Effects of Electroacupuncture on Visceral Hypersensitivity, Low-Grade Colonic Mucosal Inflammation, and Colonic Function in Rats with Irritable Bowel Syndrome

Objective This study aimed to explore the mechanisms by which electroacupuncture (EA) treats irritable bowel syndrome (IBS) in rats. Materials and Methods Forty pups born to three healthy Specific Pathogen Free-grade SD rats were used, of which ten were selected as the control group (CG). The remaining thirty pups were prepared into the IBS model and grouped into the IBS model group (IBSG), ketotifen (KT) group (KTG), EA group (EAG), with interventions conducted once daily for 14 d. Anxiety-like behavior in rats was assessed, diarrhea symptoms were examined, and visceral hypersensitivity (VHS) was evaluated. Substance P (SP), protease-activated receptor-2 (PAR-2), and serotonin (5-HT) levels were detected. Results Compared with the CG, the IBSG suggested reduced movement distance, rearing frequency, and time spent in the central area; increased fecal water content (WC) and diarrhea index (DI); increased abdominal withdrawal reflex (AWR) scores under 20, 40, 60, and 80 mmHg pressures; decreased colonic pain threshold (PT) and slow-wave (SW) frequency; increased serum SP, PAR-2, and 5-HT; and increased protein expression levels of TLR4, NF-κB, and NLRP3 in colon tissues ( P < 0.05). Compared with the IBSG, the KTG and EAG suggested increased movement distance, rearing frequency, and time spent in the central area; decreased fecal WC and DI; decreased AWR scores; increased colonic PT and SW frequency; decreased serum SP, PAR-2, and 5-HT; and reduced TLR4, NF-κB, and NLRP3 in the colon ( P < 0.05). Conclusion The comprehensive EA intervention targeting “Tianshu” (ST25), “Zusanli” (ST36), and “Shangjuxu” (ST37) was associated with alleviated VHS, reduced markers of low-grade colonic inflammation, and improved colonic function in rats with IBS. These effects were consistent with the downregulation of the TLR4/NF-κB/NLRP3 signaling pathway.