title: Cold exposure increases slow-type myosin heavy chain 1 (MyHC1) composition of soleus muscle in rats.
abstract: The aim of this study was to examine the effects of cold exposure on rat skeletal muscle fiber type, according to myosin heavy chain (MyHC) isoform and metabolism-related factors. Male Wistar rats (7 weeks old) were housed individually at 4 ± 2°C as a cold-exposed group or at room temperature (22 ± 2°C) as a control group for 4 weeks. We found that cold exposure significantly increased the slow-type MyHC1 content in the soleus muscle (a typical slow-type fiber), while the intermediate-type MyHC2A content was significantly decreased. In contrast to soleus, MyHC composition of extensor digitorum longus (EDL, a typical fast-type fiber) and gastrocnemius (a mix of slow-type and fast-type fibers) muscle did not change from cold exposure. Cold exposure increased mRNA expression of mitochondrial uncoupling protein 3 (UCP3) in both the soleus and EDL. Cold exposure also increased mRNA expression of myoglobin, peroxisome proliferator-activated receptor gamma coactivator 1α (PGC1α) and forkhead box O1 (FOXO1) in the soleus. Upregulation of UCP3 and PGC1α proteins were observed with Western blotting in the gastrocnemius. Thus, cold exposure increased metabolism-related factors in all muscle types that were tested, but MyHC isoforms changed only in the soleus.
authors.affiliation: Department of Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Fukuoka, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Mizunoya
authors.forename: Yohei
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sato
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Tatsumi
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Ikeuchi
mesh_terms: D000818:Animals; D003080:Cold Temperature; D008297:Male; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000737:chemistry*; D018995:Myosin Heavy Chains / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D018995:Myosin Heavy Chains
keywords: Wistar rat; cold exposure; fiber type; metabolism; skeletal muscle