Activity of glucose-6-phosphate dehydrogenase and acid phosphatase in nonkeratinized and keratinized oral epithelium and epidermis in the rabbit

There are very few reports in the literature on biochemical and histochemical comparative studies of enzyme activity in nonkeratinized and keratinized regions of oral epithelium in the same individuals of a species. Reported studies have dealt for the most part only with keratinized epithelium, and they suggest an important role for glucose-6-phosphate dehydrogenase and acid phosphatase in the process of keratinization. This is based on increasing activity of the two enzymes towards the surface of keratinized epithelium and decreasing activity in nonkeratinized. To eliminate the possibilitv that the differences observed are individual or species differences, non- keratinized and keratinized oral epithelia from the same animals were assayed. The ratio of activity in keratinized epithelium to that in nonkeratinized reachcd 13:l for acid phosphatase and 2:1 for glucose-6-PO₄ dehydrogenase. In nonkeratinized, activity of both enzymes decreased steadily towards the surface. In keratinized, acid phosphatase increased dramatically towards the surface; glucose-6-PO₄ dehydrogenase increased at first and then decreased. These findings offer evidence that the biochemical activities represented by the two enzymes have an important role in keratinization.