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BioMed Research International
Volume 2014 (2014), Article ID 923564, 7 pages
http://dx.doi.org/10.1155/2014/923564
Research Article

Intraportal Infusion of Ghrelin Could Inhibit Glucose-Stimulated GLP-1 Secretion by Enteric Neural Net in Wistar Rat

1Department of Endocrinology and Metabolism, The 4th Hospital Affiliated to Harbin Medical University, No. 37, Yiyuan Street, Harbin 150000, China
2Department of Endocrinology and Metabolism, The 2nd Hospital Affiliated to Harbin Medical University, No. 246, Xuefu Road, Harbin 150080, China
3Department of Laboratory Medicine, The 2nd Hospital Affiliated to Harbin Medical University, No. 246, Xuefu Road, Harbin 150080, China

Received 20 June 2014; Accepted 4 August 2014; Published 26 August 2014

Academic Editor: Flavia Prodam

Copyright © 2014 Xiyao Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

As a regulator of food intake and energy metabolism, the role of ghrelin in glucose metabolism is still not fully understood. In this study, we determined the in vivo effect of ghrelin on incretin effect. We demonstrated that ghrelin inhibited the glucose-stimulated release of glucagon-like peptide-1 (GLP-1) when infused into the portal vein of Wistar rat. Hepatic vagotomy diminished the inhibitory effect of ghrelin on glucose-stimulated GLP-1 secretion. In addition, phentolamine, a nonselective α receptor antagonist, could recover the decrease of GLP-1 release induced by ghrelin infusion. Pralmorelin (an artificial growth hormone release peptide) infusion into the portal vein could also inhibit the glucose-stimulated release of GLP-1. And growth hormone secretagogue receptor antagonist, [D-lys3]-GHRP-6, infusion showed comparable increases of glucose stimulated GLP-1 release compared to ghrelin infusion into the portal vein. The data showed that intraportal infusion of ghrelin exerted an inhibitory effect on GLP-1 secretion through growth hormone secretagogue receptor 1α (GHS1α receptor), which indicated that the downregulation of ghrelin secretion after food intake was necessary for incretin effect. Furthermore, our results suggested that the enteric neural net involved hepatic vagal nerve and sympathetic nerve mediated inhibition effect of ghrelin on incretin effect.