Effect of bromocriptine on plasma catecholamines in normal subjects and prolactin-secreting tumor patients

The effect of short term bromocriptine (5 mg/day, 5 days) on plasma epinephrine (E), norepinephrine (NE), dopamine (DA) and prolactin (PRL) was studied in 4 normal women and 6 bearing PRL-secreting tumors. When studied on placebo no significant differences were found between controls and patients in E, NE and DA plasma levels. Bromocriptine induced: a 70% decrease in PRL levels in both groups, a significant (p less than 0.05) decrease in plasma NE levels in the control group, no significant change in plasma NE levels in the hyperprolactinemic patients when considered as a group. These results do not indicate that bromocriptine is a useful tool in the diagnosis of defective central dopaminergic regulation since individual responses of the PRL-secreting tumor patients were variable. Nevertheless, the impaired response of the group as a whole may be suggesting an underlying alteration of DA2 receptor activity in these tumor patients.