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Heat Stress‐induced Insulin Sensitivity in Oxidative Skeletal Muscle
Author(s) -
Ganesan Shanthi,
Pearce Sarah,
Summers Corey,
Gabler Nicholas,
Valentine Rudy,
Baumgard Lance,
Rhoads Robert,
Selsby Joshua
Publication year - 2016
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.30.1_supplement.1290.5
Subject(s) - insulin receptor , insulin , medicine , endocrinology , protein kinase c , oxidative stress , skeletal muscle , phosphorylation , irs1 , protein kinase a , oxidative phosphorylation , kinase , biology , chemistry , insulin resistance , biochemistry
Heat‐related complications continue to be a major health concern for humans and animals and lead to potentially life‐threatening conditions ranging from heat exhaustion, heat stroke and even death. Heat stress have been shown to alter metabolic and energetic parameters in mammals and may alter glucose metabolism and insulin sensitivity. Therefore, the purpose of this investigation was to determine the extent to which short‐term HS altered markers of insulin signaling in oxidative skeletal muscle. To address this, crossbred gilts (n=8/group) were assigned to thermoneutral (TN; 24° C), HS (37° C), or pair‐fed to HS and kept under TN conditions (PFTN) groups for 12 hours. Following treatment, animals were euthanized and the semitendinosus red (STR) was recovered. HS‐induced changes were not caused by reduced feed intake as TN and PFTN were similar for nearly all measures. Twelve hours of HS increased insulin receptor protein abundance by 54% (p<0.05) and phosphorylated insulin receptor substrate (pIRS1 S307 ) by 56% (p<0.05) compared to TN. Phosphorylation of IRS1 at this site is a negative regulator of insulin signaling. Relative protein abundance and phosphorylation of phosphoinositide 3‐kinase (PI3K) and 3‐phosphoinositide dependent protein kinase‐1 (PDK1) were similar between groups. Phosphorylation of protein kinase B (pAKTs473) was decreased by 53% (p<0.05) in HS compared to TN, which indicates that insulin signaling was suppressed through pIRS1. Conversely, HS increased phosphorylation of protein kinase C (PKC)λ/ζ and pPKCδ protein abundance by 128% and 205%, respectively, compared to TN which are known to stimulate pIRS1 S307. Sarcolemma glucose transporter‐4 (Glut4) was decreased by 47% (p<0.05) in HS group compared to TN suggesting reduced glucose uptake. These data suggest that HS induces insulin sensititvity by disturbing insulin signaling via an AKT‐mediated pathway. Support or Funding Information This work is supported by USDA grants 2014‐67015‐21627 and 2011‐67003‐30007