Expression of vascular endothelial growth factor and its receptors in the cochlea of various experimental animals

CONCLUSION: The results of this study indicate that vascular endothelial growth factor (VEGF) may be an important regulator of the vascular network of the inner ear and suggest that the VEGF signalling pathway may play a role in pathophysiologic conditions. OBJECTIVE: In order to clarify the role of vascular growth factor in the modulation of the vascular network of the cochlea, we studied the expression of VEGF and its receptors-fms-like tyrosine kinase (Flt-1) and foetal liver kinase (Flk-1)-in the inner ear of 3-month-old rodents of different species: C57BL/6J mice, Wistar albino rats and Hartley albino guinea pigs. MATERIAL AND METHODS: Qualitative immunohistochemical studies were performed by using specific antibodies to VEGF and its receptors on paraffin sections of the cochlea. The expression levels of VEGF and its receptors were quantified by means of Western blot analysis of cochlea protein extracts. RESULTS: We demonstrated that VEGF and its receptors are expressed in the cochlea and described their distribution in the inner ear. In particular, VEGF and Flt-1 are present at the level of the modiolus, spiral ganglion, spiral ligament, basilar membrane, supporting cells, outer and inner hair cells and stria vascularis. Flk-1 was less strongly expressed in the cochlea and was not detected in the organ of Corti.