Vascular endothelial growth factor and its receptors expression in the rateye

Vascular endothelial growth factor (VEGF) plays a pivotal role in the angio genesis of embryonic development and tumorigenesis. Recent extensive studie s show that VEGF also affects non-vascular cells. In the present study, we performed an immunohistochemical examination of cellular distribution of VE GF and its receptors, Flt-1 and Flk-1, in the retina in vivo and in vitro. Moreover, we addressed their expression in the cornea, iris and ciliary bod y. In the retina, both Flt-1 and Flk-1 were localized to the axon of retina l ganglion cells (RGCs) and to the retinal pigment epithelium. In vitro exp eriments showed that both VEGF receptors seemed to be expressed in the cyto plasm of RGCs and Muller cells. In the extra-ocular tissues, ciliary body e pithelium showed VEGF, Flt-1 and Flk-1 expression, while iris epithelium sh owed VEGF and Flk-1 but not Flt-1. Corneal endothelium only showed Flk-1. T hese data support the hypothesis that VEGF plays a role in many ocular tiss ues via Flt-1, Flk-1 or both.