, between 1 pmol x kg(-1) and 100 pmol x kg(-) IK, and also between 10 fmol x kg(-1) and 1 pmol x kg(-1) Ac-PACAP significantly protected neuronal cell loss. In MCAO experiments, more than 60% of hemisphere was damaged. By treatment of IK (1-100 pmol x kg(-1)) and Ac-PACAP (1 fmol-1 pmol x kg(-1)), the range of brain damage decreased in a dose-dependent manner.. Ac-PACAP and IK after the brain ischemia could pass the blood-brain barrier and protect brain cell damage.

Topics: Animals; Brain Ischemia; Cerebrovascular Circulation; Hippocampus; Infarction, Middle Cerebral Artery; Injections, Intraperitoneal; Mice; Mice, Inbred C57BL; Mice, Inbred ICR; Nerve Growth Factors; Neuropeptides; Neuroprotective Agents; Neurotransmitter Agents; Pituitary Adenylate Cyclase-Activating Polypeptide; Vasoactive Intestinal Peptide

It has been reported that pituitary adenylate cyclase-activating polypeptide (PACAP) plays an important role in preventing neuronal cell death and is also a potent vasodilator. Cerebral hypotension and hypoperfusion during cerebral ischemia and neurodegenerative diseases are well known as some of the negative factors which aggravate neuronal cell death. Nevertheless, the effect of PACAP on the cerebral circulation was not understood well. Therefore, in the present study, we determined the mean arterial blood pressure (MBP), regional cerebral blood flow (rCBF) and cerebral oxygen content (pO2) in mice, and estimated the therapeutically useful doses of PACAP. Under barbiturate anesthesia, polyethylene tubes were inserted into mice to monitor MBP and to administer PACAP (5 x 10(-13)-5 x 10(-8) mol/kg) or vasoactive intestinal peptide (VIP; 5 x 10(-12) and 5 x 10(-9) mol/kg). Then, MBP, rCBF and cerebral pO2 were simultaneously measured in the mice. PACAP (5 x 10(-10)-5 x 10(-9) mol/kg) injections transiently decreased MBP, and cerebral pO2. PACAP (5 x 10(-8) mol/kg) injections produced a long-lasting potent decline of MBP, rCBF and cerebral pO2. Therefore, PACAP should be applied at low doses which do not influence the MBP and cerebral circulation to determine the therapeutically useful doses of PACAP for neuroprotection.

Topics: Animals; Blood Pressure; Brain; Brain Ischemia; Central Nervous System; Cerebrovascular Circulation; Injections, Intravenous; Male; Mice; Mice, Inbred BALB C; Nerve Growth Factors; Neuropeptides; Neuroprotective Agents; Neurotransmitter Agents; Oxygen Consumption; Pituitary Adenylate Cyclase-Activating Polypeptide; Vasoactive Intestinal Peptide; Vasodilation

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) belong to the same peptide family, and both neuropeptides have been shown to exert in vitro and in vivo neurotrophic and neuroprotective effects. The aim of the present study was to investigate and compare the protective effects of PACAP and VIP in permanent focal cerebral ischemia in rats. The effect on the progression of the cerebral infarct was also studied.. Male rats were injected 450 pmol PACAP or VIP dissolved in physiological saline intracerebroventricularly, preceding the occlusion of the middle cerebral artery. Control animals received vehicle treatment. Permanent focal ischemia was induced by the intraluminal filament occlusion of the middle cerebral artery. Animals were sacrificed 12 or 24 hours after the onset of ischemia, and infarcted brain areas were determined by staining bran sections with triphenyl-tetrazolium chloride.. Twelve hours after ischemia, the infarcted brain volume resulted to be 14.8% in the control group, 15.3% in the VIP-treated group and 5.8% in the PACAP-treated animals. Twenty-four hours after middle cerebral artery occlusion, the infarcted brain volumes were 21.5%, 20.7% and 14.3% in the control, VIP and PACAP-treated animals, respectively.. Our results provide further evidence for the neuroprotective effects of PACAP38 as given in form of a preischemic bolus. It slows down the progression of the evolution of the infarct and reduces the final infarct size. In contrast, a related peptide, VIP, does not have neuroprotective effects under the same experimental conditions.

