Changes in Enzyme Activities during the Artificially Stimulated Transition from Follicular to Luteal Cell Types in Rat Ovary

This paper reports the time course of development of the intramitochondrial cholesterol side‐chain‐cleavage activity, cytoplasmic NADP + ‐dependent isocitric dehydrogenase, malic enzyme and glucose‐6‐phosphate dehydrogenase during ovarian maturation, using as a model the immature rat ovary stimulated to develop with pharmacological doses of gonadotrophin. These enzymic activities were correlated with increases in ovarian content of DNA, cellular content of adenosine 3′:5′‐monophosphate, and the levels of plasma progesterone. The plasma progesterone concentrations followed closely the development of the [4‐ 14 C]cholesterol side‐chain‐cleavage which was mimicked by the cytoplasmic isocitric dehydrogenase; both enzymes increased in activity 28 times during the 6 days of this study. There was no correlation between adenosine 3′:5′‐monophosphate levels and cholesterol side‐chain cleavage or progesterone plasma concentrations.