In vitro effect of dopamine and pimozide on human chorionic gonadotropin secretion

In human placental explants cultured in vitro, dopamine inhibited human chorionic gonadotropin (hCG) secretion into the culture media. In the control flasks, the level of hCG secretion was 751 +/- 215 mIU/gm of tissue. When 1 mM of dopamine was added, hCG levels decreased to 321 +/- 57.6 mIU/gm of tissue (n = 6, P less than 0.1)--5 and 10 mM of dopamine significantly inhibited hCG secretion. In contrast, 1 mM of pimozide enhanced hCG secretion by 1.8-fold compared to control levels (1,707 +/- 343 versus 3,117 +/- 0.005). This in vitro effect on hCG is similar to the effect of dopamine and pimozide on hCS secretion by placental explants.