Establishment and Evaluation of a Rat Model of Anal Fistula with Damp-heat Descending Syndrome

YE Qianqian; CHEN Jingjing; LIU Yicheng; FENG Zhen; WANG Qingming

Abstract：Objective On the basis of constructing the damp heat descending syndrome in rats,combined with the virtual hanging of a stainless steel pin around the anus,a rat anal fistula model of damp-heat descending syndrome was established,and the model was preliminarily evaluated.Methods Sixteen SD male rats were randomly divided into a normal group and a model group,with 8 rats in each group.After 5 days of adaptive feeding,the model group was housed on wet bedding and fed a high-fat,high-sugar diet,supplemented with white wine via gavage every other day.After 7 days of preliminary construction of the damp-heat descending syndrome in rats,a stainless steel pin was used for virtual hanging,while the damp-heat descending syndrome was continued to be constructed for 30 days.General rat conditions,symptom scores,anal temperature,serum inflammatory factors,perianal ultrasound,and pathological sections were used as preliminary evaluation indicators for the rat model of damp-heat descending syndrome.Results Rats in the model group exhibited symptoms including squinting,red tongue,dull hair color,listlessness,unclean perianal area,darkened urine,and soft stool.The damp-heat symptom score was significantly higher in the model group compared to the normal group(P<0.05).Anal temperature in the model group rats significantly increased post-pin suspension(P<0.05),along with elevated serum levels of TNF-α and IL-8(P<0.05).Ultrasound revealed distinct strip-shaped hypoechoic areas with clear boundaries post-modeling.Pathological sections indicated the formation of fistula tracts,significant fistula fibrosis,and infiltration of inflammatory cells and granulation tissue surrounding the fistula.Conclusion The combination of wet environment,high-fat,high-sugar diet,white wine gavage,and stainless steel pin suspension successfully established a rat model of anal fistula with damp-heat descending syndrome.This model provides a robust animal model that integrates disease and syndrome for foundational research on anal fistula.