HISTOCHEMICAL DEMONSTRATION OF INCREASED ACTIVITY OF γ-GLUTAMYL TRANSPEPTIDASE IN RAT LIVER DURING HEPATOCARCINOGENESIS

Histochemical demonstration of γ-glutamyl transpeptidase (γ-GTP) during chemically induced hepatocarcinogenesis in the rats was studied. The carcinogens employed were N-OH-FAA (N-hydroxy derivative of N-2-fluorenylacetamide), and aflatoxin B1.In the control rats, activity of γ-GTP was demonstrated in the bile duct cells and occasionally along the bile canaliculi, but was not in the hepatocytes. Proliferating bile duct cells including so-called oval cells and cholangiocarcinoma cells, and hepatocytes of hyperplastic areas and nodules and hepatocellular carcinoma induced by N-OH-FAA with or without aflatoxin B1 revealed positive activity of γ-GTP, histochemically. Only focal demonstration of γ-GTP activity in the hepatocyte was observed in association with a mild hyperplastic change in rats treated with aflatoxin B1 alone.The elevation of γ-GTP activity in serum and liver tissue with appearance of fetal type of its isoenzyme pattern was also demonstrated biochemically and correlated with the histochemical appearance of γ-GTP activity in the liver tissue from the early phase of hepatobiliary carcinogenesis.These results seem to demonstrate carcino-embryonic nature of the induced γ-GTP in the development of cholangiocellular and hepatocellular carcinomas.