[Effect of acupoint catgut embedding on intestinal mucosal epithelial barrier in ulcerative colitis rats]

To observe the effect of acupoint catgut embedding on intestinal mucosal epithelial injury, and expression of epithelial tight junction proteins and mRNAs and protein kinase C(PKC) protein (intestinal mucosal epithelial barrier-related molecules) in rats with experimental ulcerative colitis (UC) of "deficiency-stasis" type, so as to explore its mechanisms underlying improvement of UC.

Male SD rats were randomly divided into normal control, UC model, medication (sulfasalazine, SASP) and catgut-embedding groups. The "deficiency-stasis" type UC model was established by gavage of adenine (10 mL/kg) for 2 weeks, cold Folium Sennae (10 mL/kg) for 2 weeks, and then enema of mixture solution of 5% trinitro-benzene-sulfonic acid (100 mg/kg) + 50% ethyl alcohol. Rats of the medication group received gavage of SASP. The catgut-embedment was applied to bilateral "Tianshu"(ST23),"Zusanli"(ST36), "Geshu"(BL17), "Pishu"(BL20), "Shenshu"(BL23) and "Dachangshu"(BL25), once every two weeks, 3 times altogether. The body mass was recorded, and histopathological changes of the colon tissues were observed after H.E. staining. The contents of serum D-lactic acid (D-LA), diamine oxidase (DAO) and protein kinase C (PKC) were detected by ELISA. The expression levels of occludin, claudin-8, cingulin and zonulin mRNAs and proteins and PKC protein of the colon tissues were detected by using quantitative real-time PCR and Western blot, separately.

Compared with the control group, the body mass and expression levels of colonic occludin, claudin-8 and cingulin mRNAs and proteins were significantly lower (P<0.01), and the colonic mucosa damage index (CMDI) score, contents of serum D-LA, DAO and PKC, as well as the expression levels of zonulin mRNA and protein and PKC protein were significantly higher in the model group (P<0.01). In comparison with the model group, the body mass, and the expression levels of occludin, claudin-8 and cingulin mRNAs and proteins were significantly higher (P<0.05, P<0.01), whereas the CMDI score, expression levels of zonulin mRNA and protein and PKC protein were remarkably lower in both the medication group and acupoint embedding groups (P<0.05,P<0.01). No significant differences were found between the acupoint embedding and medication groups in all the indexes mentioned above (P>0.05). H.E. staining showed markedly swollen, disordered arrangement of intestinal mucosal cells, and hemorrhage with infiltration of inflammatory cells in the colonic tissues after modeling, which was relatively milder in both medication and acupoint embedding groups.

Acupoint catgut embedding can reduce colonic tissue injury in UC rats, which may be related to its functions in regulating the expression of intestinal epithelial tight junction proteins and mRNAs and in inhibiting the activation of PKC protein.