Prolactin stimulation tests: different response patterns after bromocriptine, lisuride, and metergoline treatment of puerperal women.

To elucidate different mechanisms by which bromocriptine, lisuride, and metergoline may inhibit prolactin (PRL) secretion and lactation in puerperal women, the PRL secretion patterns were examined by means of a stimulation test using an intravenous bolus of metoclopramide. After seven and 14 days of treatment, no significant difference in basal serum PRL levels was observed. However, women subjected to metergoline treatment had significantly higher responses of PRL to metoclopramide as compared with those treated with either bromocriptine or lisuride. Thus, the PRL-lowering mechanism of metergoline appears to be different from those of bromocriptine and lisuride.