Topics: Animals; Body Temperature; Brain Ischemia; Infarction, Middle Cerebral Artery; Male; Neuropeptides; Neuroprotective Agents; Pituitary Adenylate Cyclase-Activating Polypeptide; Rats; Rats, Wistar; Vasoactive Intestinal Peptide

To evaluate the protective properties of peptides related functionally and/or structurally to vasoactive intestinal peptide (VIP), PC12 cultures were treated with iodoacetate as a model for neuronal ischemic/hypoxic injury. Brain tissue can be pre-conditioned against lethal ischemia by several mechanisms including sub-lethal ischemia, moderate hypoglycemia, heat shock, and growth factors. In the present study, a superactive VIP lipophilic analog (Stearyl-Norleucine17-VIP; SNV) was used to pre-condition media of PC12 cells. After removal of the conditioned media, the cultures were exposed to iodoaceate, which inhibits glycolysis. Protective efficacy against iodoacetate-induced injury was assessed by the measurements of lactate dehydrogenase (LDH) activity in the media. Treatment with iodoacetate for 2.5 h produced a twofold increase in LDH activity in the media. The protective effect of SNV had an EC50 of 1 pM. Comparison of the preconditioning time required for full protection by SNV showed no apparent difference between a 15 min and a 2 h incubation period prior to the addition of iodoacetate. Iodoacetate treatment produced a 20% decrease in the RNA transcripts encoding activity-dependent neuroprotective protein (ADNP), a novel glia-derived protein that is regulated by VIP. The iodoacetate-associated reduction in ADNP mRNA was prevented by pre-treatment with SNV. These effects imply that SNV provides a regulatory mechanism for ADNP synthesis during glycolytic stress. Furthermore, a short exposure to SNV provided potent protection from iodoacetate-induced toxicity suggesting that SNV may have therapeutic value in the treatment of ischemic/hypoxic injury.

Topics: Animals; Brain Ischemia; Disease Models, Animal; Enzyme Inhibitors; Homeodomain Proteins; Iodoacetates; Nerve Degeneration; Nerve Tissue Proteins; Neuroprotective Agents; Neurotoxins; PC12 Cells; Rats; RNA, Messenger; Vasoactive Intestinal Peptide

To explore the main pathogenic factors in the development of neuronal death during normothermic reperfusion in rabbits.. Ninety-six New Zealand rabbits were randomly allocated into two groups: group I served as non-ischemic controls; group II served as postischemic normothermic reperfusion models. Complete cerebral ischemia was induced by the four-vessel model for 30 minutes. After ischemia, rabbits in group II were further divided into three subgroups according to the duration of reperfusion: subgroup A, 30 minutes; subgroup B, 180 minutes and subgroup C, 360 minutes. Twenty-eight biochemical parameters in the brain were measured, and neuronal changes were observed by histomorphological assessment. Neurons of 12 regions were differentiated into four types: type A (normal), type B (mildly damaged), type C (severely damaged) and type D (necrotic). Bivariate correlate analysis between the levels of biochemical parameters and the percentages of each type of neurons was carried out.. The main parameters involved in the progressive decrement of type A neurons were VIP, beta-EP, PGI2, T3, T4 and Na+, K(+)-ATPase; in the increment of type B were beta-EP and TXB2; in the increment of type C were GLU and TXB2/PGI2 respectively; in the stepwise increment of percentages of type D neurons were T4, Na+, K(+)-ATPase, GLU, T3 and VIP (P < 0.05).. The main factors involved in the development of neuronal death during postischemic normothermic reperfusion in rabbits include hypermetabolism, deactivation of Na+, K(+)-ATPase, release of excitatory amino acids and disorder of neuropeptides.

Topics: Animals; beta-Endorphin; Brain Ischemia; Cell Death; Female; Male; Neurons; Rabbits; Random Allocation; Reperfusion Injury; Sodium-Potassium-Exchanging ATPase; Thromboxane B2; Vasoactive Intestinal Peptide

