This study investigated the toxic effects of cadmium on placental function and reproduction in rats. For this study, the mRNA levels of the placental prolactin-growth hormone (PRL-GH) gene family, placental trophoblast cell frequemcy and reproductive data were analyzed.

Pregnant F344 Fisher rats (200 g±23 g) were intraperitoneally injected with 0, 0.5, and 5.0 mg/kg B.W/day of cadmium (CdCl2) dissolved in saline from days 7–11 or 16–20 of pregnancy, and were sacrificed at days 11 or 20, respectively. The mRNA levels were analyzed by Northern blot hybridization and reverse transcription-polymerase chain reaction. The hormone concentration was analyzed by radioimmunoassay and the frequemcy of the placental trophoblast cells was observed by histochemical study. Reproductive data were surveyed at day 20 of the pregnancy and after the births. Statistical analysis was carried out using the SAS program (version 8.1).

The mRNA levels of the PRL-GH gene family were reduced dose dependently by cadmium. The mRNA levels of Pit-1a and -b isotype genes were also reduced by cadmium. The hormone concentration of PL-Iv and -II was decreased by cadmium. During the second half of pregnancy (days 11–21), a high dose of cadmium exposure significantly reduced the frequency of spongiotrophoblast and trophoblast giant cells that secrete the PRL-GH hormones. In the last stage of pregnancy (day 20), a high dose of cadmium exposure induced the apoptosis of spon-giotrophoblast cells in the junctional zone of the placenta. Reproductive data such as placental and infant weight, number of live fetuses were decreased, and number of resorptions and dead fetuses, post-implantation loss were increased significantly in the cadmium exposed group compared with the control.

Cadmium disrupts the functions of the placenta and these effects leads to reproductive disorders in rats.