Effects of Prenatal Exposure to Benzo(a) pyrene on the Expression of Apoptosis-related Proteins in Liver Cells of Offspring

Objective To investigate the expression of apoptosis-related proteins Bcl-xl and Bax in the liver of offspring after Benzo(a) pyrene (BaP) exposure of pregnant rats.

Methods Pregnant SD rats were randomly divided into four groups: one vehicle control (corn oil) and three BaP-treated groups (0.75 mg/kg, 1.5 mg/kg and 3 mg/kg) (n = 8). BaP solutions were given by intragastric administration from the 3^rd day to the 17^th day of pregnancy. The body weight of pregnant rats was measured. After birth, the body length, tail length and weight of the offspring were observed, and the livers were removed by the end of the experiment. Western blot method was used to detect Bcl-xl and Bax protein levels in the liver of the offspring.

Results With the increasing levels of BaP exposure during pregnancy, the growth indicators of newborn pups (such as body weight, length, tail length) were decreased, but no significant difference between the groups was observed (P > 0.05). The results from Western blot showed that, compared with the control group, the expression of Bcl-xl protein in the liver of offspring was significantly decreased in the middle and high dose groups, while the expression of Bax protein was significantly increased (P < 0.05 or P < 0.01). The ratio of Bcl-xl/Bax was also decreased with the increasing of BaP exposure.

Conclusions A low-dose BaP exposure model in pregnant rats was developed. With the increase of BaP exposure during pregnancy, the ratio of apoptosis-related protein Bcl-xl/Bax in newborn liver was decreased; it suggested that apoptosis might be one of the mechanisms in the toxic effects of BaP on the liver of offspring.