Effect of 48-h food deprivation on the expressions of myosin heavy-chain isoforms and fiber type-related factors in rats.
The primary aim of this study was to examine the effects of 48-h food deprivation on rat skeletal muscle fiber type, according to myosin heavy-chain (MyHC) isoform composition and some metabolism-related factors in both slow-type dominant and fast-type dominant muscle tissues. Male Wistar rats (7 wk old) were treated with 48-h food deprivation or ad libitum feeding as control. After the treatment, the soleus muscle (slow-type dominant) and the extensor digitorum longus (EDL, fast-type dominant) were excised. We found that 48-h food deprivation did not affect MyHC composition in either the soleus or EDL, compared with fed rats by electrophoretic separation of MyHC isoforms. However, 48-h food deprivation significantly increased the mRNA expression of fast-type MyHC2B in the EDL muscle. Moreover, food deprivation increased fatty acid metabolism, as shown by elevated levels of related serum energy substrates and mRNA expression of mitochondrial uncoupling protein (UCP) 3 and lipoprotein lipase (LPL) in both the soleus and EDL. UCP3 and LPL are generally expressed at higher levels in slow-type fibers. Furthermore, we found that food deprivation significantly decreased the protein amounts of PGC1α and phosphorylated FOXO1, which are known as skeletal muscle fiber type regulators. In conclusion, 48-h food deprivation increased mRNA expression of fast-type MyHC isoform and oxidative metabolism-related factors in EDL, whereas MyHC composition at the protein level did not change in either the soleus or EDL.
Department of Bioresource Sciences, Graduate School of Agriculture, Kyushu University.
Wataru
W
Mizunoya
Shoko
S
Sawano
Yohei
Y
Iwamoto
Yusuke
Y
Sato
Ryuichi
R
Tatsumi
Yoshihide
Y
Ikeuchi
D000818:Animals; D005227:Fatty Acids / Q000378:metabolism*; D005508:Food Deprivation / Q000502:physiology*; D051858:Forkhead Transcription Factors / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D008071:Lipoprotein Lipase / Q000235:genetics / Q000378:metabolism; D008297:Male; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010084:Oxidation-Reduction; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000071247:Uncoupling Protein 3; D000071161:Forkhead Box Protein O1
D005227:Fatty Acids; D051858:Forkhead Transcription Factors; D007473:Ion Channels; D008071:Lipoprotein Lipase; D024101:Mitochondrial Proteins; D018995:Myosin Heavy Chains; D009419:Nerve Tissue Proteins; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D020033:Protein Isoforms; D012333:RNA, Messenger; D014157:Transcription Factors; D000071247:Uncoupling Protein 3; C501429:Ppargc1a protein, rat; C000604394:Ucp3 protein, rat; C074639:Foxo1 protein, rat; D000071161:Forkhead Box Protein O1