Effects of novobiocin on the induction of gamma-glutamyltranspeptidase positive foci in the liver of rats treated with diethylnitrosamine.

Effects of novobiocin on the induction of gamma-glutamyltranspeptidase(GGT)-positive foci, an early lesion occurring during hepatocarcinogenesis, after diethylnitrosamine(DEN) initiation were investigated in Fischer 344 rats. Animals were given DEN at a dose of 20 mg/kg b. w. followed by novobiocin at doses of 50, 100 and 200 mg/kg b. w. The latter two doses, but not 50 mg/kg b. w., significantly inhibited the development of GGT-positive foci, providing evidence of the possible involvement of mono(ADP-ribosyl)ation in the initiation phase of hepatocarcinogenesis in rats.