Early-age heat exposure affects skeletal muscle satellite cell proliferation and differentiation in chicks.
Exposure of young chicks to thermal conditioning (TC; i.e., 37 degrees C for 24 h) resulted in significantly improved body and muscle growth at a later age. We hypothesized that TC causes an increase in satellite cell proliferation, necessary for further muscle hypertrophy. An immediate increase was observed in satellite cell DNA synthesis in culture and in vivo in response to TC of 3-day-old chicks to levels that were significantly higher than those of control chicks. This was accompanied by a marked induction of insulin-like growth factor-I (IFG-I), but not hepatocyte growth factor in the breast muscle. No significant difference between treatments in plasma IGF-I levels was observed. A marked elevation in muscle regulatory factors on day 5, followed by a decline in cell proliferation on day 6 together with continuous high levels of IGF-I in the TC chick muscle may indicate accelerated cell differentiation. These data suggest a central role for IGF-I in the immediate stimulation of satellite cell myogenic processes in response to heat exposure.
Halevy
O
O
Department of Animal Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel. halevyo@agri.huji.ac.il
Krispin
A
A
Leshem
Y
Y
McMurtry
J P
JP
Yahav
S
S
D000367:Age Factors; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002645:Chickens; D004268:DNA-Binding Proteins / Q000378:metabolism; D018882:Heat Stress Disorders / Q000378:metabolism*; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D064326:MEF2 Transcription Factors; D008297:Male; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D018006:Myogenic Regulatory Factors; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors; D018809:Proliferating Cell Nuclear Antigen; D014157:Transcription Factors; D017228:Hepatocyte Growth Factor; D007334:Insulin-Like Growth Factor I