Background and aims: The most important cause of fertilization failure after assisted-reproduction techniques are lack of releasing sperm-associated oocyte activating factors (SAOAFs) and sperm DNA damage. PLCζ is one of the sperm factors that plays important role in oocyte activation. The aim of this study was to compare expression of PLCζ, protamine deficiency (maturity marker of sperm chromatin) and sperm DNA damage between fertile men and oligoasthenoteratozoospermic subfertile men.

Methods: In this case-control study, semen samples were collected from 10 subfertile oligoasthenoteratozoospermic and 10 fertile men. Sperm parameters (concentration, motility, morphology), expression of PLCζ, DNA damage, and protamine deficiency were assessed by World Health Organization protocol, flow cytometery, TUNEL and chromomycin A3 staining, respectively.

Results: Percentage of PLCζ- positive sperm, DNA integrity and protamine content significantly was lower in oligoasthenoteratozoospermic men compared to fertile men. In addition, significant correlations were observed between percentage of PLCζ- positive sperm with sperm parameters and percentage of protamine deficiency. A significant correlation was also observed between percentage of DNA fragmentation and protamine deficiency.

Conclusion: In these infertile men, sperm chromatin integrity and percentage of PLCζ-positive sperm decreased extremely. This could be one cause of fertilization failure in these individuals. Therefore, the artificial oocyte activation is recommended for these type of infertile men.