On the Site of Action of Luteinizing Hormone

Abstract

THE site of action of luteinizing hormone in stimulating synthesis and secretion of ovarian steroid hormones has been the subject of some controversy. Armstrong et al.^1,2 have concluded that the primary action of this gonadotropin in rat lutein and rabbit ovarian interstitial cells is to facilitate conversion of stored cholesterol to progesterone, and suggested that increased incorporation of ¹⁴C-acetate into steroids, when it occurs, is a consequence rather than a cause of this stimulation. Savard et al.³ have proposed that LH increases steroidogenesis at least in part by a primary stimulation of the rate of de novo synthesis of sterols and steroids from small molecular precursors. In the experiments reported here, resolution of this controversy has been achieved for the rabbit ovarian interstitial gland by preventing cholesterol biosynthesis with trans-1,4-bis (2-chlorobenzyl-aminomethyl) cyclohexane dihydrochloride (AY9944), a compound which inhibits 7 dehydrocholesterol Δ⁷-reductase⁴.