Dose related promoter effect of metanil yellow on the development of hepatic pre-neoplastic lesions induced by N-nitrosodiethylamine in rats.

: The dose-dependent effect of mentanil yellow (MY) on the development of preneoplastic hepatic lesions during N-nitrosodiethylamine (DEN) induced hepatocarcinogenesis was studied in comparison with phenobarbitone (PB), in male Wistar (WR) rats. Rats were administered 200 ppm DEN through drinking water for a period of 1 month. After an interval of 2 wk, the animals were administered MY at concentrations of 0.1, 0.5 and 1.0 per cent in the diet for a period of 7 months. PB at 500 ppm served as the standard tumour promoter. The dose-dependent tumour promoter effects of MY were monitored on the basis of morphological appearance of the livers, liver weight profile, histological pattern, appearance of gamma-glutamyl transpeptidase (GGT) positive foci, total GGT activity and the induction of glycogen-deficient islands. All the three doses of MY were found to enhance liver carcinogenesis when compared with either the corresponding controls or only the DEN treated animals. MY at 0.1 per cent was found to be more effective as an enhancer of DEN-induced carcinogenesis than 0.5 and 1.0 per cent. In the present study a dose-related enhancing effect of MY on DEN-induced hepatic preneoplasia in rats has been demonstrated.