Endocrine Disruption by Heavy Metals on Steroidogenesis in Model Systems

In this study human adrenocortical carcinoma cell line NCI-H295R was used as an in vitro biological model to study the effect of heavy metals on steroidogenesis. The cell cultures were exposed to different concentrations of cadmium (1.90; 3.90; 7.80; 15.60; 31.20; 62.50 μM of CdCl2), mercury (1.0; 5.0; 25; 50; 100 μM of HgCl2), nickel (3.90; 7.80; 15.60; 31.20; 62.50; 125; 250; 500 μM of NiCl2) and compared to control. Cell viability was measured by the metabolic activity (MTT) assay for estimation of mitochondria structural integrity. Quantification of sexual steroid production directly from aliquots of the medium was performed by enzyme linked immunosorbent assay (ELISA). Cadmium decreased the release of progesterone and testosterone already at a very low concentration (1.90 μM) of CdCl2, while the cell viability remained relatively high (> 75%) up to 7.80 μM of CdCl2 and significantly (P<0.01) decreased at 15.60 μM and higher concentrations of CdCl2. Concentration-dependent depression in testosterone production was detected particularly for higher concentration of HgCl2. Progesterone production was also decreased, but at the lower concentrations (1.0 and 5.0 μM) of HgCl2 this decline was lower compared to depression of testosterone. The cell viability significantly decreased at 25 μM and higher concentration of HgCl2. Results of the our study indicate dose dependent decreases in both sexual steroid hormones by NCI-H295R cell culture following a 48 h in vitro NiCl2 exposure. The lowest concentration of progesterone was significantly (P<0.01) detected in groups with the higher doses (≥ 500 μM) of NiCl2, which elicited significant cytotoxic effect. The testosterone production was decreased as well, but this decline was more pronounced compared to depression of progesterone. These results suggest that heavy metals have detrimental effects on steroid hormone synthesis even at very low concentrations and consecutively on reproductive physiology

Quantitative assessment of heavy metal effects on sperm function using computer‐aided sperm analysis and cytotoxicity assays

One known environmental risk factor impacting on human reproduction is heavy metal pollution. Although some metals (e.g., Cu, Se and Zn) have protective effects on the male reproductive system in low doses, heavy metals can accumulate to toxic levels and result in poor semen quality and decreased sperm function. We investigated the effect of CuSO4 and CdCl2 (10, 50, 100 and 250 μg/ml or 500 μg/ml) on human sperm motility and vitality by using computer‐aided sperm analysis (CASA) and two cytotoxicity assays (WST‐1 and XTT). Several sperm motility parameters were significantly reduced after 5 hr of exposure to the highest concentrations of CuSO4 (250 μg/ml) and CdCl2 (500 μg/ml). The WST‐1 assay also revealed significantly lower absorbance values for 50, 100 and 250 μg/ml CuSO4 and for 500 μg/ml CdCl2; however, no significant effect was seen with XTT. The calculated average IC50 value was 50.31± 4.34 μg/ml for CuSO4 and 392.32 ±76.79 μg/ml for CdCl2. The effects of these metals were confirmed with MgCl2, a positive control. This study provides threshold concentrations for the harmful effect of CuSO4 and CdCl2 on human spermatozoa and recommends the use of WST‐1 as vitality assay in future in vitro studies