The purpose of this study was to determine mitochondrial biogenesis-related mRNA expression, binding of transcription factors to the PGC-1α promoter, and sub-cellular location of PGC-1α protein in human skeletal muscle following exercise in a hot environment compared to a room temperature environment. Recreationally-trained males (n = 11) completed two trials in a temperature and humidity controlled environmental chamber. Each trial consisted of cycling in either a hot (H) or room temperature (C) environment (33⁰ C and 20⁰ C, respectively) for one h at 60% of Wmax followed by 3 h of supine recovery at room temperature. Muscle biopsies were taken from the vastus lateralis pre-, post-, and 3 h post-exercise. PGC-1α mRNA increased post- (p = 0.039) and 3 h post-exercise in C (p = 0.002). PGC-1α, ERRα, and NRF-1 mRNA were all lower in H than C post- (p = 0.038, p < 0.001, and p = 0.030, respectively) and 3 h post-exercise (p = 0.035, p = 0.007, and p < 0.001, respectively). Binding of CREB (p = 0.005), MEF2 (p = 0.047), and FoxO1 (p = 0.010) to the promoter region of the PGC-1α gene was lower in H than C. Nuclear PGC-1α protein increased post-exercise in both H and C (p = 0.029), but was not different between trials (p = 0.602). These data indicate that acute exercise in a hot environment blunts expression of mitochondrial biogenesis-related mRNA, due to decreased binding of CREB, MEF2, and FoxO1 to the PGC-1α promoter.
- Mitochondrial biogenesis
- skeletal muscle
- heat stress
- Copyright © 2015, Journal of Applied Physiology