Abstract: AIM: To evaluate the alterations of ma-ternal hepatic drug-metabolizing enzymes and antioxidative function in tobacco-induced intrauterine growth retardation(IUGR).METHODS: Pregnant rats were assigned to control grouPand tobacco group.IUGrmodel was pro-duced by smoking from gestational days(GD)9 to GD 20.Fetuses were removed by laparotomy on GD 21.The fetal development parameters such as fetal body weights,littersize and placental weights were recorded.Subcelluarfractionsof liverwere prepared by differential centrifuga-tion.Activities of drug-metabolizing and antioxidative enzymes were monitored.RESULTS: In the tobacco ex-posure group,fetal body weights,littersize and placental weights were significantly reduced(P<0.01).The levels of cytochrome P450(CYP)1A1 in hepatic micro-somes increased by 37.9%,and the activities of CYP3A and glutathione S-transferase(GST)decreased to 73.3% and 86.5%when compared to control group.Meanwhile,the activities of superoxide dismutase(SOD)and catalase(Cat)decreased to 81.0% and 79.7%,respectively,whereas the activity of glutathione peroxidase(GSH-Px)increased in comparison with control group.CONCLUSION: Tobacco exposure in pregnancy results in the alter-ations of partial drug-metabolizing enzymes and antioxida-tive function in maternal liver,and these changes may play an important role in inducing IUGR.Meanwhile,to-bacco exposure in pregnancy may change the drug efficacy and increase the drug toxicity.

Key words: tobacco, intrauterine growth retarda-tion, maternal liver, drug-metabolizing enzymes, antioxi-dative enzymes