Increased mass of slow-type skeletal muscles and depressed myostatin gene expression in cold-tolerant chicks.
Temperature is maintained in birds by skeletal muscle shivering as well as by non-shivering thermogenesis in a cold environment because they lack brown adipose tissue, which is a mammalian thermogenic organ. Chicks acquire cold tolerance after their skeletal muscles mature. Here, we found that muscle fibers transformed to the slow-twitch type with increasing gene expression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), and that the mass increased with decreasing myostatin gene expression, in the leg muscles of 7-day-old and younger chicks within 24 h of cold exposure. Muscle fibers did not transform and the mass did not increase within 24 h of cold exposure in muscles from chicks older than 8 days of age. Myostatin mRNA expression remained depressed in cold-tolerant muscles for 24 h, whereas cold-enhanced growth of the muscle continued for 48 h. Myostatin expression was depressed and muscle mass was increased only in chick leg muscles that comprised both fast- and slow-twitch fibers. These results suggest that the acute regulation of PGC-1alpha and myostatin gene expression in leg muscles is required for chicks to acquire cold tolerance up to 7 days of age.
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki, Japan.
Daichi
D
Ijiri
Moe
M
Miura
Yukio
Y
Kanai
Miho
M
Hirabayashi
D000222:Adaptation, Physiological; D000818:Animals; D002645:Chickens / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D005786:Gene Expression Regulation / Q000502:physiology; D006614:Hindlimb; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism*; D055435:Myostatin / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D055435:Myostatin; D014157:Transcription Factors