E. Mcgee et al., THE EFFECTS OF INSULIN ON 3-BETA-HYDROXYSTEROID DEHYDROGENASE EXPRESSION IN HUMAN LUTEINIZED GRANULOSA-CELLS, Journal of the Society for Gynecologic Investigation, 2(3), 1995, pp. 535-541
Objective: We determined the relative effects of insulin and FSH on pr
ogesterone accumulation as well as activity, protein content, and mRNA
expression of 3beta-hydroxysteroid dehydrogenase (3betaHSD) in human
luteinized granulosa cells. Methods: Luteinized granulosa cells obtain
ed from women undergoing in vitro fertilization were plated and grown
to near confluence and treated with FSH, insulin, or a combination of
insulin and FSH. Progesterone production as well as enzyme activity, p
rotein content, and mRNA expression for 3betaHSD were evaluated. Resul
ts: Progesterone production was not affected by insulin alone but incr
eased threefold in the presence of FSH (50 ng/muL) alone. The presence
of FSH plus insulin (100 nmol/L) caused a significant increase in pro
gesterone accumulation greater than that of FSH alone. The already hig
h basal levels of 3betaHSD activity were unaffected by insulin alone b
ut increased 1.7-fold in the presence of FSH. The combination of FSH (
50 ng/mL) and insulin (100 nmol/L) increased activity 1.3-fold over FS
H alone (P < .02). Insulin (greater than 100 nmol/L) alone increased 3
betaHSD protein content as measured by Western analysis 1.8-2-fold ove
r basal levels, whereas FSH alone increased protein content 2.8-fold,
and was further augmented by the addition of insulin in a dose-related
fashion up to 3.5-fold over basal levels. Insulin increased 3betaHSD
mRNA twofold over basal levels; FSH alone increased mRNA expression of
3betaHSD 3.2-fold. In the presence of insulin plus FSH, 3betaHSD mRNA
expression increased 7.6-fold over basal levels. For comparison, insu
lin alos stimulated cytochrome P450 aromatase activity, P450 aromatase
protein, and mRNA but to a greater degree than that seen for 3betaHSD
. Conclusion: Insulin is a regulator of both 3betaHSD and aromatase ex
pression in human granulosa cells. Elevated insulin levels could there
fore affect steroid production in human granulosa cells and presumably
alter the menstrual cycle and fertility.