摘要Objective: To study the expression and inducibility in vitro ofadrenal cytochrome P-450 (CYP) 1A1 implicated in precarcinogen and premutagen activation in human fetuses. Methods: CYP1A1 mRNA expression and CYP1A1 activity of fetal adrenals were studied and compared with those of fetal liver using the reverse transcriptase-polymerase chain reaction (RT-PCR) and 7-ethoxyresorufin O-deethylase (EROD) assay. Results: 3-methylcholanthrene (3MC, 25 mg/kg ip, qd′ 3), a selective inducer of CYP1A1, could enhance adrenal and liver EROD activities in vivo in adult rat. However, EROD activity was undetected in either adrenal microsomes or 3MC (0.5- 2 m mol.L-1 for 24 h)-treated adrenal cells in vitro in human fetuses. Using RT-PCR method, the expression of CYP1A1 mRNA was detected in fetal adrenal and fetal liver tissues and the expressional percentage was 78% and 73%, respectively. Conclusion: Human fetal adrenals as well as fetal liver had the lower CYP1A1 expression and possessed the potential for risk of carcinogenesis during fetal development.