Immunohistochemical detection of vascular endothelial growth factor (VEGF) and VEGF-receptors Flt-1 and KDR/Flk-1 in the vestibule of guinea pigs.

Vascular endothelial growth factor (VEGF), known as an endothelial cell-specific mitogen, has been reported to be linked also to the NO/cGMP-pathway, which has been notified in the inner ear. Up to now, VEGF has not yet been described in the inner ear. We performed immunohistochemical analysis using specific antibodies to VEGF and to both known VEGF-receptors Flt-1 and KDR/Flk-1 on paraffin-sections of temporal bones from guinea pigs (n=5). Immunoreactivity of VEGF, Flt-1 and KDR/Flk-1 was detectable in a subpopulation of vestibular ganglion cells. VEGF could be found also in the endothelium of blood vessels, in fibrocytes of the lamina propria and in the neuroepithelium. Strong immuno-labelling to Flt-1 was evident in nerve fibres, vascular endothelium and in the neuroepithelium. Fibrocytes, endothelium of blood vessels, supporting cells and calyces in the sensory epithelium revealed immunoreactivity to KDR/Flk-1. These findings give evidence that VEGF, Flt-1 and KDR/Flk-1 are constitutively expressed in the vestibule.