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Whey protein isolate decreases murine stomach weight and intestinal length and alters the expression of Wnt signalling-associated genes

By Liam McAllan, John R. Speakman, John F. Cryan and Kanishka N. Nilaweera

Abstract

peer-reviewedK. N. N. was supported by the Teagasc Vision Programme on Obesity (RMIS5974). L. M. was supported by the Teagasc Walsh Fellowship. J. R. S.was supported by a 1000-talents professorship from the Chinese government.The present study examined the underlying mechanisms by which whey protein isolate (WPI) affects energy balance. C57BL/6J mice were fed a diet containing 10 % energy from fat, 70 % energy from carbohydrate (35 % energy from sucrose) and 20 % energy from casein or WPI for 15 weeks. Mice fed with WPI had reduced weight gain, cumulative energy intake and dark-phase VO2 compared with casein-fed mice (P< 0·05); however, WPI intake had no significant effects on body composition, meal size/number, water intake or RER. Plasma levels of insulin, TAG, leptin, glucose and glucagon-like peptide 1 remained unchanged. Notably, the intake of WPI reduced stomach weight and both length and weight of the small intestine (P< 0·05). WPI intake reduced the gastric expression of Wingless/int-1 5a (Wnt5a) (P< 0·01) and frizzled 4 (Fzd4) (P< 0·01), with no change in the expression of receptor tyrosine kinase-like orphan receptor 2 (Ror2) and LDL receptor-related protein 5 (Lrp5). In the ileum, WPI increased the mRNA expression of Wnt5a (P< 0·01) and caused a trend towards an increase in the expression of Fzd4 (P= 0·094), with no change in the expression of Ror2 and Lrp5. These genes were unresponsive in the duodenum. Among the nutrient-responsive genes, WPI specifically reduced ileal mRNA expression of peptide YY (P< 0·01) and fatty acid transporter protein 4 (P< 0·05), and decreased duodenal mRNA expression of the insulin receptor (P= 0·05), with a trend towards a decreased expression of Na–glucose co-transporter 1 (P= 0·07). The effects of WPI on gastrointestinal Wnt signalling may explain how this protein affects gastrointestinal structure and function and, in turn, energy intake and balance.Teagasc Vision ProgrammeTeagasc Walsh Fellowship Programm

Topics: Whey proteins, Stomach, Intestine, Energy Intake
Publisher: Cambridge University Press
Year: 2015
DOI identifier: 10.1017/S0007114514004024
OAI identifier: oai:t-stor.teagasc.ie:11019/777
Provided by: T-Stór
Journal:

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