Objective To investigate the mechanisms of catgut implantation at acupoints on ulcerative colitis. Methods Eighteen SD rats were randomly divided into a normal control group （NC）, a model group （MO） and a catgut implantation group （CI） with 6 rats in each group. Animals in group MO and group CI were treated by trinitro-benzene-sulfonic acid （TNBS） to establish model with colitis. No other treatment was given to the rats in group MO, but catgut was implanted at ＂Shàngjùxū＂ （上 巨虚 ST 37）, ＂Tiānshū＂ （天枢 ST 25） and ＂Dàchángshū＂ （大肠俞 BL 25） in the rats in group CI. The symptoms of diarrhea and bloody stool, and changes in histopathology were detected 15 days after the treatment. Expressions of splenic lymphocyte nuclear factor κB p65（NF-κB p65）and correlated signaling molecules（β2AR）were detected by the western blot method. Results Diarrhea and mucus bloody purulent stool were soon controlled, and mucous injures were obviously improved in group CI. The NF-κB p65 value of splenic lymphocytes was signifi cantly increased （P0.01） and expression of β2AR remarkably reduced in group MO （P0.01）, compared with group NC. But, the NF-κB p65 value was significantly decreased （P0.01） and expression of β2AR remarkably increased in group CI （P 0.01） , compared with group MO. Conclusion Catgut implantation at acupoints is obviously effective in treating experimental colitis. Modulation of NF-κB p65 and the correlated signaling molecules β2AR may be involved in the mechanisms.
