Sperm DNA Damage and Protamine Transcripts Content in Iranian Men with Unexplained Infertility

Abstract

Background: Incomplete chromatin condensation caused by altered amount of sperm protamines results in DNA fragmentation, which in turn leads to a lack of success in the development of the human embryo. Objectives: This study evaluated the sperm DNA damage and protamine transcripts content in Iranian normozoospermic fertile and infertile men. Methods: DNA damage was analyzed using comet assay. Transcript levels of protamine-1 (PRM1) and protamine-2 (PRM2) in ejaculated spermatozoa were assessed by quantitative real-time polymerase chain reaction (PCR). Results: Significantly higher levels of DNA damage were observed in unexplained infertile men (P = 0.001). DNA fragmentation correlated significantly with sperm total motility (r = -0.413, P = 0.032) and normal morphology (r = -0.424, P = 0.028). PRM1 and PRM2 transcripts contents were significantly lower in normozoospermic infertile men than healthy controls. Sperm PRM1 and PRM2 mRNA ratios were significantly higher (P = 0.035) in unexplained infertile patients than fertile men. Higher DNA damage was found to be significantly associated with reduced transcript levels of PRM1 (r = -0.453, P = 0.018) and PRM2 (r = -0.492, P = 0.009). Protamine transcripts ratios were significantly correlated with sperm normal morphology (r = -0.421, P = 0.029). Conclusions: Our findings showed the prognostic value and clinical utility of the sperm DNA damage and protamine transcripts contents for the discrimination between healthy fertile and unexplained infertile men.