In vitro effects of metal ions (Fe2+, Mn2+, Pb2+) on sperm motility and lipid peroxidation in human semen

The effects of divalent manganese ion (Mn2+), ferrous iron (Fe2+), and lead ion (Pb2+) on human sperm motility and lipid peroxidation were examined. Human semen from healthy male volunteers was incubated with 0, 5, 50, or 500 ppm divalent metal ions, and the sperm motility was determined at 0, 2, 4, 6, or 8 h by microscopy. Malondialdehyde (MDA) levels in seminal plasma was measured by high-performance liquid chromatography after 8 h of exposure. The results showed that 500 ppm Mn2+ or Pb2+ significantly inhibited sperm motility without an accompanying change in seminal MDA levels. Incubation with Fe2+ significantly inhibited sperm motility at 5 ppm, associated with a marked rise in MDA levels. Our results suggested that Fe2+ may induce lipid peroxidation to inhibit sperm motility. In the case of Mn2+ and Pb2+ there is an absence of seminal lipid peroxidation and the observed inhibition of sperm motility at high concentrations is not biologically or environmentally relevant.