Thermal injury-induced changes in the rat intestine brush border cytoskeleton

The brush border cytoskeleton maintains the selective absorptive surface of the intestine epithelium. Increased intestinal permeability caused by cutaneous thermal injury may be the result of changes in the organization of the brush border cytoskeleton.

In this study we used electron and laser confocal microscopy to examine the temporal and spatial organization of the rat brush border cytoskeleton after thermal injury.

Vesiculation of microvilli and disruption of core actin filament bundles were observed in rats with burns covering 20% total body surface area (TBSA). In rats with 40% TBSA burns changes in the brush border cytoskeleton were more pronounced, resulting in increased vesiculation of microvilli and disruption of terminal web actin filaments. Confocal microscopy of corresponding areas of the gut epithelium after staining with rhodamine-phalloidin showed rearrangement of brush border actin filaments. Although tight junctions were intact, the apical region of the gut epithelium in rats with 40% TBSA burns was constricted, possibly because of contraction of brush border actin filaments. Changes in brush border structure and cytoskeletal organization were most pronounced in the ileum of rats 18 hours after injury.

These findings suggest that disruption of the brush border cytoskeleton may, in part, be responsible for the loss of intestinal barrier function after thermal injury in animal models.