Temporal changes in colonic vascular architecture and inflammatory mediator levels in animal models of colitis.

This study investigated the temporal relationship between inflammatory mediator production and colonic vascular architecture in rabbit and rat trinitrobenzene sulfonic acid (TNBS) models of colitis. In both species significant colonic damage and loss of mucosal integrity occurred over time. In the rabbit there was a significant increase in TxB2 levels in the muscularis propria and mucosa at 1, 6, and 48 hr after TNBS, with a significant elevation in PGE2 production in the muscularis propria at 48 hr. However, elevated mediator levels were not associated with measurable changes in vascular architecture. In contrast, significant changes in the numbers and diameters of colonic blood vessels were observed in the rat, in the absence of significant elevations in TxB2 or PGE2 levels. These data suggest that the role of lipid mediators in acute colitis is species-dependent and, although there are corresponding gross and microscopic changes in both models, these occur through disparate mechanisms.