Impact of Physical Training on Sex Hormones and Their Receptors During N-Methyl-N-nitrosourea-induced Carcinogenesis in Rats.

BACKGROUND/AIM: The risk of breast cancer is related to duration of exposure to sex hormones, especially estrogen. The aim of this study was to assess the impact of physical training (PT) on estrogen and progesterone levels and expression of their receptors during carcinogenesis induced by N-methyl-N-nitrosourea (MNU) in rats.

MATERIALS AND METHODS: Fifty female Sprague-Dawley rats were intraperitoneally administered MNU and divided into four groups: low-, moderate-, and high-intensity PT, and no PT (control). Plasma levels of sex hormones and tissue expression of their receptors were quantified and statistically analyzed.

RESULTS: In the group of rats subjected to PT, a significantly higher progesterone level was observed. The highest progesterone level was noted in the low-intensity PT group. An increase in apoptosis of MNU-induced tumor cells was also demonstrated in the PT groups.

CONCLUSION: PT stimulates apoptosis of tumor cells without an increase in their proliferative activity. The increase in apoptosis of tumor cells correlates positively with the progesterone level.