Does dihydrotestosterone induce atresia in the hypophysectomized immature female rat treated with pregnant mare's serum gonadotropin?

This study was originally designed to test the hypothesis that the binding of luteinizing hormone in granulosa cells decreases with atresia. The hypophysectomized immature female rat that was primed with pregnant mare's serum gonadotropin and treated with dihydrotestosterone was used as a model for atresia. Histochemical analysis of acid phosphatase was used as a marker for atresia and topical autoradiography with iodine 125-labeled human chorionic gonadotropin for binding of luteinizing hormone. Histologically, there was no significant difference in atresia, acid phosphatase, or 125I-labeled human chorionic gonadotropin binding in antral follicles between control animals given pregnant mare's serum gonadotropin and animals treated with pregnant mare's serum gonadotropin and dihydrotestosterone. Assessment of the total follicular population, however, showed that dihydrotestosterone at dosages of 1 and 5 mg/kg resulted in decreases in atresia of 48% and 58%, respectively. Although these data disprove our hypothesis, they strongly suggest that dihydrotestosterone decreases follicular atresia by increasing the number of small preantral follicles.