Seminal plasma zinc levels and sperm motion characteristics in infertile samples

Zinc (Zn) in seminal plasma stabilizes the cell membrane and nuclear chromatin of spermatozoa. It may also have an antibacterial function. However, extremely high concentrations of Zn (10 to 100 x the normal range) may inhibit sperm motility and the function of the mannose receptor on the sperm head. In this study, we analyzed the correlation between Zn levels in seminal plasma and the characteristics of semen as measured by conventional and computer aided sperm analysis (CASA).

One hundred fifteen infertile couples were recruited for conventional semen analysis and CASA from December 1995 through January 1996, and Zn levels in semen samples were determined by flame atomic absorption spectroscopy (AAS).

A good correlation in a positive direction (r = 0.73, p = 0.0001) was noted between the total amount of Zn per ejaculate and the Zn concentration. The Zn concentration in seminal plasma was negatively correlated with the seminal pH (r = -0.35, p = 0.0081). There was no significant correlation between the total amount of Zn per ejaculate and sperm characteristics, including sperm count, motility (% sperm count), progressive motility (% motility), rapid motility (% motility), average path velocity (VAP, microns/s), straight-line velocity (VSL, microns/s), curvilinear velocity (VCL, microns/s), amplitude of lateral head displacement (ALH, microns), beat/cross frequency (BCF, beats/s), straightness (STR), and linearity (LIN). There was also no significant correlation between the Zn concentration in seminal plasma and the above sperm characteristics.

The characteristics of semen as determined by conventional semen analysis or CASA bore no correlation with total seminal Zn amount or Zn concentrations in the ejaculates. Routine determination of the Zn concentration in seminal plasma offers no advantages in infertility work-ups.