慢性束缚与慢性不可预期温和应激抑郁模型小鼠的行为学比较及其发生机制研究

A comparative study on behavior changes and cerebral morphology and function of chronic restraint stress mice and chronic unpredictable mild stress mice

【目的】通过比较慢性束缚应激(Chronic restraint stress,CRS)与慢性不可预期温和应激(Chronic unpredictable mild stress,CUMS)对C57BL/6小鼠行为学指标及大脑海马区相关功能的影响,探讨抑郁症的发生机制。【方法】分别建立CRS及CUMS小鼠模型,通过旷场试验、强迫游泳试验和悬尾试验测定小鼠的行为学指标;取小鼠脑组织,制备常规石蜡切片,运用苏木素-伊红(HE)与免疫组化染色考察小鼠大脑海马区组织形态及5-羟色胺1A受体(5-HT1AR)的表达情况,并运用荧光分光光度法测定小鼠海马组织单胺氧化酶活性的变化。【结果】与空白对照组相比,CRS组小鼠的水平穿格数、直立次数及体质量均显著减少,悬尾及强迫游泳试验累计不动时间百分比无明显变化(P>0.05);而CUMS组小鼠自发活动无明显改变(P>0.05),但悬尾及强迫游泳试验累计不动时间百分比极显著增加(P<0.01),体质量显著下降。脑组织形态学研究结果显示,CUMS组小鼠海马CA1、CA3区和齿状回均出现萎缩,而CRS组小鼠海马CA1区未受影响,CA3区和齿状回均发生萎缩。与对照组相比,CRS组与CUMS组小鼠大脑海马单胺氧化酶活性升高,5-HT1AR表达均减少,差异均分别达显著和极显著水平。【结论】CRS和CUMS均可不同程度地引起抑郁样症状,CRS对探索性行为的抑制较明显,CUMS则可引发典型的行为绝望状态;CRS与CUMS组小鼠的行为学差异可能与2组抑郁模型动物脑内海马区组织结构及功能变化的差异存在相关性。

【Objective】 The aim of this study was to explore the pathogenesis of depression by comparing the effects of chronic restraint stress（CRS） and chronic unpredictable mild stress（CUMS） on behavior and cerebral morphology of C57BL/6 mice.【Method】 Mice were randomly divided into the normal control（NC） group,CRS group,and CUMS group.After 3 weeks of stress exposure,open-field test,tail suspension test,and forced swimming test were taken to evaluate the behavior changes of mice.In addition,the cerebral morphology and function changes were investigated by HE staining and immuno-histochemistry analysis.The MAO activity of mice hippocampus was analyzed by fluorescence spectrophotometry.【Result】 The results showed that compared to the NC group,the crossing frequency,hearing frequency and body weight were all decreased significantly in the CRS group,whereas no significant changes in the CUMS group（P0.05）.However,the results of tail suspension test and forced swimming test showed that there was a significant increase in the percent of immobility time in the CUMS group compared to the NC group（P0.01）.In addition,except the hippocampus CA1 region in the CRS group,the CA1,CA3 and dentate gyrus regions of hippocampus were all atrophied in both stressed groups.Furthermore,the expression of 5-HT1A receptor in hippocampus was decreased and the MAO activity was up-regulated in both CRS and CUMS group.【Conclusion】 The results showed that both CRS and CUMS can induce depressive-like behaviors in C57BL/6 mice.CRS mainly suppresses the exploratory behavior while CUMS induced typical behavioral despair.This praxiology distinction may be relative to the differences in cerebral morphology and function of treated mice between two stressed groups.