Effect of prolactin on follicle-stimulating hormone receptor binding and progesterone production in cultured porcine granulosa cells.

OBJECTIVE

To determine the effect of prolactin (PRL) on follicle-stimulating hormone receptor (FSH-R) binding and progesterone (P) production in cultured porcine granulosa cells.

DESIGN

Controlled experiment.

SETTING

Academic research laboratory.

INTERVENTION(S): Immature granulosa cells were cultured in a serum-free medium. All cell populations were supplemented with porcine (p) FSH and cultured in the absence or presence of ovine (o) PRL.

MAIN OUTCOME MEASURE(S): Specific pFSH-R binding and P in medium.

RESULT(S): In the control cells, FSH-R binding increased 31-fold and P production increased 700-fold by day 4. Physiologic levels of oPRL potentiated the action of pFSH and resulted in a further 50% increase in pFSH-R binding and P production by day 4 over that in controls. In contrast, higher concentrations of oPRL blocked the rise in both pFSH-R binding and P production. The alteration in pFSH-R binding was associated with a change in FSH-R number.

CONCLUSION(S): Physiologic levels of PRL amplify the stimulatory effects of FSH on the acquisition of the FSH-R and P production in cultured granulosa cells. Higher concentrations of PRL cause a decrease in FSH-R binding and P production. Prolactin may act as a "co-gonadotropin" and fine-tune the process of folliculogenesis by altering the acquisition of granulosa FSH receptors.