Effects of electroacupuncture on the inflammatory response and intestinal flora in obese rats

To observe the effect of electroacupuncture (EA) on the expressions of high mobility group protein 1 (HMGB1) and myeloid differentiation factor 88 (MyD88) in the small intestine and intestinal flora of obese rats, so as to explore the potential mechanism of EA to improve obesity in rats.

After 1 week of acclimatization, 10 rats were randomly selected from 50 Wistar male rats as the normal group, and the rest rats were fed with high-fat diet for 8 weeks to establish the obese model. The successfully modeling rats were randomly divided into model group, EA group and sham EA group, with 10 rats in each group. Rats in the EA group were given EA (2 Hz, 1 mA) at “Zhongwan” (CV12), “Guanyuan” (CV4), “Zusanli” (ST36) and “Fenglong” (ST40). Rats in the sham EA group were given shallow stabs at acupoints of the EA group about 5 mm outwardly and the electrodes were clamped without being energized. Both groups were intervened for 10 min each time, 3 times (Monday, Wednesday and Friday) a week for 8 weeks. The body weights of the rats were measured before and after 8 weeks of intervention, respectively. The contents of serum lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-α were measured by ELISA, and the protein and mRNA expressions of HMGB1 and MyD88 in the small intestine were detected by Western blot and realtime quantitative PCR, respectively. 16S rRNA sequencing was performed to determine the relative abundance and diversity of the bacterial flora in the fresh feces of rats.

Compared with the normal group, the body weight, serum LPS and TNF-α contents, small intestinal HMGB1 and MyD88 protein and mRNA expression levels of rats in the model group were significantly increased (P<0.01), while the relative abundance of Lactobacillus, Muri and Bifidobacterium was decreased (p<0.01), Collinsella, Prevotella and Ruminococcus was increased (P<0.01). Compared with model group, the body weight, serum LPS and TNF-α contents, protein and mRNA expression levels of HMGB1 and MyD88 in both EA and sham EA groups were decreased (P<0.01, P<0.05), while the relative abundance of Lactobacillus, Muri and Bifidobacterium was increased (P<0.01) and Collinsella, Prevotella and Ruminococcus decreased (P<0.01). Comparison between EA group and sham EA group showed that, the contents of LPS and TNF-α in serum of rats in sham EA group were increased (P<0.01, P<0.05), the relative abundance of Lactobacillus, Muri and Bifidobacterium was lower (P<0.05, P<0.01), and Collinsella, Prevotella and Ruminococcus was higher (P<0.01).

EA can reduce the body weight of obese rats, which may be related to the regulation of the structure of intestinal flora and the reduction of inflammatory reactions in the small intestine.