单唾液酸神经节苷脂对体外循环大鼠海马Akt/GSK-3β信号通路的影响

Effectof monosialoganglioside on hippocampal Akt/GSK-3β signaling pathway in rats undergoing cardiopulmonary bypass

目的 评价单唾液酸神经节苷脂（GM-1）对体外循环（CPB）大鼠海马蛋白激酶B（Akt）/糖原合酶激酶-3β（GSK-3β）信号通路的影响.方法 健康雄性SD大鼠18只,6月龄,体重400～ 500 g,采用随机数字表法分为3组（n=6）：对照组（C组）、CPB组和GM-1组.GM-1组在预充液中加入GM-1 20 mg/kg;CPB组在预充液中加入等容量生理盐水.CPB组和GM-1组于CPB停止后3h时,C组于相应时点,取颈静脉血样,采用ELISA法测定血浆神经元特异性烯醇化酶（NSE）和S-100β蛋白的浓度,取血后处死大鼠取海马组织,透射电镜下观察海马神经元超微结构,光镜下观察神经元凋亡情况,采用Western blot法测定Akt和GSK-3β的磷酸化水平.结果 与C组比较,CPB组和GM-1组血浆NSE和S-100β蛋白的浓度升高,凋亡神经元增加,CPB组海马Akt和GSK-3β磷酸化水平降低,GM-1组海马Akt和GSK-3β磷酸化水平升高（P＜0.05）;与CPB组比较,GM-1组血浆NSE和S-l00β蛋白的浓度降低,凋亡神经元减少,海马Akt和GSK-3β磷酸化水平升高（P＜0.05）,病理学损伤减轻.结论 GM-1可能通过激活Akt/GSK-3β信号通路,减少神经元凋亡,减轻CPB诱发大鼠脑损伤.

Objective To evaluate the effect of monosialoganglioside （GM-1） on hippocampal protein kinase B （Akt） /glycogen synthase kinase 3β （GSK-3β） signaling pathway in the rats undergoing cardiopulmonary bypass （CPB）.Methods Eighteen healthy male Sprague-Dawley rats, aged 6 months, weighing 400-500 g, were randomly divided into 3 groups （n =6 each） using a random number table：control group （group C）, CPB group and GM-1 group.GM-1 20 mg/kg was added to the priming solution in group GM-1, while the equal volume of normal saline was given in group CPB.At 3 h after termination of CPB, blood samples were taken from the jugular vein for determination of plasma neuron-specific enolase （NSE） and S-100β protein concentrations using enzyme-linked immunosorbent assay.After blood sampling, the rats were sacrificed, and the hippocampi were isolated for microscopic examination of the ultrastructure of the hippocampal neurons （with electron microscope）, and for detection of neuronal apoptosis （with light microscope） and phosphorylation of Akt and GSK-3β （by Western blot）.Results Compared with group C, the concentrations of plasma NSE and S-100β protein, and the number of apoptotic neurons were significantly increased in CPB and GM-1 groups, the phosphorylation of Akt and GSK-3β was decreased in group CPB, and the phosphorylation of Akt and GSK-3β was increased in group GM-1 （P〈0.05）.Compared with group CPB, the concentrations of plasma NSE and S-100β protein, and the number of apoptotic neurons were significantly decreased, the phosphorylation of Akt and GSK-3β was increased （P〈0.05）, and the pathological changes were reduced in group GM-1.Conclusion GM-1 can reduce apoptosis in hippocampal neurons through activating Akt/GSK-3β signaling pathway, thus mitigating CPB-induced brain injury in rats.