Search

Therapeutic hypothermia with modest results is the only treatment currently available for neonatal hypoxic ischemic encephalopathy (HIE). Endothelin B (ETB) receptors in the brain are shown to have neural restorative capacity. ETB receptors agonist sovateltide alone or as an adjuvant therapy may enhance neurovascular remodeling in HIE. Sprague-Dawley rat pups were grouped based on treatments into (1) Control; (2) HIE + Vehicle; (3) HIE + Hypothermia; (4) HIE + sovateltide; and (5) HIE + sovateltide + hypothermia. HIE was induced on postnatal day (PND) 7, followed by sovateltide (5 µg/kg) intracerebroventricular injection and/or hypothermia. On PND 10, brains were analyzed for the expression of vascular endothelial growth factor (VEGF), nerve growth factor (NGF), ETB receptors, oxidative stress and cellular damage markers. Vehicle-treated animals had high oxidative stress level as indicated by an increase in lipid peroxidation factor, malondialdehyde, and decreased antioxidants, reduced glutathione and superoxide dismutase, compared to control. These effects were reversed in sovateltide alone (p < 0.001) or in combination with the therapeutic hypothermia (p < 0.001), indicating that ETB receptor activation reduces oxidative stress injury following HIE. Animals receiving sovateltide demonstrated a significant (p < 0.0001) upregulation of ETB receptor, VEGF, and NGF expression in the brain compared to vehicle-treated animals. Additionally, sovateltide alone or in combination with therapeutic hypothermia significantly (p < 0.001) reduced cell death when compared to vehicle or therapeutic hypothermia alone, demonstrating that sovateltide is neuroprotective and attenuates neural damage following HIE. These findings are important and merit additional studies for development of new interventions for improving neurodevelopmental outcomes after HIE., Competing Interests: Declaration of Competing Interest This research project involved comments and discussion of investigational use of sovateltide (IRL 1620) for which Dr. Anil Gulati has issued patent., (Copyright © 2021 IBRO. Published by Elsevier Ltd. All rights reserved.)

One common feature of most neurodegenerative diseases, including Alzheimer's disease (AD) and stroke, is the death of neuronal cells. Neuronal cell death is associated with apoptosis, generation of reactive oxygen species and oxidative stress. Neuronal cell death pathways can be reversed by endothelin B receptor agonist, IRL-1620, which was found to enhance neuroprotection by promoting vascular and neuronal growth in a rodent stroke model. Previous studies conducted at our institution indicated that the treatment with IRL-1620 significantly improved neurological and motor function while reducing oxidative stress and overall infarct area. IRL-1620 is a hydrophilic, 15 amino acid peptide and has a molecular weight of 1820Da. In this study, we have encapsulated IRL-1620 in PEGylated liposomes in order to enhance its efficacy. Each batch of liposomes encapsulating IRL-1620 was evaluated for particle size, polydispersity index, and charge (zeta potential) over a period of time to determine their stability. A dose-response bar graph was plotted based on the effect of neuroprotection by free IRL-1620 on differentiated neuronal PC-12 cells. The 1nM concentration was found to have the highest cell viability. The liposomes loaded with IRL-1620 were tested on differentiated neuronal PC-12 cells for their neuroprotective ability against apoptosis caused by removal of nerve growth factor (NGF) against free (non-encapsulated) IRL-1620. The liposomal IRL-1620 was found to proliferate the growth of serum-deprived differentiated PC-12 cells significantly (p<0.0001). In the western blot analysis, the expression of the anti-apoptotic marker, BCL-2 was found to be increased, and that of pro-apoptotic marker, BAX was found to be decreased with liposomal IRL-1620. The effects were found to be independent of the NGF levels. Finally the free IRL-1620 was found to cause neuronal outgrowth equivalent to the 75ng/ml NGF treatment., (Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.)

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by severe cognitive impairment that ultimately leads to death. Endothelin (ET) and its receptors have been considered as therapeutic targets for AD. Recent studies in our lab have shown that stimulation of ETB receptors provide significant neuroprotection following Aβ1-40 administration. It is possible that IRL-1620 may be neuroprotective due to angiogenesis. However, the effect of IRL-1620 on neurovascular remodeling following Aβ1-40 administration has not been established. The purpose of this study was to determine the effect of stimulation of ETB receptors by IRL-1620 on vascular and neuronal growth factors after Aβ1-40 administration. Rats were treated with Aβ1-40 (day 1, 7 and 14) in the lateral cerebral ventricles using stereotaxically implanted cannula and received three intravenous injections of IRL-1620 (an ETB agonist), and/or BQ788 (an ETB antagonist) at 2-h interval on day 8; experiments were performed on day 15. Rats were sacrificed for estimation of brain ETB receptors, vascular endothelial growth factor (VEGF) and nerve growth factor (NGF) expression using immunofluorescence and Western blot. In the Morris swim task, amyloid-β (Aβ)-treated rats showed a significant (p<0.0001) impairment in spatial memory. Rats treated with IRL-1620 significantly (p<0.001) reduced the cognitive impairment induced by Aβ. BQ788 treatment completely blocked IRL-1620-induced improvement in cognitive impairment. IRL-1620 treatment enhanced the number of blood vessels labeled with VEGF compared to vehicle treatment. Additionally, cells showed increased (p<0.001) positive staining for NGF in IRL-1620-treated animals. ETB, VEGF and NGF protein expression significantly (p<0.001) increased in the brain of IRL-1620-treated rats as compared to vehicle. Pretreatment with BQ788 blocked the effects of IRL-1620, thus confirming the role of ETB receptors in the neurovascular remodeling actions of IRL-1620. Results of the present study demonstrate that IRL-1620 improves both acquisition (learning) and retention (memory) on the water maze task and enhances angiogenic and neurogenic remodeling. These findings indicate that the ETB receptor may be a novel therapeutic target for AD and other neurovascular degenerative disorders., (Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.)

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., (Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.)

Endothelin antagonists are being investigated to prevent neuronal loss after cerebral ischemia. Acetaminophen has been tried in stroke patients to produce hypothermia so that injury following cerebral ischemia can be reduced. The aim of this study was to assess the effect of BQ123, an endothelin-A receptor antagonist, alone and in combination with acetaminophen on neurological outcome, oxidative stress and infarct volume in rats subjected to focal ischemia by occlusion of the middle cerebral artery. In normal rats, acetaminophen decreased, while BQ123 did not produce any change in body temperature, but rats treated with BQ123 and acetaminophen produced a significantly greater (41%) hypothermic response compared to acetaminophen group. In rats subjected to middle cerebral artery occlusion, neurologic deficit was observed; acetaminophen alone did not improve, but BQ123 alone and in combination with acetaminophen produced a significant improvement in neurological deficit. The level of malondialdehyde (MDA) increased and reduced glutathione (GSH) decreased in the brain following ischemia; acetaminophen did not but BQ123 alone and in combination with acetaminophen decreased MDA and increased GSH levels in ischemic rats. Cerebral ischemia produced significant infarction, the infarct volume decreased in response to BQ123 and its combination with acetaminophen. The infarct volume, MDA level and neurological deficit in ischemic rats significantly improved in rats treated with both BQ123 and acetaminophen compared to BQ123 alone. The results demonstrate that a combination of acetaminophen and BQ123 is more effective in reducing the neuronal damage following cerebral ischemia, and this combination may be worth investigating in stroke patients., (Copyright 2010 Elsevier B.V. All rights reserved.)