Identification of soluble forms of vascular endothelial growth factor receptors, sVEGFR-1 and sVEGFR-2, in bovine dominant follicles.

The development of dominant follicles requires the parallel growth of a vascular network, regulated by VEGF and its receptors VEGFR-1 and VEGFR-2. Here, we demonstrate the presence of mRNA for the soluble forms of VEGFR-1 and VEGFR-2 by RT-PCR and the respective proteins by Western blot, in bovine dominant follicles. The 3' end of the mRNA coding region and the deduced C-terminal amino acid sequence of the bovine VEGFR soluble forms were similar to those previously described in human and mice. The relative abundance of sVEGFR-1 was higher in dominant follicles of day 4, decreasing on day 6 and further on day 9 of the cycle. In contrast, sVEGFR-2 expression was low on day 4 follicles and increased as the cycle advanced, becoming greater on day 9. The changes of sVEGFR-1 and sVEGFR-2 with the age of the bovine dominant follicle indicate a physiological role in its growth and atresia.