Studies on the rapid cholesterol-depleting and steroidogenic actions of luteinizing hormone in the rat ovary: effects of aminoglutethimide phosphate

Abstract

Superovulated, immature rats were administered luteinizing hormone (LH) and/or aminoglutethimide phosphate (AGP), an inhibitor of cholesterol side-chain cleavage, to ascertain whether the steroidogenic action could be separated from the cholesterol-depleting action of LH. The injection of AGP [Formula: see text] and [Formula: see text] before sacrifice significantly reduced tissue levels of progesterone and 20α-dihydroprogesterone to 25–30% of normal, and increased tissue levels of free cholesterol in the absence and presence of LH given [Formula: see text] or 4 h before sacrifice. Cholesterol ester concentration was increased twofold after [Formula: see text] AGP, whereas LH injection [Formula: see text] after AGP and 4 h before sacrifice reduced the tissue concentration to the control level but not as low as that observed when only LH was given 4 h before sacrifice (50% of control level). The cholesterol ester depletion induced by LH, even though steroidogenesis was inhibited, indicates that these may represent separate events in the action of LH on luteal tissue.