PI3K/Akt信号通路在七氟醚后处理减轻大鼠局灶性脑缺血再灌注损伤中的作用

目的 评价磷脂酰肌醇3激酶/蛋白质丝氨酸苏氨酸激酶(PI3K/Akt)信号通路在七氟醚后处理减轻大鼠局灶性脑缺血再灌注损伤中的作用.方法 雄性SD大鼠64只,体重300～350 g,随机分为4组(n=16):局灶性脑缺血再灌注组(IR组)、七氟醚后处理组(SP组)、七氟醚后处理+Wortmannin组(SW组)和Wortmannin组(W组).采用电凝法阻断左侧大脑中动脉,夹闭双侧颈总动脉60 min恢复灌注的方法制备大鼠局灶性脑缺血再灌注模型.再灌注即刻SP组和SW组吸入2.5%七氟醚60 min,夹闭双侧颈总动脉30 min时SW组和W组股静脉输注Wortmannin 0.6 mg/kg.于再灌注24、48、72 h时行神经功能评分,最后1次评分后处死大鼠取脑,测定脑梗死体积,采用Western blot法检测左侧脑组织磷酸化Akt(p-Akt)和磷酸化Bad(p-Bad)的表达水平.结果 与IR组相比,SP组和SW组各时点神经功能评分升高,再灌注72 h时脑梗死体积比降低,脑组织p-Akt和p-Bad表达上调(P＜0.05),W组上述指标差异无统计学意义(P＞0.05);与SP组相比,SW组各时点神经功能评分降低,再灌注72 h时脑梗死体积比升高,脑组织p-Akt和p-Bad表达下调(P＜0.05).结论 PI3K/Akt信号通路激活后p-Bad表达上调可能参与了七氟醚后处理减轻大鼠局灶性脑缺血再灌注损伤的过程.

Role of PI3K/Akt signal pathway in sevoflurane postconditioning against focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the role of PI3K/Akt signal pathway in sevoflurane postconditioning against focal cerebral ischemia-reperfusion (I/R) injury. Methods Sixty-four adult male SD rats weighing 300-350 g were randomly assigned into 4 groups (n = 16 each):group Ⅰ focal cerebral I/R (group I/R); group Ⅱ sevoflurane postconditioning (group SP); group Ⅳ sevoflurane postconditioning + wortmannin (group SP + W) and group Ⅳ I/R + wortmannin (group I/R + W). The animals were anesthetized with intraperitoneal 10% chloral hydrate 300-350 mg/kg, tracheostomized and mechanically ventilated. ECG was continuously monitored.Right femoral artery was cannulated for BP monitoring. Focal cerebral I/R was induced by electro-coagulation of left middle cerebral artery and 60 min occlusion of bilateral common carotid arteries followed by reperfusion. The animals inhaled 2.5% sevoflurane in O2 for 60 min as soon as reperfusion was started in group Ⅱ and Ⅲ .Wortmannin 0.6 mg/kg was administered iv at 30 min before reperfusion in group Ⅲ and Ⅳ. Neurological function was assessed and scored at 24, 48 and 72 h (T1-3) of reperfusion. The animals were decapitated after the last neurological function assessment. Their brains were immediately removed for determination of infarct size. The expression of phosphorylated Akt and Bad (p-Akt, p-Bad) were determined by Westrn-blot analysis in ischemic penumbra. Results Sevoflurane postconditioning significantly improved the neurological function, decreased the infarct size and increased the expression of p-Akt and p-Bad in group Ⅱ as compared with group Ⅰ . There was no significant difference in all variables between group Ⅰ and group Ⅳ. Wortmannin attenuated the protective effect of sevoflurane postcoditioning against focal cerebral I/R injury. Conclusion Up-regulation of p-Bad expression induced by activation of PI3K/Akt signal pathway is involved in the protective effect of sevoflurane postconditioning against focal cerebral I/R injury.