低剂量米诺环素对大鼠脑缺血再灌注损伤的神经保护作用

Neuroprotective effects of low dose minocycline against focal cerebral ischemia reperfusion injury in rats

目的探讨静脉用低剂量米诺环素对大鼠局灶性脑缺血再灌注损伤后的神经保护作用及其机制。方法成年雄性SD大鼠72只,随机分为假手术组(S组)、缺血再灌注组(I/R组)和米诺环素干预组(I/R+MC组)。I/R组行大脑中动脉阻塞再灌注术;S组行假手术操作;I/R+MC组在再灌注术后,尾静脉注射3mg/kg米诺环素,每日2次,持续14d。缺血再灌注后2d,采用TTC染色法测定脑梗死体积,伊文思蓝(EB)法评估血脑屏障的通透性,蛋白质印迹法检测缺血侧脑组织内高迁移率族蛋白B1(high mobility group box-1protein,HMGB1)及离子钙接头蛋白(ionized calcium-binding adaptor molecule 1,Iba1)的表达。分别于再灌注后2、7、14d,采用改良的神经功能缺损评分(modified neurological severity score,mNSS)评估大鼠神经功能。结果缺血再灌注后2d,I/R组大鼠脑梗死体积较S组增大,缺血侧脑组织内EB的渗出量、HMGB1和Iba1蛋白表达均较S组明显增加(P<0.05)。与I/R组比较,I/R+MC组大鼠脑梗死体积减小(P<0.05),EB的渗出量、HMGB1和Iba1蛋白表达量降低(P<0.05)。I/R+MC组大鼠的神经功能缺损评分较I/R组下降(P<0.05)。结论米诺环素可能通过降低大鼠脑缺血再灌注损伤后脑梗死体积、血脑屏障的通透性及小胶质细胞激活等发挥神经保护作用。

Objective To investigate the neuroprotective effects of low dose intravenous minocycline against ischemia reperfusion injury in rats after focal cerebral ischemia reperfusion and to explore the possible mechanism.Methods Seventy-two rats were randomly divided into sham-operated group（S group）,cerebral ischemia/reperfusion group（I/R group）,and minocycline intervention group（I/R＋ MC group）.Focal cerebral ischemia was induced by filament medial cerebral artery occlusion method.Minocycline（3mg/kg）in saline was administered intravenously via the caudal vein twice a day for 14 days in the I/R＋ MC group.At 2days after ischemia reperfusion,the infarct volume was evaluated using TTC staining,the permeability of blood-brain barrier was assessed by Evan＇s blue（EB）dye extravasation,and the expressions of high mobility group box-1protein（HMGB1）and Iba1,a marker of activated microglia,were analyzed by using Western blotting analysis.The neurological function recovery was evaluated using the modified neurological severity score（mNSS）at 2d,7d,and 14 d after ischemia/reperfusion.Results Two days after cerebral ischemia reperfusion,the brain infarction volume and the extravasations of EB were significantly increased and the expressions of HMGB1 and Iba1were significantly up-regulated in I/R group compared with sham group（P〈0.05）.Compared with I/R group,minocycline at 3 mg/kg via the caudal veinsignificantly reduced the infarct volume in ischemic brain（P〈0.05）,extravasation of EB and expressions of HMGB1 and Iba1（P〈0.05）.Additionally,the rats in I/R＋MC group exhibited a significantly decreased neurological severity score compared with I/R group（P〈0.05）.Conclusion Minocycline exerts a neuroprotective effect in rats with cerebral ischemia reperfusion injury,which may be related to decrease of infarct size,inhibition of EB extravasation and microglia activation.