Role of the adrenal in PMS-induced ovulation before puberty: effect of adrenalectomy.

Abstract

Female Sprague—Dawley derived rats were given either 5 IU or 25 IU pregnant mare’s serum gonadotrophin (PMS) at 22 days of age or 27 days of age and necropsied 3 days later. Adrenalectomy (ADRX) or sham surgery was performed at 21 days of age or at 26 days of age. Five IU PMS on day 22 elicited vaginal opening on day 26 but did not cause ovulation. Ovarian and uterine weights were elevated over those of saline—injected controls. ADRX the day before PMS prevented vaginal opening on day 26 and significantly lowered the uterine weight response (149.4 ± 3.1 vs 175.9 ± 6.7, p = 0.05) but did not reduce ovarian weight. Twenty—five IU PMS on day 22 resulted in vaginal opening and ovulation in intact rats and produced elevated ovarian and uterine weights. Adrenalectomy on day 21 prevented vaginal opening but did not block ovulation in 25 IU PMS—treated rats. Ovulation occurred in all but one rat treated with 25 IU PMS on day 27 and was not affected by ADRX at either 21 days or 26 days of age. Vaginal opening occu...