Effects of RU486 in the expression of progesterone receptor isoforms in the hypothalamus and the preoptic area of the rat during postpartum estrus.

摘要

In several mammalian species females undergo postpartum estrus, a brief period of ovulation and sexual receptivity that in rats usually occurs during the first 24h following parturition. The maximal lordotic expression occurs at 12h after the initiation of parturition and depends on intracellular progesterone receptor (PR). We studied the regulation of PR expression by its antagonist, RU486 in the hypothalamus and the preoptic area of the rat during postpartum estrus by Western blot. Adult female rats were treated with RU486 (1.25 and 5mg) 3h after parturition, and Western blot was performed to assess the expression of PR-A and PR-B at 12h postpartum. RU486 (1.25 and 5mg) reduced the expression of PR-A (63% and 95%) and that of PR-B (75% and 99%), respectively in the preoptic area whereas it had no effects in the hypothalamus. These results suggest a differential regulation of PR expression in the rat brain during postpartum estrus.