glucagon-like-peptide-1 and Infarction--Middle-Cerebral-Artery

Stroke is a condition with few medical treatments available. Semaglutide, a novel Glucagon-like peptide-1 (GLP-1) analogue, has been brought to the market as a treatment for diabetes. We tested the protective effects of semaglutide against middle cerebral artery occlusion injury in rats. Animals were treated with 10 nmol/kg bw ip. starting 2 h after surgery and every second day for either 1, 7, 14 or 21 days. Semaglutide-treated animals showed significantly reduced scores of neurological impairments in several motor and grip strength tasks. The cerebral infarction size was also reduced, and the loss of neurons in the hippocampal areas CA1, CA3 and the dentate gyrus was much reduced. Chronic inflammation as seen in levels of activated microglia and in the activity of the p38 MAPK - MKK - c-Jun- NF-κB p65 inflammation signaling pathway was reduced. In addition, improved growth factor signaling as shown in levels of activated ERK1 and IRS-1, and a reduction in the apoptosis signaling pathway C-raf, ERK2, Bcl-2/BAX and Caspase-3 was observed. Neurogenesis had also been normalized by the drug treatment as seen in increased neurogenesis (DCX-positive cells) in the dentate gyrus and a normalization of biomarkers for neurogenesis. In conclusion, semaglutide is a promising candidate for re-purposing as a stroke treatment.

Topics: Animals; Apoptosis; Brain; Disease Models, Animal; Doublecortin Protein; Glucagon-Like Peptide 1; Glucagon-Like Peptides; Hippocampus; Hypoglycemic Agents; Infarction, Middle Cerebral Artery; Inflammation; Insulin Receptor Substrate Proteins; Microglia; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinase Kinases; Motor Activity; Neurogenesis; Neurons; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Proteins c-jun; Rats; Stroke; Transcription Factor RelA

Preclinical Research & Development The purpose of the present study is to evaluate the neuroprotective effect of recombinant human glucagon-like peptide-1 (rhGLP-1) as well as to explore corresponding mechanisms in diabetic rats with cerebral ischemia/reperfusion injury induced by middle cerebral artery occlusion (MCAO). Diabetes mellitus was induced by intraperitoneal injection of streptozotocin. The rats were pretreated with rhGLP-1 (20 μg/kg intraperitoneally, thrice a day) for 14 days. Thereafter, the rats were subjected to MCAO 90 min/reperfusion 24 hr. At 2 and 24 hr of reperfusion, the rats were assessed for neurological deficits and subsequently executed for the evaluation of cerebral infarct volume, oxidative stress parameters, and the expression of excitatory amino acid transporter 2 (EAAT2) and apoptotic markers. Results indicate that rhGLP-1 significantly ameliorated neurological deficits and reduced cerebral infarct volume in diabetic MCAO rats. In addition, oxidative stress parameters in ischemic penumbra were significantly alleviated in rhGLP-1-pretreated diabetic MCAO rats. rhGLP-1 significantly upregulated the ratio of Bcl-2/Bax and EAAT2 expression and downregulated cleaved caspase-3 expression in ischemic penumbra of diabetic MCAO rats. Our results suggest that rhGLP-1 could significantly ameliorate neurological deficits and reduce cerebral infarct volume in diabetic MCAO rats, which may be due to the inhibition of oxidative stress and apoptosis and the promotion of EAAT2 expression.

Topics: Animals; Apoptosis; Brain Ischemia; Diabetes Complications; Diabetes Mellitus; Excitatory Amino Acid Transporter 2; Glucagon-Like Peptide 1; Humans; Incretins; Infarction, Middle Cerebral Artery; Neuroprotective Agents; Oxidative Stress; Rats; Recombinant Proteins; Reperfusion Injury

