RESUMEN
ObjectiveTo explore the effect and possible mechanism of electroacupuncture （EA） at Fenglong （ST40） on liver lipid synthesis and insulin resistance （IR） in hyperlipidemic （HLP） rats. MethodEighteen rats were randomly divided into three groups， blank group， model group， and EA group， each consisting of six rats. The blank group rats were with fed a basic diet， while those in the model group and EA group were fed high-fat diet for 8 weeks. After modeling， the rats in the EA group received bilateral EA treatment at “Fenglong” （ST 40）. The rats in the model group underwent daily binding treatment， once a day， continuously 5 days a week， for a total of 4 weeks. Following the intervention， the levels of triglycerides （TG） and free fatty acids （FFA） in liver tissue was determined using ELISA. Serum TG， FFA， fasting insulin （FINS）， alanine transaminase （ALT）， aspartate Transaminase （AST）， tumor necrosis factor-ɑ （TNF-ɑ）and interleukin 6 （IL-6） were also measured. The fasting plasma glucose （FBG） assessed using a glucose meter and the homeostatic model assessment of insulin resistance （HOMA-IR） was calculated. Liver pathology was examined through HE staining and oil red O staining. The expression of hepatic sterol regulator binding protein 1c （SREBP1c）， recombinant fatty acid synthase （FASN） and stearoyl-CoA desaturase 1 （SCD1） were detected through immunofluorescence. The protein expression levels of liver insulin receptor substrate 1 （IRS1） and tyrosine-phosphorylated insulin receptor substrate 1 （p-IRS1-Tyr） were determined via Western blot. ResultsWhen compared to the blank group， the model group of rats exhibited elevated serum and liver tissue levels of TG and FFA， as well as increased serum levels of AST， ALT， TNF-α， IL-6， FBG， FINS， and HOMA-IR （P＜0.05）. HE staining revealed disordered arrangements of liver cells， indicating widespread fatty degeneration. Oil red O staining showed abundant bright red lipid droplets within liver cell cytoplasm， indicating severe lipid accumulation. The average fluorescence intensity of SREBP1c， FASN， and SCD1 in liver tissue significantly increased （P＜0.05）， while p-IRS1-Tyr protein expression levels significantly decreased （P＜0.05）. In comparison to the model group， the EA group of rats showed significantly reduced serum and liver tissue levels of TG and FFA， along with decreased serum levels of AST， ALT， TNF-α， IL-6， FBG， FINS， and HOMA-IR （P＜0.05）. HE staining indicated more regular arrangements of liver cells， and oil red O staining revealed a significant reduction in liver cell lipid droplets， indicating a less severe degree of lipid accumulation. The average fluorescence intensity of SREBP1c， FASN， and SCD1 in liver tissue significantly decreased （P＜0.05）， while p-IRS1-Tyr protein expression levels significantly increased （P＜0.05）， with no significant difference in IRS1 protein expression （P＞0.05）. ConclusionEA at “Fenglong” （ST 40） can significantly decrease serum lipid in HLP rats， improves liver fat accumulation， and also ameliorate insulin resistance. The mechanism may be related to the inhibition of hepatic lipid synthesis molecule expression， reduced serum inflammatory factors， and an increase in insulin substrate receptor phosphorylation levels.