Abstract: Objective：To study the effect of Benzo[a]pyrene (BaP) on the early pregnancy and its mechanism, as well as the protective effect of Schisandra chinesis extrac (SCE) on the Bap-induced damage of early embryo. Methods: Female SD rats were randomly divided into 5 groups (15 rats/group): control group, model (BaP 2 mg·kg-1·d-1) group, low-dose SCE (BaP plus SCE 40 mg·kg-1·d-1) group, middle-dose SCE (BaP plus SCE 200 mg·kg-1·d-1) group and high-dose SCE (BaP plus SCE 1 000 mg·kg-1·d-1) group. After 15 days of treatment, those female rats were mated with normal male rats to get the pregnancy. On the ninth day of gestation, all female rats were sacrificed. The ultrastructural change of embryo was observed by transmission electron microscope. The levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) in the embryonic tissues were measured by the oxidant-injury testing Kits; the level of 8-hydroxy-2 deoxyguanosine (8-OhdG) was also measured by a ELISA Kit. Results: There were no obvious abnormalities on the surface and ultrastructure in the control group and three SCE groups. The embryos in the model group were of uneven size and abnormal blood stasis on surface and abnormal ultrastructure, as well as abnormal apoptosis. The levels of SOD, GSH-Px were significantly decreased in the model group when compared with the control group (P＜0.05 or P＜0.01), while the level of MDA was increased significantly (P＜0.01). The levels of SOD in three SCE groups were significantly increased when compared with the model group (P＜0.01 or P＜0.05). The level of GSH-Px was significantly increased, and the level of MDA decreased in the high-does SCE group when compared with the model group (both P＜0.05). Compared with the control group, the model group had significantly lower level of 8-OHdG (P＜0.01). Interestingly, the levels of MDA were significantly decreased in the high-dose and middle-does SCE groups when compared with the model group (P＜0.01 or P＜0.05). Conclusions: Benzo [a] pyrene exposure before pregnancy has the embryonic toxicity in rats, including oxidative damage, DNA damage and inducted apoptosis. SCE play a protective role in the early embryo through antioxidant, anti-DNA damage and anti-apoptosis.

Key words: Schizandrin, Benzo(a)pyrene, Prenatal injuries, DNA damage