| Endoplasmic reticulum stress refers to pathological and physiological proce dure which caused by various reasons.ERS disturb the function of endoplasmic reticulum and affect the synthesis of proteins.Liver,as a significant part of metabolic system in human body,liver ERS may induce a series of metabolic diseases,such as obesity,hypertension,hyperlipidemia,diabetes et al.ERS existed in liver have became major risk factor of main diseases and thus become a threat to human’ health.Calpain-2 is a isoform of calcium-activated neutralprotease,the recent study showed that the activation of Calpain-2 in human body may associate with the pathogenesis of some diseases,such as liver ERS.However,the effect and mechanism of Calpain-2 on liver ERS is still unknown.Objectives:This study established liver ERS model after feeding rats with high fat diet for 8 weeks,and treated high fat diet rats with swimming for 8 weeks.After taking materials,analyzed calpain-2 and other indicators,to explore effect and mechanism research on calpain-2 in exercising alleviated liver ERS,and further provided theoretical evidence for exercise alleviated some diseases.Methods:30 male Sprague-Dawley rats were randomly divided into control group(C,n=10),high fat diet ERS model group(HF,n=10),high fat diet ERS model and swimming exercise group(HE,n=10).Rats in C group were fed with normal food(13% fat),rats in HF group were fed with high fat diet(45% fat),rats in HE group were fed with high fat diet meanwhile exerted with swimming for 8 weeks.After 8 weeks took materials from C,HF,HE group rats.Serum free fatty acids were measured by enzymatic colorimetric assay;the protein expression of Calpain-2 and Atg7 in liver was detected by Western Blotting;mRNA expression of Calpain-2,Atg7,Grp78,Chop and EIF2α in liver was evaluated by RT-qPCR.Results:(1)Compared with C group,the mRNA expression of Grp78,Chop and EIF2α in liver of HF group increased significantly(p<0.01).The results showed that the ERS model was established successfully through high fat diet.(2)Compared with C group,the concentration of serum FFAs in HF group increased significantly(p<0.01);the RT-qPCR’ results and the western blotting results showed that compared with C group,the mRNA and protein expression of liver Calpain-2 in HF group up-regulated significantly,while the mRNA and protein expression of liver Atg7 in HF group down-regulated significantly(p<0.01).These results suggested that high fat diet could up-regulate Calpain-2 and inhibit Atg7 in liver,thus induced markers of ERS: Grp78,Chop and EIF2α.(3)Compared with HF group,the concentration of serum FFAs in HE group decreased significantly(p<0.01);the RT-qPCR’ results and the western blotting results showed that compared with HF group,the mRNA and protein expression of liver Calpain-2 in HE group down-regulated significantly,while the mRNA and protein expression of liver Atg7 in HE group up-regulated significantly(p<0.01).Compared with HF group,the mRNA expression of Grp78,Chop and EIF2α in liver of HE group decreased significantly(p<0.01).These results showed that exercise could effectively alleviate liver ERS.Conclusions:(1)After 8 weeks high fat dietary,the liver ERS model in rats established successfully.(2)Exercise could effectively alleviate liver ERS.Calpain-2 plays a crucial role in exercise alleviating liver ERS.The potential mechanism of Calpain-2 in inducing liver ERS: high fat diet increased FFAs in serum,serum FFAs transported to liver and upregulated mRNA and protein expression of liver Calpain-2,thus inhibited Atg7’s expression in liver.The inhibition of Atg7 could induce ERS marker Grp78,Chop and EIF2α,suggested that ERS happened in liver. |
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