Orchestrating the antioxidant defenses in the epididymis.

BACKGROUND

During the post-testicular maturation that occurs in the epididymis, spermatozoa need to face biochemical and morphological changes that may make them vulnerable to oxidative damage. During spermatogenesis and the epididymal maturation, the spermatozoon acquires antioxidant enzymes needed to face possible increases of reactive oxygen species (ROS) produced by its own aerobic metabolism but also due to ROS produced in high quantities by abnormal spermatozoa.

OBJECTIVES

Provide an up-to-date review of the enzymatic antioxidant system in the epididymis.

MATERIAL AND METHODS

A thorough literature review was performed for papers concerning the players of the antioxidant defenses in the epididymis.

RESULTS

The antioxidant system in the epididymis is composed by superoxide dismutases, catalase, glutathione peroxidases, peroxiredoxins, glutathione-S-transferases, thioredoxins and thioredoxin reductase. They work together to maintain low levels of ROS during the epididymal maturation. Knockout models revealed that the absence of one of the enzyme impact sperm quality affecting a variety of proteins involved in motility, the ability to fertilize oocyte, and promotes oxidative damage to the sperm DNA.

DISCUSSION AND CONCLUSIONS

These findings suggest that each enzyme is playing a specific role, and in most of the cases, no compensatory mechanisms are put in place when one enzyme is absent. This review highlights the different antioxidant enzymes in the epididymis and their role during maturation of the spermatozoon.