Effect of chronic physiological stress on rat oocyte reserve: Role of IGF-1, AMH and Bcl-2

Ovarian activity has a complex physiology and is related to oocyte quality in women. This study investigates the effects of ovarian activity with chronic stress (CS) on behavioural parameters, estrous cycles, and ovarian follicular development in rats. Here, we examined the ovarian microenvironment against exposure to stress and to elucidate the stress-related ovarian molecular mechanisms. Twenty female Sprague-Dawley rats were divided into the control and the CS groups. The estrous cycle phases were detected by vaginal smear. Rats in the CS group were immobilized 1 h/day for 8 weeks. At the end of the experiment, all animals were subjected to behavioral tests in their metestrus phase and sacrificed on the other day (diestrus phase). The ovaries were harvested for histological analysis, blood samples were taken to measure cortisol levels. The immunoreactivities of ovarian IGF-1, AMH and Bcl-2 proteins were evaluated by immunohistochemistry. Here, we have studied CS-induced prolonged estrous cycles. We showed a lower number of developing follicles but the higher number of atretic follicles in the CS group’s ovaries. The dominant structure of ovarian histology was large interstitial glands. CS caused decreases in ovarian Bcl-2, IGF-1 and AMH immunoreactivities which have roles in follicular development. Also, anxiety was detected in CS-exposed animals. Our results showed that chronic restrainer stress can be a serious endocrine disrupter by reducing ovarian paracrine