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Heat stress‐induced autophagic regulations in rat skeletal muscle
Author(s) -
Yoshihara Toshinori,
Naito Hisashi,
Kakigi Ryo,
IchinosekiSekine Noriko,
Sugiura Takao,
Katamoto Shizuo
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.lb600
Subject(s) - autophagy , soleus muscle , pi3k/akt/mtor pathway , skeletal muscle , phosphorylation , heat stress , protein kinase b , medicine , endocrinology , chemistry , leg muscle , blot , biology , biochemistry , zoology , signal transduction , apoptosis , gene , physical medicine and rehabilitation
PURPOSE To examine the effects of acute heat stress on the regulation of autophagy in rat skeletal muscle. METHODS Twenty‐eight male Wistar rats (15 wk‐old) were used in this study. After 12h fasting, one leg was immersed in a hot water (43°C) for 30 min under anesthesia. The other leg was served as a control one. During the heat treatment, muscle temperature was recorded by a needle thermometer. The soleus muscle in both legs were removed before (Pre, n=4) and 0 (Post0, n=6), 30 (Post30, n=6), 60 (Post60, n=6) min or 24 hours (Post24h, n=6) after the heat stress. Phospho‐ and total‐Akt and mTOR, and LC3‐I/II protein expressions in the both muscles were determined by Western blotting technique. RESULTS Muscle temperature of the heat‐stressed leg was gradually increased to 41.8±0.3°C. In the soleus muscle, the levels of the autophagic makers LC3‐II were significantly increased in the Post60 group compared with Pre, Post30 and Post24h. Also, LC3‐I protein expressions were significantly decreased in the Post24h compared with Post0, Post30 and Post60. The Akt phosphorylation ratios of Post0 were significantly higher than any other groups. Moreover the phosphorylation level of mTOR was significantly increased in Post0 compared to Pre and Post24h. CONCLUSION These results show that acute heat stress lead to not only the activations of Akt/mTOR pathway but also the facilitation of protein turnover via autophagy.