Transient ischemic injury in the rat retina caused by thrombotic occlusion-thrombolytic reperfusion

PURPOSE. To establish a clinically relevant model of transient retinal isch emia by thrombotic occlusion-thrombolytic reperfusion of the central retina l artery of the rat. METHODS. Thrombus was photochemically induced in the central retinal artery by the combination of intravenous injection of photo-sensitive dye, rose b engal, and green laser irradiation focused on the artery. Transient retinal ischemia for 60 minutes was achieved by a subsequent systemic administrati on of tissue-type plasminogen activator to reperfuse the occluded vessel. S amples of retinas were excised from the animals killed 3, 9, 12, 24, 48, an d 78 hours after the reperfusion. The experimental data were processed usin g the TdT-dUTP terminal nick-end labeling (TUNEL) method to detect apoptoti c cells. RESULTS. The transient retinal ischemia caused time-sequential apoptotic ch anges in the retinal cells as evaluated by counting the number of TUNEL-pos itive cells. The most remarkable changes occurred in the central area of re tina, and further on the sections taken 24 hours after reperfusion. The per ipheral area was less affected, and the outer nuclear cell layer was almost unaffected throughout the observation period. CONCLUSIONS. The proposed method to cause retinal transient ischemia is hig hly reproducible, and it is easy to simulate the progress and topographical distribution of retinal changes observed in the clinical cases of central retinal arterial occlusion and its subsequent thrombolytic reperfusion. Thi s mag provide a useful tool for constructing the effective thrombolytic str ategies against die central retinal arterial occlusion and for evaluating t he effects of neuroprotective agents.