慢性复合应激增强大鼠海马Doublecortin的表达

CHRONIC MULTIPLE STRESS ENHANCES THE EXPRESSION OF DOUBLECORTIN IN THE HIPPOCAMPUS OF THE RATS

目的探讨慢性复合应激性学习记忆增强大鼠海马齿状回(DG)新生神经元数量变化以及Doublecortin(DCX)在海马组织中表达的变化及其意义。方法成年雄性大鼠随机分为复合应激组和正常对照组。复合应激组动物每天交替暴露于复合应激原中达6周。实验结束后,所有动物分别进行3d的Morris水迷宫测试,记录其学习和记忆成绩。运用免疫细胞化学方法观察海马DG新生神经元数量的变化,同时运用Westernblotting和RT-PCR技术分别检测DCX在海马的表达及其mRNA水平的变化。结果与对照组相比,复合应激组动物的学习与记忆成绩优于对照组(P<0.05);其海马DG新生神经元数明显增多(P<0.05);海马DCX蛋白的表达明显增加(P<0.05);海马DCX mRNA水平明显上调(P<0.05)。结论慢性复合应激致大鼠的学习与记忆能力增强,海马DG内DCX阳性细胞数增多,提示新生神经元数量增加是导致大鼠学习记忆能力增强的原因之一。

Objective To study the neurogenesis of the dentate gyrus （DG） and the expression of the doublecortin （DCX） in the hippocampus of the rat whose spatial learning and memory function was enhanced by chronic multiple stress. Methods Adult male Wistar rats were randomly divided into two groups： multiple stressed group and control group. Rats in the multiple stressed group were irregularly and alternatively exposed to the chronic multiple stress for 6 weeks. After that, all rats were tested for the performance of spatial learning and memory in Morris water maze. The number of newborn neurons in the DG was counted by using immunocytochemical method. The expression of the DCX protein and the level of DCX mRNA in the hippocampus of rats were measured by using Western blotting and RT-PCR technique, respectively. Results The results showed that ： 1. Compared with the ones of the control group, the multiple stressed rats had a significantly shorter latent period to search the platform in Morris water maze （ P 〈 0.05）. 2. The number of newborn neurons in the DG of the multiple stressed rats was extremely higher than that of the control group （ P 〈 0.05）. 3. The protein level of the doublecortin in the hippocampus of the multiple stressed rats were remarkably stronger than that of the control group（ P 〈 0.05）. 4. The level of the doublecortin mRNA in the hippocampus of multiple stressed rats were markedly higher than that of the control group （ P 〈 0.05 ）. Conclusion The newborn neurons in the dentate gyrus increased by the chronic multiple stress may participate in the course of enhancing the spatial learning and memory function of the rat.