Immunohistochemical localization of Nox in mouse circumvallate papillae

•Nox is constantly expressed and reactive oxygen species are produced in mouse circumvallate papillae.•Reactive oxygen species are involved in host defenses and the keratinization process in the upper circumvallate papillary epithelium.•Nox3 was expressed in the upper circumvallate papillary epithelium and localized in the cells of taste buds.•All cells comprising taste buds expressed Nox, with each showing a specific Nox expression pattern.

Recently it has been reported that reactive oxygen species plays an important role in several physiological processes. Reactive oxygen species are generated by reactive oxygen-synthesizing enzymes (Nox). We immunohistochemically investigated expression and localization of the Nox family in a mouse circumvallate papillae. In the epithelium of the circumvallate papilla, Nox 1, 2, 3, and 4, Noxo1, and Noxa1 were expressed. In the circumvallate papilla, Nox2 was more weakly expressed in the lateral than in the upper part, and Nox3 was not expressed. In the taste buds, Nox 1, 2, 3, and 4, Noxo1, and Noxa1 were expressed; the Nox expression pattern varied with the cell type. In type II cells, Nox 1, 3, and 4, Noxo1, and Noxa1 were expressed. In type III cells, Nox2, besides Nox 1, 3, and 4, Noxo1, and Noxa1, were specifically expressed, unlike in other taste bud cells. In the mouse circumvallate papilla, Nox is always expressed, suggesting the generation of reactive oxygen species. Of note, all cells comprising taste buds expressed Nox, with each showing a specific Nox expression pattern.

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