Abnormal plasma catecholamine responses in acromegalics.

Plasma dopamine, norepinephrine, and epinephrine responses to bromocriptine (2.5 mg orally) or to LRH (100 microgram iv) were studied in seven acromegalic patients. In contrast to normal men, in whom plasma concentrations of catecholamines decrease markedly, acromegalic subjects fail to show decreases in plasma dopamine, norepinephrine, or epinephrine in response to bromocriptine (four of four studied) or LRH (three of four studied). Mean basal plasma catecholamine concentrations do not differ in acromegalic patients, normal men, and a group of nonacromegalic endocrine control patients. Since it appears that bromocriptine and LRH suppress plasma catecholamine concentrations through mechanisms at brain catecholamine neurons, these data are compatible with disordered catecholamine neurons in the brain of patients with acromegaly.