Alterations in rat hippocampal norepinephrine and serotonin levels under physical exercise and psychological stress

AIM: This study is to determine changes of hippocampal norepinephrine (NE) and serotonin (5-HT) in long term physical exercise and chronic psychological stress, and to study the roles of the two monoamine transmitters in the effect of exercise counteracting stress-induced hippocampal damages in brain. METHODS: Levels of hippocampal NE and 5-HT in rats undergoing 4-week voluntary wheel running exercise (exercise group) or 3-week restraint stress (stress group) or 4-week exercise and 3-week stress (exercise-stress group) were detected by high-performance liquid chromatography using electrochemical detection. RESULTS: It is showed that levels of hippocampal NE and 5-HT increased significantly (P<0.01) in the exercised rats, and in the stressed rats,hippocampal 5-HT levels significantly decreased(P<0.05). Additionally, the NE levels maintained significant high (P<0.01) in exercise-stressed rats compared to the pure stressed ones. On the other hand, no obvious difference was observed in hippocampal 5-HT levels between stress group and exercise-stress group, which were all significant lower (P<0.05) than that in exercise group. CONCLUSION: It is suggested that both the NE and 5-HT may play important roles in mediating the exercise-induced positive effects and the 5-HT may play an important role in stress-induced negative effects on the hippocampus. Moreover, NE may take more action in the exercise attenuating stress-induced hippocampal damages. The hippocampal NE may be more susceptible to exercise, and the hippocampal 5-HT may be more susceptible to stress.