oxadiazoles and Stroke

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

Topics: Angiotensin II Type 1 Receptor Blockers; Animals; Animals, Genetically Modified; Antihypertensive Agents; Atherosclerosis; Benzimidazoles; Benzoates; Blood Pressure; Cardiovascular Diseases; Culture Techniques; Disease Models, Animal; Drug Therapy, Combination; Endothelium, Vascular; Gene Knockout Techniques; Glucose; Humans; Hypertension; Kidney; Lipid Metabolism; Metabolic Diseases; Oxadiazoles; Renin-Angiotensin System; Stroke; Telmisartan

The oxazole derivative, irampanel, a non-competitive AMPA receptor antagonist, is under development by Boehringer Ingelheim for the potential treatment of stroke [329079]. Phase I/IIa trials for stroke had been initiated by July 2000 [374144]. Phase II trials were ongoing in April 2001 [407163]; in April 2002, however, the drug did not appear on the company's research and development pipeline [446554], and a company spokesperson declined to confirm its current status [450591]. The compound was also originally under investigation for other neurological disorders, including epilepsy and pain [329079], although by October 1999, development was only ongoing for stroke [346080].

Topics: Animals; Clinical Trials, Phase I as Topic; Disease Models, Animal; Humans; Oxadiazoles; Receptors, AMPA; Stroke

Ischaemic stroke of the brain accounts for about one third of all deaths in industrialized countries. Many of the patients who survive are severily impaired. Thus, there is an enormous need for pharmacotherapy for the treatment of ischaemic stroke. Why is such a treatment not available yet? Are the pathophysiological sequelae of brain ischaemia not well understood? Have there been no attempts for clinical development of neuroprotective drugs? Everyone who is engaged in stroke research knows that the opposite is true: The cellular processes occuring after brain ischaemia have been studied for a long time, and we have a thorough understanding of the cellular processes which are involved. Many compounds underwent clinical trials, but most of them failed. One hypothesis to explain this disappointing fact might be that the cellular consequences of stroke are manyfold, but that the clinically tested compounds were selective for only one molecular mechanism. The aim of this review is to give a summary of the pathophysiological mechanisms which occur during and after an ischaemic stroke, and to comment on the preclinical studies where multiple disease-related mechanisms were targeted pharmacologically. Moreover, a novel class of neuroprotective compounds, the oxadiazole derivatives, will be presented. Compounds of this chemical class target two key mechanisms which are important for the pathophysiology of stroke, namely voltage-gated sodium channels, as well as glutamate receptors of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype.

Topics: Brain Ischemia; Drug Evaluation, Preclinical; Drug Therapy, Combination; Excitatory Amino Acid Antagonists; Fibrinolytic Agents; Humans; Neuroprotective Agents; Oxadiazoles; Receptors, AMPA; Stroke

Vascular smooth muscle (VSM) cell phenotypic expression and autophagic state are dynamic responses to stress. Vascular pathologies, such as hypoxemia and ischemic injury, induce a synthetic VSM phenotype and autophagic flux resulting in a loss of vascular integrity and VSM cell death respectfully. Both clinical pilot and experimental stroke studies demonstrate that sphingosine-1-phosphate receptor (S1PR) modulation improves stroke outcome; however, specific mechanisms associated with a beneficial outcome at the level of the cerebrovasculature have not been clearly elucidated. We hypothesized that ozanimod, a selective S1PR type 1 ligand, will attenuate VSM synthetic phenotypic expression and autophagic flux in primary human brain VSM cells following acute hypoxia plus glucose deprivation (HGD; in vitro ischemic-like injury) exposure. Cells were treated with ozanimod and exposed to normoxia or HGD. Crystal violet staining, standard immunoblotting, and immunocytochemical labeling techniques assessed cellular morphology, vacuolization, phenotype, and autophagic state. We observed that HGD temporally decreased VSM cell viability and concomitantly increased vacuolization, both of which ozanimod reversed. HGD induced a simultaneous elevation and reduction in levels of pro- and antiautophagic proteins respectfully, and ozanimod attenuated this response. Protein levels of VSM phenotypic biomarkers, smoothelin and SM22, were decreased following HGD. Furthermore, we observed an HGD-induced epithelioid and synthetic morphological appearance accompanied by disorganized cytoskeletal filaments, which was rescued by ozanimod. Thus, we conclude that ozanimod, a selective S1PR

