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目的研究尾吊模拟失重效应对大鼠海马神经元形态数目和学习记忆相关分子NMDAR2A,BDNF及促凋亡相关分子Bax,Caspase-3表达的影响,探讨模拟失重所致大鼠学习记忆能力下降的机制。方法24只8周龄SD大鼠随机分为对照组及模拟失重组,每组12只,采用30°尾吊方法模拟失重效应。采用HE及尼氏染色观察模拟失重效应对海马神经元数目形态的影响;采用Western blot检测模拟微重力效应对NMDAR2A,BDNF,Bax,Caspase-3蛋白表达的影响。结果 HE染色及尼氏染色结果发现,尾吊大鼠海马组织神经元数目显著低于对照组,同时其形态也发生了一定的改变。Western blot实验结果显示,与对照组相比,尾吊大鼠海马组织NMDAR2A、BDNF蛋白表达水平显著降低,Bax,Caspase-3蛋白表达水平显著提高。结论尾吊模拟失重效应可影响大鼠海马神经元形态与数目,下调学习记忆相关分子表达,上调促凋亡相关分子表达。
Objective To investigate the effects of tail-hang simulated weightlessness on the number of hippocampal neurons, the expression of NMDAR2A, BDNF and the expressions of Bax and Caspase-3 in rat hippocampus, and to explore the effects of simulated weightlessness on the learning and memory ability of rats induced by simulated weightlessness mechanism. Methods Twenty-four SD rats of 8 weeks old were randomly divided into control group and simulated weightless group, with 12 rats in each group. The 30-degree tail-hanging method was used to simulate the weightlessness effect. The effects of simulated weightlessness on the number and morphology of hippocampal neurons were observed by HE and Nissl staining. The effects of simulated microgravity on the expressions of NMDAR2A, BDNF, Bax and Caspase-3 were examined by Western blot. Results HE staining and Nissl staining showed that the number of neurons in the hippocampus of tail-suspended rats was significantly lower than that of the control group, and the morphology of the neurons was also changed. Western blot results showed that compared with the control group, the expression levels of NMDAR2A and BDNF in the hippocampus of the tail-suspended rats were significantly decreased, while the expressions of Bax and Caspase-3 were significantly increased. Conclusion The tail-hang simulation of weightlessness can affect the morphology and number of hippocampal neurons, down-regulate the expression of learning and memory-related molecules and up-regulate the expression of pro-apoptotic molecules.