电针预处理对大鼠脑缺血再灌注时神经元NLRP3表达的影响

Effect of electroacupuncture pretreatment on expression of NLRP3 in neurons during cerebral ischemia-reperfusion in rats

目的 评价电针预处理对脑缺血再灌注时神经元NOD样受体热蛋白结构域相关蛋白3（NLRP3）表达的影响.方法 清洁级健康雄性SD大鼠54只,7周龄,体重250～ 280 g,采用随机数字表法分为3组（n=18）：假手术组（S组）、缺血再灌注组（I/R组）和电针预处理组（E组）.I/R组采用阻塞大鼠右侧大脑中动脉90 min后再灌注的方法制备脑缺血再灌注损伤模型.E组电针刺激百会穴进行预处理,电针刺激参数为疏密波,频率2 Hz/15 Hz,强度1 mA,持续30 min,1次/d,连续5d,于末次电针刺激后24 h时制备脑缺血再灌注损伤模型.于再灌注72h时,行神经行为学评分,然后处死大鼠,取脑组织,采用TTC染色法测定脑梗死体积,计算脑梗死体积百分比;采用Westernblot法检测NLRP3、caspase-1和IL-1β的表达;采用免疫荧光组化法检测神经元NLRP3表达情况.结果 与S组比较,I/R组脑梗死体积百分比和神经行为学评分降低,脑组织神经元NLRP3、caspase-1和IL-1β的表达上调（P＜0.05）;与I/R组比较,E组脑梗死体积百分比和神经行为学评分升高,脑组织神经元NLRP3、caspase-1和IL-1β的表达下调（P＜0.05）.结论 电针预处理减轻大鼠脑缺血再灌注时神经组织炎症反应的机制可能与下调神经元NLRP3的表达有关.

Objective To evaluate the effect of electroacupuncture （EA） pretreatment on NODlike receptor pyrin domain-containing 3 （NLRP3） in neurons during cerebral ischemia-reperfusion （I/R） in rats.Methods Fifty-four adult male Sprage-Dawley rats,aged 7 weeks,weighing 250-280 g,were randomly divided into 3 groups （n =18 each） using a random number table：sham operation group （group S）,group I/R,and EA pretreatment group （group E）.Cerebral I/R was induced by occlusion of the right middle cerebral artery for 90 min using a nylon thread inserted into the internal carotid artery and advanced intracranially to block the blood flow,followed by reperfusion.In group E,the acupoint Baihui was stimulated with an electric stimulator （sparse-dense wave,frequency 2 Hz/15 Hz,intensity ≤ 1 mA） for 30 min once a day for 5 consecutive days,and the model of cerebral I/R was established at 24 h after the last stimulation.At 72 h of reperfusion,neurological function was assessed and scored.The rats were then sacrificed,and their brains were removed for determination of cerebral infarct volume （using TTC staining）,expression of NLRP3,caspase-1 and interleukin-1beta （IL-1β） in brain tissues （by Western blot）,and expression of NLRP3 protein in neurons （by immunofluorescence histochemistry）.The percentage of cerebral infarct volume was calculated.Results Compared with group S,the percentage of cerebral infarct volume and neurological scores were significantly decreased,and the expression of NLRP3,caspase-1 and IL-1β in brain tissues was significantly up-regulated in group I/R （P〈0.05）.Compared with group I/R,the percentage of cerebral infarct volume and neurological scores were significantly increased,and the expression of NLRP3,caspase-1 and IL-1β in brain tissues was significantly down-regulated ingroup E （P〈0.05）.Conclusion The mechanism by which EA pretreatment reduces inflammatory responses during cerebral I/R injury may be related to down-regulation of NLRP3 expression in neurons in rats.