Endoplasmic reticulum stress-mediated high-fat diet, palmitic acid-induced insulin resistance in skeletal muscle and interventional effects of fenofibrate / 中国药理学通报

ABSTRACT

Aim To investigate endoplasmic reticulum stress ( ERS)-mediated high-fat diet and palmitic acid-induced insulin resistance ( IR) in skeletal muscle and interventional effects of fenofibrate both in vivo and in vitro tests. Methods Female SD rats were randomly subjected to a standard control diet ( SCD) or high-fat diet ( HFD) for 20 weeks, then the HFD group was di-vided into high-fat-diet group and high-fat-diet group treated with fenofibrate ( HFD +FF, 30 mg · kg-1 · d-1 ) for another 8 weeks. The changes of IR and ex-pression of peroxisome proliferator-activated receptor α( PPARα) , glucose regulated protein 78 ( GRP78 ) and transcription factors GADD153 ( CHOP ) were as-sessed respectively. C2C12 myotubes were divided into normal control group ( NC ) , model group ( palmitic acid, PA) , postive control drug group ( tunicamycin, TM) and treatment group ( fenofibric acid, FA+PA) , the expressions of GRP78 and CHOP were assessed re-spectively. Insulin-stimulated phosphorylation of Akt was also analyzed to detect changes of insulin sensitivi-ty in C2 C12 . Results The high-fat diet induced obvi-ous IR and upregulated ERS markers GRP78 and CHOP in skeletal muscle of rats, and these responses were attenuated by treatment with fenofibrate. Incuba-tion of myotubes with palmitic acid or tunicamycin sig-nificantly increased expression of ERS markers GRP78 and CHOP. Meanwhile, insulin-stimulated phosphoryl-ation of Akt was inhibited obviously. Pre-incubation with FA markedly inverted PA-induced ERS and insu-lin-stimulated phosphorylation of Akt. Conclusion Fenofibrate ( fenofibric acid) has obvious effects of IR on skeletal muscle tissues and cells, which may be re-lated with reduced expression of GRP78 and CHOP in ERS.