In vivo and in vitro modulation of growth hormone and prolactin of a mixed somatotropic-lactotropic pituitary microadenoma.

Both in vivo and in vitro responses of prolactin and growth hormone to stimuli were studied in an acromegalic, amenorrheic woman with a chromophobe adenoma of the pituitary gland. Preoperative testing revealed a prolactin rise after thyrotropin-releasing hormone and chlorpromazine and a decline after L-dopa and bromocriptine administration. During 3.5-hour incubations, cultured tumor cells produced significant increases of growth hormone and prolactin after dibutyryl adenosine 3',5'-cyclic monophosphate stimulation, while bromocriptine inhibited both hormones.