[Studies on the antipregnancy effect of LHRH-A in mid gestational rats].
In the present study, the antipregnancy effect of (D-Ala6, Pro9-Ethylamide10) LHRH (LHRH-A) on midgestation rats was observed. The results indicate that LHRH-A could terminate pregnancy of all experimented rats by abortion after subcutaneous administration of 200 micrograms LHRH-A (dissolved in vegetable oil) once a day at days 9 to 11 of their pregnancy. It was also found that the serum progesterone level was significantly lowered after the administration of LHRH-A (P less than 0.05); the concomitant administration of megestrol acetate with LHRH-A could almost completely block the antipregnancy effect of LHRH-A on the midgestation rats; LHRH-A showed a strong direct inhibitory effect on luteal cell progesterone secretion in pseudopregnant and midgestation rats. Hence, it is considered that the probable mechanisms for the antipregnancy effect of LHRH-A may be mainly due to the decrease of serum progesterone level caused by the direct inhibitory effect of LHRH-A on midgestation corpus luteum progesterone production.
Zhu
B T
BT
Department of Pharmacology, Faculty of Basic Medical Science, Shanghai Medical University.
Chu
Y H
YH
D000028:Abortion, Induced / Q000662:veterinary; D000818:Animals; D003282:Contraceptives, Postcoital, Hormonal / Q000494:pharmacology*; D005260:Female; D005865:Gestational Age; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D008184:Luteal Cells / Q000378:metabolism; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains
D003282:Contraceptives, Postcoital, Hormonal; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; C010661:surfagon