Lean and Obese Zucker Rats Exhibit Different Patterns of p70S6kinase Regulation in the Tibialis Anterior Muscle in Response to High Force Muscle Contraction

摘要

Increased phosphorylation of the 70 kDa ribosomal S6 kinase (p70s6k) signaling is strongly correlated with the degree of muscle adaptation following exercise. Here, we compare the phosphorylation of p70s6k, Akt and mTOR in the tibialis anterior (TA) muscles of lean and obese Zucker rats following a bout of eccentric exercise. Exercise increased p70S6k (Thr 389) phosphorylation immediately after (33.3 ± 7.2%) and during recovery [1-hr; (24.0 ± 14.9%), and 3-hr (24.6 ± 11.3%)], in the lean TA and at 3-hr (33.5 ± 8.0%) in the obese TA. mTOR (Ser 2448) phosphorylation was elevated in the lean TA immediately after exercise (96.5 ± 40.3%) but remained unaltered in the obese TA. Exercise increased Akt (Thr 308) and Akt (Ser 473) 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 p p70s6k signaling following an acute bout of exercise.