These results suggest that oxidative stress related damage to sperm DNA impedes the process of methylation, while antioxidant supplementation appears to have the potential to reduce DNA damage and normalize sperm DNA methylation.

Male obesity has been linked with a reduction in sperm concentration and motility, an increase in sperm DNA damage and changes in reproductive hormones. Recent large observational studies have linked male obesity with a reduced chance of becoming a father. One of the potential underlying pathological mechanisms behind diminished reproductive performance in obese men is sperm oxidative stress. The primary aim of this study was to determine if sperm oxidative stress was more common in obese/overweight men. A total of 81 men had their body mass index (BMI) correlated with seminal reactive oxygen species (ROS) production (Nitro Blue Tetrazolium assay), sperm DNA damage (TUNEL), markers of semen inflammation (CD45, seminal plasma PMN elastase and neopterin concentration) and routine sperm parameters, together with reproductive hormones. The principal finding from this study was that oxidative stress did increase with an increase in BMI, primarily due to an increase in seminal macrophage activation. However, the magnitude of this increase was small and only of minor clinical significance as there was no associated decline in sperm DNA integrity or sperm motility with increasing ROS production. Increased BMI was also found to be significantly linked with a fall in sperm concentration and serum testosterone, and an increase in serum oestradiol.

No abstract

Oxidative stress is a well-established cause of male infertility, with reactive oxygen species (ROS) causing infertility principally by impairing sperm motility and DNA integrity. Currently, most clinics do not test their infertile patients for the presence of oxidative stress because the available tests are expensive or difficult to perform. As antioxidant therapy may improve sperm DNA integrity and pregnancy outcomes, it has become apparent that there is an unmet clinical need for an inexpensive and easy-to-perform assay to identify sperm oxidative stress. The aim of this study was to develop a standardized protocol for performing a photometric nitro blue tetrazolium (NBT) assay for the measurement of seminal ROS production via production of coloured formazan, whilst correlating these results with impaired sperm function (motility and DNA integrity). Semen samples from 21 fertile and 36 male aetiology infertile men were assessed for ROS production (NBT assay), sperm DNA integrity (TUNEL), apoptosis (Annexin V) and sperm motility. Infertile men's semen contained on average fourfold higher levels of ROS than fertile men. The production of ROS by sperm was positively correlated with sperm DNA fragmentation and apoptosis, whilst being negatively correlated with sperm motility. Receiver-operating characteristic plot analysis established a cut-off point of 24 microg formazan/10(7) sperm having a sensitivity of 91.7% and a specificity of 81% for determining the fertility status of an individual. This study has been successful in establishing a standardized protocol for performing a photometric seminal NBT assay that has significant clinical utility in identifying men with impaired fertility because of oxidative stress.