Quantitative expression of phospholipase C zeta, as an index to assess fertilization potential of a semen sample

BACKGROUND: Failed fertilization post-ICSI has been mainly attributed to the sperm's inability to induce oocyte activation. Phospholipase C zeta (PLC zeta) is considered to be one of the factors for the induction of oocyte activation. The aim of this study was to quantitatively assess the expression of PLC zeta in globozoospermic men or those with previously low or failed fertilization in comparison with fertile men or those with high fertilization potential. In addition, the relationship between expression of PLC zeta and that of other sperm markers was evaluated. METHODS: Real-time PCR was carried out to evaluate relative expression of PLC zeta mRNA. Chromatin maturity and acrosin activity were assessed by CMA3 staining and a colorimetric method. RESULTS: The expression of PLC zeta was significantly lower in globozoospermic men (P < 0.01, n = 8) or individuals with previously low or failed fertilization (P < 0.01, n = 36) in comparison to fertile men (n = 24). In addition, a significant difference was observed between globozoospermic (P < 0.01) and individuals with previously low or failed fertilization (P = 0.003) in comparison to high fertilization individuals (n = 17). Expression of PLC zeta was not correlated with either chromatin maturity or acrosin activity. However, a significant correlation was observed between the percentage of fertilization and relative expression of PLC zeta (r = 0.4, P < 0.01). CONCLUSION: In this study, for the first time, we have shown that assessment of relative expression of PLC zeta may provide a useful marker for the ability of sperm to induce oocyte activation after ICSI.