An acute increase in serum prolactin does not modify gonadotropin release in female rats.
Attempts were made to find out whether hyperprolactinemia has an effect on the hypothalamo-pituitary response to estrogen feedback and LHRH stimulation. Adult female rats of Wistar strain were ovariectomized and received subcutaneous injection of 20 micrograms estradiol benzoate (EB) 3-4 weeks later (day-0). A second injection of 20 micrograms EB, when administered at noon on day-3, induced a highly significant increase in serum LH (p less than 0.001 vs. basal values), but not FSH, estimated at 1800 h on the same day. This EB-promoted LH release was not altered by pretreatment with rat PRL (5 micrograms/day), which was administered subcutaneously daily in the morning (1100 h) between day-1 and day-3. No statistical difference in the serum LH concentration was found when compared with the values for the control animals pretreated with 0.9% saline alone. Serum gonadotropins 15 min after LHRH administration (100 ng/100 g BW) in 32-day-old female rats were not statistically different between the animals pretreated with 5 micrograms PRL, which was given subcutaneously daily (at 0800 h) for 3 days, and the controls pretreated with 0.9% saline. These results suggest that an acute increase in serum PRL may not exert a negative effect on the gonadotropin release induced by estrogen feedback and LHRH stimulation.
D000818:Animals; D004958:Estradiol / Q000494:pharmacology; D005246:Feedback; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D006065:Gonadotropins, Pituitary / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains
D006065:Gonadotropins, Pituitary; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D011388:Prolactin