title: Feeding a DHA-enriched diet increases skeletal muscle protein synthesis in growing pigs: association with increased skeletal muscle insulin action and local mRNA expression of insulin-like growth factor 1.
abstract: Dietary n-3 PUFA have been demonstrated to promote muscle growth in growing animals. In the present study, fractional protein synthesis rates (FSR) in the skeletal muscle of growing pigs fed a DHA-enriched (DE) diet (DE treatment) or a soyabean oil (SO) diet (SO treatment) were evaluated in the fed and feed-deprived states. Feeding-induced increases in muscle FSR, as well as the activation of the mammalian target of rapamycin and protein kinase B, were higher in the DE treatment as indicated by the positive interaction between diet and feeding. In the fed state, the activation of eIF4E-binding protein 1 in the skeletal muscle of pigs on the DE diet was higher than that in pigs on the SO diet (P<0·05). Feeding the DE diet increased muscle insulin-like growth factor 1 (IGF-1) expression (P<0·05) and insulin action (as demonstrated by increased insulin receptor (IR) phosphorylation, P<0·05), resulting in increased IR substrate 1 activation in the fed state. However, no difference in plasma IGF-1 concentration or hepatic IGF-1 expression between the two treatments was associated. The increased IGF-1 expression in the DE treatment was associated with increased mRNA expression of the signal transducer and activator of transcription 5A and decreased mRNA expression of protein tyrosine phosphatase, non-receptor type 3 in skeletal muscle. Moreover, mRNA expression of protein tyrosine phosphatase, non-receptor type 1 (PTPN1), the activation of PTPN1 and the activation of NF-κB in muscle were significantly lower in the DE treatment (P<0·05). The results of the present study suggest that feeding a DE diet increased feeding-induced muscle protein synthesis in growing pigs, and muscle IGF-1 expression and insulin action were involved in this action.
authors: Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors: Hong-Kui
authors: HK
authors: Wei
authors: Yuanfei
authors: Y
authors: Zhou
authors: Shuzhong
authors: S
authors: Jiang
authors: Ya-Xiong
authors: YX
authors: Tao
authors: Haiqing
authors: H
authors: Sun
authors: Jian
authors: J
authors: Peng
authors: Siwen
authors: S
authors: Jiang
mesh_terms: D000821:Animal Feed; D000818:Animals; D003687:Dehydroepiandrosterone / Q000737:chemistry*; D004032:Diet; D015525:Fatty Acids, Omega-3 / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000378:metabolism; D013024:Soybean Oil; D013552:Swine; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D015525:Fatty Acids, Omega-3; D007328:Insulin; D016328:NF-kappa B; D012333:RNA, Messenger; D050799:STAT5 Transcription Factor; D003687:Dehydroepiandrosterone; D007334:Insulin-Like Growth Factor I; D013024:Soybean Oil; D011972:Receptor, Insulin; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases