Evaluation of Ki-67 antigen expression in the zona reticularis of the adrenal cortex of female rats in persistent estrus.

BACKGROUND Hyperandrogenism and chronic anovulation are basic characteristics of polycystic ovary syndrome (PCOS), and androgens from the adrenal glands play an important role in the hyperandrogenism. Our aim was to evaluate the proliferative activity in the zona reticularis cells of the adrenal cortex of female rats in persistent estrus, a model developed to mimic PCOS. METHODS Forty-four female Wistar-Hannover rats were randomly divided into two groups: control (n = 17) and animals which received 1.25 mg testosterone propionate s.c. on the second day of life (n = 27). At 90 days of age, after confirmation of persistent estrus, the animals were sacrificed, and the adrenal glands were removed and fixed in 10% buffered formalin to investigate Ki-67 antigen (marker of proliferation) expression by immunohistochemical analysis. Student's t-test and Levene's test were used in the statistical analysis. RESULTS The mean percentage of Ki-67-stained nuclei per 1000 cells in the zona reticularis of the adrenal cortex was 15.58 +/- 1.14 (SEM) and 51.59 +/- 1.81 in the control and persistent estrus animals, respectively (P < 0.001). CONCLUSIONS Proliferative activity in the zona reticularis cells of the adrenal cortex of the androgenized female rats was significantly greater than that of the control animals.