[Effect of electroacupuncture on colonic autophagy and AMPK/mTOR signaling pathway in rats with acute ulcerative colitis].

Abstract

Objective: To observe the effect of electroacupuncture （EA） at "Zhongwan" （CV12）, "Tianshu" （ST25） and "Shangjuxu" （ST37） （an acupoint prescription "Changbingfang" for treatment of intestinal disorders） on autophagy and expression of AMPK/mTOR signaling pathway in rats with ulcerative colitis （UC）, so as to explore its mechanism underlying improvement of UC.

Methods: Thirty-two male SD rats were randomly divided into control, model, medication and EA groups, with 8 rats in each group. The UC model was established by free drinking of 5% dextran sulfate sodium salt solution for 7 days. EA stimulation （10 Hz/50 Hz） was delivered to CV12, ST25 and ST37 for 20 min, once a day for 3 consecutive days. Rats of the medication group received gavage of mesalazine suspension （200 mg/kg） once a day, 3 times in total. The rats' general conditions were recorded for calculating the disease activity index （DAI） score （0-4 points）. Histomorphological changes of colon were observed via HE staining. The levels of serum interleukin 6 （IL-6）, tumor necrosis factor-α （TNF-α） and IL-10 were measured by ELISA. The mRNA expressions of LC3B and p62 were tested by fluorescence quantitative PCR. Western blot was used to detect the expression levels of LC3B, p62 and AMPK/mTOR pathway related proteins in colon tissues.

Results: Compared with the control group, the DAI score, contents of serum IL-6 and TNF-α, the expression levels of p62 protein and mRNA, ratio of p-mTOR/mTOR were significantly increased （P<0.01）； while the content of serum IL-10, the expression levels of LC3B mRNA, ratio of LC3BⅡ/LC3BⅠ and p-AMPK/AMPK were decreased （P<0.01, P<0.05） in the model group. Relevant to the model group, modeling-induced increases of DAI score, serum IL-6, TNF-α and IL-10 contents, expressions of p62 protein and mRNA, LC3B mRNA, ratio of p-mTOR/mTOR, LC3BⅡ/LC3BⅠ and p-AMPK/AMPK were reversed in both medication and EA groups （P<0.01, P<0.05）. The effect of EA was apparently superior to that of mesalazine in up-regulating ratio of LC3BⅡ/LC3BⅠ and p-AMPK/AMPK, p62 mRNA expression （P<0.01, P<0.05）, and in down-regulating ratio of p-mTOR/mTOR （P<0.05）. H.E. staining showed severe damage of the colonic mucosal barrier with infiltration of a large number of inflammatory cells in the model group, which was milder in medication and EA groups.

Conclusion: EA of acupoint recipe "Changbingfang" can improve the symptoms in UC rats, which may be related to its functions in promoting colonic autophagy, increasing AMPK phosphorylation level, and decreasing mTOR phosphorylation level.