Rho–Associated Protein Kinase Inhibitor (Y–27632) Prevents Neuronal death Induced by Ischemia–Reperfusion injury in the rat retina by Inhibiting Leukocyte–Endothelial Adhesion.

Abstract

Abstract: : Purpose: To investigate the neuroprotective effects of rho–associated protein kinase inhibitor, Y–27632, against ischemia–reperfusion injury (IR) or N–methyl–D–aspartate (NMDA) induced retinal damage. Methods: Retinal damage was induced by IR with increasing intraocular pressure for 45 minutes or by intravitreous injection of NMDA (20nmol) in Sprague–Dawley (SD) rats. Y–27632 (100 nmol) or PBS was injected into the vitreous cavity at 48, 24, 12, 6, 3 hours prior to or simultaneously IR or NMDA injection. Seven days after IR or NMDA injection, morphometric analysis as the number of ganglion cell layer (GCL) and the thickness of the inner plexiform layer (IPL) was performed. TUNEL experiments and retrograde labeling with a fluorescent tracer were performed for evaluating surviving retinal ganglion cells (RGCs). To elucidate the effects of Y–27632 on leukocyte–endothelial adhesion, retinal vessels were fixed and stained with silver nitrate at 6 hr after IR. Results: In morphometric analysis, Y–27632 treated eyes provided significant neuroprotective effects 3 hours prior to and simultaneously on IR but not on NMDA models. In TUNEL method, Y–27632 treated eyes prevented IR induced apoptosis, but not NMDA induced apoptosis. In analysis of retrograde labeling of RGCs, the mean number of survived RGCs was significantly increased by treating Y–27632 in IR model. Silver staining revealed that Y–27632 treated eyes reduced the number of leukocyte attachment sites visualized as silver rings at endothelial cell borders after IR. Conclusions: The present study indicated that rho–associated protein kinase inhibitor, Y–27632, might exert neuroprotective effects by controlling the leukocyte–endothelial interaction.

Keywords: neuroprotection • cell death/apoptosis • cell adhesions/cell junctions