title: Molecular and metabolomic effects of voluntary running wheel activity on skeletal muscle in late middle-aged rats.
abstract: We examined the molecular and metabolomic effects of voluntary running wheel activity in late middle-aged male Sprague Dawley rats (16-17 months). Rats were assigned either continuous voluntary running wheel access for 8 weeks (RW+) or cage-matched without running wheel access (RW-). The 9 RW+ rats averaged 83 m/day (range: 8-163 m), yet exhibited both 84% reduced individual body weight gain (4.3 g vs. 26.3 g, P = 0.02) and 6.5% reduced individual average daily food intake (20.6 g vs. 22.0 g, P = 0.09) over the 8 weeks. Hindlimb muscles were harvested following an overnight fast. Muscle weights and myofiber cross-sectional area showed no difference between groups. Western blots of gastrocnemius muscle lysates with a panel of antibodies suggest that running wheel activity improved oxidative metabolism (53% increase in PGC1α, P = 0.03), increased autophagy (36% increase in LC3B-II/-I ratio, P = 0.03), and modulated growth signaling (26% increase in myostatin, P = 0.04). RW+ muscle also showed 43% increased glycogen phosphorylase expression (P = 0.04) and 45% increased glycogen content (P = 0.04). Metabolomic profiling of plantaris and soleus muscles indicated that even low-volume voluntary running wheel activity is associated with decreases in many long-chain fatty acids (e.g., palmitoleate, myristoleate, and eicosatrienoate) relative to RW- rats. Relative increases in acylcarnitines and acyl glycerophospholipids were also observed in RW+ plantaris. These data establish that even modest amounts of physical activity during late middle-age promote extensive metabolic remodeling of skeletal muscle.
authors.affiliation: Abbott Nutrition R&D, Columbus, Ohio, USA.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Garvey
authors.affiliation: Division of Physical Therapy, Ohio University, Athens, Ohio, USA Ohio Musculoskeletal & Neurological Institute (OMNI), Heritage College of Osteopathic Medicine, Athens, Ohio, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Russ
authors.affiliation: Abbott Nutrition R&D, Columbus, Ohio, USA.
authors.forename: Mary B
authors.initials: MB
authors.lastname: Skelding
authors.affiliation: Abbott Nutrition R&D, Columbus, Ohio, USA.
authors.forename: Janis E
authors.initials: JE
authors.lastname: Dugle
authors.affiliation: Abbott Nutrition R&D, Columbus, Ohio, USA.
authors.forename: Neile K
authors.initials: NK
authors.lastname: Edens
keywords: Aging; exercise; metabolomics; muscle; rat; running wheel