Effect of Bromoergocriptine on TRH-Induced Growth Hormone and Prolactin Release in Acromegalic Patients
MIYUKI ISHIBASHI,
TOHRU YAMAJI and
KINORI KOSAKA
The Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo Hongo, Tokyo, Japan
In an attempt to evaluate the dynamics of growth hormone (GH)and prolactin secretion in acromegalic patients, the responseof serum GH as well as prolactin to 2-bromo-ergocriptine (CB154)alone or to CB154 combined with thyrotropin-releasing hormone(TRH) was studied in 8 subjects with this disease. Oral administrationof CB154 unequivocally decreased serum prolactin levels in allof the 8 patients, while GH-inhibitory action of the drug wasobserved only in 6 subjects who responded to TRH with secretionof GH. The response of serum GH to TRH was not qualitativelyand quantitatively altered by the treatment of patients withCB154 in a daily dose of 5 mg for two weeks. This treatment,on the other hand, remarkably suppressed basal levels of prolactinand completely blocked TRH-induced prolactin release in allof the subjects. The results suggest that there exists a dissociationbetween GH and prolactin responses to CB154 in acromegali cpatients,and that CB154 and TRH may not share a common site of actionon GH release in this pathologic state.