Hypoprolactinemia and ovarian function

Thirty-two patients with ovarian hyperstimulation were randomized to receive bromocriptine or placebo from cycle day 5 onward. Bromocriptine decreased serum and follicular fluid prolactin (PRL), accelerated ovarian follicle growth, increased serum and follicular fluid estradiol, lowered luteal phase progesterone, and shortened the luteal phase length of the cycle. The maximal luteal phase estradiol and progesterone concentrations correlated with each other in the placebo group, but not in the bromocriptine group. These findings indicate that hypoprolactinemia interferes with ovarian function. The unchanged concentrations of gonadotropic hormones and pattern of luteinizing hormone pulsation during bromocriptine suggest direct ovarian effects of hypoprolactinemia. Because PRL suppression enhanced follicular responses and inhibited corpus luteum formation and function, the follicular and corpus luteum actions of PRL may be different.