Stress-induced activation of ovarian heat shock protein 90 in a rat model of polycystic ovary syndrome

Aim: Polycystic ovarian syndrome is the most common endocrine disorder affecting infertile women of reproductive age. This study evaluated the activation of heat shock protein 90 (Hsp 90) during the formation of stress-induced polycystic ovaries. Material & Methods: Female Sprague-Dawley rats (180-200 g) were subjected to one of two stress-inducing conditions; animals were either treated with adrenocorticotropic hormone daily for 18 days or were exposed to daily cold stress for three weeks. Non-treated rats sampled during proestrus or diestrous served as controls. Blood samples were collected from the left ventricles of anesthetized rats and concentrations of folliclestimulating hormone, luteinizing hormone, estradiol, testosterone and corticosterone were measured in all rats. The expression of messenger RNA for androgen receptor, estrogen receptor-a and -b, nerve growth factor receptor, and glucocorticoid receptor, and protein expression for Hsp 90 was also assessed in the rat ovaries. Results: Stress increased glucocorticoid receptor and androgen receptor expression, and decreased estrogen expression. Nerve growth factor receptor expression was greater in treated than diestrous rats and less in treated than proestrous rats. Ovarian Hsp 90 protein expression was increased in rats treated with adrenocorticotropic hormone or cold stress. Serum follicle-stimulating hormone levels were reduced and testosterone and corticosterone levels increased by stress, whilst luteinizing hormone and estradiol levels were similar to levels in diestrous and proestrus control rats respectively. Conclusions: The results indicate that stress, via the activation of ovarian Hsp 90 and changes in steroid hormone receptor expression and serum reproductive hormone levels, may be involved in the induction of polycystic ovaries in rats.