BQ-123对蛛网膜下腔出血大鼠神经功能缺陷的改善作用及其机制

Improvement effect of BQ-123 on nerve function damage after subarachnoid hemorrhage in rats

目的:探讨内皮素受体拮抗剂(BQ-123)对蛛网膜下腔出血(SAH)神经功能损伤的影响,阐明其作用机制。方法:120只雄性SD大鼠分为假手术组、SAH模型组、低剂量(50μg·kg^(-1))BQ-123组和高剂量(75μg·kg^(-1))BQ-123组。采用二次注血法制作SAH大鼠模型;HE染色观察各组大鼠海马区神经细胞的形态变化;免疫组织化学法和RT-PCR法检测海马区磷酸化雷帕霉素靶蛋白(mTOR)、自噬相关基因beclin-1和微管相关蛋白1轻链(LC3)-Ⅱ的表达;穿梭箱实验检测各组大鼠学习记忆功能,抓力测定实验评价各时间点各组大鼠前肢拉力情况。结果:与假手术组比较,SAH组大鼠海马区神经细胞结构损伤,神经细胞存活率降低(P<0.05),磷酸化mTOR、beclin-1和LC3-ⅡmRNA表达水平升高(P<0.05),大鼠学习记忆功能和拉力值降低(P<0.05);与SAH组比较,BQ-123组大鼠海马区神经细胞结构损伤减轻,神经细胞存活率升高(P<0.05),磷酸化mTOR mRNA表达水平降低(P<0.05),beclin-1和LC3-ⅡmRNA表达水平升高(P<0.05),动物学习记忆功能和拉力值增加(P<0.05);与低剂量BQ-123组比较,高剂量BQ-123组上述变化更为明显(P<0.05)。结论:BQ-123可显著改善SAH大鼠神经功能缺陷,其机制与调控mTOR-自噬通路信号途径有关。

Objective： To study the effect of endothelin receptor antagonist BQ-123 on the nerve function damage after subarachnoid hemorrhage （SAH） in the rats, and to explore the mechanisms. Methods： Total 120 male SD rats were divided into sham group, SAH group, low dose of BQ-123 group （50 μg kg-1 ） and high dose of BQ-123 group （75 μg kg-1 ）. The SAH rat models were established by injecting the autologous blood into cisterna magna twice. The morphological changes of hippocampus nerve cells of rat brain tissue were detected with HE staining, and the expressions of mTOR, Beclin-1 and LC3-Ⅱ in the hippocampus of rats were detected with immunohistochemistry and RT-PCR~ the shuttle-box experiment was used to evaluate the abilities of learning and memory, and the holding power evaluation was used to evaluate the forelimb pulling force of the rats in various groups at each time point. Results： Compared with sham group, the morphological damages of neurons of the rats in SAH group were increased, the survival rate of neurons of the rats in SAH group was decreased （P〈0. 05）, the expression levels of mTOR mRNA, Beclin-1 mRNA and LC3-Ⅱ mRNA in hippocampus tissue of the rats were increased （P〈0.05）, and the abtilities of learning and memory and the values of holding power were decreased （P〈0.05）. Compared with SAH group, the morphological damages of neurons of the rats in BQ-123 groups were decreased, the survival rates of neurons of the rats in BQ-123 groups were increased （P%0. 05）, the expression levels of roTOR mRNA of rats were decreased （P〈0.05）, the expression levels of Beclin-1 mRNA and LC3-Ⅱ mRNA in hippocampus tissue were increased （P〈0.05）, and the abilities of learning and memory and the values of holding power were increased （P 〈 0.05）. The changes were more significant in high dose of BQ-123 group compared with low dose of BQ-123 group （P〈0.05）. Conclusion： BQ-123 can improve the nerve function damage after SAH in the rats, its mechanism may be related to regulating the mTOR/autophagy signaling pathway.