Abstract: Objective: To investigate the effect of puerarin on cognitive ability and hippocampal tissue NO-cGMP signaling in rats with exercise induced fatigue. Methods: A total of 30 adult male SD rats were randomly assigned to 3 groups (10 rats in each group): no exercise control, exercise and exercise plus puerarin groups. The rats in both exercise groups were subjected to increasing weight-loading swimming training for 10 d. The cognitive ability of rats was evaluated by morris water maze test, and the hippocampal iNOS mRNA and nNOS mRNA expression levels and cGMP and NO contents were measured. Results: The exercise control group showed a significant decrease in percent residence time in the central area, the number of original platform passes, and hippocampal nNOS mRNA expression level but a significant increase in hippocampal cGMP and NO contents and iNOS mRNA expression level as compared to the no exercise control. The percent residence time in the central area, the number of original platform passes and nNOS mRNA expression level of the exercise plus puerarin group were significantly higher than those of the exercise control group, whereas the hippocampal cGMP and NO contents and iNOS mRNA expression lelvel of the exercise plus puerarin group were significantly lower than those of the exercise control group. Conclusion: Puerarin administration can result in a marked decrease in hippocampal NO content in rats with exercise induced fatigue, which may be related to the decreased expression of iNOS mRNA. Moreover, puerarin has some neuroprotective effect on rats with exercise induced fatigue by inhibiting hippocampal NO and stabilizing cGMP production.

Key words: puerarin, hippocampus, exercise induced fatigue, NO-cGMP signaling system