DISTRIBUTION OF CYTOCHROME-CYP2E1 IN MURINE LIVER AFTER ETHANOL AND ACETONE ADMINISTRATION

The effects of acetone and ethanol administration on cytochrome CYP2E1 in murine liver were investigated. A monoclonal antibody (Mab 1-98-1) specific to rat ethanol-inducible P450 recognized a major band of M(r) 51 000 in Western immunoblots of mouse liver microsomes. This band was increased 1.8-fold by 10% ethanol in drinking water for 2 weeks, 4.7-fold by 1% acetone in drinking water for 1 week, and 2.5-, 2.1- and 6.8-fold by ethanol in a liquid diet for 9 days, 2 weeks and 3 weeks respectively. Immunohistochemical staining experiments with the same antibody showed specific localization in centrilobular regions of liver lobules, with variations in intensity that corresponded to differences detected in Western immunoblots. Uniform cellular increases in centrilobular staining occurred with all ethanol treatments, whereas a more heterogeneous increase in individual cells was noted after acetone. Lipid accumulation in hepatocytes was pronounced after 3 weeks on the ethanol lipid diet but was less so in other treatment groups, and thus did not consistently correlate with enzyme induction. Microsomal aniline p-hydroxylase activity was also induced by the acetone and ethanol treatments, with a progressive increase from 9 days to 3 weeks on the ethanol liquid diet. Changes in this activity in general paralleled those found with immunohistochemistry and immunoblotting. The results demonstrate that (i) the mouse is a good model for correlative biochemical and histochemical studies of CYP2E1 induction, (ii) in the mouse liver, this P450 is preferentially localized in centrilobular regions constitutively as well as in induced states, (iii) the centrilobular pattern varies under different induction conditions, and (iv) there is a progressive inductive increase in CYP2E1 protein and enzyme activity with chronic ethanol treatment over at least 3 weeks.