Farren Hardneck

In order to address the large percentage of unexplained male infertility in humans, more detailed investigations using sperm functional tests are needed to identify possible causes for compromised fertility. Since many environmental and lifestyle factors might be contributing to infertility, future studies aiming to elucidate the effect of such factors on male fertility will need the use of appropriate research models. The current study aimed to assess the effects of two heavy metals, namely copper sulphate, and cadmium chloride, on non-human primate (NHP) sperm function in order to establish the possibility of using these primate species as models for reproductive studies. Our combined results indicated that the functionality of NHP spermatozoa is inhibited by the two heavy metals investigated. After in vitro exposure, detrimental effects, and significant lowered values (p < 0.05) were obtained for sperm motility, viability and vitality, acrosome intactness, and hyperactivation. These metals, at the tested higher concentrations, therefore, have the ability to impair sperm quality thereby affecting sperm fertilizing capability in both humans and NHPs.

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.