Key result
An acute bout of eccentric exercise increased p70S6k phosphorylation immediately after (33.3%) in lean rats, but only at 3 h (33.5%) in obese rats, suggesting insulin resistance alters muscle signaling.
Why the study?
Does eccentric exercise differentially affect p70S6k, Akt, and mTOR phosphorylation in the tibialis anterior muscles of lean versus obese Zucker rats?
Does eccentric exercise differentially affect p70S6k, Akt, and mTOR phosphorylation in the tibialis anterior muscles of lean versus obese Zucker rats?
Insulin resistance in obese Zucker rats is associated with an impaired ability to activate p70S6k, Akt, and mTOR signaling pathways in skeletal muscle following acute exercise.
May warrant caution extrapolating to obese patients; leaves open optimal eccentric exercise timing in human insulin resistance.
Increased phosphorylation of the 70-kDa ribosomal S6 kinase (p70S6k) signaling is strongly correlated with the degree of muscle adaptation following exercise. Herein we compare the phosphorylation of p70S6k, Akt, and mammalian target of rapamycin (mTOR) in the tibialis anterior (TA) muscles of lean and obese Zucker rats following a bout of eccentric exercise. Exercise increased p70S6k (Thr389) phosphorylation immediately after (33.3+/-7.2%) and during [1 h (24.0+/-14.9%) and 3 h (24.6+/-11.3%)] recovery in the lean TA and at 3 h (33.5+/-8.0%) in the obese TA Zucker rats. mTOR (Ser2448) phosphorylation was elevated in the lean TA immediately after exercise (96.5+/-40.3%) but remained unaltered in the obese TA. Exercise increased Akt (Thr308) and Akt (Ser473) phosphorylation in the lean but not the obese TA. These results suggest that insulin resistance is associated with alterations in the ability of muscle to activate p70S6k signaling following an acute bout of exercise.
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Katta et al. (2009) studied Insulin resistance and obesity. Eccentric exercise vs. Lean vs obese Zucker rats was evaluated on Phosphorylation of p70S6k, Akt, and mTOR in the tibialis anterior muscle. An acute bout of eccentric exercise increased p70S6k phosphorylation immediately after (33.3%) in lean rats, but only at 3 h (33.5%) in obese rats, suggesting insulin resistance alters muscle signaling.
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