The Correlation Between The Selective Loss Of Rat Retinal Ganglion Cells And Local Blood Supply Of Retinae Following The Acute Intraocular High Pressure

Purpose:To detect whether the changes of local blood supply in rat retinae following acute high intraocular pressure is differential from the central to the peripheral.And if yes,the relationship between the inhomogenous changes of local blood supply and the selective loss of retinal ganglion cells(RGCs) in rat retinae was further investigated.Methods:Part 1:90 adult Sprague-Dawley rats(200-250 g) were used in this study.Firstly,60 rats were subjected to 20 combinations(n=3 in each combination) of different gelatin concentrations(0%,1%,3%and 5%) and perfusion pressures(100%,120%,140%,160%and 180%MAP) during retinal perfusion.Based on the data from these 60 rats,the optimal perfusion condition of gelatin-ink,under which the central and peripheral retinal vessels were completely filled,was gotten.Secondly,12 rats were used for evaluation of the retinal vessel labeling outcome of the gelatin-ink perfusion method under the optimal condition(n=6) by using the vWf immunostaining(n=6) as control.Finally,we investigated whether this improved labeling technique affected the following labeling of neurons and glial cells in the same retinaePart 2:The temporal-spatial changes of blood supply in the central, middle and peripheral retinae following the acute introeular high pressure were detected by the above improved gelatin-ink perfusion method and fluorescent microsphere injection method.Part 3:The temporal-spatial changes of ganglion cell loss in the central,middle and peripheral retinae following the acute introcular high pressure were detected by fluorogold retrograde labelling.Based on these and the data of part two,linear correlation and linear regression between loss percentages of ganglion cells and increased ratios of local blood supply were made.Results:Part 1:Infusing rats first with 20 ml of 37℃ink plus 3% gelatin at 140%MAP,and subsequently with 20 ml of 37℃ink plus 5% gelatin at 180%rat MAP allowed the gelatin-ink to completely fill the rat retinal vessels.Rat retinal vessels labeled by the perfusion method were more in number than that by vWf immunostaining.Moreover,the improved gelatin-ink perfusion had no effect on and caused no contamination to the following fluorogold labeling or immunostaining of retinal neurons or glial cells in the same tissue.Part 2:During the reperfusion following acute high intraocular pressure,the blood supply in the central,middle and peripheral retina all first increased,and then decreased,and at last recovered.The increased percentages of local blood supply in the central and middle retina all were higher than that of the peripheral at each survival time points during the whole reperfusion.Part 3:The reperfusion of retina following acute high intraocular pressure has similar effects on the survival of ganglion cells in the central and middle retina.The loss percentages of ganglion cells in the peripheral retinae was significantly higher than that of the central and middle during the reperfusion,especially on the first day of reperfusion.There were significant correlation between the loss ratio of ganglion cells and the increased percentages of corresponding local blood supply during the reperfusion following the acute high intraocular pressure, especially on the first day of reperfusion.Moreover,the correlativity in the peripheral retina was significantly higher than that of the central and middle retina during the whole reperfusion.Conclusion:①Improved gelatin-ink perfusion is a method for accurate morphological characterization of rat retinal vessels,which is superior to vWf immunostaining.The gelatin-ink perfusion technique can double label with neurons/glial cells in the same retinae.②There were temporal-spatial changes in the rat retinal ganglion cell loss and local blood supply after the acute high intraocular pressure.③There is significant correlation between the seletive loss of retinal ganglion cells and inhomogenous changes of local blood supply during the reperfusion following the acute high intraocular pressure.And the correlation has special temporal-spatial features.