The Effect of Y27632 on Retinal Tissue Histomorphology in Rats with Acute Retinal Ischemia-Reperfusion

Objective: To study the effect of rho kinase inhibitor Y27632 on retinal histomorphology in rats with retinal ischemia-reperfusion injury. Methods: In this experimental study, sixty SD rats were randomly divided into 4 groups, 15 in each group: normal group, ischemia-reperfusion injury group (IRI group), saline group, and Y27632 group. Twenty-four hours (10 rats) and 168 hours (5 rats) after the induction of ischemia-reperfusion, the rats were sacrificed and the retinas were stained with HE and ADP. Histopathological change in the retina was examined and the thickness of the retina was measured. Data were analyzed by one-way ANOVA. Results: The retinal structure was clear and the structure of the three layer cells was orderly in the normal group. In the IRI group, after 24 hours of reperfusion, retinal thickness increased, the inner and outer plexiform layers were loose, the retinal ganglion cells and the inner and outer nuclear layers showed evidence of edema and were disordered and the retinal ganglion cells were reduced. After 168 hours, retinal edema subsided, and thickness was reduced and atrophic. The number of ganglion cells and inner and outer nuclear cells decreased. Capillaries were seen in the anterior retina and nerve fiber layer. After 24 hours of reperfusion, the retinal thickness of the IRI group was greater than that of the nomal group (P=0.005), and the thickness of the Y27632 group was lower than that of the saline group (P=0.032). After 168 hours of reperfusion, the retinal thickness of the IRI group was lower than that of nomal group (P<0.001), and the thickness of the Y27632 group was higher than that of the saline group (P=0.025). In the norml group, the retinal blood vessels were distributed uniformly and radially around the papillae, and the structure of the capillary network was clear. After 24 hours of reperfusion, retinal vessels in the IRI group were thinner, more rigid and had less branching. Large non-perfusion areas were observed around the retina and around the optic papilla, and neovascularization buds were gradually reticulated around the non-perfusion area. In the Y27632 group, there was a non-perfusion area around the optic papilla and the middle retina, and neovascularization was around the non-perfusion area. The area of the non-perfusion zone in 4PD of the posterior pole was significantly less than that in the IRI andsaline groups. Conclusions: Y27632 intravitreal injection can reduce retinal edema, apoptosis of retinal ganglion cells, retinal neovascularization and retinal atrophy in the early stage of retinal ischemia-reperfusion. It has a protective effect on the optic nerve. Key words: glaucoma; ischemia; reperfusion injury; Rho kinase; Y27632; rats