Blockade of ovulation in rabbits by RU-486, a competitive progesterone antagonist.
The effect of an anti-progesterone compound, RU-486, administration (20-150 mg) on ovulation in rabbits was investigated. All of the seven control oil-treated rabbits ovulated, whereas, ovulation was blocked in one (12.5%) of eight rabbits treated with 20 mg RU-486, and in 4-6 (66.7-85.7%) of the 6 or 7 rabbits treated with 40-150 mg RU-486. Two successive injections of 10 mg progesterone (P) 4 and 8 hr after RU-486 injection did however recover ovulation in 3 (75.0%) out of 4 rabbits. These results indicate that P secreted from mature follicles during the ovulatory LH surge also play a significant role in follicular rupture of the rabbit, a copulatory ovulator.
Kanayama
K
K
Department of Veterinary Physiology, College of Agriculture and Veterinary Medicine, Nihon University, Kanagawa, Japan.
Sankai
T
T
Nariai
K
K
Endo
T
T
D000818:Animals; D003307:Copulation; D005260:Female; D006727:Hormone Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D007279:Injections, Subcutaneous; D008297:Male; D015735:Mifepristone / Q000008:administration & dosage / Q000494:pharmacology*; D010060:Ovulation / Q000187:drug effects*; D011374:Progesterone / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D011817:Rabbits; D012016:Reference Values
D006727:Hormone Antagonists; D015735:Mifepristone; D011374:Progesterone