These authors contributed equally to this article and share senior co-authorship.
Detection of Neurotrophin-4 (NT-4) in Ejaculated Bull Spermatozoa and its Effect on Spermatozoa Mitochondrial Activity
Article first published online: 21 MAY 2012
© 2012 Blackwell Verlag GmbH
Reproduction in Domestic Animals
Volume 48, Issue 1, pages 131–136, February 2013
How to Cite
Wang, C.-Q., Zhang, J., Sun, Y.-F., Wang, D., Li, C.-J., Li, W.-H., Lu, C., Liu, Z., Wu, H., Hou, X.-F., Chen, C. and Zhou, X. (2013), Detection of Neurotrophin-4 (NT-4) in Ejaculated Bull Spermatozoa and its Effect on Spermatozoa Mitochondrial Activity. Reproduction in Domestic Animals, 48: 131–136. doi: 10.1111/j.1439-0531.2012.02048.x
- Issue published online: 15 JAN 2013
- Article first published online: 21 MAY 2012
- Submitted: 22 Dec 2011; Accepted: 16 Apr 2012
Recently, we demonstrated that two members of neurotrophins, nerve growth factor and brain-derived neurotrophic factor, and two types of receptor, tyrosine kinase A (TrkA) and tyrosine kinase (TrkB), exist in ejaculated bull spermatozoa, and play a crucial role in the normal function of spermatozoa. Neurotrophin-4 (NT-4) is another neurotrophic factor that signals predominantly through the TrkB receptor tyrosine kinase, and no reports of detection of NT-4 in spermatozoa have been published. In the present study, the presence of NT-4 in mature bull spermatozoa was investigated using RT-PCR, immunofluorescence and Western blotting. The result shows that there was no RT-PCR evidence for NT-4 transcripts in bovine spermatozoa. However, the NT-4 protein was present in bovine spermatozoa, and the NT-4 immunoreactivity was localized to the equatorial segment and midpiece of bovine spermatozoa. In addition, effects of NT-4 on function of spermatozoa were studied. Significant increased mitochondria activity of mature bovine spermatozoa was observed in response to 300 or 500 ng/ml exogenous NT-4 (p < 0.05), in comparison with the control, while addition of inhibitors (40 ng/ml k252α) specific for tyrosine protein kinase significantly blocked the increase of mitochondria activity. However, NT-4 had no effects on the viability or acrosome reaction of spermatozoa (p > 0.05). Consequently, this study provided evidence that NT-4 protein was presented in the mature bull spermatozoa and can influence the mitochondrial activity of bovine spermatozoa through TrkB tyrosine kinase–dependent pathways.