Steroid Production by the Isolated Rabbit Ovarian Follicle. III. Actinomycin D-Insensitive Stimulation of Steroidogenesis by LH

Abstract

The action of LH on steroidogenesis by isolated rabbit ovarian follicles has been examined. Follicles were incubated in culture medium at 37 C with medium being changed every 15 min. Media were analyzed for progestin, androgen and estrogen using established radioimmunoassay procedures. 'progestin and androgen secretion declined rapidly within 1.5 hr of incubation. Addition of LH (NIH-LH-S16), 5 mug/ml, for as little as 1 sec caused a dramatic increase in synthesis and secretion of androgen (greater than 100%) with lesser increases in secretion of progestin and estrogen. When puromycin and cycloheximide were added separately with LH there was inhibition of steroidogenesis for as long as either inhibitor was present in the medium. Addition of puromycin or cycloheximide after a mixture of LH and puromycin or cycloheximide delayed steroidogenesis until all of either inhibitor was removed. Actinomycin D in the medium failed to inhibit LH-induced steroidogenesis. These data suggest that the action of LH on steroidogenesis by the rabbit ovarian follicle probably occurs at the translational level and the binding of LH to the follicular ce-ls is a very rapid process.