Metal ions and human sperm mannose receptors

Zinc and lead concentrations were measured in seminal plasma from fertile d onors? infertile men with varicocoele and men undergoing work-ups for in vi tro fertilization. Ejaculated spermatozoa from these subjects were incubate d in vitro with various metal ions and/or dibromoethane and dibromochloropr opane. Mannose receptor expression was correlated with metal and toxicant l evels. Sperm distributions of potassium channels were compared with lead io ns and calcium channels with zinc ions. Mannose receptor expression by capa citated spermatozoa increased linearly with seminal plasma zinc levels, and correlated inversely with lead levels. Cobalt had no effect on mannose rec eptor expression, but nickel had a concentration-dependent biphasic effect. Mannose receptor expression was not affected by dibromoethane and dibromoc hloropropane if the cholesterol content of the sperm membrane was high, but mannose receptor expression was decreased in low cholesterol spermatozoa b y exposures below estimated permissive exposure limits. Potassium channels and lead ions co-localized over the entire head of human spermatozoa, while both calcium channels and zinc ions were confined to the equatorial segmen t of the head, Mannose receptor expression on the external surface of the h uman sperm plasma membrane is a biomarker for the effects of transition and heavy metals and organic toxicants on sperm fertility potential.