Effect of acupoint thread-embedding on tight junction of intestinal mucosa epithelium in rats with ulcerative colitis

Abstract

To observe the effect of acupoint thread-embedding on tight junction of intestinal mucosal epithelial barrier in rats with ulcerative colitis (UC) under the state of "deficiency and stasis", and to explore its mechanism. Sixty male SD rats were randomly divided into a control group (n=12) and a UC model group (n=48). The rats were gavaged with adenine and folium sennae by stages to prepare the "deficiency and stasis" state, and then 5% 2,4,6-trinitrobenzene sulfonic acid (TNBS, 100 mg/kg) and 0.25 mL 50% ethanol were used to induce UC model. Thirty rats with successful model establishment were selected and randomly divided into a model group, a medication group and a thread-embedding group, 10 rats in each group. The rats in the thread-embedding group were intervened with thread-embedding at "Zusanli" (ST 36), "Tianshu" (ST 25), "Geshu" (BL 17), "Pishu" (BL 20), "Shenshu" (BL 23) and "Dachangshu" (BL 25), once every 14 days, totaling 3 times. The rats in the medication group were gavaged with sulfasalazine, once a day. The rats in the control group, model group and thread-embedding group were gavaged with the same amount of 0.9% sodium chloride solution at the same time for 42 days. The general condition and body weight of rats in each group were observed. The appearance and morphological changes of colonic tissue were observed by naked eye and HE staining. The serum levels of calmodulin-dependent protein kinaseⅡ(CaMKⅡ) and myosin light chain kinase (MLCK) were detected by ELISA. The mRNA levels of colonic tight junction (TJ) proteins including occludin, claudin1, claudin2 and ZO-1were detected by quantitative real-time PCR. The protein expressions of occludin, claudin1, claudin2, ZO-1 and CaMKⅡ, MLCK were detected by Western blot. Compared with the control group, in the model group the body weight was decreased (P<0.01), colon tissue was significantly swelled with bleeding and a large number of inflammatory cells infiltration, and the colon tissues damage index score was increased (P<0.01), serum CaMKⅡ and MLCK levels were increased (P<0.01), and the mRNA and protein expression levels of occludin, claudin1 and ZO-1 in colon tissue were decreased (P<0.01), the mRNA and protein expression levels of claudin2 were increased (P<0.01), and the protein expression levels of CaMKⅡ and MLCK were increased (P<0.01). Compared with the model group, in the medication group and thread-embedding group the weight was increased (P<0.01), the colonic lesions were significantly alleviated, the tissues damage index scores were decreased (P<0.01), the serum CaMKⅡ and MLCK contents were decreased (P<0.01), the mRNA and protein expression levels of occludin, claudin1 and ZO-1 in colonic tissue were increased (P<0.01, P<0.05), the mRNA and protein expression levels of claudin2 were decreased (P<0.01), and the protein expression levels of CaMKⅡ and MLCK were decreased (P<0.01, P<0.05). There was no significant difference of each index between the medication group and thread-embedding group (P>0.05). The thread-embedding could repair the tight junction of intestinal mucosa epithelium and reduce the permeability of intestinal mucosa epithelium, which may be related to the decrease of the expression of CaMKⅡ, MLCK and other protein kinases.