title: Medium-chain triacylglycerol suppresses the decrease of plasma albumin level through the insulin-Akt-mTOR pathway in the livers of malnourished rats.
abstract: Recent studies have shown that medium-chain triacylglycerol (MCT) improved serum albumin concentration in elderly people with protein-energy malnutrition (PEM) and in malnourished rats. However, the mechanism for this effect has not been clarified. Dietary MCT promotes insulin secretion from the pancreas, and insulin activates mammalian target of rapamycin (mTOR) complex 1 (mTORC1) via the activation of phosphoinositide 3-kinase (PI3K) and its downstream effecter, Akt. mTORC1 promotes mRNA translation through S6K and 4E-BP1. Therefore, we hypothesized that dietary MCT elevates albumin synthesis through promotion of insulin-Akt-mTOR transduction in the liver. To test this hypothesis, we measured phosphorylated Akt, mTOR and albumin in the livers of malnourished rats. In the present study we examined rats fed low-protein diets containing either MCT or long-chain triacylglycerol (LCT) with energy restriction. The plasma and liver albumin levels were significantly higher in the MCT-fed group than in the LCT-fed group. In addition, plasma insulin concentration, liver phosphorylated Akt/Akt and phosphorylated mTOR/mTOR levels were significantly higher in the MCT-fed group than in the LCT-fed group. These results suggest that one of the mechanisms for the albumin improvement effect of dietary MCT is the promotion of albumin synthesis through the insulin-Akt-mTOR signaling pathway of the liver.
authors.affiliation: Central Research Laboratory, The Nisshin OilliO Group, Ltd., 1 Shinmei-cho, Yokosuka, Kanagawa, Japan. se-sekine@nisshin-oillio.com
authors.forename: Seiji
authors.initials: S
authors.lastname: Sekine
authors.forename: Shin
authors.initials: S
authors.lastname: Terada
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Aoyama
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018753:Diet, Protein-Restricted; D002149:Energy Intake; D007328:Insulin / Q000097:blood*; D047908:Intracellular Signaling Peptides and Proteins; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects; D009929:Organ Size / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011502:Protein-Energy Malnutrition / Q000188:drug therapy; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism; D012709:Serum Albumin / Q000096:biosynthesis*; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014280:Triglycerides / Q000097:blood / Q000494:pharmacology*
chemical_list: D002352:Carrier Proteins; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D019893:Ribosomal Protein S6 Kinases; D012709:Serum Albumin; D058570:TOR Serine-Threonine Kinases; D014280:Triglycerides; C499526:Eif4ebp1 protein, rat; C526901:Rps6kb1 protein, rat