Effect of ovine corticotrophin releasing factor, bromocriptine, and dopamine on release of ACTH and beta-endorphin in a patient with Cushing's disease.

Release of immunoreactive ACTH and beta-endorphin (beta-EP) in response to corticotrophin-releasing factor (CRF) and dopaminergic agents was studied in vivo and in vitro in a patient with Cushing's disease. Iv administration of synthetic ovine (o) CRF significantly stimulated plasma ACTH release, accompanied by increase of plasma cortisol levels. Oral administration of bromocriptine significantly suppressed plasma cortisol levels. Although reduced responses of plasma ACTH and cortisol to o-CRF was observed 1 month after removal of the pituitary adenoma, these normalized 6 months after operation. In vitro perifusion of the pituitary adenoma obtained by surgery revealed that o-CRF also stimulated ACTH and beta-EP release in a dose-responsive manner (10(-9)M 10(-5)M) and that dopamine suppressed their basal secretion. Gel exclusion chromatography of the perfusates showed that the predominant component of ACTH and beta-EP before and after o-CRF stimulation coeluted with standard ACTH and beta-EP, respectively. The present data suggest that o-CRF is a potent secretagogue for ACTH and beta-EP release from the human pituitary adenoma causing Cushing's disease and that ACTH secretion from certain adenomas, possibly originating from the intermediate lobe of the pituitary gland, is partly regulated by a dopaminergic mechanism.