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.

Effect of somatostatin on growth hormone and prolactin response to dermorphin in man.

The effects of iv somatostatin (somatotrophin release inhibiting factor (SRIF) on growth hormone (GH) and prolactin (Prl) response to dermorphin (D) were tested in 6 healthy men. In all subjects D induced a significant increase in GH and Prl levels, as expected. SRIF completely blocked the GH-releasing activity of D, whereas it only reduced the Prl-releasing activity.

Dermorphin, a new opioid peptide, stimulates thyrotropin secretion in normal subjects.

The effect of a recently described, potent opioid peptide, dermorphin (DER), on TSH secretion in euthyroid subjects has been studied. DER infused at a rate of 5.5 micrograms/Kg/min for 30 min induced a significant increase in serum TSH concentration at 60, 90, and 120 min after the infusion was begun.

Responses of plasma renin activity, aldosterone, adrenocorticotropin, and cortisol to dermorphin, a new synthetic potent opiate-like peptide, in man.

This study was designed to investigate the effect of dermorphin (D), a new synthetic potent opiate-like peptide (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2), on PRA, plasma aldosterone (PA), plasma cortisol (PC), and plasma ACTH levels in normal men. D infusion (5.5 micrograms/kg X min for 30 min) significantly increased PRA (P less than 0.

Stimulatory effect of dermorphin, a new synthetic potent opiate-like peptide, on human growth hormone secretion.

Two new related heptapeptides (dermorphins) with potent central and peripheral opiate-like activity have been isolated from the skin of South American frogs, and have been chemically characterized as H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2 (dermorphin) and H-Tyr-D-Ala-Phe-Gly-Tyr-Hyp-Ser-NH2 (Hyp6-dermorphin). The response of GH to infusion of a synthetic dermorphin (5.5 micrograms/kg/min for 30 min) was studied in 9 healthy men.

Prolactin-releasing activity of dermorphin, a new synthetic potent opiate-like peptide, in normal human subjects.

Dermorphins (D) are heptapeptides (H-Tyr-D-Ala-Phe-Gly-Tyr-X-Ser-NH2; X, Pro or Hyp) with powerful central and peripheral opiate-like activity, originally isolated from the skin of South American frogs. To study the effect of a synthetic D on PRL secretion in man, either D (5.5 micrograms/kg .

Effect of ketanserin, an inhibitor of 5-HT2 receptors, on the aldosterone-stimulating action of metoclopramide.

To estimate the possible involvement of a peripheral serotonergic pathway in the mechanism of the aldosterone-stimulating effect of metoclopramide (M) the plasma aldosterone (PA), renin activity (PRA) and prolactin (PRL) response to M was studied in 6 normal subjects before and after administration of ketanserin (K), a pure, specific, and selective blocking agent of 5-hydroxytryptamine type 2 (5-HT2) receptors. With K preadministration the M-induced increase of PRL was similar to that observed in control conditions, in accordance with the specific and peripheral antiserotonergic action of the drug. K potentiated the PA and PRA elevation in response to M.

Effect of pentagastrin on adrenocorticotropin hormone and thyroid-stimulating hormone release in normal subjects.

The possible role of gastrin on TSH, ACTH and cortisol secretion was evaluated by intravenous administration of pentagastrin, the carboxyl-terminal tetrapeptide of gastrin (0.5 microgram/kg b.w.

Effect of ketanserin, a new inhibitor of 5-HT2 receptors, on plasma renin activity and aldosterone levels in normal subject.

The effect of intravenous administration (10 mg) of ketanserin, a pure, specific and selective blocking agent of 5-HT2 receptors (R 41 468: 3-[2-[4-(4-fluorobenzoyl)-1-piperidinyl]ethyl]-2,4(1H,3H)-quinazolinedione) on the renin-angiotensin-aldosterone system and blood pressure in 5 normal male volunteers was compared to the effect of saline alone. Ketanserin induced a small increase in plasma levels of both renin activity and aldosterone, which was not significantly different from that observed during control test. There was no significant effect on systolic and diastolic blood pressure.

Failure of metergoline to affect the circadian periodicity of plasma cortisol levels in healthy man.

To investigate the role of serotoninergic system on the control of circadian periodicity of human hypothalamic-pituitary-adrenal axis, effect of a potent 5-HT antagonist, metergoline, on diurnal variation in plasma cortisol levels was studied in five male volunteers. The administration of metergoline did not result in a significant change of plasma cortisol concentrations and its circadian rhythmicity. These results suggest that metergoline does not influence the diurnal secretion of cortisol in normal subjects.