摘要
目的 通过不同方式的天敌应激 ,对大鼠内分泌改变进行观察 ,阐明海马类固醇激素受体系统对精神应激反应的调节机制。方法 以猫为天敌刺激 ,大鼠每天接受 1次猫暴露应激实验。大鼠分为 4组 :急性单次应激组、2周持续应激组、4周持续应激组及对照组。采用放免法分析血清皮质醇水平 ,采用MR、GR的寡核苷酸探针 ,原位杂交观察海马MR、GRmRNA的表达。结果 接受单次应激后 ,大鼠开始产生血清皮质醇水平的升高。 2周应激大鼠的皮质醇水平最高 ,4周应激大鼠出现缓慢下降。MRmRNA表达高峰在急性应激时 ,GRmRNA表达高峰则在持续 2周应激时。应激可使海马CA3、CA1区MR/GR比值呈现逐步递减的趋势 ,并以天敌应激持续 2周时最为显著 ;但在天敌应激持续 2周以后 ,CA3区MR/GR比值开始出现部分恢复。结论 天敌应激源可使应激大鼠基础血清皮质醇水平升高 ,且恢复非常缓慢。海马CA3、CA1区MR、GR对天敌应激内分泌反应发挥明显的影响 ,支持MR/GR的平衡紊乱 ,可导致HPA轴负反馈效应失效和GCs水平的过度升高。
Objective To investigate the effects of different mode of predatory exposure stress on the endocrine aspect of rats, and explore the regulating mechanism of steriods receptors in hippocampus on psychological stress responses. Methods The psychological stress paradigm is as follow: A cat was used as predator stimulus. The cat-exposure stress test was carried out once a day. Four groups of rats were randomly divided: (1) Acute single stress; and (2) 2-week consistent stress ; and (3) 4-week consistent stress ; and (4) Control. Serum cotisol levels were analyzed by radioimmunoassay. The expressions of mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) mRNA in hippocampus were evaluated by hybridization in situ. Results Rats began to display elevated serum cortisol level after single stress. The cortisol level in 2-week stressed animals arose to the highest, but it dropped slightly in 4-week exposed animals. There was an expression peak of MR mRNA in acute stress group, but an expression peak of GR mRNA in 2-week consistent stress group. MR/GR ratio of hippocampal CA3 and CA1 regions was decreased with the duration of predator stress. This ratio was lowest in 2-week consistent stress group, and had a partial restoration afterwards. Conclusions Predatory stressor may cause elevated basal serum cortisol levels in stressed rats. Repeated predator exposure exerted intensive endocrinal responses those are very slow to rehabituate. This study supports that the disturbance of negative feedback effects on HPA is associated with the imbalance of hippocampal MR/GR, which may cause excessive secretion of GCs.
出处
《中国行为医学科学》
CAS
CSCD
2003年第4期361-363,470,共4页
Chinese Journal of Behavioral Medical Science
基金
广东省自然科学基金项目 (0 2 1 2 1 9)
汕头市重点科技计划项目(2 0 0 1- 55)
关键词
应激
皮质醇
海马
糖皮质激素受体
盐皮质激素受体
Stress
Cortisol
Hippocampus
Glucocorticoid receptor
Mineralocorticoid receptor
