异氟醚后处理对大鼠脑缺血再灌注损伤的影响

Effects of isoflurane postconditioning on cerebral ischemia-reperfusion injury in rats

目的 评价异氟醚后处理对大鼠脑缺血再灌注损伤的影响.方法 健康雄性SD大鼠32只,体重280～320 g,采用随机数字表法,将其分为4组（n=8）：假手术组（S组）、脑缺血再灌注组（I/R组）、异氟醚预处理组（Ⅰ-pre组）和异氟醚后处理组（Ⅰ-post组）.采用改良Pulsinelli四血管阻断法制备大鼠全脑缺血再灌注损伤模型.Ⅰ-pre组缺血前吸入1.5％异氟醚2h,Ⅰ-post组再灌注即刻吸入1.5％异氟醚30 min.于再灌注24h时行神经行为学评分,再灌注72h时处死大鼠取海马,采用TUNEL法检测凋亡神经元,计算神经元凋亡率,免疫组化法检测caspase-3表达,Western blot法检测磷酸化c-Jun氨基末端激酶（p-JNK）表达.结果 与S组比较,I/R组、Ⅰ-pre组和Ⅰ-post组格子爬行数减少,转体时间延长,悬挂时间缩短,海马神经元凋亡率升高,caspase-3和p-JNK表达上调（P＜0.05）；与I/R组比较,Ⅰ-pre组和Ⅰ-post组格子爬行数增多,转体时间缩短,悬挂时间延长,海马神经元凋亡率降低,caspase-3和p-JNK表达下调（P＜0.05）；与Ⅰ-pre组比较,Ⅰ-post组格子爬行数减少,悬挂时间缩短,海马神经元凋亡率升高,caspase-3表达上调（P＜0.05）,p-JNK表达差异无统计学意义（P＞0.05）.结论 异氟醚后处理可减轻大鼠脑缺血再灌注损伤,且其效果弱于预处理,其机制与激活海马JNK信号转导通路抑制神经元凋亡有关.

Objective To evaluate the effects of isoflurane postconditioning on cerebral ischemia-reperfusion （I/R） injury in rats.Methods Thirty-two male Sprague-Dawley rats,weighing 280-320 g,were randomly divided into 4 groups （n=8 each）：group sham operation （group S）,group I/R,group isoflurane preconditioning （group Ⅰ-pre）,and group isoflurane postconditioning （group Ⅰ-post）.Global cerebral I/R was induced by 4-vessel occlusion method described by Pulsinelli.1.5％ isoflurane was inhaled for 2h before ischemia in group Ⅰ-pre.1.5％ isoflurane was inhaled for 30 min immediately after onset of reperfusion in group Ⅰ-post.Neurological function was assessed and scored at 24h of reperfusion.The rats were sacrificed at 72h of reperfusion and hippocampi were isolated for determination of neuronal apoptosis （by TUNEL）,caspase-3 expression （by immuno-histochemistry）,and phosphorylated c-Jun N-terminal kinase （p-JNK） protein expression （by using Western blot） in hippocampal tissues.Apoptotic rate was calculated.Results Compared with S group,the number of grid cross was decreased,twist time was prolonged,hanging time was shortened,apoptotic rate was increased,and the expression of caspase-3 and p-JNK protein was up-regulated in I/R,I-pre and Ⅰ-post groups （P ＜ 0.05）.Compared in I/R group,the number of grid cross was increased,twist time was shortened,hanging time was prolonged,apoptotic rate was decreased,and the expression of caspase-3 and p-JNK protein was down-regulated in Ⅰ-pre and Ⅰ-post groups （P ＜ 0.05）.Compared with I/R group,the number of grid cross was decreased,hanging time was shortened,apoptotic rate was increased,and the expression of caspase-3 was up-regulated （P ＜ 0.05）,and no significant changes in the expression of p-JNK protein were found in Ⅰ-post group （P ＞ 0.05）.Conclusion Isoflurane postconditioning can reduce cerebral I/R injury,the efficacy is weaker than that of preconditioning and the mechanism is related to activation of JNK signal transduction pathway and inhibition of neuronal apoptosis in hippocampus of rats.