Electroacupuncture Preconditioning Alleviates Lipopolysaccharides-Induced Acute Lung Injury by Downregulating LC3‐II/I and Beclin 1 Expression

Abstract

Our study aimed to investigate the effect of electroacupuncture pretreatment on the inflammatory response and expression levels of LC3-II/I and Beclin 1 using a model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Eighteen male Sprague-Dawley (SD) rats were randomly divided into three groups: normal control group (NC, n = 6), LSP modeling group (LM, n = 6), and electroacupuncture group (EA, n = 6). Rats in the EA group received electroacupuncture pretreatment at bilateral Zusanli (ST36) and Chize (LU5) points for five days (30 min each time daily, frequency; 3 Hz/15 Hz, intensity; 1 mA). Rats in the EA and LM groups were then injected with 5 mg/kg LPS (Beijing, Solarbio Company, concentration; 5 mg/mL) through the tail vein, while those in the NC group were injected with 5 mg/kg saline. The animals were sacrificed six hours after LPS or saline injection through cervical vertebrae by dislocation under deep anesthesia. Orbital blood was collected for the analysis of serum inflammatory factors including interleukin-1β (IL-1β) and transforming growth factor-β (TGF-β). The lower left lung was excised, stained with hematoxylin-eosin (HE), and subjected to histopathological analysis. The mRNA and protein expression of Beclin 1 and LC3 II/I in the lower right lung tissues were detected via RT-qPCR and Western blot analyses, respectively. The results showed that lung injury score was significantly higher in the LM group than that of the NC group ( $P<0.01$ ) and EA group ( $P<0.01$ ). The IL-1β contents were significantly decreased in the EA group ( $P<0.01$ ) than in the LM group. In contrast, the GF-β contents were increased in the EA group significantly when compared with the LM group ( $P<0.01$ ). RT-qPCR and Western blot detection showed that the relative gene expression of LC3‐II/I and Beclin 1 was significantly lower in the EA group than in the LM group ( $P<0.01$ ). However, the relative protein expression level of LC3‐II/I and Beclin 1 was slightly lower in the EA group than the in LM group ( $P>0.05$ ). These results show that electroacupuncture pretreatment reduces the inflammatory response in ALI and can protect lung tissue by inhibiting the gene and protein expression levels of LC3‐II/I and Beclin 1.