Impact des peptides gastro-intestinaux dans la pathogénèse de l'obésité

Authors: Miegueu, Pierre
Advisor: Cianflone, Katherine M.
Abstract: While central effects of gastrointestinal peptides (GP) on the regulation of food intake have been described, their peripheral effects, specifically on fat tissue are not well known. The aim of the five studies presented in this thesis was to investigate the impact of seven GP on the modulation of adipose tissue. In the first study, I showed that desacyl ghrelin, obestatin and acyl ghrelin variably affect 3T3-L1 cells. Only desacyl ghrelin (DAG) stimulates proliferation, adipogenesis and lipogenesis. I demonstrated that the DAG-signalling pathway implicates GHSR-1/PLC/PI3K. In a second study, I showed that motilin stimulated triglyceride synthesis, stimulated fatty acid uptake and up-regulated mRNA of PPARγ2, C/EBPα, CD36, FABP4 and DGAT1 in adipocytes. The inhibition of the motilin receptor significantly impaired motilin-stimulated fatty acid uptake in 3T3-L1 adipocytes. In a third study, I identified for the first time the presence of the secretin receptor in fat cells and showed that secretin stimulated both lipogenesis and lipolysis in mature adipocytes, enhancing substrate cycling. In a fourth study, I determined that substance P reduced fatty acid uptake, down regulated mRNA expression of IRS-1, GLU4, PPARγ2, C/EBPα, FABP4 and DGAT1, and stimulated pro-inflammatory adipocytokine secretion. Finally, in a fifth study I showed that, in addition to stimulating preadipocyte proliferation and adipogenesis, amylin has an additive effect to insulin on fatty acid uptake. Together, these studies show an important contribution of GP in the pathogenesis of obesity and highlight the direct effects of gastrointestinal peptide on modulation of adipose tissue.
Document Type: Thèse de doctorat
Issue Date: 2012
Open Access Date: 19 April 2018
Grantor: Université Laval
Collection:Thèses et mémoires

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