Effects of exercise in a cold environment on gene expression for mitochondrial biogenesis and mitophagy

Abstract

Cold exposure during cycling and recovery enhances PGC-1α transcription, but aspects of mitophagy and a more intense cold exposure without recovery occurring in the cold have not been explored.

Purpose: Determine the expression of genes related to mitochondrial biogenesis and mitophagy following an acute cycling bout at a temperature below freezing compared to that of room temperature.

Methods: Eleven male participants cycled at 65% W_max for 1 h at -2 °C and 20 °C and then recovered at room temperature for 6 h. A muscle biopsy was taken from the vastus lateralis before exercise, 3 h, and 6 h post-exercise for gene expression analysis.

Results: Exercising heart rate and skin temperature were lower in the cold (p < 0.001; p = 0.004), while core temperature was higher (p = 0.016). Temperature had no effect on gene expression (p > 0.05). BNIP3 and BNIP3L mRNA were not influenced by exercise (p = 0.329; p 0.233). PGC-1α and VEGF were higher after cycling (p < 0.001), but the extent of PGC-1α upregulation was reduced 6 h post-exercise (p 0.006). TFAM increased 6 h post-exercise (p = 0.001). NRF2, ERRα, PINK1, and PARK2 decreased 3 h post-exercise (p 0.035; p = 0.005; p = 0.002; p = 0.001), but this downregulation was diminished after 6 h of recovery (p = 0.017; p 0.006; p = 0.043; p = 0.047). NRF1 was marginally attenuated with exercise (p = 0.001).

Conclusions: Exercise induced alterations in gene expression for mitochondrial biogenesis and mitophagy, but these effects were independent of temperature.

Keywords: Cycling; Human; PGC-1α; Skeletal muscle; Temperature; mRNA.