[Effect of Eletroacupuncture Intervention on Insulin Resistance, Lipid Metabolic Disorder and Expression of Hepatic SREBP-1 c and Fatty Acid Synthase Proteins in Rats with Hyperlipidemia].

OBJECTIVE: To observe the effect of electroacupuncture(EA) of "Fenglong" (ST 40) and "Sanyinjiao" (SP 6) on lipid metabolic disorder, insulin resistance (IR) and expression of sterol regulatory element blinding protein-1 (SREBP-1) c and fatty acid synthase (FAS) proteins in the liver tissue in hyperlipidemia rats with IR, so as to reveal its mechanisms underlying improvement of IR.
METHODS: Forty male SD rats were randomly divided into blank control, model, medication and EA groups (n＝8 in each group). The IR model was established by feeding the rat with high-fat diet. Rats of the medication group were treated by intragastric administration of pioglitazone (10 mL/kg). For rats of the EA group, EA (2 Hz/100 Hz，1 mA) was applied to bilateral ST 40 and SP 6, once daily for 14 days. The insulin sensitivity index (ISI) was assessed by calculating 60－120 min glucose infusion rate (GIR 60－120) with euglycemic hyperinsulinemic clamp in reference to Kraegen's and colleagues' methods. Fasting blood samples (10 mL) were collected and analyzed for fasting blood glucose (FBG) using enzyme method, serum fasting insulin(FINS) using ELISA, free fatty acid(FFA) using spectrophotometry, and total triglyceride(TG) and total cholesterol(TC) employing glycerine phosphate oxidase peroxidase (GPO-PAP) assay, low density lipoprotein(LDL), high density lipoprotein(HDL) levels using combined filiter paper activity and lipase activity methods, respectively. The IR level was assessed by calculating homeostatic model assessment of insulin resistance (HOMA-IR) using the formula (FBG×FINS)/22.5. The expression levels of SREBP-1 c and FAS proteins in the liver tissue were detected by Western blot.
RESULTS: Following modeling, the GIR 60－120 and serum HDL were significantly decreased(P<0.01), and the HOMA-IR, serum FBG, FINS, FFA, TG, TC and LDL, and the expression levels of hepatic SREBP-1 c and FAS proteins were significantly increased in comparison with the blank control group(P<0.01). After the intervention, the decreased GIR 60－120 and serum HDL levels were considerably up-regulated (P<0.01), and the increased FBG, FINS, FFA, TG, TC and LDL, and hepatic SREBP-1 c and FAS protein levels were notably down-regulated in both EA and medication groups relevant to the model group (P<0.05, P<0.01). No significant differences were found between the EA and medication groups in all the indexes mentioned above (P>0.05).
CONCLUSION: EA intervention is able to improve the disorder of lipid metabolism of IR rats, which may be associated with its effects in reducing the expression of SREBP-1 c and FAS proteins and in lowering the synthesis of fatty acid.