Dietary fish oil inhibits the early stage of recovery of atrophied soleus muscle in rats via Akt-p70s6k signaling and PGF2α.
Skeletal muscle recovery from disuse atrophy requires the recruitment of insulin signaling for muscle growth, which is driven by protein synthesis. Dietary fish oil, which is rich in long-chain n-3 polyunsaturated fatty acids, is known to enhance insulin signaling and protein metabolism. Therefore, this study was performed to evaluate whether dietary fish oil facilitates muscle recovery during remobilization after disuse atrophy. Ten days of immobilization, followed by 3 or 13 days of remobilization, were applied to the hindlimbs of rats fed corn oil [corn oil diet group as control (CO)] or fish oil [fish oil diet group (FO)] as source of dietary fat. The immobilization-induced reductions in soleus muscle weight and myosin heavy-chain content were significantly restored by 3 days of remobilization in CO. However, in FO, these muscle recovery measurements did not significantly change until 13 days of remobilization. At 3 days of remobilization, both groups had significant elevations in p70 ribosomal S6 kinase (p70s6k) activation and at a greater extent in CO than in FO. The activation of Akt was also increased on Day 3, but it was not significant in FO. Throughout the remobilization period, levels of prostaglandin F2α (PGF2α) and cyclooxygenase-2 mRNA were significantly augmented. However, FO had a lesser increase in PGF2α than CO until Day 13. These findings indicate that dietary fish oil inhibits the early stage of soleus muscle recovery after disuse atrophy by suppressing the activation of Akt-p70s6k signaling and PGF2α synthesis.
You
Jae-Sung
JS
Department of Food and Nutrition, Research Institute of Human Ecology, Seoul National University, Seoul 151-742, Republic of Korea.
Park
Mi-Na
MN
Lee
Yeon-Sook
YS
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D015237:Dinoprost / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005395:Fish Oils / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D019417:Hindlimb Suspension; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009133:Muscular Atrophy / Q000188:drug therapy*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism*
D017931:DNA Primers; D004042:Dietary Fats, Unsaturated; D005395:Fish Oils; D015237:Dinoprost; D051057:Proto-Oncogene Proteins c-akt; D019893:Ribosomal Protein S6 Kinases