In severely burned rats,
hyperemia,
edema and other pathological
injuries occur in the intestinal mucosa. Ultramicroscopically, the microvilli, tight junction and organelles are disrupted.
Occludin is a functional component of tight junctions. The purpose of the present study is to investigate changes of
occludin expression, and to further elucidate the relationship between
occludin expression and ultrastructure damage. The fluorescence intensity of
occludin was detected in intestinal wall by the method of immunofluorescence histochemistry and confocal
laser scanning microscopy (CLSM). Expression of
occludin and its
mRNA were determined by western blotting and RT-PCR, respectively. Changes of intestinal mucosa ultrastructure were observed by TEM. The results showed that fluorescence intensity of
occludin at 3PBH was enhanced, higher than that of the control group, being 80.77+/-8.38 and 72.86+/-4.74, respectively, and reached a peak at 12PBH (116.14+/-6.89). The expression levels of
occludin at 3PBH and 6PBH were 1.21+/-0.02 and 1.53+/-0.14 times that of the control group, respectively, and there were significant differences (P<0.01) between 3PBH group and 6PBH group and control group. The levels of
occludin mRNA were also enhanced. At 12PBH, the level reached a peak (P<0.01), being 2.00+/-0.24 times that of the control group. Coincidently, the structure of the tight junction between epithelial cells was disrupted on a large scale under TEM. We speculate that up-regulation of epithelial
occludin may play a role in enhancing paracellular permeability and be related to the damage to the tight junction.