Contraction-induced changes in TNFα and Akt-mediated signalling are associated with increased myofibrillar protein in rat skeletal muscle

Karagounis, Leonidas G., Yaspelkis III, Benjamin B., Reeder, Donald W., Lancaster, Graeme I., Hawley, John A., & Coffey, Vernon G. (2010) Contraction-induced changes in TNFα and Akt-mediated signalling are associated with increased myofibrillar protein in rat skeletal muscle. European Journal of Applied Physiology, 109(5), pp. 839-848.

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Resistance training results in skeletal muscle hypertrophy, but the molecular signalling mechanisms responsible for this altered phenotype are incompletely understood. We used a resistance training (RT) protocol consisting of three sessions [day 1 (d1), day 3 (d3), day 5 (d5)] separated by 48 h recovery (squat exercise, 4 sets × 10 repetitions, 3 min recovery) to determine early signalling responses to RT in rodent skeletal muscle. Six animals per group were killed 3 h after each resistance training session and 24 and 48 h after the last training session (d5). There was a robust increase in TNF? protein expression, and IKKSer180/181 and p38MAPK Thr180/Tyr182 phosphorylation on d1 (P < 0.05), which abated with subsequent RT, returning to control levels by d5 for TNF? and IKK Ser180/181. There was a trend for a decrease in MuRF-1 protein expression, 48 h following d5 of training (P = 0.08). Notably, muscle myofibrillar protein concentration was elevated compared to control 24 and 48 h following RT (P < 0.05). AktSer473 and mTORSer2448 phosphorylation were unchanged throughout RT. Phosphorylation of p70S6k Thr389 increased 3 h post-exercise on d1, d3 and d5 (P < 0.05), whilst phosphorylation of S6Ser235/236 increased on d1 and d3 (P < 0.05). Our results show a rapid attenuation of inflammatory signalling with repeated bouts of resistance exercise, concomitant with summation in translation initiation signalling in skeletal muscle. Indeed, the cumulative effect of these signalling events was associated with myofibrillar protein accretion, which likely contributes to the early adaptations in response to resistance training overload in the skeletal muscle.

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15 citations in Scopus
14 citations in Web of Science®
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ID Code: 64138
Item Type: Journal Article
Refereed: Yes
DOI: 10.1007/s00421-010-1427-5
ISSN: 1439-6327
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > HUMAN MOVEMENT AND SPORTS SCIENCE (110600) > Exercise Physiology (110602)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Deposited On: 08 Nov 2013 00:38
Last Modified: 12 Nov 2013 05:16

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