Abstract
The effect of acute injection of cimetidine, a selective histamine-2 receptor blocker, on prolactin (PRL) secretion was investigated in subjects with physiological puerperal hyperprolactinemia and pathological hyperprolactinemia. Failure of cimetidine to affect basal PRL levels was observed in all the subjects not responding to nomifensine, an antidepressant drug which enhances dopaminergic neurotransmission by inhibiting dopamine reuptake in the central dopamine synapses. In the subjects with puerperal and idiopathic hyperprolactinemia who responded to nomifensine test, cimetidine stimulated PRL secretion. These results indicate that cimetidine can be useful in the differential diagnosis between hyperprolactinemia states due to pituitary tumor or nontumor.