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Heat stress activates the A kt/m TOR signalling pathway in rat skeletal muscle
Author(s) -
Yoshihara T.,
Naito H.,
Kakigi R.,
IchinosekiSekine N.,
Ogura Y.,
Sugiura T.,
Katamoto S.
Publication year - 2013
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/apha.12040
Subject(s) - skeletal muscle , phosphorylation , muscle hypertrophy , soleus muscle , medicine , chemistry , heat shock protein , endocrinology , plantaris muscle , p70 s6 kinase 1 , biology , biochemistry , protein kinase b , gene
Aim It is well known that various stimuli, such as mechanical stress and nutrients, induce muscle hypertrophy thorough the A kt/m TOR signalling pathway, which is a key mediator of protein synthesis and hypertrophy in skeletal muscle. It was recently reported that heat stress also induces an increase in muscle weight and muscle protein content. In addition, heat stress enhances A kt/m TOR signalling after one bout of resistance exercise. However, it remains unclear whether increased temperature itself stimulates the A kt/m TOR signalling pathway. Methods Forty‐two male W istar rats (279.5 ± 1.2 g) were divided into a control group ( CON ) or one of five thermal stress groups at 37, 38, 39, 40 or 41 °C ( n = 7 each group). After overnight fasting, both legs were immersed in different temperatures of hot water for 30 min under sodium pentobarbital anaesthesia. The soleus and plantaris muscles were immediately removed from both legs after the thermal stress. Results The phosphorylation of m TOR or 4 E ‐ BP 1 and heat shock protein ( HSP ) expression levels were similar among groups in both the soleus and plantaris muscles. However, A kt and p70 S 6 K phosphorylation significantly increased at 41 °C in the soleus and plantaris muscles. Moreover, we observed a temperature‐dependent increase in A kt and p70 S 6 K phosphorylation in both muscles. Conclusion Our data indicate that the altered temperature increased phosphorylation in a temperature‐dependent manner in rat skeletal muscle and may itself be a key stimulator of A kt/m TOR signalling.