BackgroundAlthough a dextran sodium sulfate (DSS)-induced colitis is commonly used as an ulcerative colitis (UC) model in adult rodents, there are no studies using this model in young animals. We examined differences in the severity of DSS-induced colitis as a function of the concentration of DSS administered and sought to establish a DSS-induced colitis model in young rats.MethodsWe administrated different concentrations of DSS solution (2%, 3%, and 4%) to 4-week-old weanling rats and compared their clinical findings, colonic histologic findings, mucosal leukotriene B4(LTB4) production, and mucosal blood flow with control weanling rats and 8-week-old adult rats given 4% DSS for induced colitis.ResultsClinical symptoms, such as diarrhea and rectal bleeding, histologic findings, and disturbance of mucosal microcirculation in weanling rats given 4% DSS were significantly more severe than those in adult rats given the same treatment. Three of 10 rats given 2% DSS had no bloody stool and 2 of 10 rats given 4% DSS died during the experimental periods. Clinical symptoms, hemoglobin levels, histologic damage scores, mucosal LTB4production, and mucosal blood flow became more severely deranged as the concentration of DSS increased from 2% to 4%.ConclusionThese findings suggest that we can adjust disease severity in UC model for young children by giving different concentrations of DSS to weanling rats.