Effects of Cadmium on Placental Function and Reproduction in Rats / 대한산업의학회지

OBJECTIVES: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: Cadmium disrupts the functions of the placenta and these effects leads to reproductive disorders in rats.

Effects of Toluene on the Expression of Placental PRL-GH Family Genes and Reproduction in the Rat / 대한산업의학회지

OBJECTIVES: The purpose of this experimental study was to investigate the toxic effects of toluene on the placental functions and reproductionin the rat. In this study, the expression of placental prolactin-growth hormone (PRL-GH) and Pit-1 genes, the frequency of placental trophoblast cells, and the reproductive data were analyzed. METHODS: The pregnancy of the Sprague-Dawley rats (250+/-25 g) was determined by verifying the presence of the copulatory plug or sperm in the vaginal smear and the day on which this was observed was defined as pregnancy day 0. The pregnant rats were divided into three groups. The control group was intraperitoneally (ip) injected with sesame oil, and the other two groups were given either 150 or 750 mg/kg BW/day of toluene resuspended in sesame oil during pregnancy days 7-11 and 16-20. The rats from the three experimental groups were sacrificed on pregnancy days 11 and 20, respectively. The mRNA levels of the PRL-GH, Pit-1a and b isotype genes were analyzed by Northern blot hybridization and Reverse transcription-polymerase chain reaction (RT-PCR), respectively. The hormonal concentration was analyzed by Radioimmunoassay. The frequency of the placental trophoblast cells was determined by means of a histochemical study. Reproductive data, such as the placenta and infnat weight, pregnancy period and litter size were surveyed at pregnancy day 20 and after birth. Statistical analysis was carried out by means of the SAS program (version 8.1). RESULTS: The mRNA levels of the PRL-GH family genes were reduced in a linear fashion by exposure to toluene. The mRNA levels of the Pit-1a and b isotype genes, which induce the expression of the PRL-GH family genes, were also reduced by exposure to toluene. The placental lactogen Iv and II concentrations in the rat placenta, fetus and maternal blood were also decreased by exposure to toluene. During the last stage of gestation, exposure to a high dose of toluene reduced the frequency of the spongiotrophoblast cells that secrete the PRL-GH hormones. Reproductive data such as the placenta and infant weight, and litter size were reduced, and the pregnancy period was extended in the toluene exposed group as compared with the control group. CONCLUSIONS: Toluene disrupts the PRL-GH hormone metabolism in the rat placenta and this leads to reproductive disorder.