Colite do cólon excluso: modelo experimental em ratos

In 1981 Glotzer et al. described a kind of proctocolitis, limited to a segment of colon, excluded from the fecal stream, with pathological features similar to the ulcerative colitis. The purpose of the present study was to establish a experimental model in order to evaluate the pathologic alterations of the colonic mucosa, excluded from the intestinal transit. Thirty five PUCPR Wistar male rats, with a mean age of 120 days were allocated in 4 groups. Under ether anesthesia, the animals were submitted to a 0,5cm resection of the left colon. A proximal terminal colostomy was performed and the distal rectal stump was closed. The excluded segment of the bowel was evaluated macro and microscopically a week (A group), 2 weeks (D group), 4 weeks (B group) and 8 weeks (C group) after the operation. The inflammatory reaction, collagen concentration and changes in the goblets cells were analyzed .Mo was considered the features of the excluded colon seen at the beginning of the experiment and Mf was these features seen at the end of experiment. When we compared these two different phases of the experiment, we verified that a mild acute and cronic inflammatory reaction was present in all of the groups. Ulcers were seen in 11 colons (p=0,0010) and they were not related to the exclusion phase. A significant reduction in the thickness of the colonic wall was observed in all the specimens. In Mo, the mature collagen (type I) was the predominant one (p=0.008) whereas in Mf, the immature collagen ( type III) was the predominant one (p=0.008). Reduction of total collagen, loss of collagen type I and the increase of collagen type III were constant. There was no significant change in the percentage of area occupied by the goblets cells. It was concluded that in rats, the exclusion of the distal colon by colostomy of up to 8 weeks, determines: colon atrophy and the occurrence of superficial ulcerated lesions with low-level inflammatory reaction.