[Study on the experimental ulcerative colitis model induced by dextran sulfate sodium in rats: estimation of mucosal...

We have developed a new method that is applicable for a macroscopic and objective evaluation of erosion in the large intestine in the experimental ulcerative colitis model induced by dextran sulfate sodium (DSS) in rats. The large intestine (without cecum) fixed in 10% neutral buffered formalin solution for more than one week was opened and stained with 1% alcian blue solution. The mucosal surface was stained in light and shade-blue. Histopathological examination revealed that the dark blue area on the mucosal surface had no epithelia and that the connective tissues in the lamina propria were stained with alcian blue. Salazosulfapyridine at 15 and 50 mg/kg twice a day inhibited the erosion area (dark blue area) by 29.6% and 50.2%, respectively. Also, prednisolone at 0.5 mg/kg, twice a day inhibited the erosion by 53.3%. Thus, by measuring the dark blue area stained with 1% alcian blue solution, we could estimate macroscopically and objectively the area of erosions. This method seems to be a useful index for assessing the damages produced in the experimental ulcerative colitis model in rats.