RELATION BETWEEN ALBUMIN-POSITIVE HEPATOCYTES AND GLUTATHIONE-S-TRANSFERASE-POSITIVE FOCI IN NAGASE ANALBUMINEMIC RATS TREATED WITH 3'-METHYL-4-DIAMINOAZOBENZENE

Hepatomas were induced in Nagase analbuminemic rats (NARs) by administration of 3'-methyl-4-diaminoazobenzene (3'-Me-DAB), and the correlation between the change in the population of albumin-positive (Alb+) hepatocytes and the area of placental form of glutathione-S-transferase (GST-P) positive foci, an index of preneoplastic foci, was investigated immunohistochemically. The population of Alb+ hepatocytes increased with prolongation in the period of 3'-Me-DAB administration, and this increase was highest in animals without cancer, reaching about twice that in non-cancerous areas of the liver of cancer-bearing animals. This difference occurred because GST-P positive foci contained few Alb+ hepatocytes, which were numerous in non-cancerous areas of the liver in cancer bearing cases. An inverse correlation was also found between the percentage occupancy of GST-P positive foci and the densiry of Alb+ hepatocytes. This inverse relationship between GST-P positive foci and Alb+ hepatocytes was confirmed by studies on partially hepatectomized animals. We inferred from these results that the influence of carcinogens on the albumin gene may be mediated by a different mechanism from that for inducing carcinogenesis.