Introduction
Physiological seminal ROS
Sperm motility | Downstream activation of protein tyrosine kinase which phosphorylates tyrosine residues in the sperm cytoskeleton Inhibition of phosphotyrosine phosphate from dephosphorylating tyrosine residues |
Capacitation | Downstream activation of protein tyrosine kinase which phosphorylates tyrosine residues in the sperm cytoskeleton Inhibition of phosphotyrosine phosphate from dephosphorylating tyrosine residues |
Acrosome reaction | Induction of phosphorylation of plasma membrane proteins to facilitate the release of acrosomal enzymes to penetrate the zona pellucida |
Fertilisation | Inhibition of deactivation of phospholipase A2. Phospholipase A2 cleaves fatty acids from the plasma membrane which increases fluidity allowing fusion between the sperm and oocyte |
Pathological seminal ROS
DNA | Direct injury to purines/pyrimidines Chromosomal rearrangement Single-strand breaks Double-strand breaks Cross-linking |
Mitochondria | Damage to mitochondrial DNA Decreased ATP production Caspase release from damaged mitochondrial membrane |
Cell membrane | Lipid peroxidation of polyunsaturated fatty acids |
Name | Technique | Advantages | Disadvantages | |
---|---|---|---|---|
Direct: | Chemiluminescence assay | Detection of oxidation or reduction through the by-product generation of light to measure ROS | Robust High sensitivity and specificity It can measure both intra- and extracellular ROS | Time-consuming Expensive (equipment) Variables such as the volume of semen may affect measurement |
Indirect: | Lipid peroxidation level | Levels of malondialdehyde (MDA) by-products of lipid peroxidation are measured by thiobarbituric acid assays by colorimetry or fluoroscopy | Can be used for frozen samples | Non-specific |
The Male Infertility Oxidative System (MiOxsys) | Measurement of the transfer of electrons from reductant to oxidant in millivolts | Fast Can be used for both semen and seminal plasma Can be used for frozen samples Cost-effective | Affected by the viscosity of the sample | |
Total antioxidant capacity (TAC) | An enhanced chemiluminescent assay which measures the suppression of chemiluminescence in seminal plasma and the time to recovery | Fast Measures the total antioxidants in seminal plasma | Does not measure enzymatic antioxidants Expensive (microplate readers) |