Prolactin and growth hormone responses to dermorphin in patients with prolactin-secreting pituitary adenoma.

We have recently shown that dermorphin (D), a new potent opioid peptide (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2) stimulates prolactin (PRL) and growth hormone (GH) secretion in humans. In 11 patients with a PRL-secreting pituitary adenoma (eight microprolactinomas and three macroprolactinomas with suprasellar extension), diagnosed by pituitary dynamic function tests, and radiological evidence with confirmation at surgery, the PRL and GH responses to D were studied to evaluate the effect of pathological hyperprolactinemia on the opioid-induced secretion of GH and PRL. No PRL response to D was observed in all 11 patients. Plasma GH increased after D in all patients, except in three patients bearing a macroprolactinoma. This study shows that the effect of D on PRL and GH secretion can be dissociated in patients with PRL-secreting pituitary adenoma, perhaps for a different derangement in the hypothalamic-pituitary mechanism(s) underlying the opioidergic regulation of GH and PRL secretion. In addition our data indicate that D can be employed as a useful opioid probe in humans.