Variation of serum prolactin-releasing activity in women with the galactorrhea-amenorrhea syndrome after bromocriptine treatment.

Serum methanol extracts were obtained from nine women with the galactorrhea-amenorrhea syndrome, 24 pregnant women in the third trimester, and 18 normal men and women. The serum extract released prolactin (PRL) in significant amounts from rat anterior pituitary in vitro. The extracts from patients with galactorrhea-amenorrhea released PRL in large quantities. A significant positive correlation was observed between the PRL-releasing activity and serum PRL levels in individual samples from the pregnant women and normal subjects but not from the patients with galactorrhea-amenorrhea. Bromocriptine therapy suppressed serum PRL levels of five patients without tumors but increased the PRL-releasing activity in three out of five patients after treatment for 1 or 2 months. Apparently hypothalamic regulation of PRL secretion was disrupted in these three patients after bromocriptine therapy.