The effect of an antiprogestin compound (RU486) on gonadotropin and prolactin release in vivo
Arakawa, S.; Ohkawa, T.; Kambegawa, A.; Okinaga, S.; Arai, K.
Asia-Oceania Journal of Obstetrics and Gynaecology 14(4): 501-507
1988
ISSN/ISBN: 0389-2328 PMID: 3149185 DOI: 10.1111/j.1447-0756.1988.tb00141.xDocument Number: 372563
The authors administered oil (group A), 5 mg progesterone (P4; group B), or 5 mg of P4 + 5 mg of RU486 (antiprogestin; group C) to castrated female rats treated with estradiol benzoate (EB). Serum LH, FSH, and prolactin (PRL) levels were measured 24 hours after injection by specific radioimmunoassay (RIA) methods. Serum LH levels in group B were significantly lower than those of groups A and C , but serum levels of FSH and PRL showed different patterns. The authors administered oil (group D) or 5 mg RU486 (group E) to normal cycling female rats. The serum levels of LH, FSH, and PRL in group E were higher than those of group D. These results confirmed that P4 has an inhibitory effect on LH release in spayed rats pretreated with EB and in normal rats with estrous cycles. The FSH and PRL levels are reportedly depressed by an intrinsic surge of P4 in normal rats during estrous cycles. This inhibitory effect of P4 on the hypothalamic-pituitary system was cancelled by the RU486. No significant difference was observed in pituitary weight or pituitary content of LH and FSH in this series of experiments.