| ObjectiveIn the study, the model of retina ischemia-reperfusion injury (RIRI) was established and given intraperitoneal injection of aminoguanidine after the injury, aiming to observe the retina morphological changes and to investigate the expression of indicators such as NO and iNOS in retina ischemia-reperfusion injury and the therapeutic effect aminoguanidine injection has on ischemia-reperfusion injury. The experiment is designed to investigate the mechanism of aminoguanidine injection on experimental retina ischemia-reperfusion injury, and to provide theoretical basis to the therapeutically use of aminoguanidine injection on retina ischemia-reperfusion injury.Materials and methodsEighty healthy male rabbits, weight approximate 3.0 kilograms, were randomly divided into normal groups (16 rabbits), injury groups (32 rabbits) and treatment groups (32 rabbits). The normal groups don't establish the model of rabbit retina ischemia-reperfusion injury (RIRI). The injury groups and the treatment groups establish the model of rabbit retina ischemia-reperfusion injury with both eyes through elevating intraocular pressure to make retinal ischemia, then resuming normal intraocular pressure. The rabbits of treatment groups were given intraperitoneal injection of aminoguanidine. Meanwhile, the rabbits of the normal groups and the injury groups were given Sodium Chloride with identical methods. The injury groups and the treatment groups do fundus photography and angiography at ischemia instant, 6h, 24h and 72h with two rabbits alive each time .The normal group as take two rabbits do fundus photography and angiography .Then the other rabbits were put to death at 1h, 6h, 24h and 72h, and the eyes were enucleated. Part of retinal slice is stained HE and TUNEL to observation the changing of morphology and calculated apoptosis cells. Part of the retina is detected NO concentration through nitrate reductase enzymatic, and iNOS vigor by colorimetric detection. All the data were statisticed with the SPSS13.0 software.Results1. The fundus photography and fluorescence angiographyNormal retinal is jacinth, and blood vessels in it are good. After high intraocular pressure, retinal is pale, with vascular in it sharply get shorter and retinal arterial occlusion. After reperfusion, retinal vessels dilate, dull red in colour. The heaviest retinal edema is at 24h, when large white batt outfit infiltrates can be seen.There is not fluorescent element leakage in Normal retinal. After high intraocular pressure, fluorescent element confined to the optic disc, and fluorescent element is not seen in retinal vessels. After reperfusion, fluorescent element is can be seen in retinal vessels. Fluorescent element leakage also can be seen outside of the retinal vessels. The most serious leakage of fluorescent element is at 24h.Of each time–point, in the treatment groups, the degree of Retinal edema is lighter than the injury groups, and the degree of vascular occlusion and the proportion are lighter than the injury groups too, and the amount of fluorescent element leakage and area are also smaller than the injury groups.2. HE stain of retinaThe normal groups: The inner limiting membrane of retina is smooth and complete. The demarcations between three layers of cells are clear .The size of ganglion cells is large and the nuclear chromatin distribution is uniform. The cells in inner nuclear layer and outer nuclear layer are in multilayer arrangement, and compacted at thickness and dyeing.The injury groups: After injured 1h, retinal tissue is mild edema. After injured 6h, retina had become more edema, and there are a few cells with vacuolar degeneration. After injured 24h, there is serious edema in every retinal layer. The space of cells is increasing. The amount of ganglion cells number is sharply reduced. After injured 72h, retinal edema was abatement .Thickness of retina obviously became thinness.The treatment groups: After injured 1h, retinal tissue is mild edema. After injured 6h, retina had become more edema, and there are none cells with vacuolar degeneration. After injured 24h, the retina thickness of each layer is thinner than the injury groups. The cells in inner nuclear layer and outer nuclear layer arranged a little pultaceous and the space of cells is increasing. The amount of ganglion cells number is reduced. After injured 72h, retinal edema was abatement .Thickness of retina obviously became thinness.The experiment cued: the pathology change in treatment group of each time - point was lighter than the injury groups.3. The location and calculation of TUNEL stained apoptosis cellsApoptosis cells were not found in normal groups. After injured 1h, the apoptosis cells slightly expressed in the inner nuclear layer. After injured 6h, the apoptosis cells expressed increase. After injured 24h, the expressed of apoptosis cells reach the peak. After injured 72h,The number of apoptosis cells is significantly reduced. The change trend of TUNEL-positive cells expression in treatment groups was similar with the injury groups except that the expression amount was relatively obviously less. There were statistical significances of the number of apoptotic cells between the injury groups and the treatment groups at the same time. In the same group (the injury groups and the treatment groups) between adjacent times there were statistical significances of the number of apoptotic cells (p < 0.05), and the number of apoptotic cells of 24h reaches the peak.4. Changes of NO concentrationIn normal groups there is a small amount of NO. After injured 1h, the NO concentration slightly rises. After injured 6h, the NO concentration continues to increase. After injured 24h, the NO concentration reaches the peak. After injured 72h,The NO concentration is significantly reduced. The change trend of NO concentration in treatment groups was similar with the injury groups except that the expression amount was relatively obviously less. There were statistical significances of the number of apoptotic cells between the injury groups and the treatment groups at the same time. In the same group (the injury groups and the treatment groups) between adjacent times there were statistical significances of the NO concentration (p < 0.05), and the NO concentration of 24h reaches the peak.5. Changes of iNOS dynamicThe iNOS dynamic is not found in normal groups. After injured 1h, the iNOS dynamic slightly rise. After injured 6h, the iNOS dynamic continue to increase. After injured 24h, the iNOS dynamic reaches the peak, and then begin to abate. After injured 72h,The iNOS dynamic is significantly reduced. The change trend of iNOS dynamic in treatment groups was similar with the injury groups except that the expression amount was relatively obviously less. There were statistical significances of the number of apoptotic cells between the injury groups and the treatment groups at the same time. In the same group (the injury groups and the treatment groups) between adjacent times there were statistical significances of the iNOS dynamic (p < 0.05), and the iNOS dynamic of 24h reaches the peak.ConclusionsThe pathology change in treated group of each time-point is lighter than the injury group, and so aminoguanidine injection had a definite protective effect on retina in ischemia-reperfusion injury. Retina ischemia-reperfusion injury can cause the increase of NO concentration and iNOS dynamic. Aminoguanidine maybe through inhibiting iNOS activity and then reducing the NO concentration achieves its therapeutic effect on the RIRI. |
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