LH effect on the pattern of steroidogenesis in cultured Graafian follicles of the rat: dependence on macromolecular synthesis.
Graafian follicles explanted from proestrous rats before the preovulatory gonadotropin surge secreted predominantly 17beta-estradiol, and only small amounts of progestins and androgens, during 12 h of culture in hormone-free medium. Addition of ovine luteinizing hormone (NIH-LH-S18; 0.1-1.0 mug/ml) to the medium stimulated within 1-2 h the rate of accumulation of these steroids. However, accumulation of androstenedione and estradiol ceased after 4-6 h in the LH-treated cultures, whereas progesterone continued to accumulate and became the major secretory product at 6-12 h. Incubation of the follicles with LH for only 5 min resulted in significant stimulation of the accumulation of progesterone, androstenedione and estradiol during a subsequent 6-h culture period in hormone-free medium containing antibodies to LH; 30 min exposure to the hormone sufficed to elicit a maximal steroidogenic response and to induce ovum maturation in 95% of the follicles. Addition of actinomycin D (act D; 8 mug/ml) within the first hour after exposure of follicles to LH suppressed the LH-effect on progesterone but augmented the LH effect on estradiol accumulation; when addition of this inhibitor was delayed until 2 h, progesterone accumulation continued unabated for a further 10 h. By contrast, puromycin (80 mug/ml) inhibited progesterone accumulation when added to the medium at any time (1, 2 or 3 h) after the hormone. It is suggested that (i) a short-lived protein is essential for the stimulatory effect of LH on follicular steroidogenesis; (ii) the act D-sensitive product (mRNA?) required for the production of this protein is synthesized in adequate amount during the first 2 h of LH action, and is stable for at least 10 h; and (iii) LH may stimulate the production of an additional act D-sensitive regulatory protein that inhibits enzymes engaged in the cleavage of the 17-side-chain of progesterone, or cells equipped with these enzymes.
D000241:Adenosine / Q000378:metabolism; D000735:Androstenedione / Q000096:biosynthesis; D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D003609:Dactinomycin / Q000494:pharmacology; D004958:Estradiol / Q000096:biosynthesis; D005260:Female; D006908:Hydroxyprogesterones / Q000096:biosynthesis; D007930:Leucine / Q000378:metabolism; D007986:Luteinizing Hormone / Q000494:pharmacology*; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D011359:Proestrus; D011374:Progesterone / Q000096:biosynthesis; D014176:Protein Biosynthesis; D011691:Puromycin / Q000494:pharmacology; D012313:RNA / Q000096:biosynthesis; D011863:Radioimmunoassay; D051381:Rats; D013256:Steroids / Q000096:biosynthesis*; D013997:Time Factors
D006908:Hydroxyprogesterones; D013256:Steroids; D003609:Dactinomycin; D000735:Androstenedione; D011691:Puromycin; D011374:Progesterone; D004958:Estradiol; D012313:RNA; D007986:Luteinizing Hormone; D004247:DNA; D007930:Leucine; D000241:Adenosine