The Role Of Adrenomedullin In Experimental Ulcerative Colitis Mice

Objective:To observe the effect of AM on UC mice and explore its possible mechanism.Methods:(1)Grouping of animals:30 C57BL/6 mice were randomly divided into normal control group,model group and AM intervention group,with 10 in each group.(2)Modeling:The mice in the control group were given free drinking water,and the model group and AM group were given 4% DSS water solution for 7 days,then the acute UC model was established.(3)After the success of the model,mice in each group returned to normal drinking water,the control group and model group was given 0.5 ml saline enema,the AM group was given 0.5 ml AM enema,during the experiment,the changes of spirit,hair,diet and defecation were observed,and the changes of body mass of mice were recorded,After 7 days of continuous enema,retaine the mice blood and colon tissues,evaluate the index of disease activity,intestinal mucosa and histological damage in the 3 groups of mice.(4)The pathological changes of mouse colon were evaluated by HE staining,the expression of TLR4,MyD88,NF-κB protein in colonic tissue was detected by Western Blot and the expression of NF-κB、TNF-α、IL-6 in serum was detected by Elisa.SPSS 22.0 was used for all statistical analysis and data were expressed as mean±SD values((?(±S),a one-way analysis of variance was used for comparison of means between any two groups,the difference was statistically significant with P<0.05.Results:(1)After DSS was made,compared with AM group,the mental state of the model group became worse,the activity decreased,the body mass decreased,and the stool became thinner and thinner.In severe cases,bloody purulent stool was found in the model group.(2)The score of disease activity index,intestinal mucosa and histological injury in the model group were significantly higher than those in the control group and AM group(P<0.01).(3)Western Blotting results showed that the expression levels of TLR4,MyD88 and NF-κB in the model group were significantly increased compared with the control group(P<0.01).After AM,the expression of the three proteins was lower than that of the model group(P<0.05).(4)The results of ELISA showed that compared with the control group,NF-κB,TNF-α and IL-6 were highly expressed in the serum of the model group(P<0.01).After AM intervention,the expression of the three was significantly lower than that of the model group(P<0.05).Conclusion:AM intervention can attenuate colonic injury in UC mice by inhibiting TLR4/MyD88/NF-κB signaling pathway and down-regulating the expression of inflammatory factors such as TNF-α and IL-6,which may play a therapeutic role in UC mice.