Regional cerebral blood flow (rCBF) during controlled hemorrhagic hypotension (140-20 mm Hg) was assessed 10-14 days after chronic unilateral sectioning of parasympathetic and/or sensory fibers innervating pial vessels in spontaneously hypertensive rats (SHR). rCBF was measured in the cortical barrel fields bilaterally by laser Doppler blood flowmetry. Immunohistochemistry of middle cerebral artery (MCA) whole mount preparations was used to verify the surgical lesion. During hemorrhagic hypotension, rCBF was equivalent on the two sides in shams, after selective sensory denervation, or in parasympathetically sectioned animals exhibiting small decreases (less than or equal to 30%) in immunoreactive vasoactive intestinal peptide (VIP)-containing fibers. After chronic parasympathetic denervation, decreases in perfusion pressure were accompanied by greater reductions in rCBF on the lesioned side; changes in vascular resistance were also attenuated on that side. The rCBF response to hypercapnia (PaCO2 50 mm Hg), however, was symmetrical and robust. To examine the effects of impaired neurogenic vasodilation on the pathophysiology of cerebral ischemia, infarct size was measured 24 h following tandem MCA occlusion in denervated animals. Infarction volume was larger after selective parasympathetic sectioning (sham, 156 +/- 27 vs. 196 +/- 32 mm3, respectively) but only in those denervated animals demonstrating greater than or equal to 40% decrease in immunoreactive VIP-containing fibers within the ipsilateral MCA. Lower than expected blood flow/perfusion pressure in the cortex distal to an occluded blood vessel may relate the observed blood flow responses to the occurrence of larger cortical infarcts in parasympathetically denervated animals. If true, the findings suggest a novel role for neurogenic vasodilation in the pathophysiology of cerebral ischemia and in rCBF regulation within the periinfarction zone.

Topics: Animals; Blood Pressure; Brain; Brain Chemistry; Brain Ischemia; Cerebral Arteries; Cerebral Hemorrhage; Cerebral Infarction; Cerebrovascular Circulation; Hypercapnia; Hypotension; Immunohistochemistry; Male; Parasympathetic Nervous System; Rats; Rats, Inbred SHR; Vasoactive Intestinal Peptide

Histochemical changes in peptidergic and catecholaminergic neurons during ischemia were investigated in the cerebral neocortex of the gerbil. Catecholaminergic fibers were observed by catecholamine histofluorescence with glyoxylic acid solution, and peptidergic neuron systems such as vasoactive intestinal polypeptide (VIP), somatostatin (SOM), and neuropeptide Y (NPY) were observed by immunohistochemistry. Two hours after unilateral occlusion of the internal carotid artery, catecholaminergic fibers disappeared in the neocortex on the occlusion side, while peptidergic nerve fibers except for NPY fibers were intact after 2 hours of ischemia. NPY fibers had decreased in number on the occlusion side 2 hours after ischemia. VIP-, SOM-, and NPY-immunoreactive neurons showed a decrease of 60% six hours after ischemia, and these neurons completely disappeared in the cerebral neocortex 24 hours after ischemia. These results suggest that catecholaminergic neuron system is more vulnerable than the peptidergic one in ischemic event.

Topics: Animals; Brain Ischemia; Catecholamines; Cerebral Cortex; Gerbillinae; Immunohistochemistry; N-Methylaspartate; Neurons; Neuropeptide Y; Neuropeptides; Somatostatin; Vasoactive Intestinal Peptide

VIP is extensively localized in the brain, spinal cord and peripheral neurons, and is especially rich in the nerves innervating the cerebral vasculature. VIP is a potent vasodilator of cerebral vessels. The aim of this study was to investigate VIP contents in brain microvessels and their changes during incomplete brain ischemia.. (1) Bilateral carotid artery ligation was performed in Wistar rats under urethane anesthesia to produce cerebral ischemia, which was further aggravated by bleeding to hypotension with a mean arterial pressure of 50-60 mmHg. At 5, 15 and 30 min after ligation, the rats were decapitated to obtain brain tissue. A sham surgery group served as controls. In some rats cerebral ischemia was confirmed by EEG. (2) Brain microvessels were prepared by brain homogenization in HEPES-Ringer buffer and gradient centrifugation in 30% BSA, followed by filtration through a glass bead column. (3) VIP contents were determined by radioimmunoassay. The results were that VIP contents of 30 min ischemic rats were significantly higher than in the controls (P less than 0.01). VIP contents of cerebral microvessels were also measured in two groups of gerbils. It was found that VIP contents in ischemic gerbils were significantly higher than in the controls (P less than 0.01). These results indicate that: (1) VIP is present in rat and gerbil brain microvessels. (2) During brain injury by ischemia, the increase in VIP content in cerebral microvessels may induce vasodilation and cause an increase in cerebral blood flow. This may well be an autoregulatory response to protect the ischemic brain and may have important pathophysiological implications.

Topics: Animals; Brain; Brain Ischemia; Gerbillinae; Male; Microcirculation; Rats; Rats, Inbred Strains; Vasoactive Intestinal Peptide