【摘要】 目的探讨慢性复合应激对大鼠学习与记忆的作用,以及Ca2+/钙调蛋白依赖性蛋白激酶Ⅱ(CaMKⅡ)、钙调蛋白(CaM)mRNA、环腺苷酸反应元件结合蛋白(CREB)mRNA水平的变化及其在学习和记忆中的作用。方法Wistar大鼠被随机分为慢性复合应激组(16只)和对照组(16只)。慢性复合应激组动物给予6周的慢性复合应激刺激,制备慢性复合应激模型;Morris水迷宫和Y迷宫测试大鼠空间学习和记忆的行为表现;免疫组织化学、Western blotting和RT-PCR检测大鼠海马CaMKⅡ、CaM mRNA和CREB mRNA水平的变化;观察分析CaMKⅡ在海马CA1和CA3区的分布和表达;电镜观察海马CA3区突触间隙的宽度和突触后致密物质(PSD)的厚度的变化。结果慢性复合应激6周后,应激组大鼠的学习与记忆能力均高于对照组(P<0.05,P<0.01);应激组海马CA3区突触间隙的宽度为5.0580±1.4216,PSD的厚度为20.9547±2.5693。与对照组相比,海马CA1和CA3区辐射层和始层CaMKⅡ的免疫染色明显增强,特别是始层;CaMKⅡ、CaM mRNA及CREB mRNA水平均明显增高(P<0.05,P<0.01)。结论慢性复合性应激后,大鼠的学习与记忆能力增强;海马CaMKⅡ、CaM mRNA和CREB mRNA水平增加可能是参与了慢性复合应激性学习记忆增强的机制。更多还原

【Abstract】 Objective To investigate the effects of chronic multiple-stress on learning and memory and on the levels of calcium/calmodulin-dependent protein kinase Ⅱ(CaMKⅡ),calmodulin(CaM) mRNA,and cAMP-response element binding protein(CREB) mRNA in the hippocampus of rats and possible mechanisms. Methods The Wistar rats were divided randomly into stressed(n=16) and control groups(n=16).The stressed group was given chronic multiple-stress for 6 weeks to prepare the chronic multiple-stressed model.The rats’ performance of spatial learning and memory was tested by Morris water maze(MWM) and Y-maze.The expressions of CaMKⅡ,CaM mRNA and CREB mRNA in hippocampus of rats’ were detected by immunohistochemistry,Western blotting and RT-PCR respectively.The width of synaptic cleft and the thickness of post-synaptic densities(PSD) were observed in the hippocampal CA3 region of rats under electron microscopy.Results After the exposure to chronic multiple-stress for 6 weeks,the ability of learning and memory of the stressed group was higher than that of the control group(P<0.05,P<0.01).The width of synaptic cleft was 5.0580±1.4216 and the thickness of PSD was 20.9547±2.5693 in the hippocampal CA3 of stressed rats.Compared with the control group,the CaMKⅡ immunostaining of stressed animals was stronger in the stratum radiatum and oriens of hippocampal CA1 and CA3,especially in the stratum oriens.The expressions of CaMKⅡ,CaM mRNA, and CREB mRNA in the hippocampus of the stressed group was significantly higher(P<0.05,P<0.01).Conclusion The capacity of learning and memory was enhanced following chronic multiple-stress.The increase in the levels of hippocampal CaMKⅡ,CaM mRNA,and CREB mRNA revealed that they might have participated in the enhancing effect of chronic multiple-stress on learning and memory.更多还原