Conversion of Cholesterol to Progesterone by Corpus Luteum Slices

Abstract

The conversion of cholesterol-7-³H to progesterone was studied in slices of bovine corpus luteum by measuring both the total amount of progesterone synthesized and the radioactivity in the final product derived from cholesterol-7-³H. The addition of luteinizing hormone to the incubating slices caused an increase in the amount of progesterone synthesized but only a slight increase in the conversion of radioactive cholesterol. The addition of NADP +glucose-6-phosphate, on the other hand, increased both the amount of progesterone and, to a greater extent, the conversion of added cholesterol-7-³H to progesterone. Neither added LH nor added NADP -fglucose-6-P influenced the penetration of the radioactive cholesterol into the slices. It was concluded that NADPH increases progesterone synthesis primarily through its action on the transformation of cholesterol, whereas LH affects the transformation of cholesterol to a slight extent only and acts mainly on precursors prior to cholesterol in the biosynthetic pathway. The action of LH is probably not mediated via the formation of NADPH. (Endocrinology75: 215, 1964