Topics: Autophagy; Brain; Cell Survival; Cells, Cultured; Glucose; Humans; Hypoxia; Indans; Ligands; Male; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Oxadiazoles; Phenotype; Reperfusion Injury; Sphingosine-1-Phosphate Receptors; Stroke

Collateral growth after acute occlusion of an intracranial artery is triggered by increasing shear stress in preexisting collateral pathways. Recently, sphingosine-1-phosphate receptor-1 (S1PR1) on endothelial cells was reported to be essential in sensing fluid shear stress. Here, we evaluated the expression of S1PR1 in the hypoperfused mouse brain and investigated the effect of a selective S1PR1 agonist on leptomeningeal collateral growth and subsequent ischemic damage after focal ischemia.. In C57Bl/6 mice (n = 133) subjected to unilateral common carotid occlusion (CCAO) and sham surgery. The first series examined the time course of collateral growth, cell proliferation, and S1PR1 expression in the leptomeningeal arteries after CCAO. The second series examined the relationship between pharmacological regulation of S1PR1 and collateral growth of leptomeningeal anastomoses. Animals were randomly assigned to one of the following groups: LtCCAO and daily intraperitoneal (i.p.) injection for 7 days of an S1PR1 selective agonist (SEW2871, 5 mg/kg/day); sham surgery and daily i.p. injection for 7 days of SEW2871 after surgery; LtCCAO and daily i.p. injection for 7 days of SEW2871 and an S1PR1 inverse agonist (VPC23019, 0.5 mg/kg); LtCCAO and daily i.p. injection of DMSO for 7 days after surgery; and sham surgery and daily i.p. injection of DMSO for 7 days. Leptomeningeal anastomoses were visualized 14 days after LtCCAO by latex perfusion method, and a set of animals underwent subsequent permanent middle cerebral artery occlusion (pMCAO) 7 days after the treatment termination. Neurological functions 1 hour, 1, 4, and 7 days and infarction volume 7 days after pMCAO were evaluated.. In parallel with the increase in S1PR1 mRNA levels, S1PR1 expression colocalized with endothelial cell markers in the leptomeningeal arteries, increased markedly on the side of the CCAO, and peaked 7 days after CCAO. Mitotic cell numbers in the leptomeningeal arteries increased after CCAO. Administration of the S1PR1 selective agonist significantly increased cerebral blood flow (CBF) and the diameter of leptomeningeal collateral vessels (42.9 ± 2.6 μm) compared with the controls (27.6 ± 5.7 μm; P < 0.01). S1PR1 inverse agonist administration diminished the effect of the S1PR1 agonist (P < 0.001). After pMCAO, S1PR1 agonist pretreated animals showed significantly smaller infarct volume (17.5% ± 4.0% vs. 7.7% ± 4.0%, P < 0.01) and better functional recovery than vehicle-treated controls.. These results suggest that S1PR1 is one of the principal regulators of leptomeningeal collateral recruitment at the site of increased shear stress and provide evidence that an S1PR1 selective agonist has a role in promoting collateral growth and preventing of ischemic damage and neurological dysfunction after subsequent stroke in patients with intracranial major artery stenosis or occlusion.

Topics: Animals; Dimethyl Sulfoxide; Disease Models, Animal; Endothelial Cells; Male; Mice; Oxadiazoles; Receptors, Lysosphingolipid; Sphingosine-1-Phosphate Receptors; Stroke; Thiophenes; Time Factors

