title: Genetic strain-dependent protein metabolism and muscle hypertrophy under chronic isometric training in rat gastrocnemius muscle.
abstract: Genetic strain-dependent reactivity to mechanical stimuli in rat skeletal muscle has not been examined. This study aimed to examine whether genetic strain-dependency is associated with reactivity in protein metabolism and the resultant muscle hypertrophy after isometric resistance training (RT). The right triceps of Sprague-Dawley (SD) and Wistar rats underwent 12 sessions of RT. After RT, a transition from the IIb to the IIx myosin heavy-chain isoform was observed in both strains. In SD rats, the lateral gastrocnemius muscle (LG) mass of the trained legs (TRN) was significantly higher than that of the control legs (CON) (7.8 %, P<0.05). Meanwhile, in Wistar rats, the LG mass was unchanged. In SD rats, the levels of 70-kDa ribosomal protein S6 kinase (p70S6k) and forkhead box 3a (FOXO3a) phosphorylation in the TRN were significantly greater than those of the CON (2.2- and 1.9-fold, respectively; P<0.05). The expression of muscle ring finger-1 (MuRF1) and muscle atrophy F-box (MAFbx/atrogin-1) in the TRN were significantly lower than those of the CON (0.6- and 0.7-fold, respectively; P<0.05). However, in Wistar rats, there was no significant difference. These results suggest a genetic strain difference in protein metabolism. This phenomenon may be useful for studying individual differences in response to RT.
authors.affiliation: Graduate School of Health and Sport Sciences, Nippon Sport Science University, Tokyo, Japan. kobakoji0518@yahoo.co.jp
authors.forename: K
authors.initials: K
authors.lastname: Kobayashi
authors.forename: R
authors.initials: R
authors.lastname: Ogasawara
authors.forename: A
authors.initials: A
authors.lastname: Tsutaki
authors.forename: K
authors.initials: K
authors.lastname: Lee
authors.forename: E
authors.initials: E
authors.lastname: Ochi
authors.forename: K
authors.initials: K
authors.lastname: Nakazato
mesh_terms: D000818:Animals; D006984:Hypertrophy / Q000503:physiopathology; D008297:Male; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology*; D010805:Physical Conditioning, Animal / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity
chemical_list: D009124:Muscle Proteins