Chronic low frequency/low volume resistance training reduces pro-inflammatory cytokine protein levels and TLR4 mRNA in rat skeletal muscle.
Skeletal muscle is the source of pro- and anti-inflammatory cytokines, and recently, it has been recognized as an important source of interleukin 6 (IL-6), a cytokine that exerts inhibitory effects on several pro-inflammatory cytokines. Although dynamic chronic resistance training has been shown to produce the known "repeated bout effect", which abolishes the acute muscle damage, performing of high-intensity resistance training has been regarded highly advisable, at least from the hypertrophy perspective. On the other hand, a more therapeutic, "non-damaging" resistance training program, mainly composed of concentric forces, low frequency/low volume of training, and the same exercise, could theoretically benefit the muscle when the main issue is to avoid muscle inflammation (as in the treatment of several "low-grade" inflammatory diseases) because the acute effect of each resistance exercise session could be diminished/avoided, at the same time that the muscle is still being overloaded in a concentric manner. However, the benefits of such "less demanding" resistance training schedule on the muscle inflammatory profile have never been investigated. Therefore, we assessed the protein expression of IL-6, TNF-alpha, IL-10, IL-10/TNF-alpha ratio, and HSP70 levels and mRNA expression of SCF(beta-TrCP), IL-15, and TLR-4 in the skeletal muscle of rats submitted to resistance training. Briefly, animals were randomly assigned to either a control group (S, n = 8) or a resistance-trained group (T, n = 7). Trained rats were exercised over a duration of 12 weeks (two times per day, two times per week). Detection of IL-6, TNF-alpha, IL-10, and HSP70 protein expression was carried out by western blotting and SCF(beta-TrCP) (SKP Cullin F-Box Protein Ligases), a class of enzymes involved in the ubiquitination of protein substrates to proteasomal degradation, IL-15, and TLR-4 by RT-PCR. Our results show a decreased expression of TNF-alpha and TLR4 mRNA (40 and 60%, respectively; p < 0.05) in the plantar muscle from trained, when compared with control rats. In conclusion, exercise training induced decreased TNF-alpha and TLR-4 expressions, resulting in a modified IL-10/TNF-alpha ratio in the skeletal muscle. These data show that, in healthy rats, 12-week resistance training, predominantly composed of concentric stimuli and low frequency/low volume schedule, down regulates skeletal muscle production of cytokines involved in the onset, maintenance, and regulation of inflammation.
Zanchi
Nelo Eidy
NE
Laboratory of Applied Nutrition and Metabolism, Physical Education and Sport School, University of Sao Paulo, Av. Prof. Mello Moraes, 65, São Paulo, SP, 05508-900, Brazil. neloz@usp.br
Lira
Fabio Santos
FS
de Siqueira Filho
Mário Alves
MA
Rosa
José Cesar
JC
de Oliveira Carvalho
Carla Roberta
CR
Seelaender
Marilia
M
Santos
Ronaldo Vagner T
RV
Lancha
Antonio Herbert
AH
D000818:Animals; D016207:Cytokines / Q000276:immunology*; D005260:Female; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009220:Myositis / Q000276:immunology* / Q000517:prevention & control*; D010805:Physical Conditioning, Animal / Q000379:methods*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology*
D016207:Cytokines; D012333:RNA, Messenger; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4