Peer-Reviewed Journal Details
Mandatory Fields
McAllan L, Speakman JR, Cryan JF, Nilaweera KN
The British journal of nutrition
Whey protein isolate decreases murine stomach weight and intestinal length and alters the expression of Wnt signalling-associated genes.
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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<񁖜5); 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<񁖜5). WPI intake reduced the gastric expression of Wingless/int-1 5a (Wnt5a) (P<񁖜1) and frizzled 4 (Fzd4) (P<񁖜1), 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<񁖜1) and caused a trend towards an increase in the expression of Fzd4 (P=񁖜94), 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<񁖜1) and fatty acid transporter protein 4 (P<񁖜5), and decreased duodenal mRNA expression of the insulin receptor (P=񁖜5), with a trend towards a decreased expression of Na-glucose co-transporter 1 (P=񁖜7). 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.
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