Abstract
Ions, small molecules, and drugs are absorbed in the intestinal epithelium mediated by transcellular and paracellular pathways. The function of various transporters expressing in the apical and basolateral membranes of intestinal epithelial cells has been well characterized. In contrast, claudins and occludin, components of the tight junctions (TJs), determine the paracellular permeability to ions and low molecular weight compounds, but the properties for permeability has not been clarified in detail. In the present study, we examined the effects of anti-histamine drugs, chlorpheniramine and diphenhydramine, on transepithelial electrical resistance (TER) and permeability to lucifer yellow (LY), a marker of paracellular permeability, using murine colonic MCE301 cells. Chlorpheniramine significantly decreased the steady state of TER and increased permeability to LY, whereas the effects of diphenhydramine were not significant. The mRNAs of occludin and claudin-1-claudin-8 except for claudin-5 were expressed in MCE301 cells. Both anti-histamine drugs did not change solubility of claudins to 0.5% Triton X-100 solution. In contrast, the detergent solubility and intracellular localization of occludin were significantly increased by chlorpheniramine. These results indicate that occludin is dissociated from the TJs by chlorpheniramine. Chlorpheniramine increased protein phosphatase-2A (PP-2A) activity, which was inhibited by cantharidin, a potent PP-2A inhibitor. Furthermore, the changes of TER, permeability to LY, and de-phosphorylation and tight junctional localization of occludin caused by chlorpheniramine were recovered by cantharidin. These results suggest that chlorpheniramine could increase paracellular permeability to low molecular weight compounds mediated by the activation of PP-2A and internalization of occludin in the colonic epithelial cells.
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