Immunohistochemical localization of cytochrome P450 1A1 in precision-cut rat liver slices after in vitro exposure to beta-naphthoflavone.

Mono- and polyclonal antibodies have been used to study the localization and distribution of cytochrome P450 1A1 (CYP1A1) in cultured precision-cut liver slices with various immunohistochemical methods. Neither in non-incubated slices nor in slices incubated in the absence of beta-naphthoflavone (BNF) for 24 hrs was CYP1A1 immunohistochemically detectable. After incubation in the presence of BNF (25 microM), however, CYP1A1 was well visible in parenchymal and biliary epithelial cells. CYP1A1 was not evenly distributed, but was localized predominantly in hepatocyte layers near the surfaces of the slices. This distribution could be due to the preferential uptake of BNF by outer cell layers or due to functional changes of inner cells. Together with results obtained with other methods (e.g. RT-PCR) this investigation also demonstrates that precision-cut liver slices are a useful tool for the detection of in vitro induction of CYP1A1.