Enhancement of altered hepatic foci in rat liver and inhibition of intercellular communication in vitro by the pyrethroid insecticides fenvalerate, flucythrinate and cypermethrin

Male Sprague-Dawley rats dosed with N-nitrosodiethylamine (NDEA) 24 h after two-thirds partial hepatectomy were treated with the pyrethroid insecticides fenvalerate, flucythrinate or cypermethrin in the diet for 20 weeks. Altered hepatic foci were analyzed by quantitative stereology from paraffin-embedded section stained for γ-glutamyltranspeptidase (GGT) or glutathione S-transferase P (GST-P). The present results demonstrate that the pyrethroids tested all enhance the development of NDEA-initiated, GGT-positive foci in rat liver at non-hepatotoxic doses. On the contrary, the volume fractions of GST-P-positive foci were not elevated as compared to the control group