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Xie, T.Y.* ; Ngo, S.T.* ; Veldhuis, J.D.* ; Jeffery, P.L.* ; Chopin, L.K.* ; Tschöp, M.H. ; Waters, M.J.* ; Tolle, V.* ; Epelbaum, J.* ; Chen, C.C.* ; Steyn, F.J.*

Effect of deletion of ghrelin-o-acyltransferase on the pulsatile release of growth hormone in mice.

J. Neuroendocrinol. 27, 872-886 (2015)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
Ghrelin, a gut hormone originating from the post-translational cleavage of preproghrelin, is the endogenous ligand of the Growth Hormone Secretagogue Receptor 1a (GHS-R1a). Within the growth hormone (GH) axis, the biological activity of ghrelin requires octanoylation by ghrelin-O-acyltransferase (GOAT), conferring selective binding to the GHS-R1a receptor via acylated ghrelin. Complete loss of preproghrelin-derived signalling (through deletion of the Ghrl gene) contributes to a decline in peak GH release, however, the selective contribution of endogenous acyl-ghrelin to pulsatile GH release remains to be established. We assessed the pulsatile release of GH in ad libitum fed male germline goat(-/-) mice, extending measures to include mRNA for key hypothalamic regulators of GH release, and peripheral factors that are modulated relative to GH release. The amount of GH released was reduced in young goat(-/-) mice when compared to age-matched wild-type (WT) mice, whereas pulse frequency and irregularity increased. Altered GH release did not coincide with alterations in hypothalamic Ghrh, Srif, Npy or Ghsr mRNA expression, or pituitary GH content, suggesting that loss of Goat does not compromise canonical mechanisms that contribute to pituitary GH production and release. While loss of Goat resulted in an irregular pattern of GH release (characterised by an increase in the number of GH pulses observed during extended secretory events), this did not contribute to a change in the expression of sexually dimorphic GH-dependent liver genes. Of interest, circulating levels of IGF-1 were elevated in goat(-/-) mice. This rise in circulating levels of IGF-1 was correlated with an increase in GH pulse frequency, suggesting that sustained or increased IGF-1 release in goat(-/-) mice may occur in response to altered GH release patterning. Our observations demonstrate that germline loss of Goat alters GH release and patterning. While the biological relevance of altered GH secretory patterning remains unclear, we propose that this may contribute to sustained IGF-1 release and growth in goat(-/-) mice. This article is protected by copyright. All rights reserved.
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Publication type Article: Journal article
Document type Scientific Article
Keywords Ghrh ; Ghrelin-o-acyltransferase (goat) ; Ghrelin; Igf-1 ; Pulsatile Growth Hormone Secretion ; Somatostatin
Language english
Publication Year 2015
HGF-reported in Year 2015
ISSN (print) / ISBN 0953-8194
e-ISSN 1365-2826
Quellenangaben Volume: 27, Issue: 12, Pages: 872-886 Article Number: , Supplement: ,
Publisher Blackwell
Publishing Place Oxford
Reviewing status Peer reviewed
Institute(s) Institute of Diabetes and Obesity (IDO)
Institute of Pancreatic Islet Research (IPI)
POF-Topic(s) 30201 - Metabolic Health
90000 - German Center for Diabetes Research
Research field(s) Helmholtz Diabetes Center
PSP Element(s) G-502200-001
G-502600-005
PubMed ID 26442444
Scopus ID 84947923794
Erfassungsdatum 2015-12-09