GH-releasing Peptide-2 does not Stimulate Arginine Vasopressin Secretion in Healthy Men

Abstract

Abstract. Ghrelin has a stimulating effect on arginine vasopressin (AVp). however, it is not known whether GhRp-2, a synthetic ghrelin receptor agonist, also has a stimulating effect on AVp release in men. to determine whether the GhRp-2 test is useful for assessing AVp secretion, blood Acth, Gh, FSh, Lh, pRL, tSh and AVp levels, as well as glucose, osmolality, sodium and hematocrit, were measured before and 15, 30, 45 and 60 min after an intravenous bolus of 100 µg GhRp-2 in 10 healthy men with and without fasting. blood pressure was measured at 15-min intervals. AVp secretion was not stimulated by the GHRP-2 test with and without fasting. There were no significant differences in hematocrit, blood pressure and plasma osmolality before and after GFRP-2 injection, although significant (p<0.001) peak blood Gh, and Acth and pRL levels were observed 30 and 15 min after GhRp-2 injection with and without fasting, respectively, and the maximal peaks were significantly (p<0.05) higher with fasting than without fasting. these results suggest that AVp secretion is not stimulated by the GhRp-2 test both with and without fasting, though Gh, Acth and pRL levels were higher with than without fasting.

Concordant and discordant adrenocorticotropin (ACTH) responses induced by growth hormone-releasing peptide-2 (GHRP-2), corticotropin-releasing hormone (CRH) and insulin-induced hypoglycemia in patients with hypothalamopituitary disorders: evidence for direct ACTH releasing activity of GHRP-2

“…Previous studies in humans suggested that GHRP's ACTH-releasing activity may be mediated via CRH and/or AVP [3,5,7,11], or independent on both peptides [12]. Very recently, Kamoi et al [13] showed that GHRP-2 does not stimulate AVP secretion.…”

Is there an undiscovered neurocircuit for regulating GH secretion? -Pitfalls of GHRP-2 and ITT as GH provocative tests-

“…2) For assessment of pituitary function, in a random order with more than 8 h of overnight fasting with intervals of more than 1 week, a single dose (100 µg) of GHRP-2 [9,10], a single dose (0.1 U/kg) of regular insulin (Novo Nordisk, Tokyo, Japan) [3,4,5], a single dose of TRH (500 µg: hTRH "Tanabe" injection, Tokyo, Japan) and a single dose (10 mL) of HRHs combined with CRH (100 µg; hCRH "Mitsubishi" injection, Tokyo, Japan), GRH (100 µg; hGRH "Sumitomo" injection, Tokyo, Japan), LH-RH (100 µg: hLH-RH "Tanabe" injection, Tokyo, Japan ), and TRH [12], and a single dose (1 mg) of glucagon (Novo Nordisk, Tokyo, Japan) [14,15] were administered as an intravenous bolus and subcutaneous bolus injections, respectively, at 09:00. After one year later, these tests were repeatedly performed.…”

“…After one year later, these tests were repeatedly performed. As a first trial test, after more than 8 h of overnight non-fasting, a single dose (100 µg) of GHRP-2 was administered [10]. He remained supine for more than 30 min before the injections and throughout the study period.…”

“…Blood samples were collected into tubes from a catheter inserted into an antecubital vein before and every 15 min for 1 h after the injection of GHRP-2, before and every 30 min for 1.5 h after the injection of regular insulin, before and 15, 30, 45, 60, 90, and 120 min after the injection of HRHs, before and every hour weight and height were 70 kg and 168 cm, respectively, was recruited for evaluation of a GHRP-2 (KP-102, Kaken Pharmaceuticals, Tokyo, Japan) test as a diagnostic test of GH reserve in healthy men [10].…”

“…GHRP-2 which is a 6-amino acids peptide as one of the GHRPs causes potent GH release by binding to a specific receptor, for which ghrelin has been shown to be the natural ligand, and is used for assessing GH secretion [9,10].…”