Mechanism underlying reduction of cerebral ischemia-reperfusion injury by electroacupuncture preconditioning in rats: relationship between cannabinoid type 1 receptor and NLRP3 inflammasome / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the relationship between cannabinoid receptor 1 (CB1R) and the NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) during the reduction of cerebral ischemia-reperfusion (I/R) injury by electroacupuncture (EA) preconditioning in rats.Methods:Forty SPF healthy male Sprague-Dawley rats, aged 7-9 weeks, weighing 250-280 g, were divided into 5 groups ( n=8 each) according to the random number table method: sham operation group (Sham group), cerebral I/R group (I/R group), EA preconditioning group (EA group), CB1R antagonist AM251+ EA preconditioning group (AM251+ EA group), and CB1R agonist WIN 55, 212-2 group (WIN group). Cerebral I/R was induced by middle cerebral artery occlusion (MCAO) in anesthetized animals. In EA group, EA preconditioning was performed, and the acupoint Baihui (GV20) was stimulated for 30 min with disperse-dense waves, the intensity of 1 mA and frequency of 2/15 Hz once a day for 5 consecutive days, and the model of cerebral I/R injury was developed at 24 h after the last EA. In AM251+ EA group, CB1R antagonist AM251 1 mg/kg was intraperitoneally injected at 30 min before each stimulation, and the remaining operations were the same as those previously described in EA group. CB1R agonist WIN 55, 212-2 1.5 mg/kg was intraperitoneally injected for 5 consecutive days, and the model of cerebral I/R injury was prepared at 24 h after the last injection in WIN group. Neurological behavior was assessed and scored at 3 days of reperfusion. Then the rats were sacrificed, and brains were removed, and the infarct volume was measured by TTC staining, and the tissues in the ischemic penumbra were extracted for determination of the expression of NLRP3, caspase-1 and interleukin-1bata (IL-1β) by Western blot. Results:Compared with Sham group, the percentage of cerebral infarct volume was significantly increased, the neurobehavioral score was decreased, and the expression of NLRP3, caspase-1 and IL-1β was up-regulated in I/R group ( P<0.05). Compared with I/R group, the percentage of cerebral infarct volume was significantly decreased, the neurobehavioral score was increased, and the expression of NLRP3, caspase-1 and IL-1β was down-regulated in EA and WIN groups ( P<0.05). Compared with EA group, the percentage of cerebral infarct volume was significantly increased, the neurobehavioral score was decreased, and the expression of NLRP3, caspase-1 and IL-1β was up-regulated in AM251+ EA group ( P<0.05). Conclusions:EA preconditioning may inhibit the activation of NLRP3 inflammasomes by activating CB1R, thus alleviating cerebral I/R injury in rats.