Aging increases oxidative stress in semen

Abstract

Purpose: As age increases, oxidative stress increases, sperm motility decreases, and DNA fragmentation increases. To date, reports of age-related effects on semen have focused on reactive oxygen species (ROS) or total antioxidant capacity (TAC) as indicators of oxidative stress. However, assessments of ROS and TAC must be considered within a more comprehensive context in order to correctly evaluate oxidative stress and interpret findings. In this regard, the purpose of this study was to investigate the relationship between the static oxidation reduction potential (sORP) and paternal age with the goal of using the sORP as an indicator of semen oxidative stress.

Materials and methods: Semen samples from 173 men were analyzed for the following parameters: volume, motility, and beat cross frequency (BCF). The sORP was measured by using the MiOXSYS™ system. The correlation between semen parameters and the sORP level was analyzed as a function of age. The rate of sORP positivity was compared between men <34 and ≥34 years of age, with a positive sORP defined as a level ≥1.38.

Results: Volume, motility, and BCF were negatively correlated with age (p<0.001). The semen sORP level was positively correlated with age (p<0.05). The rate of sORP positivity was significantly increased in men ≥34 years of age compared with that in men <34 years of age (33% compared with 12%, respectively; p<0.01).

Conclusions: The sORP may play a role in age-related decreases in semen parameters (volume, motility, and BCF). The rate of sORP positivity increased significantly after 34 years of age.

Keywords: Aging; Oxidation reduction; Oxidative stress; Semen; Sperm.

Fig. 1. Correlation between age and semen parameters. Scatter plots and linear regression lines showing the relationship between age and each of the semen parameters measured: (A) volume, (B) motility, and (C) beat cross frequency (BCF).

Fig. 2. Correlation between age and the static oxidation reduction potential (sORP) level in semen. Scatter plot and linear regression line showing the relationship between age and the sORP in semen.

Fig. 3. Receiver operating characteristic (ROC) curves and paternal age cutoff. A ROC curve was used to identify the paternal age criterion (cutoff, sensitivity, specificity, and area under curve [AUC]) that best predicted static oxidation reduction potential positivity.

Fig. 4. Comparisons of the rate of static oxidation reduction potential (sORP) positivity between men aged <34 and ≥34 years. The vertical axis shows the rate of positive sORP, with the horizontal axis showing age. sORP ≥1.38 was defined as a positive level. ^**p<0.01.