Study Of Retinal Neuronal Cell And Intraocular Pressure In Type1Diabetic Mice

Purpose: Little is known about retinal neuronal loss in retinasof diabetic mice. The purpose of this study was quantitativeassessment retinal neural cell number in diabetic mice.Methods: Five-week-old C57BL/6mice were used as diabeticmodel with streptozotocin (STZ). Mice were studied over the courseof6,12weeks after onset of diabetes. Intraocular pressure (IOP) wasmeasured with a non-invasive TonoLab tonometer. The retinalganglion cells (RGCs) were counted at two different time points afterthe induction of diabetes and examined by using immunofluorescencetechnique and quantitative analysis.Results: The diabetic mice had significantly elevated IOP levelsat6and12weeks after onset of diabetes compared with theage-matched control mice (p<0.01and p<0.001, respectively). Thetemporal course of Brn3a+RGCs and NeuN+RGCs loss induced byintraperitoneal injection of streptozotocin (STZ) followed a similartrend. At the6and12weeks after onset of diabetes, the number ofBrn3a+RGCs (p<0.05at6weeks; p<0.001at12weeks, respectively) and NeuN+RGCs (p<0.05at6weeks; p<0.001at12weeks,respectively) was significantly lower in diabetic mice thanage-matched control mice. In the retinal flatmounts, the number ofBrn3a+RGCs (p<0.05at6weeks, p<0.01at12weeks, respectively)was also significantly lower in diabetic mice than control mice. IOP indiabetic mice was negatively related with RGCs in cross sections.Conclusion: This is a specific quantitative study of neural cellloss in the retina during diabetes. These data suggest that retinal neuralcell reduction occurs and elevated IOP in diabetic mice. It indicatesthat RGCs loss may be an important component of diabeticretinopathy (DR).