d-ala(2)-mephe(4)-met(0)-ol-enkephalin and Nelson-Syndrome

ACTH excretion by cultured nonenzymatically dispersed pituitary tumor cells from a patient with Nelson's syndrome was studied. Hormone release was suppressed by 74 +/- 6% by the addition of 1 microM of the met-enkephalin analog FK 33824, while naloxone (1 microM) stimulated ACTH release by 70 +/- 5%. Somatostatin, dexamethasone, bromocriptine, and cyproheptadine in a concentration of 1 microM each inhibited ACTH release by 25 +/- 2%, 35 +/- 2%, 52 +/- 2%, and 61 +/- 4%, respectively, while lysine vasopressin (0.1 microM) and dibutyryl cAMP (5 mM) stimulated ACTH release by 112 +/- 8% and 220 +/- 4%, respectively. In conclusion, it was shown that the stimuli mentioned above directly affect ACTH secretion by the pituitary tumor cells. The inhibitory action of the met-enkephalin analog and the stimulatory action of naloxone on ACTH secretion make the presence of opiate receptors on this type of tumor likely.

Topics: Adenoma; Adrenocorticotropic Hormone; Adult; Cells, Cultured; D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; Endorphins; Enkephalins; Female; Hormones; Humans; Naloxone; Nelson Syndrome; Pituitary Neoplasms