Direct and indirect effects of electrical stimulation on the motility of human sperm

BACKGROUND: Electroejaculation is a technique that is becoming more frequently available for obtaining sperm from men with spinal cord injury or psychogenic anejaculation. However, the effect of electrical stimulation on the movement of human sperm has not been clarified. METHODS: Electrical stimulation was applied to ejaculated semen or washed sperm via a pair of electrodes in the sperm-counting chamber while sperm motility was recorded using a computer-assisted semen analyzer. RESULTS: When monopolar pulse stimulation was applied to sperm, the motility rate and velocity of sperm near both electrodes decreased according to the number of pulses and current despite low electrical voltages. However, motility of sperm in the center between electrodes did not change. When extremely high-voltage electrical stimulation with more than 80 V/2 mm (distance between electrodes) was applied to sperm, sperm stopped moving regardless of their location between the electrodes, despite a low electrical current and low energy. Replicating clinical rectal probe electroejaculation, continuous sinusoidal alternating current at 50 V/10 mm was applied to a untreated ejaculated semen. The motility of sperm, except for those adjacent to both electrodes, did not change after stimulation for 60s, despite a high electrical energy. CONCLUSIONS: The motility of sperm near electrodes was decreased when high electric current flowed, despite low electrical voltages. In addition, sperm lost their motility when extremely high-voltage electrical stimulation was applied. However, electrical stimulation during clinical rectal probe electroejaculation seems to have no effect on sperm motility.