Platelet-activating factor [1-O-alkyl-2-acetyl-sn-glycero-3- phosphocholine; PAF] is present in human sperm and its content has a significant and positive relationship with motility. PAF-acetylhydrolase (PAFah), the enzyme that removes the acetyl group (responsible for PAF’s activity), is present in semen and serves as a decapacitating factor. Semen from men with spinal cord injury (SCI) contains sperm with poor motility and this condition may be a result of abnormal PAFah activity in the semen. The study objective was to determine the relationship between PAFah content in semen and sperm motility in men with SCI compared to non-SCI men.

Using a between-subjects design, semen PAF-AH activity was compared in semen specimens from control versus SCI subjects. PAFah activity levels were correlated with sperm motility in each group.
Semen was obtained from 10 men with SCI and 10 age-matched healthy fertile men as control subjects. Sperm motility was determined (WHO, 1999) prior to measurement of PAFah activity (spectrophotometric analysis; AZWELL Inc, Japan). Data were analyzed by Student’s t-test and linear regression.
Mean (±SEM) seminal PAFah content was significantly higher in SCI subjects (1,068.4 ± 163.78 IU/L, range 589.0 - 1,881 IU/L) compared to controls (413.5 ± 40.99 IU/L; range 192.0 - 691.0 IU/L, p < 0.001). Mean sperm motility was significantly lower in SCI subjects (27.9
4.56%, range 4 52%) compared to controls (63.9 ± 3.13%; range 54 - 80%, p < 0.001). Linear regression analysis revealed a significant negative correlation between PAFah content in semen and sperm motility (R= 0.212, p < 0.05). Regression analysis demonstrated a biological correlation between PAFah and sperm motility in SCI subjects (R= 0.45, p 0.058) and control subjects (R= 0.383; p 0.056).

PAFah activity levels are elevated in semen of men with SCI compared to age-matched healthy control subjects. PAFah was negatively correlated with sperm motility in SCI and control subjects. Additional studies will elucidate the role of PAFah in semen on sperm motility and determine if high PAFah activity contributes to low sperm motility in men with SCI.
Source: Zhu, N. L. Brackett, T. Aballa, D. B; FERTILITY & STERILITY doi:10.1016/j.fertnstert.2004.07.221