Effects of heavy metals on dental hard tissues formation and pulpal polyamines.

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Although some heavy metals are known to cause disturbances of hard tissues formation, the precise mechanisms remains obscure. In these studies, effects of heavy metal, cadmium, on the polyamines and diamines metabolisms in rat incisor pulp were investigated.1. The chromatographic patterns of dental pulpal polyamines and diamines are different from those of hepatic's. The specific patterns of pulpal polyamines may be due to the unique histology of pulp. The putrescine content in the rat incisor pulp showed the diurnal changes and, in other experiment, it was observed the diurnal rhythm in the pulpal putrescine in rat incisor is induced by feeding mainly. Putrscine and polyamines in rat incisor pulp decreased with age. This result may indicates that the cellular proliferation of rat incisor pulp occurs actively in younger rats and that the duration of life cycle of pulp cells increase with age.2. The sex difference in the cadmium effect on pulpal polyamines in rat incisor were studied. This is of interest because of the sex difference in rat dental tissues to cadmium. The sex difference were observed in cadmium effects on diamines and polyamines contents in rat incisor pulp in vivo, but, in vitro experiment using cultured pulp cells, sex difference was not observed in the response of cells to cadmium.3. The colchicine effect on the pulpal histamine and putrescine contents in rat bone marrow was studied and histamine content showed diaphasic changes in time course study. The effects of LPS and thioacetamide on histidine- and ornithine-decarboxylases activities in rat incisor pulp were studied. Histidine decarboxylase activity was easily induced by these drugs.