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

Vascular endothelial growth factor (VEGF) is known as an endothelial cell-s pecific mitogen. There are no reports concerning the presence of VEGF in th e inner ear. To gain information, immunohistochemical analysis using specif ic antibodies to VEGF and to both known VEGF receptors Flt-1 and KDR/Flk-1 was performed on paraffin-sectioned temporal bones from five guinea pigs. I mmunoreactivity of VEGF, Flt-1 and KDR/Flk-1 was detectable in spiral gangl ion cells. VEGF could also be found in the endothelium of blood vessels, in the spiral ligament and ill the organ of Corti. Flt-1 was found in the lim bus epithelium, in all supporting cells of the organ of Corti, in Claudius cells, cells of the sulcus and in the spiral ligament. Flk-1 could be detec ted in some supporting cells of the organ of Corti (inner pillar cells and Deiters' cells). Immunoreactivity to Flk-1 was also found in endothelium of blood vessels and in the spiral ligament. Hair cells showed VEGF immunosta ining, but did not contain staining to Flt-1 nor Flk-1. In the stria vascul aris any immunoreactivity to all used VEGF and VEGF receptor antibodies cou ld not be detected. The findings were supported by Western blot analysis on inner ear tissues and ovaries from guinea pigs. We may conclude that the g rowth factor EGF and both receptors participate in cochlear physiology. (C) 2001 Elsevier Science B.V. All rights reserved.