title: Changes in triacylglycerol-accumulated fiber type, fiber type composition, and biogenesis in the mitochondria of the soleus muscle in obese rats.
abstract: Little is known about the effects of obesity on skeletal muscle consisting of approximately 80% type I (slow) fibers, such as that in the soleus muscle, although type I fibers have an enhanced capacity for mitochondrial respiration and fatty acid oxidation. We investigated the effects of obesity on the soleus muscle in the rat. Rats were fed a high-fat diet (protein:fat:carbohydrate = 20:57:23; 508 kcal/100 g) or a control diet (protein:fat:carbohydrate = 20:10:70; 366 kcal/100 g) for 10 weeks. We analyzed the accumulation of intramyocellular triacylglycerol (IMTG), fiber type composition, and the biogenesis and function of the mitochondria in the soleus muscle of the rat during 10 weeks of feeding, using histochemical and real-time polymerase chain reaction analyses. Obesity increased body weight and markedly elevated IMTG levels in type I, but not in type II, fibers of the soleus muscle throughout the feeding period. Obesity also inhibited the biogenesis and function in the mitochondria and altered the fiber type composition in the soleus muscle. The suppression of biogenesis and function in the mitochondria, and the alteration in the fiber type composition may be attributable to the marked IMTG accumulation in the soleus muscle of the rat.
authors.affiliation: Department of Geriatric Dentistry, Tsurumi University School of Dental Medicine, Yokohama, Japan.
authors.forename: Syuhei
authors.initials: S
authors.lastname: Kaneko
authors.forename: Ryo-Hei
authors.initials: RH
authors.lastname: Iida
authors.forename: Takeo
authors.initials: T
authors.lastname: Suga
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Fukui
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Morito
authors.forename: Akira
authors.initials: A
authors.lastname: Yamane
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism* / Q000473:pathology; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000473:pathology; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism* / Q000473:pathology; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D009765:Obesity / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013194:Staining and Labeling; D013997:Time Factors; D014280:Triglycerides / Q000378:metabolism*; D015430:Weight Gain
chemical_list: D024101:Mitochondrial Proteins; D009124:Muscle Proteins; D014280:Triglycerides