Heterogeneous distribution of glucose-6-phosphate dehydrogenase in lingualepithelium

Lingual epithelium undergoes oxidative stress and apoptosis with consequent renewal of superficial keratinized cells by proliferation and differentati on of the stem cells of the basal germinative layer. In 3 distinct areas of lingual epithelium of rat and rabbit, the anterior third, central third an d posterior third, we determined the activity of hexose monophosphate shunt enzymes and antioxidant enzymes, which are essential for support of cell p roliferation and differentation. Enzymatic assays of the epithelium showed that glucose-6-phosphate dehydrogenase (G6PD) activity was highest in the a nterior third, whereas activity of glutathione peroxidase, 6-phosphoglucona te dehydrogenase, glutathione reductase, superoxide dismutase and catalase was similar over all areas. Histochemical localization of activity and immu nohistochemical localization of protein of G6PD showed that all types of pa pillae had a similar G6PD content; moreover, the presence of different G6PD isoforms in the 3 areas was excluded by electrophoretic analysis. We concl ude that the higher G6PD activity in the anterior part of the epithelium is due only to the anatomical organization of the epithelial surface of this area, in which many filiform and fungiform papillae are arranged in a compa ct manner, which corresponds with a higher number of proliferating and diff erentiating cells. These processes need products of G6PD activity. This stu dy indicates that G6PD is a good marker for the number of differentiating c ells in tongue epithelium.