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonists have been shown to be neuroprotective in previous studies in animal models of Alzheimer's or Parkinson's disease. Recently, novel dual-GLP-1/GIP receptor agonists that activate both receptors (DA) were developed to treat diabetes. We tested the protective effects of a novel potent DA against middle cerebral artery occlusion injury in rats and compared it with a potent GLP-1 analog, Val(8)-GLP-1(glu-PAL). Animals were evaluated for neurologic deficit score, infarct volume, and immunohistochemical analyses of the brain at several time points after ischemia. The Val(8)-GLP-1(glu-PAL)-treated and DA-treated groups showed significantly reduced scores of neurological dysfunction, cerebral infarction size, and percentage of TUNEL-positive apoptotic neurons. Furthermore, the expression of the apoptosis marker Bax, the inflammation marker iNOS, and the survival marker Bcl-2 was significantly increased. The DA-treated group was better protected against neurodegeneration than the Val(8)-GLP-1(glu-PAL) group, and the scores of neurological dysfunction, cerebral infarction size, and expression of Bcl-2 were higher, whereas the percentage of TUNEL-positive neurons and the levels of Bax and iNOS were lower in the DA group. DA treatment reduced the infarct volume and improved the functional deficit. It also suppressed the inflammatory response and cell apoptosis after reperfusion. In conclusion, the novel GIP and GLP-1 dual-receptor agonist is more neuroprotective than a GLP-1 receptor agonist in key biomarkers of neuronal degeneration.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Brain; Disease Models, Animal; Drug Evaluation, Preclinical; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Lipopeptides; Male; Motor Activity; Nerve Degeneration; Neurons; Neuroprotective Agents; Nitric Oxide Synthase Type II; Random Allocation; Rats, Sprague-Dawley; Receptors, Gastrointestinal Hormone

In recent years, GLP-1 and its analogs have been developed for the treatment of type 2 diabetes. It has been reported that stimulating the GLP-1 receptor can protect neurons against metabolic and oxidative insults, and therefore can be used in the treatment of stroke and Parkinson׳s disease. The present study aimed to examine the neuroprotective effects of rhGLP-1 (7-36) and its possible mechanisms against acute ischemia/reperfusion injuries induced by middle cerebral artery occlusion (MCAO) in diabetic rats. The type 2 diabetic rat model was established by a combination of a high-fat diet and low-dose streptozotocin (STZ). RhGLP-1 (7-36) (20, 40, 80μg/kg) was given intraperitoneally before reperfusion. The neuroprotective effects of rhGLP-1 (7-36) were evaluated by changes in neurological deficit scores and 2,3,5-Triphenyltetrazolium chloride (TTC) staining. Changes in blood glucose were used to assess hypoglycemic effects. The content of malondialdehyde (MDA) and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), inducible nitric oxide syntheses (iNOS) and endothelial nitric oxide syntheses (eNOS) after MCAO/R administration (2h and 46h) were examined to investigate the possible mechanisms of RhGLP-1 (7-36). Haematoxylin and eosin (H&E) staining was used for histopathological observation. Compared with the control group, rhGLP-1 (7-36)-treated groups decreased nerve function deficiency scores; significantly reduced infarction volume percentage, MDA, iNOS and blood glucose; and significantly increased SOD, GSH-PX and eNOS. In addition, rhGLP-1 (7-36) groups enhanced the density of surviving neurons and increased vascular proliferation. The current study suggests a neuroprotective effect of rhGLP-1 (7-36) in diabetic MCAO/R rats since anti-oxidative and anti-nitrosative stress effects can contribute to beneficial effects against ischemia/reperfusion injury.

Topics: Animals; Blood Glucose; Brain; Brain Ischemia; Diabetes Mellitus, Experimental; Dose-Response Relationship, Drug; Glucagon-Like Peptide 1; Glutathione Peroxidase; Hypoglycemic Agents; Infarction, Middle Cerebral Artery; Male; Malondialdehyde; Neuroprotective Agents; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Peptide Fragments; Random Allocation; Rats, Sprague-Dawley; Reperfusion Injury; Severity of Illness Index; Superoxide Dismutase

