Aging and ovarian steroidogenesis in the rat.
Ovaries obtained from rats of 4 and 18 mo of age were incubated in vitro with 3H-pregnenolone as the added precursor. Incorporation of radioactivity into progesterone (P), 20alpha-dihydroprogesterone (20alpha-P), 17alpha-hydroxyprogesterone (17alpha-OHP), androstenedione, and testosterone were studied by serial paper and thin-layer chromatography. Significantly more P, 17alpha-OHP and androgen was produced by the older ovaries. Addition of hCG (100 I.U.) to the incubate increased 20alpha-P production in the ovaries of both age groups, depressed 17alpha-OHP and androgen formation in the ovaries of older rats, and had no effect on progesterone synthesis in either age group. Serum progesterone in 4-mo-old rats was 13.5 +/- 1.91 ng/ml at estrus and 3.69 +/- 0.9 ng/ml at diestrus, whereas serum progesterone in 18-mo-old rats was 0.85 +/- 0.15 ng/ml at constant estrus and 1.23 +/- 0.54 ng/ml at constant diestrus. Treatment with hCG for 20 days increased serum progesterone to 29.6 ng/ml in young rats and to 4.21 +/- 2.0 ng/ml in older rats. Shorter treatments were less effective. These data reveal a definite change in steroidogenic competence in older rat ovaries.
D000367:Age Factors; D000375:Aging; D000728:Androgens / Q000096:biosynthesis*; D000818:Animals; D006063:Chorionic Gonadotropin / Q000378:metabolism; D005260:Female; D006908:Hydroxyprogesterones / Q000096:biosynthesis*; D066298:In Vitro Techniques; D008297:Male; D010053:Ovary / Q000187:drug effects / Q000378:metabolism*; D011374:Progesterone / Q000096:biosynthesis / Q000097:blood; D011849:Radioactive Tracers; D051381:Rats
D000728:Androgens; D006063:Chorionic Gonadotropin; D006908:Hydroxyprogesterones; D011849:Radioactive Tracers; D011374:Progesterone