To explore the mechanism of electroacupuncture (EA) at “Zusanli” (ST36) in combination with omeprazole in treating gastrointestinal injury induced by indomethacin in mice.

Thirty C57BL/6J mice were randomly divided into normal control, model, omeprazole, EA combined with omeprazole (combination), and combination + nuclear factor E2-related factor 2 (Nrf2) inhibitor (inhibitor) groups, with 6 mice in each group. The gastrointestinal injury mouse model was established by intragastric administration of indomethacin (30 mg/kg). EA was applied to bilateral ST36 for 20 min, a total of 2 times. The omeprazole (10 mg/kg) was given by gavage. Mice in the inhibitor group were intraperitoneally injected with the Nrf2 inhibitor ML385 (30 mg/kg). HE staining was used to observe the morphological changes of the gastrointestinal mucosa. The contents of glutathione (GSH), malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) in gastric tissue and the activities of SOD and glutathione peroxidase (GSH-Px) in colon tissue were detected by colorimetric method. The level of reactive oxygen species (ROS) in colon tissue was detected by flow cytometry. The mRNA and protein expressions of Nrf2/heme oxygenase-1 (HO-1) signaling pathway-related factors Kelch-like epichlorohydrin-related protein factor 1 (Keap1), Nrf2, HO-1 and NADPH oxidase 1 (NOX1) in colon tissue were detected by qPCR and Western blot, respectively.

After modeling and compared with the normal control group, the mice of model group showed severe gastrointestinal mucosal damage, with decreased GSH content and SOD activity in gastric tissue (P<0.01), increased MDA content (P<0.01), elevated ROS levels, and increased Keap1 and NOX1 mRNA and protein expressions in colon tissue (P<0.01), reduced SOD and GSH-Px activities (P<0.01, P<0.05), decreased Nrf2 and HO-1 mRNA and protein levels in colon tissue (P<0.01). Compared with the model group, the gastric mucosal injury was improved, the content of GSH and the activity of SOD in the gastric tissue were increased (P<0.01, P<0.05), while the content of MDA was decreased (P<0.05, P<0.01) in both omeprazole and combination groups. In comparison with the model and the omeprazole groups, the combination group showed improved colonic mucosal injury, decreased ROS level (P<0.01), increased SOD and GSH-Px activities (P<0.05), up-regulated mRNA and protein expressions of Nrf2 and HO-1 (P<0.01), and down-regulated mRNA and protein expressions of Keap1 and NOX1 (P<0.01, P<0.05) in colon tissue. However, the improvement of gastrointestinal oxidative stress of combination treatment was reversed after the injection of Nrf2 inhibitor in the inhibitor group (P<0.01, P<0.05).

The integration of acupuncture and medication can effectively ameliorate indomethacin-induced gastrointestinal oxidative stress injury, which may be related to its function in activating the Nrf2/HO-1 signaling pathway.

To investigate the effect of electroacupuncture (EA) on intestinal motility and visceral sensitivity in functional constipation (FC) mice and its regulatory mechanism on Piezo1/2 channels in enterochromaffin (EC) cell.

Twenty-four male C57BL/6J mice were randomly divided into normal control, model, and EA groups (n=8 in each group). The FC model was established by gavage of loperamide hydrochloride. EA (1 mA, 3 Hz/15 Hz) was applied to unilateral “Tianshu” (ST25) and “Shangjuxu” (ST37) for 20 min per session, once daily for 5 consecutive days per week, two weeks altogether. Fecal parameters (number of stool particles in 6 h, characters, and fecal water content), intestinal motility (the time of the first blue stool excretion after gavage of Evans blue solution and small intestinal transit rate), and visceral sensitivity (assessed by abdominal withdrawal reflex [AWR] in responding to colorectal dilation) were observed. A transmission electron microscopy (TEM) was used to observe EC cells' ultrastructure. Triple immunofluorescence, Western blot and real-time qPCR were used to detect the expressions of Piezo1/2 in the EC cells and colon, and ELISA was employed to detect the contents of serum and colonic 5-HT and colonic Ca²⁺.

Compared with the normal group, the model group showed a significant reduction in the number of stool particles, fecal character score, and fecal water content, small intestinal transit rate, AWR scores at 0.25 mL, 0.35 mL and 0.65 mL, contents of serum and colonic 5-HT and colonic Ca²⁺, expression levels of colonic Piezol1 and Piezol 2 proteins and mRNAs, and the positive areas of Piezol1 and Piezol2, EC, Piezol1/EC and Piezol2/EC (P<0.01, P<0.001,P<0.05), and an evident increase in the time of the first blue stool particle excretion (decrease of intestinal propulsion) and AWR 3-points threshold (P<0.01). Following EA treatment, both the decrease and increase of the indexes mentioned above were reversed completely (P<0.05, P<0.001, P<0.01). TEM showed mitochondrial swelling and a reduction in the secretory granules of EC cells in the model group, which was partially restored following EA treatment.

EA of ST25 and ST37 can alleviate FC-related intestinal dysmotility and visceral hypersensitivity in FC mice, which may be associated with its functions in up-regulating Piezo1/2 channels of EC cell, promoting Ca²⁺ influx and 5-HT secretion.