BROMOCRIPTINE SUPPRESSES ACTH SECRETION FROM HUMAN PITUITARY TUMOUR CELLS IN CULTURE BY A DOPAMINERGIC MECHANISM

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Abstract
Bromocriptine (0.13-13 .mu.M) significantly inhibited ACTH secretion in a dose-dependent manner when added to cell cultures of a human corticotrophic adenoma for 24 h. Haloperidol (13 .mu.M), but not serotonin (13 .mu.M), blocked this inhibition but had no significant effect when added alone. Dopamine (10 .mu.M) reduced ACTH secretion during a 4 h incubation, but serotonin (0.01-10 .mu.M) was ineffective. An ectopic ACTH secreting lung carcinoid was nonresponsive to doses of bromocriptine up to 13 .mu.M. These results demonstrate a direct suppressive action of bromocriptine on a human pituitary corticotrophic adenoma through dopaminergic rather than serotoninergic mechanisms.