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Horm Metab Res 2003; 35(8): 455-459
DOI: 10.1055/s-2003-41801
Original Basic
© Georg Thieme Verlag Stuttgart · New York

Ghrelin is Released from Rat Hypothalamic Explants and Stimulates Corticotrophin-releasing Hormone and Arginine-vasopressin[*]

A.  M.  Mozid 1 , G.  Tringali 2 , M.  L.  Forsling 3 , M.  S.  Hendricks 1 , S.  Ajodha 1 , R.  Edwards 1 , P.  Navarra 2 , A.  B.  Grossman 1 , M.  Korbonits 1
  • 1Department of Endocrinology, St. Bartholomew’s Hospital, London, UK
  • 2Department of Pharmacology, Catholic University, Rome, Italy
  • 3Department of Physiology, UMDS, London, UK
Further Information

Publication History

Received 29 January 2003

Accepted without revision 14 April 2003

Publication Date:
02 September 2003 (online)

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Abstract

Ghrelin and synthetic growth hormone secretagogues have diverse effects on the hypothalamus including effects on appetite and the growth hormone axis as well as on the hypothalamus-pituitary-adrenal (HPA) axis. We previously studied the effect of synthetic growth hormone secretagogues on CRH and AVP release from rat hypothalami in vitro, and now report on the effects of ghrelin on CRH and AVP release. The ghrelin protein content and ghrelin output from rat hypothalamic explants was measured using a specific novel ghrelin enzyme immunoassay. The effect of 10 - 8 M to 10 - 6 M ghrelin on CRH and AVP release was studied in the rat hypothalamic explants, where stimulation with des-octanoyl ghrelin was used as control. The presence of both ghrelin mRNA and protein could be shown in the rat hypothalamus. Ghrelin output was detected in the incubation fluid of rat hypothalamic explants and could be stimulated with high potassium concentrations. Our data also demonstrated a dose-dependent effect of ghrelin on both CRH and AVP release, while des-octanoylated ghrelin showed no effect on either peptide. In summary, the current data suggest that ghrelin is expressed in the hypothalamus both at RNA and the protein levels. Ghrelin stimulates the HPA axis in the rat via stimulation of both CRH, and particularly, AVP release from the hypothalamus. The local autocrine/paracrine and endocrine effects of ghrelin in the hypothalamus could influence all the hormonal systems involved in ghrelin effects, including growth hormone release, the HPA axis and appetite.

Key words

Ghrelin - Growth hormone secretagogue receptor - Hypothalamus - Corticotrophin-releasing hormone - Arginine-vasopressin

1 These data were presented at the September 2002 Meeting of the European Neuroendocrine Association, Munich, Germany.

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1 These data were presented at the September 2002 Meeting of the European Neuroendocrine Association, Munich, Germany.

M. Korbonits M.D., PhD. 

MRC Clinician Scientist · Senior Lecturer in Endocrinology · Endocrine Oncology · Department of Endocrinology · St. Bartholomew's Hospital

59 Bartholomew Close · Unit 1.1 · London · EC1A 7BE · UK

Phone: +44(20)76018613 or 8746

Fax: +44(20)76017015

Email: m.korbonits@qmul.ac.uk