The human sperm glutathione system: a key role in male fertility and successful cryopreservation.

The equilibrium of the creation and scavenging of free radicals is mandatory in the spermatozoa to fertilize and initiate a full-term pregnancy. The glutathione (GSH) enzymatic system studies have discovered its relationship with oxidative stress in the ejaculate and new strategies to regulate its activity in the semen could be developed. Intracellular sperm GSH system components are altered in infertile men, and these alterations seem to be linked to sperm morphology. We have been able to correlate embryo morphology on 8 cell embryos with the sperm expression of GPx family members; this relationship appears quite promising for discovery of molecular causes of male infertility. Oxidative stress imbalance potentially leads to damage of the structure of plasma membrane. The freezing and subsequent thawing of sperm is a physically stressful process carried out during routine procedures in assisted reproduction, which results in a highly variable and unpredictable reduction of motile sperm. Subsequently, oxidative status can positively or negatively affect the motility, viability, and fertilizing capacity of thawed sperm. A reserve of glutathione, together with GPx expression, is necessary to eliminate free radicals using GSH or GPx-4 like structural protein and seems to be essential for a good post thaw recovery.