Seminal plasma nitric oxide (NO) and its correlation with sperm quality

Abstract

Objective: Previous work in animals and humans suggested that NO may have detrimental effects on sperm concentration, and varying effects on sperm motility. The objectives of this study were: 1. To determine if NO is detectable in seminal plama, 2. If seminal plasma NO levels differed in men with normal and abnormal semen analysis, and 3. To determine if there are correlations between seminal plasma NO and sperm concentration, morphology and motility. Design: Prospective cohort study. Materials/Methods: Subjects consisted of 9 men with a normal semen analysis by WHO criteria (Normal Group), 5 of whom were donors to a sperm bank with proven fertility. The remainder consisted of 24 subjects seen in the infertility clinic and had abnormality of at least one parameter in the semen analysis based on the WHO critera (Abnormal Group). The subjects in this group had not fathered children. IRB approval was obtained through the Human Subjects Committee. The age range and semen characteristics are shown in Table 1. Subjects produced semen by masturbation after 3 days of abstinence and samples were transported to the laboratory within 30 minutes of collection. An aliquot was removed for semen analysis using computer-assisted semen analysis. For morphology determination sperm was stained with a PAP stain. The remainder of the sample was stored frozen at -70° C, and later analyzed for NO using the Dasibi Nitric Oxide Analyzer (Model 2108). This machine measured the total NO within a sample by measuring levels of nitrate and nitrite (NOx). Comparisons of NOx levels between the 2 groups was done using the Student’s t-test. Spearman correlation analysis was then used to correlate NOx levels with sperm concentration, motility and morphology.Table 1Characteristics of Normal and Abnormal Semen Analysis GroupsNormalAbnormalP-valueMean Age (yrs)31.4 ± 3.135.6 ± 8.3NSSperm Concentration (million/cc)117.4 ± 1755.2 ± 100.004Sperm Motility (%)69.3 ± 3.849.8 ± 4.20.012Sperm Morphology (%)55.2 ± 7.215.8 ± 1.90.001 Open table in a new tab Results: There were no significant differences in the age group of the subjects in the two groups studied. Subjects with abnormal semen had significant impairment of at least one parameter of their semen analysis, with either lower sperm concentraion (p = 0.004), motility (p = 0.012), and or morphology (p <0.001) (Table 1). Levels of NOx were dectable in all samples. There were no differences in NOx levels between the two groups. Furthermore, there were no significant correlations between NOx levels and sperm concentration, motility or morphology. Conclusions: This study demonstrates that NOx is detectable in seminal plasma. The source and physiological significance of NO in seminal plasma remains to be determined. This study does not support a correlation between seminal plasma NO and sperm quality. Supported by: Dept. of OB/GYN Funds, Harbor-UCLA Medical Center.