Akt—GSK3β通路在丙泊酚后处理对脑缺血再灌注大鼠长时程脑保护效应中的作用

Role of Akt-GSK3β signaling pathway in long-term neuroprotection induced by propofol postconditioning in a rat model of focal cerebral ischemia/reperfusion injury

目的探讨丝氨酸-苏氨酸激酶（Akt）-糖原合成酶激酶3β（GSK3β）（Akt—GSK3β）通路在丙泊酚后处理对脑缺血再灌注大鼠长时程脑保护效应中的作用。方法健康雄性sD大鼠216只，体重250～280g，采用随机数字表法，将其随机分为4组（H=54）：假手术组（s组）、脑缺血再灌注组（I／R组）、溶媒对照组（I组）和丙泊酚后处理组（P组），除S组外，其余各组采用线栓法阻塞大脑中动脉1，P组在再灌注即刻开始股静脉输注丙泊酚20mg·kg-1·h-1，输注时间2h，S组和I／R组给予等容量生理盐水，I组给予等容量10％脂肪乳。于术后3、7、14和28d时分别取6只大鼠，取脑组织，测定脑梗死体积，再分别取6只大鼠，采用Westernblot法检测缺血侧海马Akt、GSK3β及磷酸化Akt、GSK3β表达水平，于术后28d时取6只大鼠，采用免疫荧光法检测缺血侧海马齿状回（DG）神经元再生情况。结果与s组比较，I／R组、I组和P组脑梗死体积增加，海马DG区新生神经元数量升高，I／R组和I组海马组织Akt磷酸化和GSK3β磷酸化水平降低，P组海马组织Akt磷酸化和GSK3~磷酸化水平升高（P〈0．05）；与I／R组比较，P组脑梗死体积降低，海马DG区新生神经元数量升高，海马组织Akt磷酸化和GSK3β磷酸化水平升高（P〈0．05）。结论丙泊酚后处理对脑缺血再灌注大鼠具有长时程脑保护效应，其机制与Akt-GSK3β通路有关。

Objective To evaluate the role of Akt-glycogen synthase kinase-3 beta （GSK3β） signaling pathway in the long-term neuroprotection induced by propofol postconditioning in a rat model of focal cerebral ischemia/reperfusion （I/R） injury. Methods Two hundred and sixteen male Sprague-Dawley rats, weighing 250-280 g, were randomly divided into 4 groups （n = 54 each）： sham operation group （group S）, I/R group, intralipid control group （group I） and propofol postconditioning group （group P）. The model of focal cerebral I/R injury was established by middle cerebral artery occlusion. Propofol 20 mg· kg-1· h-1 was infused over 2 h starting from the onset of reperfusion in group P, the equal volume of normal saline was given in groups S and I/R and the equal volume of 10% intralipid was given in group I. Six rats were chosen at 3, 7, 14 and 28 days after occlusion and sacrificed, and brains were removed for determination of the cerebral infarct size by TTC staining. Another 6 rats were chosen at 3, 7, 14 and 28 days after occlusion to detect the expression of Akt, GSK3β3 and phosphorylation of Akt and GSK3β by Western blot. The left 6 rats were chosen at 28 day after occlusion to measure the number of newly generated neurons in hippocampal dentate gyrus on the isehemie side. Results Compared with group S, the cerebral infarct volume was significantly enlarged, the newly generated neurons number was increased in the other 3 groups, and the phosphorylation of Akt and GSK3β was decreased in groups I/R and I,while increased in group P （ P 〈 0.05 ）. The cerebral infarct volume was significantly smaller, and the newly generated neurons number and phosphorylation of Akt and GSK3β were higher in group P than in group I/R （ P 〈 0.05）. Conclusion The mechanism by which propofol postconditioning provides the long-term neuroproteetion is related to Akt-GSK3β signahng pathway in a rat model of focal cerebral I/R injury.