Experimental hyperprolactinemia and hypoprolactinemia and human chorionic gonadotropin during early pregnancy

The effect of experimental hyperprolactinemia and hypoprolactinemia on human chorionic gonadotropin (hCG) concentration was studied in 34 healthy volunteers between weeks 6 and 11 of normal pregnancy. Hyperprolactinemia was induced in 12 women with 150 mg of sulpiride daily for 2 weeks; treatment led to a mean plasma prolactin (PRL) rise from 14.6 to 84.1 microgram/liter after 1 week and to 83.0 microgram/liter after 2 weeks. Hypoprolactinemia was effected in 11 women wit 5.0 to 7.5 mg of bromocriptine, daily for 2 weeks; treatment decreased the mean plasma prolactin from 19.2 to 6.0 microgram/liter after 1 week and to 5.2 microgram/liter after 2 weeks. These PRL changes were significant (P less than .001) in comparison with the plasma PRL concentrations in the 11 control women. Hyperprolactinemia induced by the sulpiride treatment was accompanied by a significant decrease in hCG concentration, whereas no difference in hCG was seen between hypoprolactinemia and control groups. This may suggest a synergistic action of hCG and PRL, or a direct effect of sulpiride on hCG, but the final mechanism and biologic importance of the phenomenon remain to be investigated.