Absence of nerve growth factor and comparison of tyrosine kinase receptor A levels in mature spermatozoa from oligoasthenozoospermic, asthenozoospermic and fertile men

BackgroundNerve growth factor (NGF) and the Tyrosine kinase receptor (TrkA) are expressed in mammalian ovaries and testes, where they are involved in oocyte maturation and spermatogenesis. We assessed the possibility that NGF and TrkA gene products are present in human spermatozoa, and explored differences in levels of NGF and TrkA in spermatozoa from oligoasthenozoospermic, asthenozoospermic and fertile men.MethodsThe presence of NGF and TrkA in human spermatozoa was investigated using RT-PCR, immunofluorescence and Western blotting. Real-time PCR and ELISA were used to determine expression levels of NGF and TrkA.ResultsNo NGF transcripts were detected in human spermatozoa. The levels of TrkA mRNA in spermatozoa from oligoasthenozoospermic samples were significantly lower than those in spermatozoa from fertile and asthenozoospermic samples (P < 0.05). NGF concentrations in seminal plasma samples from oligoasthenozoospermic men were lower than those in seminal plasma from fertile and asthenozoospermic men, but these differences were not statistically significant (P > 0.05).ConclusionsThe levels of both NGF protein in seminal plasma and TrkA mRNA in spermatozoa are low in samples from oligoasthenozoospermic men.