title: Selective regulation of myofiber differentiation by energy status during postnatal development.
abstract: The role of energy status in postnatal regulation of porcine skeletal muscle development has been determined in littermate animals kept for 3-4 wk on a high (H) or low (L) energy intake (H = 2L), at a thermally neutral [26 degrees C (26H and 26L, respectively)] or low [10 degrees C (10H and 10L, respectively)] environmental temperature. A variety of skeletal muscles was assessed at 7 wk of age for changes in myofiber hypertrophy and differentiation. In contrast with findings in adult humans and rats, there was no selective preservation of type I slow-oxidative fiber size during energy restriction. However, differentiation between mature skeletal myosin heavy-chain isoforms was markedly affected by energy status, and in rhomboideus there were particularly striking effects of both nutrition and temperature: proportions of type I fibers from the four groups 26H, 26L, 10H, and 10L were 34 +/- 2, 50 +/- 4, 73 +/- 2, and 72 +/- 3 (P < 0.005 for diet at 26 degrees C; P < 0.001 for temperature). These changes may have been induced by alterations in both thyroid status and contractile activity. They support the hypothesis of a key role for rhomboideus muscle in thermoregulation and demonstrate the plasticity of skeletal muscle differentiation to environmental change during postnatal life.
authors.affiliation: Department of Cellular Physiology, Babraham Institute, Cambridge, United Kingdom.
authors.forename: A P
authors.initials: AP
authors.lastname: Harrison
authors.forename: A M
authors.initials: AM
authors.lastname: Rowlerson
authors.forename: M J
authors.initials: MJ
authors.lastname: Dauncey
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D002454:Cell Differentiation / Q000502:physiology; D004734:Energy Metabolism; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000502:physiology*; D018482:Muscle, Skeletal / Q000254:growth & development*; D051381:Rats; D013552:Swine