Effects of steroid blockers on LH-induced ovulation in the domestic fowl, Gallus domesticus

Abstract

The spontaneous ovulation of hens was suppressed by daily injection of PMSG [pregnant mare serum gonadotropin]. The LH [luteinizing hormone] injected to overcome the block was accompanied by 1 of 4 compounds known to inhibit steroidogenesis at different sites in the biosynthetic pathway. A dose of 300 mg aminoglutethmide phosphate, which inhibits the conversion of cholesterol to 20.alpha.-hydroxycholesterol, blocked the LH-induced ovulation and prevented the normal rise in plasma progesterone. Metyrapone, an inhibitor of 11.beta.-hydroxylase and SC 12937 [20,25-diazacholesterol] and AY 9944 [trans-1-4-bis-2-chlorobenzylaminomethyl-cyclo-hexane dihydrochloride], inhibitors of cholesterol synthesis, did not prevent ovulation or the progesterone rise induced by exogenous LH. Progesterone administration overcame the inhibitory effect of aminoglutethimide and progesterone may be involved in the ovulatory process of the fowl.