THE LEC (LONG-EVANS CINNAMON) RAT AS AN ANIMAL-MODEL FOR BILIRUBIN-INDUCED TOOTH PIGMENTATION

The LEC (Long-Evans Cinnamon) rat is well known as a useful animal mod el for hepatic disease. We noticed the green pigmentation in incisors 2-3 week after acute hepatitis accompanied by severe jaundice. This st udy was under-taken to elucidate the cause of this phenomenon. Half of the pigmented teeth were examined by histopathological analysis and m icroradiographic analysis. Pigmentation was observed as a green stripe that ran parallel to the incremental line in the dentine. The microra diographic analysis disclosed enhanced permeability of the pigmented a rea as compared with other areas. The rest of pigmented teeth were dri ed powdered and bilirubin was extracted with chloroform/methanol/aceti c acid 30:20:0.5; v/v under sonication. After centrifugation,the super natant was collected and evaporated. The residue was dissolved in chlo roform and its absorption spectrum measured after diazo reaction to re veal the presence of bilirubin. The spectral characteristics indicated the presence of bilirubin in the pigmented teeth. Thus, the LEC mt ma y be useful animal model for bilirubin-induced tooth pigmentation.