Follicle-stimulating hormone and insulin regulation of 17 beta-estradiol secretion and granulosa cell proliferation within immature rat ovaries maintained in perifusion culture.
The present study examined the effects of FSH and insulin (IN) on 17 beta-estradiol (E2) secretion and granulosa cell proliferation. For these studies, immature rat ovaries were maintained in perifusion culture and continuously exposed to FSH (0-800 ng RP-1 eq/ml) and /or IN (0.2 U/ml). At specific times, the ovaries were removed from perifusion, and the perifusate was assayed for E2 by RIA. The ovaries were then incubated with [3H]thymidine ([3H]T) in order to estimate granulosa cel mitotic activity. FSH increased E2 secretion in a dose-dependent manner (P less than 0.05), but did not enhance [3H]T incorporation (P greater than 0.05) after 48 h of perifusion. Conversely, IN increased [3H]T incorporation (P less than 0.05) without stimulating E2 secretion (P greater than 0.05) after 48 h of perifusion. FSH alone or in combination with IN stimulated [3H]T incorporation at 24 h of perifusion compared to both zero hour control (P less than 0.05) and IN treatments (P less than 0.05). The inability of FSH to stimulate [3H]T incorporation after 48 h did not appear to be due to increased E2, since IN stimulated [3H]T incorporation in the presence of 100 ng E2/ml. Further, continuous exposure to FSH was required to maintain E2 secretion, demonstrating that after 24 h, FSH loses its capacity to stimulate granulosa cell [3H]T incorporation, but not E2 secretion. Finally, when ovaries are pretreated with FSH for 48 h and then exposed to FSH and/or IN, [3H]T incorporation was stimulated, and E2 secretion inhibited. These data suggest that 1) initially, FSH acts to stimulate mitosis then promotes granulosa cell E2 secretion; and 2) once granulosa cells begin to secrete E2 they are still capable of mitosis, but their mitotic activity is no longer directed by FSH.
Peluso
J J
JJ
Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington 06032.
Delidow
B C
BC
Lynch
J
J
White
B A
BA
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006107:Granulosa Cells / Q000166:cytology* / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D009924:Organ Culture Techniques; D010053:Ovary / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012741:Sexual Maturation
D007328:Insulin; D004958:Estradiol; D005640:Follicle Stimulating Hormone