Luteotrophic and Luteolytic Mechanisms in Rat Corpora Lutea¹

Abstract

Chronic LtH administration begun either on the first day of diestrus or toward the end of pseudopregnancy maintained maximal progesterone secretion and inhibited 20α-OHsteroid dehydrogenase activity. Total steroidogenesis and ovarian cholesterol levels were not altered by LtH treatment. The luteotrophic action of LtH was explained in part by its antagonistic action toward luteal 20α-OH-steroid dehydrogenase and in part by its mobilization of a progesterone precursor. Chronic LH administration to animals bearing nonfunctional corporalutea reduced the ovarian output of progesterone and 20α-OH-pregn-4-en-3-one. On the other hand, chronic administration of LH to animals bearing functional corpora lutea caused a fall in ovarian vein progesterone concentration coincident with a rise in 20α-OH-pregn-4-en-3-one without reducing total steroidogenesis. The acute administration of LH to immature rats near the time of PMS-induced ovulation stimulated progesterone secretion and partially depleted ovarian cholesterol. (Endocrinology84: 886, 1969)