The impact of whey protein isolate on energy balance regulation

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dc.contributor.advisor Cryan, John F. en
dc.contributor.advisor Nilaweera, Kanishka N. en McAllan, Liam 2015-10-23T08:41:07Z 2015-10-23T08:41:07Z 2014 2014
dc.identifier.citation McAllan, L. 2014. The impact of whey protein isolate on energy balance regulation. PhD Thesis, University College Cork. en
dc.identifier.endpage 301
dc.description.abstract Using C57BL/6J mice fed whey protein isolate (WPI) enriched high fat (HFD) or low-fat diets (LFD), this study tested the hypothesis that WPI directly impacts on adiposity by influencing lipid metabolism. WPI suppressed HFD-induced body fat and increased lean mass at 8 weeks of dietary challenge despite elevated plasma triacylglycerol (TAG) levels, suggesting reduced TAG storage. WPI reduced HFD-associated hypothalamic leptin and insulin receptor (IR) mRNA expression, and prevented HFD-associated reductions in adipose tissue IR and glucose transporter 4 expression. These effects were largely absent at 21 weeks of HFD feeding, however WPI increased lean mass and cause a trend towards decreased fat mass, with notable increased Lactobacillus and decreased Clostridium gut bacterial species. Increasing the protein to carbohydrate ratio enhanced the above effects, and shifted the gut microbiota composition away from the HFD group. Seven weeks of WPI intake with a LFD decreased insulin signalling gene expression in the adipose tissue in association with an increased fat accumulation. WPI reduced intestinal weight and length, suggesting a potential functional relationship between WPI, gastro-intestinal morphology and insulin related signalling in the adipose. Extending the study to 15 weeks, did not affect adipose fat weight, but decreased energy intake, weight gain and intestinal length. The functionality of protein sensing lysophosphatidic acid receptor 5 (LPA5) in 3T3-L1 pre-adipocytes was assessed. Over-expression of the receptor in 3T3-L1 pre-adipocytes provided a growth advantage to the cells and suppressed cellular differentiation into mature fat cells. In conclusion, the data demonstrates WPI impacts on adiposity by influencing lipid metabolism in a temporal manner, resulting possibly due to changes in lean mass, hypothalamic and adipose gene expression, gut microbiota and gastrointestinal morphology. The data also showed LPA5 is a novel candidate in regulating of preadipocyte growth and differentiation, and may mediate dietary protein effects on adipose tissue. en
dc.description.sponsorship Teagasc (Walsh Fellowship) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2014, Liam McAllan. en
dc.rights.uri en
dc.subject Whey protein isolate en
dc.subject Adiposity en
dc.subject Obesity en
dc.subject Mice en
dc.subject Lipid metabolism en
dc.subject Energy balance en
dc.subject Gene expression en
dc.title The impact of whey protein isolate on energy balance regulation en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD (Medicine and Health) en
dc.internal.availability Full text available en No embargo required en
dc.description.version Accepted Version
dc.contributor.funder Teagasc en
dc.description.status Not peer reviewed en Medicine en Pharmacology and Therapeutics en
dc.check.type No Embargo Required
dc.check.reason No embargo required en
dc.check.opt-out Not applicable en
dc.thesis.opt-out false
dc.check.embargoformat Not applicable en
dc.internal.conferring Spring Conferring 2015

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© 2014, Liam McAllan. Except where otherwise noted, this item's license is described as © 2014, Liam McAllan.
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