Impact of hot and cold exposure on human skeletal muscle gene expression

Abstract

Many human diseases lead to a loss of skeletal muscle metabolic function and mass. Local and environmental temperature can modulate the exercise-stimulated response of several genes involved in mitochondrial biogenesis and skeletal muscle function in a human model. However, the impact of environmental temperature, independent of exercise, has not been addressed in a human model. Thus, the purpose of this study was to compare the effects of exposure to hot, cold, and room temperature conditions on skeletal muscle gene expression related to mitochondrial biogenesis and muscle mass. Recreationally trained male subjects (n = 12) had muscle biopsies taken from the vastus lateralis before and after 3 h of exposure to hot (33 °C), cold (7 °C), or room temperature (20 °C) conditions. Temperature had no effect on most of the genes related to mitochondrial biogenesis, myogenesis, or proteolysis (p > 0.05). Core temperature was significantly higher in hot and cold environments compared with room temperature (37.2 ± 0.1 °C, p = 0.001; 37.1 ± 0.1 °C, p = 0.013; 36.9 ± 0.1 °C, respectively). Whole-body oxygen consumption was also significantly higher in hot and cold compared with room temperature (0.38 ± 0.01 L·min^-1, p < 0.001; 0.52 ± 0.03 L·min^-1, p < 0.001; 0.35 ± 0.01 L·min^-1, respectively). In conclusion, these data show that acute temperature exposure alone does not elicit significant changes in skeletal muscle gene expression. When considered in conjunction with previous research, exercise appears to be a necessary component to observe gene expression alterations between different environmental temperatures in humans.

Keywords: ARNm; biogenèse mitochondriale; mRNA; mitochondrial biogenesis; myogenesis; myogenèse; proteolysis; protéolyse; temperature; température.

Figure 1

A. mRNA expression of myogenic genes normalized to pre-temperature exposure. Values are mean ± SE. † p < 0.05 from pre-temperature exposure mRNA expression. RT = room temperature. (MSTN: myostatin, MYOG: myogenin, MYF5: myogenic regulatory factor 5, MYF6: myogenic regulatory factor 6, MYOD: myogenic differentiation). B. mRNA expression of myogenic genes normalized to RT. Values are mean ± SE.

Figure 2

A. mRNA expression of proteolytic genes normalized to pre-temperature exposure. Values are mean ± SE. † p < 0.05 from pre-temperature exposure mRNA expression. RT = room temperature. (MuRF1: muscle RING-finger protein 1, FOXO3: forkhead box O3). B. mRNA expression of proteolytic genes normalized to RT. Values are mean ± SE.

Figure 3

A. mRNA expression of genes related to mitochondrial biogenesis normalized to pre-temperature exposure. Values are mean ± SE. † p < 0.05 from pre-temperature exposure mRNA expression.* p < 0.05 significant interaction (cold > hot). RT = room temperature. (ERRα: estrogen related receptor alpha, GABPA: GA binding protein, MEF2A: myocyte enhancer factor 2A, NRF1: nuclear respiratory factor 1, PGC1 α: peroxisome proliferator-activated receptor gamma coactivator 1 alpha, SIRT1: sirtuin 1, TFAM: mitochondrial transcription factor A, VEGF: vascular endothelial growth factor). B. mRNA expression of genes related to mitochondrial biogenesis normalized to RT. Values are mean ± SE.

Figure 4

Whole body oxygen consumption averages for each hour. Values are mean ± SE. * p < 0.05 from cold; † p < 0.05 from hot. RT = room temperature.