Effects of dopamine infusion on pituitary hormone secretion in humans.

Dopamine, infused at a rate of 4 mug/kg/min for 3-4 h unaccompanied by any significant changes in cardiovascular dynamics, induced a prompt and sustained suppression of circulating prolactin (PRL) levels in normal men and women as well as in patients with hyperprolactinemia. At the discontinuation of the infusion, there was a marked rebound in PRL levels in normal subjects and a rapid return to basal levels in hyperprolactinemic patients. Dopamine infusion also induced a significant fall in LH levels in the normal subjects with a marked rebound in LH levels following the infusion. No significant changes in GH, TSH, and FSH levels were observed. These data indicate that in man a dopaminergic mechanism ixists in the regulation of PRL secretion and that dopamine also exerts an inhibitory effect of LH release.