Cooling of male rat skeletal muscle during endurance-like contraction attenuates contraction-induced PGC-1 mRNA expression

This study aimed to determine effects of cooling on contraction-induced peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1 alpha) and vascular endothelial growth factor (VEGF) gene expression, phosphorylations of its related protein kinases, and metabolic responses. Male rats were separated into two groups; room temperature (RT) or ice-treated (COLD) on the right tibialis anterior (TA). The TA was contracted isometrically using nerve electrical stimulation (1-s stimulation x 30 contractions, with 1-s intervals, for 10 sets with 1-min intervals). The TA was treated before the contraction and during 1-min intervals with an ice pack for the COLD group and a water pack at RT for the RT group. The muscle temperature of the COLD group decreased to 19.42 +/- 0.44 degrees C (p < 0.0001, -36.4%) compared with the RT group after the experimental protocol. An increase in mRNA expression level of PGC-1 alpha, not VEGF, after muscle contractions was significantly lower in the COLD group than in the RT group (p < 0.0001, -63.0%). An increase in phosphorylated AMP-activated kinase (AMPK) (p = 0.0037, -28.8%) and a decrease in glycogen concentration (p = 0.0231, +106.3%) after muscle contraction were also significantly inhibited by cooling. Collectively, muscle cooling attenuated the post-contraction increases in PGC-1 alpha mRNA expression coinciding with decreases in AMPK phosphorylation and glycogen degradation.