Expression of Transforming Growth Factor-β Receptors in Normal Rat Retina and Experimental Choroidal Neovascularization

Abstract Purpose: Transforming growth factor-β (TGF-β) plays an important role in the development of choroidal neovascularization. TGF-β transduces signals through the mediation of type I and type II receptors. We investigated the expression of TGF-β receptors in a normal rat retina and a model of experimentally induced choroidal neovascularization. Methods: Choroidal neovascularization was induced by laser photocoagulation in rat eyes. The expression of TGF-β receptors was determined using immunohistochemical and in situ hybridization methods. Results: In normal adult rat retinas, immunoreactivity and mRNA expression of TGF-β receptor type I (TβRI) and TGF-β receptor type II (TβRII) were found in the ganglion cells. During the process of neovascularization, immunoreactivity and mRNA expression of TβRI and TβRII were widely distributed in laser lesions soon after photocoagulation; thereafter, these receptors were specifically detected in the endothelial cells of choroidal neovascularization. Conclusions: The expression of TGF-β receptors in normal rat retinas suggests that TGF-β plays an important role in the homeostasis of normal retina. The upregulation of TGF-β receptors in choroidal neovascularization strongly suggests that TGF-β is most likely transduced through specific receptors and plays an important role in the development of choroidal neovascularization.