GIRK通道在匹罗卡品癫痫模型中的表达改变

Alternation of GIRK channel expression in pilocarpine epilepsy model

目的:研究匹罗卡品诱导癫痫发作后不同时期G蛋白门控内向整流钾离子(GIRK)通道在大鼠海马神经元细胞膜表面表达变化情况,并探索可能的调控机制。方法:将成年雄性SD大鼠随机分为对照组和匹罗卡品造模组。利用致痫剂匹罗卡品诱导癫痫持续状态(status epilepticus,SE)后,分别在急性期(24 h)和慢性期(30 d)取海马组织提取膜蛋白,利用Western印迹方法检测海马膜蛋白GIRK通道亚基蛋白GIRK1、GIRK2的表达改变,并同时检测海马组织PI3K/Akt通路激活情况。建立细胞癫痫模型,观察PI3K抑制剂渥曼青霉素和LY294002对海马神经元内向整流钾通道(Kir)电流的影响。结果:匹罗卡品诱导大鼠SE发作后,急性期细胞膜上GIRK1和GIRK2蛋白的表达较对照组相比显著下调(P<0.05)。海马膜蛋白中GIRK1的表达在大鼠SE发作后慢性期较对照组下降(P<0.05),而GIRK2蛋白表达量没有显著改变。p-Akt(308)与Akt蛋白表达量的比值在匹罗卡品诱导大鼠SE发作后急性期与对照组相比显著上升(P<0.05),而在SE发作后慢性期差异无统计学意义。在细胞癫痫模型中,渥曼青霉素和LY294002对痫样放电神经元的Kir电流未发现显著影响。结论:在匹罗卡品诱导大鼠SE发作后急性期,海马中GIRK通道蛋白表达量下调,PI3K/Akt通路存在明显激活。

Objective: To study the alternation in the expression of G protein-gated inwardly rectifying potassium(GIRK) channels on the cell membrane of hippocampal neurons at different periods after pilocarpine induced seizures, and to explore its possible regulatory mechanisms. Methods: Adult male SD rats were randomly divided into a control group and a pilocarpine model group. Pilocarpine was used to induce status epilepticus(SE). The hippocampal tissus were taken to extract membrane proteins in the acute phase(24 h) and the chronic phase(30 d) after SE. The expression changes of hippocampal membrane protein GIRK channel subunit proteins GIRK1 and GIRK2 were detected by Western Blot, and the expression of p-Akt and Akt proteins in the whole hippocampus was also detected at the same time. The cell epilepsy model was used to observe the changes of Kir currents in hippocampal neurons after the addition of PI3 K inhibitor wortmannin and LY294002. Results: The expression of GIRK1 and GIRK2 protein on the rat neuronal membrane was significantly down-regulated compared with the control group in the acute phase after the SE induced by pilocarpine(P<0.05). The expression of GIRK1 in the hippocampal membrane protein of rats decreased in the chronic phase after the onset of SE(P<0.05), while the expression of GIRK2 protein did not change significantly. The ratio of p-Akt(308) and Akt protein expression levels increased significantly in the acute phase after the seizure induced by pilocarpine in rats compared with the control group(P<0.05), but did not change in the chronic phase after the seizure of SE. In the cellular epilepsy model, wortmannin and LY294002 had no significant effect on the Kir current of epileptiform neurons. Conclusions: In the acute phase after seizures of SE induced by pilocarpine in rats and mice, the expression of GIRK channel protein in the hippocampus is down-regulated to varying degrees, and the PI3 K/Akt pathway is significantly activated during the same period.