Effect of Berberine on endoplasmic reticulum stress and insulin resistance in skeletal muscle of metabolic syndrome rats and its mechanism / 中华老年医学杂志

ABSTRACT

Objective To investigate the effect of Berberine on insulin resistance and its mechanism in Otsuka Long-Evans Tokushima Fatty(OLETF) rats with metabolic syndrome(MS).Methods LETO(Long-evans Tokushima Otsuka)rats(the control group receiving standard normal diet,n=10)and diabetic OLETF rats(the MS group receiving high-fat diet for 24 weeks,n=30).Rats in the MS group were randomly divided into 3 subgroups(n=10,each subgroup).Each subgroup was gavaged with normal saline,high-dose Berberine(100 mg · kg-1 · d-1)and low-dose Berberine (50 mg · kg-1 · d-1) respectively,and the high-fat diet remained unchanged.After 6 weeks of berberine treatment,body weight,blood glucose and lipid metabolism parameters were determined.The oral glucose tolerance test(OGTT) and insulin tolerance test(ITT) were used to detect insulin resistance.Expression levels of the protein and mRNA of 78 kDa glucose-regulated protein (GRP7 8),Caspase-12 and CCAAT/enhancer-binding protein(C/EBP) homologous protein(CHOP) in skeletal muscles were detected by Western blot and RT-PCR.Results After Berberine treatment,the body weight,fasting plasma glucose,fasting insulin[(28.9 ± 2.0) mU/L,(31.5± 2.4) mU/L vs.(36.9 ± 4.7) mU/L],total cholesterol,triglycerides,and low-density lipoprotein cholesterol were decreased,while the high-density lipoprotein cholesterol(HDL-C) levels were increased in MS rats with high-dose berberine and low-dose berberine as compared with the control group (P ＜ 0.05) respectively.Berberine treatment could reduce the protein and mRNA expression levels of GRP78,Capase-12 and CHOP in the skeletal muscle of MS rats(P＜0.05).Conclusions Berberine may alleviate insulin resistance in rats with metabolic syndrome by reducing endoplasmic reticulum stress in skeletal muscle.