Vascular endothelial growth factor A is a putative paracrine regulator in seasonally controlled spermatogenesis: Insights from a ruminant model, the roe deer

Abstract

Vascular endothelial growth factor A (VEGFA) influences spermatogenesis, but its impact on seasonally regulated sperm production is still not fully understood. Thus, we investigated both expression levels and localisation of VEGFA and its receptors VEGFR1 and 2 in roe buck testis via real-time reverse transcription polymerase chain reaction and immunohistochemistry in relation to seasonal changes in the cellular composition of the testis. VEGFA was expressed by interstitial cells while its receptors were found on endothelial and perivascular cells. Inside the tubules, VEGFA was located in spermatogonia and spermatocytes, VEGFR1 was present on elongating spermatids and VEGFR2 on Sertoli cells. VEGFR1 mRNA was expressed tenfold lower than VEGFR2 and VEGF mRNAs. Relative VEGF and VEGFR2 expression (divided by the number of VEGFA and VEGFR2 expressing cells) showed an increase towards the rut (July/August) and a decrease thereafter. The results suggest involvement of VEGFA in the adjustment of vascular permeability as well as in spermiogenesis and the proliferation of spermatogonia.

Keywords::

• Vascular endothelial growth factor
• seasonal reproduction
• spermatogenesis
• roe deer

Acknowledgements

The authors thank Dr Frank Göritz and his team for performing the castrations.

Declaration of interest: The study was supported by grants of the DFG (Fi698/3-1 and Blo319/7-1). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.