title: Whey protein isolate decreases murine stomach weight and intestinal length and alters the expression of Wnt signalling-associated genes.
abstract: 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.
authors.affiliation: Teagasc, Moorepark Food Research Centre, Fermoy,County Cork,Republic of Ireland.
authors.forename: Liam
authors.initials: L
authors.lastname: McAllan
authors.affiliation: State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences,Beijing,People's Republic of China.
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
authors.affiliation: Department of Anatomy and Neuroscience,University College Cork,Cork,Republic of Ireland.
authors.forename: John F
authors.initials: JF
authors.lastname: Cryan
authors.affiliation: Teagasc, Moorepark Food Research Centre, Fermoy,County Cork,Republic of Ireland.
authors.forename: Kanishka N
authors.initials: KN
authors.lastname: Nilaweera
mesh_terms: D050154:Adiposity; D000818:Animals; D002417:Cattle; D018752:Diet, Fat-Restricted / Q000191:economics; D004386:Duodenum / Q000254:growth & development / Q000378:metabolism* / Q000473:pathology; D002149:Energy Intake; D005525:Food-Processing Industry / Q000191:economics; D005753:Gastric Mucosa / Q000378:metabolism*; D005786:Gene Expression Regulation; D007082:Ileum / Q000254:growth & development / Q000378:metabolism* / Q000473:pathology; D007220:Industrial Waste / Q000032:analysis / Q000191:economics; D007494:Ireland; D008297:Male; D008810:Mice, Inbred C57BL; D009929:Organ Size; D009928:Organ Specificity; D050177:Overweight / Q000097:blood / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D010101:Oxygen Consumption; D013270:Stomach / Q000254:growth & development / Q000473:pathology; D013997:Time Factors; D015430:Weight Gain; D000067816:Whey Proteins / Q000191:economics / Q000378:metabolism / Q000627:therapeutic use*; D060449:Wnt Signaling Pathway
chemical_list: D007220:Industrial Waste; D000067816:Whey Proteins
keywords: Energy intake; Intestine; Stomach; Whey proteins