Effect Of Chronic Stress On The Behaviors, Immunity Function And Neuroendocrine Function In Rats

[Objective] To study the effects of chronic psychological stress on behaviors, and learning and memory abilities, and immunological function, and neuroendocrine function, and to improve the important and scientific basis for intervention in sub-health.[Methods] 20 SD rats, adult and health, were randomly divided into control group and chronic stress group(n=10 in each group).The rat mode of stress was made by different multi-stress,4 weeks running. After stress, the Open-field test, Morris water maze test and suspend tail test were performed to test the change of mood and behaviors, and learning and memory abilities of rats. After the experiment, thymus index and spleen index were measured. ELISA was applied to measure levels of interleukine-1β(IL-1β) and interleukine-2(IL-2) in blood serum. RIA was applied to measure levels of ACTH and CORT in blood serum. Expression of 5-HT in neural cells in rats'brain tissue were measured with ABC of immunohistoc-hemical method.[Results] Chronic stress significantly suppressed body weight gain. The increases of body weight in the chronic group were significantly lower than that in the control group. Compared with the control group, the chronic stress group had relatively fewer crossing scores, and rearing scores, and total scores. In suspend tail test, the chronic group had relatively longer staying time. In hidden-platform training of Morris water maze, the mean escape latency of the chronic group was longer than that of the control group. In spatial probe tests, compared with the control group, the number of times passing over hidden platform decreased in the chronic stress group, the swimming distance through the quadrant of hidden platform and the whole distance were shortened. The chronic stress group significantly decreased levels of IL-1βand IL-2 in blood serum. The chronic stress group significantly increased levels of ACTH and CORT in blood serum.5-HT expressions in brain decreased in chronic stress group. Moreover, Pearson correlation analysis results showed that the levels of IL-1βand IL-2 were negatively correlated with the levels of ACTH and CORT. Path analysis results showed that total scores was positively correlated with the levels of IL-1βand IL-2. Staying time and escape latency were negatively correlated with the levels of IL-2. The level of CORT were positively correlated with staying time and escape latency, and negatively correlated with total scores.[Conclusion] It was showed that chronic stress could result in anxiety and depression, and suppression of learning and memory, and behavior changes. Chronic stress could suppress the weight and immunological function. Chronic stress may activate the function of HPA. The correlation of behavior and immunity indicate that the behavior may participate in the immunoloregulation.