FTY720 is a known sphingosine 1-phosphate receptor agonist. In the present study, we investigated the neuroprotective effect of postischemic administration of FTY720 in rats with 2 hours transient middle cerebral artery occlusion (MCAO).. One hundred eleven male rats were randomly assigned to sham-operated and MCAO treated with vehicle, 0.25 mg/kg and 1 mg/kg of FTY720, another selective sphingosine 1-phosphate receptor-1 agonist SEW2871 (5 mg/kg), or 0.25 mg/kg of FTY720 plus a sphingosine 1-phosphate antagonist, VPC23019 (0.5 mg/kg). Drugs were injected intraperitoneally immediately after reperfusion. Neurological score and infarct volume were assessed at 24 and 72 hours after MCAO. Western blotting, immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling were conducted at 24 hours after MCAO.. FTY720 significantly reduced infarct volume and improved neurological score at 24 and 72 hours after MCAO compared with the vehicle group. SEW2871 showed similar neuroprotective effects to FTY720, whereas VPC 20319 abolished the neuroprotective effects of FTY720. FTY720 significantly retained Akt and extracellular signal-regulated kinase phosphorylation and Bcl-2 expression and decreased cleaved caspase-3 expression and terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling-positive neurons at 24 hours after MCAO. VPC23019 blocked the antiapoptotic effects of FTY720.. These data suggest that activation of sphingosine 1-phosphate-1 by FTY720 reduces neuronal death after transient MCAO.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Brain; Brain Ischemia; Disease Models, Animal; Drug Administration Schedule; Fingolimod Hydrochloride; Immunosuppressive Agents; In Situ Nick-End Labeling; Infarction, Middle Cerebral Artery; Male; MAP Kinase Signaling System; Nerve Degeneration; Neuroprotective Agents; Oxadiazoles; Propylene Glycols; Rats; Rats, Sprague-Dawley; Receptors, Lysosphingolipid; Sphingosine; Stroke; Thiophenes; Treatment Outcome

Biotin is a member of the vitamin B-complex family. Biotin deficiency has been associated with hyperglycaemia and insulin resistance in animals and humans. In the present study, we investigated the pharmacological effects of biotin on hypertension in the stroke-prone spontaneously hypertensive rat (SHRSP) strain. We observed that long-term administration of biotin decreased systolic blood pressure in the SHRSP strain; also, a single dose of biotin immediately decreased systolic blood pressure in this strain. Pretreatment with the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazole [4,3-alpha]quinoxalin-1-one abolished the hypotensive action of biotin in the SHRSP strain, while pretreatment with the NO synthase inhibitor NG-nitro-l-arginine methyl ester had no effect on the action of biotin. Biotin reduced coronary arterial thickening and the incidence of stroke in the SHRSP strain. These results suggest that the pharmacological dose of biotin decreased the blood pressure of the SHRSP via an NO-independent direct activation of soluble guanylate cyclase. Our findings reveal the beneficial effects of biotin on hypertension and the incidence of stroke.

Topics: Animals; Biotin; Coronary Vessels; Genetic Predisposition to Disease; Glucose Tolerance Test; Guanylate Cyclase; Hypertension; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Oxadiazoles; Quinoxalines; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Stroke; Time; Vitamins

Compound 8a (BMS-191011), an opener of the cloned large-conductance, Ca2+-activated potassium (maxi-K) channel, demonstrated efficacy in in vivo stroke models, which led to its nomination as a candidate for clinical evaluation. Its maxi-K channel opening properties were consistent with its structural topology, being derived by combining elements from other known maxi-K openers. However, 8a suffered from poor aqueous solubility, which complicated elucidation of SAR during in vitro evaluation. The activity of 8a in in vivo stroke models and studies directed toward improving its solubility are reported herein. Enhanced solubility was achieved by appending heterocycles to the 8a scaffold, and a notable observation was made that inclusion of a simple amino group (anilines 8k and 8l) yielded excellent in vitro maxi-K ion channel opening activity and enhanced brain-to-plasma partitioning compared to the appended heterocycles.

Topics: Animals; Brain; Crystallography, X-Ray; Female; In Vitro Techniques; Ion Channel Gating; Large-Conductance Calcium-Activated Potassium Channels; Molecular Structure; Oocytes; Oxadiazoles; Patch-Clamp Techniques; Plasma; Rats; Rats, Inbred SHR; Solubility; Stroke; Structure-Activity Relationship; Xenopus laevis

A variety of water-soluble prodrugs of BMS-191011 was synthesized and evaluated for solution state stability and rate of conversion to BMS-191011 in rat and human plasma. The deoxycarnitine ester prodrug (11c) was selected for clinical evaluation based on its superior chemical stability, crystallinity and cleavage to BMS-191011 in human plasma.

Topics: Animals; Betaine; Blood; Carnitine; Crystallization; Dose-Response Relationship, Drug; Drug Stability; Heterocyclic Compounds, 3-Ring; Humans; Neuroprotective Agents; Oxadiazoles; Potassium Channels; Prodrugs; Rats; Solubility; Stroke; Structure-Activity Relationship; Water