Stroke is a leading cause of death and serious, long-term disability worldwide. We report that rats receiving liraglutide show markedly attenuated infarct volumes and neurological deficit following ischemic insult. We have also investigated the effect of liraglutide on apoptosis and oxidative stress pathways after ischemic injury in diabetic and non-diabetic rats. Male Sprague-Dawley rats weighing 300-350g were used. Diabetes was induced by streptozotocin. Rats were pretreated with either vehicle or liraglutide (50μg/kg, s.c.) for 14days and thereafter subjected to middle cerebral artery occlusion (MCAO). Twenty-four hours after occlusion, rats were assessed for neurological deficit, motor function and subsequently sacrificed for estimation of infarct volume, oxidative stress and apoptotic markers. Vehicle-treated non-diabetic and diabetic rats showed significant (p<0.001) neurological deficit following cerebral ischemia. Liraglutide pretreatment resulted in significantly (p<0.001) less neurological deficit compared to vehicle-treated MCAO rats. Cerebral ischemia produced significant (p<0.0001) infarction in vehicle-treated rats; however, the infarct volume was significantly (p<0.001) less in liraglutide-pretreated rats. Oxidative stress markers were increased following ischemia but were attenuated in liraglutide-treated rats. Anti-apoptotic protein Bcl-2 expression was decreased and pro-apoptotic protein Bax expression was increased in vehicle-treated MCAO rats compared to sham (p<0.0001). On the other hand liraglutide pretreatment showed significantly (p<0.01) increased expression of Bcl-2 and decreased expression of Bax in MCAO rats. In vehicle-treated group, the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells significantly (p<0.0001) increased in the ischemic hemisphere compared to sham-operated group. The number of TUNEL-positive cells in vehicle group was 73.5±3.3 and 85.5±5.2/750μm(2) in non-diabetic and diabetic vehicle-treated MCAO rats, respectively. Following liraglutide treatment the number of TUNEL-positive cells was remarkably attenuated to 25.5±2.8 and 41.5±4.1/750μm(2) (p<0.001) in non-diabetic and diabetic rats, respectively. The results demonstrate that glucagon-like peptide 1 (GLP-1) agonist, liraglutide, is a neuroprotective agent and attenuates the neuronal damage following cerebral ischemia in rats by preventing apoptosis and decreasing oxidative stress.

Topics: Animals; Apoptosis; Brain Ischemia; Diabetes Mellitus, Experimental; Disease Models, Animal; Glucagon-Like Peptide 1; Hypoglycemic Agents; Infarction, Middle Cerebral Artery; Liraglutide; Male; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Sprague-Dawley

The number of diabetes mellitus (DM) patients is increasing, and stroke is deeply associated with DM. Recently, neuroprotective effects of glucagon-like peptide-1 (GLP-1) are reported. In this study, we explored whether liraglutide, a GLP-1 analogue exerts therapeutic effects on a rat stroke model. Wistar rats received occlusion of the middle cerebral artery for 90 min. At one hour after reperfusion, liraglutide or saline was administered intraperitoneally. Modified Bederson's test was performed at 1 and 24 h and, subsequently, rats were euthanized for histological investigation. Peripheral blood was obtained for measurement of blood glucose level and evaluation of oxidative stress. Brain tissues were collected to evaluate the level of vascular endothelial growth factor (VEGF). The behavioral scores of liraglutide-treated rats were significantly better than those of control rats. Infarct volumes of liraglutide-treated rats at were reduced, compared with those of control rats. The level of derivatives of reactive oxygen metabolite was lower in liraglutide-treated rats. VEGF level of liraglutide-treated rats in the cortex, but not in the striatum significantly increased, compared to that of control rats. In conclusion, this is the first study to demonstrate neuroprotective effects of liraglutide on cerebral ischemia through anti-oxidative effects and VEGF upregulation.

Topics: Animals; Blood Glucose; Diabetes Complications; Disease Models, Animal; Glucagon-Like Peptide 1; Humans; Infarction, Middle Cerebral Artery; Liraglutide; Neuroprotective Agents; Oxidative Stress; Rats; Stroke; Vascular Endothelial Growth Factor A