Spinal cord injury (SCI) causes male infertility, with low sperm motility the major long-term cause. It has been suggested in previous studies that some seminal components may be responsible for the pathological asthenozoospermia. It is hypothesized that platelet-activating factor (PAF) acetylhydrolase (PAFah), which originates in the epididymis and other accessory sexual glands, may be a causative factor. This enzyme catalyzes PAF to acetate and biologically inactive lyso-PAF. PAF is well recognized to be an important phospholipid mediator that stimulates sperm motility and enhances sperm capacitation and fertilization. The present study was designed to analyze differences in PAFah activity in semen of men with SCI and age-matched healthy men. PAFah assay reagent kits were used to measure enzymatic activity by monitoring the production rates of 4-nitrophenol on a spectrophotometer during a given interval. The results showed that subjects with SCI had a higher concentration of PAFah than men in the control group (P < .001). A statistically significant negative correlation was found between enzymatic activity and sperm motility (r2 = 0.8449; P < .001). Further studies will determine whether seminal vesicle dysfunction in men with SCI leads to abnormal PAFah activity, resulting in low sperm motility.
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