The activity of paraoxonase type 1 (PON-1) in boar seminal plasma and its relationship with sperm quality, functionality, and in vivo fertility

Paraoxonase 1 (PON-1) is a hydrolytic enzyme present in body fluids, capable of protecting cells against oxidative stress. The hypothesis was hereby to test that PON-1, present in seminal plasma (SP), acts protecting boar spermatozoa when showing a reasonable high activity in the ejaculate. SP-PON-1 activity differed (p<0.001) among boars (from 0.10 to 0.29IU/mL). Intra-boar variability was also observed (p<0.05), but only in two of the 15 boars. SP-PON-1 activity differed among ejaculate portions, showing the spermatozoa-peak portion of spermatozoa-rich ejaculate fraction the highest levels (0.35 +/- 0.03IU/mL, ranging from 0.12 to 0.69) and the post-sperm ejaculate fraction the lowest levels (0.12 +/- 0.01IU/mL, ranging from 0.03 to 0.21). SP-PON-1 activity was positively correlated with the percentage of spermatozoa with rapid and progressive movement (p<0.01) and negatively correlated with the generation of intracellular reactive oxygen species (p<0.01) in semen samples after 72h of liquid storage. SP-PON-1 activity was highest (p<0.01) in boars with highest farrowing rates. In conclusion, SP-PON-1 activity differed among boars and ejaculate fractions/portions. SP-PON-1 activity was positively correlated with sperm quality and functionality of liquid-stored semen samples and it evidenced a positive association with in vivo fertility.