EXPRESSION OF CYTOCHROME P4502E1 IN RAT FETAL HEPATOCYTE CULTURE

Cytochrome P450 (CYP) 2E1 is present at very low levels or cannot be d etected in rat fetal liver. Experiments were carried out to develop an ex vivo model of CYP2E1 expression in fetal liver. Fetal hepatocytes were prepared from pregnant rats on gestation days ranging from 12 to 19 and placed into culture for 2 days. Expression of CYP2E1 was observ ed at all gestational periods as evident from immunoblots and oxidatio n of para-nitrophenol and N,N-dimethylnitrosamine by fetal liver micro somes. Northern blot analysis indicated production of CYP2E1 mRNA by t he fetal hepatocytes cultured for 2 days but not by freshly isolated f etal rat hepatocytes. The addition of ethanol to the hepatocyte cultur es did not have a significant effect on CYP2E1 catalytic oxidation of substrates or CYP2E1 mRNA levels. The content of CYP2E1, CYP2E1 mRNA l evels, and CYP2E1 catalytic activity was greater in the fetal cultures grown in the presence of 2.5% fetal calf serum than in that grown wit h 15% fetal calf serum, suggesting that factors present in the serum l imit expression or stability of CYP2E1. CYP2E1 was not detectable in t wo human fetal livers; however, expression did occur when human fetal hepatocytes were placed into culture for 4 days. These results suggest that cultures of rat and human fetal hepatocytes may be a valuable mo del with which to study factors that regulate expression of CYP2E1 and the influence of ethanol and other inducers on expression and stabili zation of CYP2E1.