Possible roles of myostatin and PGC-1alpha in the increase of skeletal muscle and transformation of fiber type in cold-exposed chicks: expression of myostatin and PGC-1alpha in chicks exposed to cold.
This study examined the hypothesis that myostatin and PGC-1alpha are involved in the increase in skeletal muscle mass and transformation of fiber type in cold-exposed chicks. One-week-old chicks were exposed to acute (24h) or long-term (8d) cold at 4 degrees C or kept warm at 30 degrees C. Acute cold exposure induced a significant increase in the skeletal muscle weight and the ratio of slow- to fast-fiber specific troponin I expression (sTnI/fTnI), accompanied by a significant decrease in lactate dehydrogenase activity. Expression of myostatin mRNA in the muscle was significantly lower in cold-exposed chicks than in the controls, whereas PGC-1alpha mRNA expression was significantly enhanced. These changes in the gene expression rapidly returned to the levels of the control chicks after the end of cold exposure, whereas the changes in fiber type and enzymatic activity were not resumed within 24h after removal of cold exposure. On the other hand, long-term exposure to cold resulted in a remarkable increase in skeletal muscle weight, accompanied by a significant increase in the ratio of sTnI/fTnI and the enzymatic activities of cytochrome oxidase and lactate dehydrogenase. However, the expression level of myostatin mRNA in cold-exposed chicks was not different from that in their age-matched control chicks and that of PGC-1alpha mRNA was significantly lower than in the controls. These results indicate that myostatin and PGC-1alpha expression in the skeletal muscle rapidly change in response to acute cold, suggesting the possibility that these two genes could be involved in the increase in muscle mass and transformation of fiber type, respectively, at the initial stage of adaptation in cold-exposed chicks.
Graduate School of Life and Environmental Science, University of Tsukuba, Tsukuba-shi, Ibaraki, Japan.
Daichi
D
Ijiri
Yukio
Y
Kanai
Miho
M
Hirabayashi
D000818:Animals; D002645:Chickens / Q000254:growth & development*; D003080:Cold Temperature; D015870:Gene Expression; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology; D018482:Muscle, Skeletal / Q000737:chemistry / Q000254:growth & development*; D055435:Myostatin / Q000235:genetics / Q000502:physiology*; D009929:Organ Size; D012333:RNA, Messenger / Q000032:analysis; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
D055435:Myostatin; D012333:RNA, Messenger; D014157:Transcription Factors; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1