Integrating 16S rDNA and metabolomics to uncover the therapeutic mechanism of electroacupuncture in type 2 diabetic rats.

Objective: This study aimed to investigate the impact of electroacupuncture (EA) on blood glucose levels, gut microbiota, short-chain fatty acids (SCFAs), and glucagon-like peptide-1 (GLP-1) in a rat model of type 2 diabetes mellitus (T2DM).

Methods: Forty Sprague-Dawley (SD) rats were randomly assigned to five groups (n = 8/group) using a random number table: normal control, T2DM model, electroacupuncture (EA), EA + antibiotics (EA + A), and antibiotics (A). The normal rats received a standard diet and saline gavage, while the other groups were fed a high-fat diet and emulsion. The EA + A and A groups received additional antibiotic solution gavage. The normal, model, and A groups were immobilized and restrained for 30 min, six times per week, for 4 weeks. The EA and EA + A groups received EA treatment at specific acupoints for 30 min, six times per week, for 4 weeks. EA parameters were continuous waves at 10 Hz and 1-2 mA. During the intervention, water and food consumption, body weight, fasting blood glucose (FBG), and oral glucose tolerance test (OGTT) were monitored. Pancreatic tissue was examined using hematoxylin and eosin (H&E) staining. Fecal microbial communities were analyzed by 16S rDNA sequencing, and short-chain fatty acids (SCFAs) were measured using gas chromatography-mass spectrometry (GC-MS). Serum levels of fasting insulin (FINS), glycated hemoglobin (HbA1c), and glucagon-like peptide-1 (GLP-1) were determined using enzyme-linked immunosorbent assay (ELISA).

Results: EA significantly improved daily water intake, food consumption, and body weight in T2DM rats (p < 0.01). EA also reduced FBG, the area under the curve of the OGTT, FINS, and homeostasis model assessment of insulin resistance (HOMA-IR) in T2DM rats (p < 0.05). The ELISA results showed a lower concentration of HbA1c in the EA group (p < 0.05). EA improved the overall morphology and area of pancreatic islets, increased the number of β-cell nuclei, and alleviated β-cell hypertrophy. The abundance of operational taxonomic units (OTUs) in the EA group increased than the model group (p < 0.05), and EA upregulated the Shannon, Chao1, and Ace indices (p < 0.05). EA increased the concentrations of acetic acid, butyric acid, and GLP-1 (p < 0.05). Correlation analysis revealed negative associations between Lactobacillaceae (R = -0.81, p = 0.015) and Lactobacillus (R = -0.759, p = 0.029) with FBG. Peptostreptococcaceae and Romboutsia were negatively correlated with HbA1c (R = -0.81, p = 0.015), while Enterobacteriaceae was positively correlated with OGTT (R = 0.762, p = 0.028). GLP-1 was positively correlated with acetic acid (R = 0.487, p = 0.001), butyric acid (R = 0.586, p = 0.000), isovaleric acid (R = 0.374, p = 0.017), valeric acid (R = 0.535, p = 0.000), and caproic acid (R = 0.371, p = 0.018). Antibiotics disrupted the intestinal microbiota structure and weakened the therapeutic effects of EA.

Conclusion: EA effectively improved glucose metabolism in T2DM rats. The hypoglycemic effects of EA were associated with the regulation of gut microbiota, SCFAs, and GLP-1.