ESSENTIAL ROLE OF GROWTH-HORMONE IN ISCHEMIA-INDUCED RETINAL NEOVASCULARIZATION

Retinal neovascularization is the major cause of untreatable blindness , The role of growth hormone (GH) in ischemia-associated retinal neova scularization was studied in transgenic mice expressing a GH antagonis t gene and in normal mice given an inhibitor of GH secretion (MK678), Retinal neovascularization was inhibited in these mice in inverse prop ortion to serum levels of GH and a downstream effector, insulin-like g rowth factor-I (IGF-I), Inhibition was reversed with exogenous IGF-I a dministration, GH inhibition did not diminish hypoxia-stimulated retin al vascular endothelial growth factor (VEGF) or VEGF receptor expressi on, These data suggest that systemic inhibition of GH or IGF-I, or bot h, may have therapeutic potential in preventing some forms of retinopa thy.