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

ABSTRACT

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.