Effect of exercise intensity and duration on the levels of stress hormones and hypothalamic-pituitary-gonadal axis in adult male rats: an experimental study.

Purpose: The effect of exercise on stress has been demonstrated in several studies which have shown that exercise intensity and duration have various effects on the reproductive axis. This study evaluated the effect of different intensities and durations of exercise on the hormonal indices of stress, such as corticosterone (CORT), norepinephrine (NEP), and also reproductive performance indices, including gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and testosterone (T).

Methods: In this experimental study, 30 adult Wistar rats were randomly divided into five groups as follows: no-exercise, RME-1 (regular moderate exercise for 1 month), RME-6 (regular moderate exercise for 6 months), RIE-1 (regular intensive exercise for 1 month), and RIE-6 (regular intensive exercise for 6 months). At the end of the experiment, the serum levels of the abovementioned hormones and hypothalamic expression of the Gnrh gene were measured using the enzyme-linked immunosorbent assay and the real-time polymerase chain reaction method, respectively.

Results: The levels of stress hormones, including CORT and NEP, increased only in the RIE-1 group compared with the no-exercise group. In addition, an increase was observed in T hormone levels in the RME-1 group compared with those in the no-exercise group, whereas LH and T hormone levels showed a greater decrease in the RIE-6 group than in the no-exercise group. Gnrh expression levels showed an increase and a decrease in the RME-1 and RIE-6 groups compared with the no-exercise group, respectively.

Conclusion: These results confirmed the effects of different intensities and durations of exercise on sex hormone levels.