Superoxide dismutase gene expression is activated by a single bout of exercise in rat skeletal muscle

The goal of this experiment was to examine contraction-mediated activation of superoxide dismutase (SOD) gene expression in rat superficial vastus lat eralis (SVL, type IIb) and deep vastus lateralis (DVL, type IIa) muscles. F emale Sprague-Dawley rats were randomly divided into exercise (E) and contr ol (C) groups that were sacrificed at 0, 1, 2, 4, 10, 24, and 48 h (n=6) fo llowing an acute bout of treadmill exercise (25 m/min, 5% grade) to exhaust ion (running time congruent to1 h). Nuclear factor-kappaB (NF-kappaB) in DV L and SVL showed maximal binding at 2 and 10 h respectively, and remained e levated. Activator protein-1 (AP-I) showed maximal binding at 1 h post-exer cise, and returned to resting levels at 10 h in both muscles. Mn SOD mRNA a bundance in the DVL was increased at 0 (P <0.01), I, and 2 h (P <0.05) post exercise, whereas Mn SOD protein was unchanged. In SVL, Mn SOD mRNA abundan ce was not altered by exercise, whereas Mn SOD protein content was increase d at 10 (P<0.05) and 24 h (P<less than>0.075) post-exercise. CuZn SOD mRNA was unchanged with exercise in DVL and SVL, but CuZn SOD protein was elevat ed 48 h after exercise in both DVL and SVL (P<0.01). Activities of Mn SOD, CuZn SOD and total SOD showed no change with exercise in either muscle exam ined. These findings indicate that an acute bout of exercise can increase b inding of NF-<kappa>B and AP-I in both SVL and DVL, which may stimulate Mn SOD mRNA transcription in the more oxidative type DVL muscle. The increased CuZn SOD protein contents seen post-exercise, without increases in mRNA ab undance in both DVL and SVL, suggest a translational mechanism in this SOD isoform.