title: Postexercise whole body heat stress additively enhances endurance training-induced mitochondrial adaptations in mouse skeletal muscle.
abstract: A recent study demonstrated that heat stress induces mitochondrial biogenesis in C2C12 myotubes, thereby implying that heat stress may be an effective treatment to enhance endurance training-induced mitochondrial adaptations in skeletal muscle. However, whether heat stress actually induces mitochondrial adaptations in skeletal muscle in vivo is unclear. In the present study, we report the novel findings that 1) whole body heat stress produced by exposure of ICR mice to a hot environment (40°C, 30 min/day, 5 days/wk, 3 wk) induced mitochondrial adaptations such as increased mitochondrial enzyme activity (citrate synthase and 3-hydroxyacyl CoA dehydrogenase) and respiratory chain protein content (complexes I-V) in skeletal muscle in vivo and 2) postexercise whole body heat stress additively enhanced endurance training-induced mitochondrial adaptations (treadmill running, 25 m/min, 30 min/day, 5 days/wk, 3 wk). Moreover, to determine the candidate mechanisms underlying mitochondrial adaptations, we investigated the acute effects of postexercise whole body heat stress on the phosphorylation status of cellular signaling cascades that subsequently induce mitochondrial gene transcription. We found that whole body heat stress boosted the endurance exercise-induced phosphorylation of p38 MAPK, increased the phosphorylation status of p70S6K, a biomarker of mammalian target of rapamycin complex 1 activity, and unexpectedly dephosphorylated AMP-activated protein kinase and its downstream target acetyl-CoA carboxylase in skeletal muscle. Our present observations suggest that heat stress can act as an effective postexercise treatment. Heat stress treatment appeared to be clinically beneficial for people who have difficulty participating in sufficient exercise training, such as the elderly, injured athletes, and patients.
authors: Department of Sports Sciences, The University of Tokyo, Tokyo, Japan.
authors: Yuki
authors: Y
authors: Tamura
authors: Department of Sports Sciences, The University of Tokyo, Tokyo, Japan.
authors: Yutaka
authors: Y
authors: Matsunaga
authors: Department of Sports Sciences, The University of Tokyo, Tokyo, Japan.
authors: Hiroyuki
authors: H
authors: Masuda
authors: Department of Sports Sciences, The University of Tokyo, Tokyo, Japan.
authors: Yumiko
authors: Y
authors: Takahashi
authors: Department of Sports Sciences, The University of Tokyo, Tokyo, Japan.
authors: Yuki
authors: Y
authors: Takahashi
authors: Department of Sports Sciences, The University of Tokyo, Tokyo, Japan.
authors: Shin
authors: S
authors: Terada
authors: Department of Sports Sciences, The University of Tokyo, Tokyo, Japan.
authors: Daisuke
authors: D
authors: Hoshino
authors: Department of Sports Sciences, The University of Tokyo, Tokyo, Japan hatta@idaten.c.u-tokyo.ac.jp.
authors: Hideo
authors: H
authors: Hatta
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D006358:Hot Temperature; D008297:Male; D008813:Mice, Inbred ICR; D008928:Mitochondria / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D015398:Signal Transduction / Q000502:physiology
chemical_list: D055372:AMP-Activated Protein Kinases
keywords: exercise; heat stress; mitochondria; skeletal muscle; training