EXPRESSION AND INDUCIBILITY OF CYTOCHROME-P450-3A9 (CYP3A9) AND OTHERMEMBERS OF THE CYP3A-SUBFAMILY IN RAT-LIVER

Quantitative reverse-transcriptase polymerase chain reaction was used to determine the content of mRNA derived from four CYP3A genes (CYP3A2 , CYP3A9, CYP3A18, and CYP3A23) in rat liver. CYP3A2 and CYP3A9 gene e xpression was age- and sex-dependent, whereas CYP3A18 and CYP3A23 mRNA were observed before and after puberty at fairly constant levels that were about 20% higher in males than in females. CYP3A9 mRNA was detec ted only in adult rats, with a nearly twofold higher expression in fem ales. CYP3A9 induction was different from other CYP3A isoenzymes, sinc e phenobarbital was a more effective inducer than dexamethasone and cl otrimazole. The results presented for CYP3A23 are those anticipated fo r CYP3A1, which may be an allelic variant of CYP3A23 not detected in t hese experiments. These data show that rat CYP3A genes are variably ex pressed depending on age, sex, or inducer type. (C) 1997 Academic Pres s, Inc.