am-630 and Reperfusion-Injury

Remote ischemic preconditioning (RIPC) has protective effects on spinal cord ischemia reperfusion (I/R) injury, but the potential mechanisms remain unclear. In our study, the effects and underlying mechanisms of RIPC on blood-spinal cord barrier (BSCB) breakdown following I/R injury were investigated.. animals underwent intraperitoneal administration with cannabinoid-1 (CB1) receptor antagonist AM251, cannabinoid-2 (CB2) receptor antagonist AM630 or vehicle 15 minutes before three 3-minute occlusion-reperfusion cycles on the right femoral artery or a sham operation. 30 minutes after the preconditioning, aortic arch was exposed with or without 14-minute occlusion. Neurological function was assessed with Tarlov scoring system. The disruption of BSCB was assessed by measuring Evans Blue (EB) extravasation. The expression of tight junction protein occludin was determined by western blot analyses. The expression and localization of CB1 and CB2 receptors were assessed by western blot and immunofluorescence.. RIPC attenuated the motor dysfunction, BSCB disruption and downregulation of occludin after I/R injury, which were impaired by blocking CB1 and CB2 receptors. Moreover, RIPC upregulated the elevated perivascular expression of CB1 and CB2 receptors following I/R injury.. These results indicated that RIPC, through activation and upregulation of CB1 and CB2 receptors, was involved in preserving the integrity of BSCB after spinal cord I/R injury.

Topics: Animals; Disease Models, Animal; Down-Regulation; Femoral Artery; Indoles; Ischemic Preconditioning; Male; Permeability; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Reperfusion Injury; Spinal Cord; Up-Regulation

The aim of this study was to examine the influence of endogenous cannabinoids on neuroprotection of the spinal cord afforded by limb remote ischemic preconditioning.. In experiment 1 (RIPC group), 3 cycles of limb remote ischemic preconditioning within different episodes (2, 3, or 5 minutes) were induced before spinal cord ischemia in rats (N = 5, n = 8). In experiment 2, animals were pretreated intravenously by the vehicles, cannabinoid 1 (AM251, 1 mg/kg) or cannabinoid 2 (AM630, 1 mg/kg) receptor antagonist 15 minutes before remote ischemic preconditioning, or else they were subjected to a sham operation. Thirty minutes after the pretreatment, spinal cord ischemia was induced (N = 8, n = 8). In experiment 3, the arachidonylethanolamide and 2-arachidonoylglycerol contents in the spinal cord after remote ischemic preconditioning and spinal cord ischemia were detected in rats (N = 2, n = 12). Spinal cord ischemia was induced by 12 minutes of thoracic aorta occlusion in rats. Neurologic function was assessed 24 and 48 hours after reperfusion. Histopathologic examination was performed and the number of normal neurons in anterior spinal cord were counted.. In experiment 1, 3 cycles of limb remote ischemic preconditioning (3 minutes of ischemia/3 minutes of reperfusion) induced ischemic tolerance on the spinal cords of the rats. The RIPC group showed a significant reduction in motor deficit index (P < .01) as well as an increase in the number of normal neurons (P < .01). In experiment 2, the cannabinoid 1 receptor antagonist AM251 pretreatment abolished the protective effects of remote preconditioning. In experiment 3, arachidonylethanolamide content in spinal cord was elevated by remote ischemic preconditioning in rats.. These results indicated that endogenous cannabinoids, through acting on cannabinoid 1 receptors, were involved in the neuroprotective phenomenon on spinal cords of limb remote ischemic preconditioning.

Topics: Animals; Cannabinoid Receptor Antagonists; Cannabinoid Receptor Modulators; Indoles; Ischemia; Ischemic Preconditioning; Male; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Reperfusion Injury; Spinal Cord