Transient retinal ischemia-reperfusion in rats

Objective To investigate the effect of transient ischemia-reperfusion on th e 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 ce ll death at diffesent periods of reperfusion was studied using the TdT-deox ynucleotide terminal nick-end labeling (TUNEL) method and light microscopy. Retinal IL-1 beta and TNF alpha were quantified by an enzyme-linked immuno sorbent assay (ELISA). Results A few migrating leukocytes were noticed in the retina after transie nt retinal ischemia-reperfusion. Rare TUNEL-positive (T +) cells were notic ed in the outer granular layer or the rod and cone layer, and not in gangli on 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 reper fusion in the eyes treated with 1 or 5 minutes ischemia over the control ey es (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 o f ischemia can induce the upregulation of retinal IL-1 beta and apoptosis o f retinal neuronal cells. This kind of apoptosis in individual cells, howev er, was not sufficient to affect the whole retinal function.