title: Muscle-specificity of age-related changes in markers of autophagy and sphingolipid metabolism.
abstract: Our previous findings indicate that the gastrocnemius muscle of aging rats exhibits impairments of muscle quality (force/unit muscle tissue) and autophagy and increased sarcoplasmic reticulum stress. The purpose of this study was to examine age-related changes in soleus muscle contractility and in markers of autophagy in the soleus and gastrocnemius muscles. We assessed in situ muscle force and size in the soleus muscle of adult (7-8 months) and aged (24-26 months) male, F344/BN rats. We used immunoblotting to compare abundance of markers of autophagy, sarcoplasmic reticulum (SR) stress and sphingolipid metabolism in the soleus and medial gastrocnemius (MG) muscles of these animals. Relative to adults, aged rats maintained soleus muscle quality and increased muscle size, resulting in increased tetanic force production. Immunoblotting revealed a general pattern of an age-related reduction of basal autophagy, despite increases in indicators of SR stress and upstream autophagic pathway activation in the MG. The MG also exhibited changes in markers of sphingolipid metabolism suggestive of increased muscle ceramide. Minimal age-related changes were observed in the soleus. The soleus maintains muscle mass and quality with age, and exhibits fewer age-related changes in markers of stress and autophagy than the MG. Based on these data, we suggest that maintenance of autophagy may preserve muscle quality by preventing excessive SR stress.
authors: Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation & Communication Sciences, Ohio University, W279 Grover Center, Athens, OH, 45701, USA. russd@ohio.edu.|Ohio Musculoskeletal & Neurological Institute (OMNI), Heritage College of Osteopathic Medicine, Athens, OH, USA. russd@ohio.edu.
authors: David W
authors: DW
authors: Russ
authors: Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation & Communication Sciences, Ohio University, W279 Grover Center, Athens, OH, 45701, USA.
authors: Iva M
authors: IM
authors: Boyd
authors: Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation & Communication Sciences, Ohio University, W279 Grover Center, Athens, OH, 45701, USA.
authors: Katherine M
authors: KM
authors: McCoy
authors: Laboratory for Integrative Muscle Biology, Division of Physical Therapy, School of Rehabilitation & Communication Sciences, Ohio University, W279 Grover Center, Athens, OH, 45701, USA.
authors: Katherine W
authors: KW
authors: McCorkle
mesh_terms: D000375:Aging / Q000378:metabolism* / Q000473:pathology*; D000818:Animals; D001343:Autophagy / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000166:cytology* / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D009929:Organ Size; D009928:Organ Specificity; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013107:Sphingolipids / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: D015415:Biomarkers; D002518:Ceramides; D013107:Sphingolipids; D018995:Myosin Heavy Chains
keywords: Ceramide; Muscle quality; Sarcopenia; Skeletal muscle