title: PGC-1α and FOXO1 mRNA levels and fiber characteristics of the soleus and plantaris muscles in rats after hindlimb unloading.
abstract: Fifteen-week-old rats were subjected to unloading induced by hindlimb suspension for 3 weeks. The peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and forkhead box-containing protein O1 (FOXO1) mRNA levels and fiber profiles of the soleus and plantaris muscles in rats subjected to unloading (unloaded group) were determined and compared with those of age-matched control rats (control group). The body weight and both the soleus and plantaris muscle weights were lower in the unloaded group than in the control group. The PGC-1α mRNA was downregulated in the soleus, but not in the plantaris muscle of the unloaded group. The FOXO1 mRNA was upregulated in both the soleus and plantaris muscles of the unloaded group. The oxidative enzyme activity was reduced in the soleus, but not in the plantaris muscle of the unloaded group. The percentage of type I fibers was decreased and the percentages of type IIA and IIC fibers were increased in the soleus muscle of the unloaded group, whereas there was no change in fiber type distribution in the plantaris muscle of the unloaded group. Atrophy of all types of fibers was observed in both the soleus and plantaris muscles of the unloaded group. We conclude that decreased oxidative capacity and fiber atrophy in unloaded skeletal muscles are associated with decreased PGC-1α and increased FOXO1 mRNA levels.
authors.affiliation: Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Fumiko
authors.initials: F
authors.lastname: Nagatomo
authors.forename: Hidemi
authors.initials: H
authors.lastname: Fujino
authors.forename: Hiroyo
authors.initials: H
authors.lastname: Kondo
authors.forename: Hideki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Motoki
authors.initials: M
authors.lastname: Kouzaki
authors.forename: Isao
authors.initials: I
authors.lastname: Takeda
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ishihara
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics*; D005786:Gene Expression Regulation; D019417:Hindlimb Suspension; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism* / Q000473:pathology; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism* / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009133:Muscular Atrophy / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009929:Organ Size; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics*; D051381:Rats; D011916:Rats, Inbred F344; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics*; D000071161:Forkhead Box Protein O1
chemical_list: D000251:Adenosine Triphosphatases; D051858:Forkhead Transcription Factors; D009419:Nerve Tissue Proteins; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D013385:Succinate Dehydrogenase; D014157:Transcription Factors; C501429:Ppargc1a protein, rat; C074639:Foxo1 protein, rat; D000071161:Forkhead Box Protein O1