d-Lys-GHRP-6 does not modify the endocrine response to acylated ghrelin or hexarelin in humans.
Neuropeptides. 2007 Feb; 41(1):45-9.N

Abstract

Acylated ghrelin exerts numerous endocrine and non-endocrine activities via the GH Secretagogue receptor type 1a (GHS-R1a). D-Lys-GHRP-6 has been widely studied in vitro and in vivo in animal studies as GHS-R1a antagonist; its action in humans has, however, never been tested so far. Aim of our study was to verify the antagonistic action of D-Lys-GHRP-6 on the endocrine responses to acylated ghrelin and hexarelin, a peptidyl synthetic GHS, in humans. The effects of different doses of D-Lys-GHRP-6 (2.0microg/kg iv as bolus or 2.0microg/kg/h iv as infusion) on both spontaneous and acylated ghrelin- or hexarelin (1.0microg/kg iv as bolus) -stimulated GH, PRL, ACTH and cortisol levels were studied in six normal volunteers (age [mean+/-SEM]: 25.4+/-1.2yr; BMI: 22.3+/-1.0kg/m(2)). The effects of D-Lys-GHRP-6 (2.0microg/kg iv as bolus+4.0microg/kg/h iv) on the GH response to 0.25microg/kg iv as bolus acylated ghrelin was also studied. During saline, spontaneous ACTH and cortisol decrease was observed while non changes occurred in GH and PRL levels. Acylated ghrelin and hexarelin stimulated (p<0.05) GH, PRL, ACTH and cortisol secretions. D-Lys-GHRP-6 administered either as bolus or a continuous infusion did not modify both spontaneous and acylated ghrelin- or hexarelin-stimulated GH, PRL, ACTH and cortisol secretion. D-Lys-GHRP-6 did not modify even the GH response to 0.25microg/kg iv acylated ghrelin. In conclusion, D-Lys-GHRP-6 does not affect the neuroendocrine response to both ghrelin and hexarelin. These findings question D-Lys-GHRP-6 as an effective GHS-R1a antagonist for human studies.

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Authors+Show Affiliations

Benso A
Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Turin, Turin, Italy.
Prodam F
No affiliation info available
Lucatello B
No affiliation info available
Gramaglia E
No affiliation info available
Riganti F
No affiliation info available
Schneider H
No affiliation info available
van der Lely AJ
No affiliation info available
Muccioli G
No affiliation info available
Ghigo E
No affiliation info available
Broglio F
No affiliation info available

MeSH

AcylationAdrenocorticotropic HormoneAdultGhrelinGrowth Hormone-Releasing HormoneHuman Growth HormoneHumansHydrocortisoneKineticsLysineMaleOligopeptidesPeptide HormonesProlactinReference Values

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17112585