LOCALIZATION AND SIGNIFICANCE OF GAMMA-GLUTAMYL TRANSPEPTIDASE DURING EXPERIMENTAL THYROID CARCINOGENESIS IN RATS

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Gamma-glutamyl transpeptidase (GGT) has been one of useful marker enzymes in experimental hepatocarcinogenesis in rodents, with an implication of its onco-fetal property. Human and experimental neoplasms of various organs have been investigated for their GGT activities from the same standpoint in experimental hepatocarcinogenesis. We have recently demonstrated the induction of GGT activity in the early lesions of experimental thyroid carcinogenesis in rats. In the present study, the distribution of rather strong GGT activity was confirmed in microscopic putative precancerous lesions to thyroid carcinomas induced by diisopropanolnitrosamine (DIPN), an established thyroid carcinogen. In contrast to no GGT activity in adult rat thyroid follicles, a significant reaction for GGT was revealed in fetal rat thyroid tissues in this investigation. From these facts, it is concluded that GGT is a potent histochemical marker during experimental thyroid carcinogenesis in rats, proposing an onco-fetal property of GGT also in the thyroid.