title: Aging alters the reduction of pro-apoptotic signaling in response to loading-induced hypertrophy.
abstract: This study tested the hypothesis that loading decreased apoptosis in skeletal muscle in an aging-dependent fashion. One wing of young and aged Japanese quails was loaded for 7 or 21 days to induce hypertrophy. The contralateral wing served as the intra-animal control. Loading increased fast-twitch quail patagialis muscle mass by 28 and 49%, after 7 or 21 days of loading, respectively in young adult birds. Muscle mass was not elevated after 7 days of loading, but increased by 29% after 21 days of loading in aged birds. Seven days of loading reduced DNA fragmentation and cytosolic accumulation of cytochrome c in muscles from young birds but not in muscles from aged birds. ARC protein content was lower and H2O2 content was higher in muscles from aged birds following 7 days of loading. The mitochondria-free cytosolic protein fraction from muscles loaded for 7 days had 41 and 29% lower AIF content than control muscles in young and aged birds, respectively. XIAP, an apoptotic suppressor protein increased after 7 days of loading in muscles from young adult but not aged birds. Our results suggest that loading suppresses pro-apoptotic signaling in quail muscle but aging delays or attenuates these anti-apoptotic changes.
authors.affiliation: Division of Exercise Physiology, Laboratory of Muscle Biology and Sarcopenia, School of Medicine, West Virginia University, Robert C. Byrd Health Sciences Center, Morgantown, WV 26506-9227, USA.
authors.forename: Parco M
authors.initials: PM
authors.lastname: Siu
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Alway
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D017209:Apoptosis; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis; D003370:Coturnix; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D006984:Hypertrophy; D020287:In Situ Nick-End Labeling; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D015398:Signal Transduction / Q000502:physiology*; D013997:Time Factors; D016474:Weight-Bearing; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism
chemical_list: D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D015415:Biomarkers; D051636:X-Linked Inhibitor of Apoptosis Protein; D045304:Cytochromes c; D006861:Hydrogen Peroxide