EFFECT OF COPPER-ION ON THE MOTILITY, VIABILITY, ACROSOME REACTION AND FERTILIZING-CAPACITY OF HUMAN SPERMATOZOA IN-VITRO

The objective of this study is to provide additional information on th e effect of copper ion (Cu2+) in preventing pregnancy. Human spermatoz oa, selected by the swim-up method, were incubated for 0, 5 or 24 h in the presence of 10 ng, 1 mu g, 10 mu g or 100 mu g of Cu2+ mL(-1) in BWW culture medium, and then evaluated in terms of their motility, via bility, acrosome reaction (AR) and the capacity to penetrate zona-free hamster eggs. AR and penetration in zona-free hamster eggs were asses sed at 5 h of incubation. Motility, viability and AR in sperm incubate d for 5 h were significantly affected by Cu2+ at a concentration of 10 0 mu g mL(-1) but not at the lower concentrations. Incubation for 24 h did not affect motility and viability of sperm incubated in the prese nce of concentations of Cu2+ ranging from 10 ng mL(-1) to 10 mu g mL(- 1), but a concentration of 100 mu g mL(-1) caused a significant decrea se in both parameters. In contrast, the penetration rate of zona-free hamster oocytes significantly decreased compared with that of controls , when only sperm were incubated in the presence of concentrations of Cu2+ ranging from 10 ng mL(-1) to 10 mu g mL(-1), and no penetration w as observed in the presence of 100 mu g mL(-1) of Cu2+ When only oocyt es were exposed to Cu2+, th, penetration rate dropped to 50% of that o f the controls. Finally, when both gametes were exposed to Cu2+ before co-incubation, the penetration rate fell to zero for every concentrat ion tested. Results showed that copper, at concentrations similar to t hose released from intrauterine devices (IUD), affects the fertilizing capacity of human gametes in vitro and interferes with the sperm-oocy te interaction leading to fertilization. These effects suggest that th e principle action of Cu2+ released from Cu-IUD is to act as a preconc eption contraceptive agent when delivered in endometrial and oviducal fluids.