Effect of electroacupuncture on the intestinal flora-short chain fatty acid metabolism axis in simple obesity rats.

Objectives: To observe the effect of electroacupuncture (EA) on the intestinal flora-short chain fatty acids (SCFAs) metabolism axis in rats with simple obesity, so as to explore the underlying mechanism of EA in reducing obesity.

Methods: Male SD rats were randomly divided into control group, model group and EA group, with 6 rats in each group. The obesity model was established by feeding the rats with high-fat diet. Rats in the EA group were treated with EA at "Quchi" (LI11) and "Zusanli" (ST36) for 15 min, once daily for 21 consecutive days. The changes of body weight were observed every other day. H.E. staining was used to observe the pathological changes of adipose tissue and liver. The blood lipid content was detected by automatic biochemical analyzer. The diversity of intestinal flora in rat feces was analyzed by 16S rRNA high-throughput sequencing. The content of SCFAs in rat feces was detected by ultra-high performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS/MS). The correlation between the relative abundance of fecal intestinal flora and the content of SCFAs in rats was analyzed by Pearson method.

Results: Compared with the control group, the body weight of rats, the serum total cholesterol (TC) and triglyceride (TG) were significantly increased (<0.01) in the model group. The results of 16S rRNA sequencing showed that, at the genus level the relative abundance of Bacteroides, Butyrivibrio and Roseburia in were decreased significantly(<0.05), while that of the Lachnospiraceae_NK4A136_group increased(<0.05). After the intervention, compared with the model group, the body weight, serum TC and TG contents of rats in the EA group were significantly decreased (<0.05, <0.01)；the results of 16S rRNA sequencing showed that, the relative abundance of the Bacteroidota phylum significantly increased (<0.01) and Firmicutes decreased (<0.01) at the phylum level, and at the genus level the relative abundances of Bacteroides, Butyrivibrio and Roseburia significantly increased (<0.01, <0.05)；the contents of acetic acid and propionic acid in SCFAs significantly increased (<0.01). H.E. staining showed an increase of the diameter of adipocytes, with obvious lipid droplets and inflammatory infiltration in the model group, which was relatively milder in the EA group. PCoA analysis showed that there were significant differences in the structure of intestinal flora between the control group and the model group, as well as the model group and the EA group. At the phylum level, the relative abundance of Bacteroidota was positively correlated with acetic acid and propionic acid contents, with that of Firmicutes negatively correlated with acetic acid and propionic acid contents (<0.001). At the genus level, the relative abundances of Bacteroides, Streptococcus and Butyricimonas were positively correlated with acetic acid content (<0.01, <0.05), and the relative abundances of Bacteroides, Streptococcus and Roseburia were positively correlated with propionic acid content (<0.001, (<0.05).

Conclusions: EA can improve the disorder of lipid metabolism in obese rats by improving the disorder of intestinal flora-SCFAs metabolic axis, thus playing a role in inhibiting obesity.