Fertility of rabbit sperm exposed in vitro to cadmium and lead

The heavy metals Cd2+ and Pb2+ have been associated with male reproductive toxicology, including possible inhibition of sperm undergoing hyperactivated motility, indicative of capacitation. The objective of the present study was to test fertility of rabbit sperm exposed to Cd2+ or Pb2+ in vitro, followed by insemination of superovulated does. Semen was washed to remove seminal plasma and minimize possible binding of the heavy metals by proteins. Only 400,000 treated or control sperm were inseminated as a sensitive test of treatment, and the time sperm resided in the female before possible fertilization was varied by inseminating from 0 to 12 h after ovulating the does. Only 6 of 22 males tested showed appreciable spontaneous hyperactivation and neither Cd2+ nor Pb2+ affected hyperactivation, or presumably associated capacitation. Sperm from four of these six males were used to inseminate 66 rabbits, and 1483 oocytes and embryos were collected about 27 h later. No effect of 0.1 mM Cd2+ on fertilizing ability of sperm was found (75% fertilization with control sperm and 78% with treated sperm). With 0.025 mM Pb2+ the fertilization rate in pregnant does only was 82% for controls and lower (68%) with treated sperm. These tested concentrations of Cd2+ and Pb2+ are much higher than reported concentrations in semen of exposed workers.