Enteral delivery of proteins stimulates protein synthesis in human duodenal mucosa in the fed state through a mammalian target of rapamycin–independent pathway  

Oleh:

Coeffier, Moise ; Claeyssens, Sophie ; Bole-Feyso, Christine ; Guerin, Charlene

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: The American Journal of Clinical Nutrition vol. 97 no. 02 (Feb. 2013), page 286-294.
Topik: Glutamine; Protein metabolism

Ketersediaan

Perpustakaan FK Nomor Panggil: A07.K.2013.01 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

Background: Glutamine modulates duodenal protein metabolism in fasted healthy humans, but its effects in a fed state remain unknown. Objective: We aimed to assess the effects of either glutamine or an isonitrogenous protein mixture on duodenal protein metabolism in humans in the fed state. Design: Twenty-four healthy volunteers were randomly included in 2 groups. Each volunteer was studied on 2 occasions in a random order and received, during 5 h, either an enteral infusion of maltodextrins alone (0.25 g · kg-1 · h-1; both groups) that mimicked a carbohydrate fed state or maltodextrins with glutamine (group 1) or an isonitrogenous (22.4 mg N · kg-1 · h-1) protein powder (group 2). Simultaneously, a continuous intravenous infusion of 13C-leucine and 2H5-phenylalanine (both 9 µmol · kg-1 · h-1) was performed. Endoscopic duodenal biopsies were taken. Leucine and phenylalanine enrichments were assessed by using gas chromatography–mass spectrometry in duodenal proteins and the intracellular free amino acids pool to calculate the mucosal fractional synthesis rate (FSR). Proteasome proteolytic activities and phosphokinase expression were assessed by using specific fluorogenic substrates and macroarrays, respectively. Results: The FSR and proteasome activity were not different after the glutamine supply compared with after maltodextrins alone. In contrast, the FSR increased (1.7-fold increase; P < 0.05) after protein-powder delivery without modification of total proteasome activity. The protein powder increased insulinemia, PI3 kinase, and erk phosphorylation but did not affect the mammalian target of rapamycin (mTOR) pathway and mitogen-activated protein kinase signal-integrating kinase 1 phosphorylation. A trend for an increase of eukaryotic translation initiation factor 4E phosphorylation was observed (P = 0.07). Conclusion: In the carbohydrate fed state, enteral proteins but not glutamine increased duodenal protein synthesis through an mTOR independent pathway in humans.

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