Effect of acupuncture combined with medicine on indomethacin-induced colonic injury in mice based on the Nrf2/HO-1 signaling pathway

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.