Abstract
Abstract: :
Purpose: Proliferation of abnormal vessels in various retinal diseases including diabetic retinopathy may involve the upregulation of vascular endothelial growth a factor (VEGF). Since protein kinase C (PKC)–ßII is a key mediator of VEGF effect, selective PKC–ßII inhibitors are considered as potential therapeutic agents in diabetic retinopathy. In the present study, we examined possible inhibitory effects of riluzole, anti–ALS drug that has recently been demonstrated to possess PKC inhibitor activity, on the VEGF–induced endothelial cell proliferation in culture and on the neovascularization in a rat model of ROP. Methods: in viro; HUVEC and cultured bovine retinal endothelial cells were used. Cellular proliferation was assessed by counting nuclei after staining with Hochest 33258. Phosphorylation of PKC was demonstrated using western blots and ELISA. in vivo; ROP was modeled in rat pups. Score of retinopathy was assesed using fluorescein angiography of retinal flat mount. Sections were examined for extra–retinal neovascularization and stained with antibodies for immunohistochemistry. Results: in viro;In both HUVEC and REC cultures, exposure to VEGF promoted proliferation of endothelial cells. Riluzole attenuated the VEGF–induced cell proliferation in a concentration–dependent manner. Like GF109203X (a pan–PKC inhibitor), riluzole blocked increases in levels of phospho–PKC. Especially the level of phospho–PKCßI and ßII was inhibited without altering the level of phospho–Flk–1, the VEGF receptor tyrosine kinase. in vivo;Average score of retinopathy was reduced by about 50 % in ROP rats that received riluzole. Particularly, the degree of extra–retinal vessel formation was reduced by 80 % in riluzole–treated rats compared with control rats. Conclusions: Present results have demonstrated that riluzole inhibits VEGF–induced retinal endothelial proliferation in vitro and oxygen–induced endothelial proliferation in vivo, likely by inhibiting the PKC cascade. Considering that riluzole is an FDA approved, relatively safe drug, it should be considered as a potential therapeutic agent in proliferative retinopathy.
Keywords: retinal neovascularization • diabetic retinopathy • vascular occlusion/vascular occlusive disease