To investigate the regulative effects of electroacupuncture at Zusanli point on the tight junction protein zonula occludens (ZO)-1 of small intestinal mucosal epithelium in rats with intestinal ischemia-reperfusion injury.

Thirty SD rats were divided into model group, electroacupuncture Zusanli group, electroacupuncture non-meridian non-acupoint group according to the random number table method, 10 rats in each group. After anesthesia, the rats in each group were cut along the median abdominal line, the superior mesenteric artery was separated, and its initial position was clamped with a non-invasive vascular clamp. After 30 minutes, the clamp was released to restore blood flow for 60 minutes, causing intestinal ischemia/reperfusion injury. In the electroacupuncture Zusanli group, electroacupuncture was performed at Zusanli point for 30 minutes immediately after ischemia, with an intensity of 2- 3 mA and a frequency of 2 - 100 Hz; in the electroacupuncture non-meridian non-acupoint group, rats were stimulated at non-meridian and non-acupoints with the same frequency and intensity immediately after ischemia (0.5 cm beside the lateral side of Zusanli point) for 30 minutes; the model group received no treatment. At 60 minutes of ischemia-reperfusion injury, the rats in each group were killed by abdominal aortic bloodletting, and the blood and 10 cm distal ileal tissue of each rat were retained. The collected rat blood was centrifuged at 10 000×g for 10 min at 4 ℃ and the supernatant was taken to obtain 20 μL of plasma. An automatic biochemical analyzer was used to detect the functional indexes of the rat plasma organs, including glutamic-pyruvic transaminase (GPT), creatine kinase isoenzyme (CK-MB), urea nitrogen and creatinine. Immunofluorescence staining and Western blotting were used to detect the distribution and expression of tight junction protein ZO-1 in the small intestinal mucosa of rats in each group. Data were compared by one-way ANOVA and LSD-t test.

At 60 minutes of ischemia-reperfusion injury, the levels of GPT, CK-MB, urea nitrogen and creatinine in the model group were (88.1±11.6) μ/L, (482.3±69.7) μ/L, (11.6±3.7) mmol/L, (52.3±13.2) μmol/L, electroacupuncture Zusanli group were (37.3±6.4) μ/L, (213.7±44.3) μ/L, (5.2±1.4) mmol/L, (30.1±5.7) μmol/L, electroacupuncture non-meridian non-acupoint group were (85.7±13.4) μ/L, (460.2±72.3) μ/L, (10.8±4.2) mmol/L, (53.4±12.1) μmol/L, respectively. There were statistically significant differences in the indexes of the three groups (F=69.4063, 55.3611, 10.9582, 14.6817; P < 0.05). Compared with the model group, the levels of GPT, CK-MB, urea nitrogen and creatinine in the plasma of rats in the electroacupuncture Zusanli group were all decreased, and the differences were statistically significant (t=12.126, 10.285, 5.116, 4.883; P< 0.05), while the levels of GPT, CK-MB, urea nitrogen and creatinine in the plasma of rats in the electroacupuncture non-meridian non-acupoint group were similar to the model group, and the differences between the 2 groups were not statistically significant (P> 0.05). The plasma GPT, CK-MB, urea nitrogen and creatinine levels of rats in the electroacupuncture Zusanli group were lower than those in the electroacupuncture non-meridian non-acupoint group, and the differences were statistically significant (t=-10.307, -9.193, -4.000, -5.509; P< 0.05). Immunofluorescence staining showed that at 60 minutes of ischemia-reperfusion injury, the distribution of tight junction protein ZO-1 in the small intestine mucosal epithelium of the rats in the model group was abnormal, the continuity was destroyed, and the expression was reduced. The distribution density of tight junction protein ZO-1 in small intestinal mucosal epithelium of rats in electroacupuncture Zusanli group was relatively dense, complete and continuous. In the electroacupuncture non-meridian non-acupoint group, the expression of ZO-1 protein in the small intestinal mucosal epithelium of rats was broken and partially missing, and the fluorescence of intestinal epithelial tight junction protein ZO-1 was weak and the continuity was disappeared. The results of Western blotting showed that at 60 minutes of ischemia-reperfusion injury, the expression of ZO-1 protein in the small intestinal mucosal epithelium of the rats of electroacupuncture Zusanli group (1.67±0.43) was significantly higher than that of model group (0.86±0.31) and electroacupuncture non-meridian non-acupoint group(0.89±0.29), and the differences were statistically significance (t=4.517, 3.965; P< 0.05). The expression of ZO-1 protein in intestinal tissue of electroacupuncture non-meridian non-acupoint group compared with the model group, the difference was no statistically significant (P>0.05).

Electroacupuncture at Zusanli point can effectively regulate the normal distribution and expression of tight junction protein ZO-1 in the intestinal mucosa, effectively protect the intestinal mucosal barrier function after intestinal ischemia-reperfusion injury, and reduce the damage of organ function after intestinal ischemia-reperfusion.