Inhibition of liver glutathione S-transferase placental form-positive foci development in the rat hepatocarcinogenesis by Porphyra tenera (Asakusa-nori). |
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Authors: | T Ichihara H Wanibuchi T Taniyama Y Okai Y Yano S Otani S Imaoka Y Funae S Fukushima |
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Institution: | Department of Pathology, Osaka City University Medical School, Osaka, Japan. |
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Abstract: | The effects of Asakusa-nori, Porphyra tenera (PT), a popular edible seaweed in Japan, on the development of putative preneoplastic lesions, glutathione S-transferase placental form (GST-P)-positive foci, in the male F344 rat liver were examined using a medium-term bioassay system. PT significantly decreased both the number and area of GST-P-positive foci in rat livers initiated with diethylnitrosamine (DEN). To investigate possible mechanisms of inhibition, effects of PT on 5-bromo-2'-deoxyuridine (BrdU) labeling in GST-P-positive foci and the surrounding area of hepatocytes were studied. The ratio of the GST-P-positive foci to surrounding tissue labeling indices was decreased in the PT-treated group as compared with the DEN alone group. Ornithine decarboxylase activity in the liver was slightly increased and spermidine/spermine N'-acetyltransferase activity was slightly decreased in the PT-treated animals. These results suggest that PT possesses chemopreventive effects against DEN-induced hepatocarcinogenesis. |
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