Melatonin, advanced oxidation protein products and total antioxidant capacity as seminal parameters of prooxidant-antioxidant balance and their connection with expression of metalloproteinases in context of male fertility.

Currently, in highly developed, industrialized countries male factors are identified as the primary cause of infertility in about 60% of childless couples. Standard semen analysis parameters, such as sperm morphology, number and motility, are important in predicting the fertility of large populations, but they are not sufficient to fully specify a particular donor sperm's ability to fertilize the egg. The semen also comprises components, which may also affect sperm fertilizing ability and which have thus far remained little explored: the biochemical parameters of the seminal plasma secreted by the testis, the seminiferous tubules and the prostate gland, such as: matrix metalloproteinases (MMP-2 and MMP-9) and their specific tissue inhibitors (TIMP-1 and TIMP-2). We highlight the need for a better determination of prooxidant-antioxidant balance parameters such as: melatonin, advanced oxidation protein products (AOPPs) and total antioxidant capacity (TAC) in human semen when establishing the diagnostics of male subfertility or infertility. We also discuss their connection with seminal plasma metalloproteinases and their inhibitors. In particular, we believe that the cumulative and synergic effects of the sperm redox parameters on male fertility need to be better explored and we suggest that they should be studied in conjunction with other biologically active parameters of the ejaculate such as the expression of metalloproteinases and their tissue inhibitors. This will enable a better understanding of how their correlated effects impact semen condition.