Transient retinal ischemia-reperfusion in rats

OBJECTIVE: To investigate the effect of transient ischemia-reperfusion on the retina in rats. METHODS: Retinal ischemia-reperfusion was induced in rats by increasing the intraocular pressure. After 1 or 5 minutes of ischemia, retinal neuronal cell death at different periods of reperfusion was studied using the TdT-deoxynucleotide terminal nick-end labeling (TUNEL) method and light microscopy. Retinal IL-1 beta and TNF alpha were quantified by an enzyme-linked immunosorbent assay (ELISA). RESULTS: A few migrating leukocytes were noticed in the retina after transient retinal ischemia-reperfusion. Rare TUNEL-positive (T+) cells were noticed in the outer granular layer or the rod and cone layer, and not in ganglion cell layer in control eyes, but they were significantly increased in the outer granular layer, the inner granular layer, and ganglion cell layer in the eyes treated with 1 or 5 minutes of retinal ischemia-reperfusion (P < 0.05). Retinal IL-1 beta was significantly increased at 6 hours after reperfusion in the eyes treated with 1 or 5 minutes ischemia over the control eyes (P < 0.05), but retinal TNF alpha was not significantly increased (P > 0.05). CONCLUSION: Transient retinal ischemia-reperfusion for only 1 or 5 minutes of ischemia can induce the upregulation of retinal IL-1 beta and apoptosis of retinal neuronal cells. This kind of apoptosis in individual cells, however, was not sufficient to affect the whole retinal function.