Antioxidant imbalance in abnormal sperm

By Sally Robertson, B.Sc.Nov 13 2012

An imbalance exists in oxidative stress markers, such as reactive nitrogen species (RNS), reactive oxygen species (ROS), and total antioxidant capacity (TAC), in infertile men with abnormal semen parameters, report researchers.

This imbalance is associated with higher sperm DNA fragmentation (DF), warn Mojtaba Valojerdi (Royan Institute, Tehran, Iran) and colleagues.

"ROS must be inactivated continuously by antioxidants in semen to maintain only a small amount of free radicals available for normal sperm function," explains the team. "Reactive species in seminal fluid of infertile men are a potential cause for DF, which is considered one of the most important causes of male infertility."

As reported in Andrologia, the team's analysis of samples from 102 infertile couples showed that peroxynitrite, a marker for RNS, was significantly increased in all men with abnormal sperm parameters (asthenoteratozoospermia, oligozoospermia, and asthenooligoteratozoospermia).

The peroxynitrite level was highest in the asthenooligoteratozoospermic samples - those with a low number of sperm, poor sperm movement, and abnormal sperm morphology - at 24.27 nmol x 10^-6 compared with 12.37nmol x 10^-6 in normozoospermic couples.

Similarly, the ROS marker, superoxide anion, was significantly increased in the abnormal groups compared with the normal groups and, again, was highest in the asthenooligoteratozoospermic patients, at 59.35 nmol x 10^-6 compared with 33.98 nmol x 10^-6 in individuals with normal sperm.

By contrast, TAC was significantly lower in all of the abnormal sperm parameters groups compared with the normozoospermic individuals and was at the lowest level in asthenooligoteratozoospermic individuals, at 1301.44 mmol versus 1645.14 mmol.

Further analysis showed that DF was lowest in the normozoospermic samples and highest in the asthenooligoteratozoospermic samples, followed by the asthenoteratozoospermic samples.

Furthermore, levels of peroxynitrite and superoxide anion significantly correlated with DF, and it was possible to predict the amount of DF from these values, reports the team.

"In conclusion and to the best of our knowledge, this is the first report about the relationship between peroxynitrite and DF in infertile couples with normal and abnormal semen parameters," conclude Valojerdi et al.

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