ABSTRACT
BackgroundThe progressive death of retinal ganglion cells (RGCs) is the primary pathological characteristics of visual defects in glaucomatous eye.Research showed that endoplasmic reticulum stress (ERS) is involved in this progression.Glucose-regulated protein 78 ( GRP78 ) is a special marker of ERS.To understand the change in expression of GRP78 in the retina under the pressure induced is very important for the protection of visual function.Objective The present study was to observe the expression of GRP78 in rat retina with acute high intraocular pressure (IOP) and investigate the possible effect of ERS in acute glaucoma damage. MethodsFiftysix Wistar rats were randomly assigned to normal control group,anterior chamber punctured group and 12 hours,1 day,3,7,14 days groups following acute IOP rising.The acute high IOP models were established in the right eyes of 4.0 Wistar rats by paracentesis of the anterior chamber and infusion of normal saline solution into the anterior chamber.The histopathology changes of the retina were examined by hemotoxylin and eosin staining.The expression of GRP78 protein and mRNA in the retina were detected by immunohistochemistry and real-time fluorescence quantitative PCR.ResultsThe retinal layers and cells were clear with normal alignement in the rats of the normal control group and the anterior chamber punctured group.The edema and thickening of retinas appeared in 12 hours after molding and peaked in 1 day after molding.Then the retina decreased in thickness and atrophied from 3 days through 14 days.The expression levels of GRP78 protein (A value) were 0.195±0.006 in the nounal rats and gradually increased from 12 hours through 3 days (0.268±0.017) following molding with the peak value at 1 day (0.499±0.039 ),showing significant differences in comparison with the normal control group (t =0.098,0.304,0.073,P＜0.05),and the reduction in expression at 7 and 14 days were not significantly different from the normal control group ( t =0.002,0.001,P＞0.05 ).The relative value of GRP78 mRNA ( 2△△C1 ) in the retina was 1.011 ±0.013 in the normal control group and gradually up-regulated from 12 hours through 3 days with the peak value at Iday (2.141±0.171 ) and then down-regulated from the third day onwards.A significant difference was seen in 2-△△C1value between the normal control group and 12 hours group,1 day group or 3 group ( t =0.525,1.130,0.409,P＜0.05 ).However,the 2-△△C1 values of GRP78 mRNA at 7 and 14 days was similar to that of the normal control group (t=0.020,0.004,P＞0.05).ConclusionsGRP78 participates in the process of RGCs damage following acute high IOP.The results suggest that interfering with ERS may be helpful for protecting the retina and optical nerve from pressure-induced damage.
ABSTRACT
Background Recently,the study on the cause of optic nerve damage induced by glaucoma is of concern in ophthalmology.Some research showed that the immune system is associated with glaucoma-induced optic neuropathy.Acute ischemia-reperfusion is an ideal model of studying optic neuropathy.ObjectiveThe present study investigates the effect of T and B lymphocyte deficiency on the retinal neurocytes of mice with acute intraocular hypertension.Methods Sixteen SPF CB-17/Icr.Cg-Prkdc~(scid)Lyst~(bg)/CrlVR mice 6-8 week-old (severe combined immunodeficiency mouse,SCID) were used in this study and 16 age-matched SPF wild type (C57BL/6) mice served as controls.The ischemia-reperfusion injury models were induced in the right eyes of 10 SCID mice and 10 C57BL/6 mice through intra-anterior chamber infusion of balanced saline solution for 45minutes to increase the intraocular pressure to 104mmHg,and the left eyes served as model controls.The other 6 SCID mice and 6 C57BL/6 mice served as normal control group.10g/L (2μL) of FlouroGold was injected into the brains of the mice for the labeling of surviving retinal ganglion cells 21 days after ischemia-reperfusion.The thickness of retinal inner nuclear layer was measured by H&E staining under the fluorescent microscope 21 days after ischemic insult.The use of the animals followed the Standard of Association for Research in Vision and Ophthalmology.Results In normal control mice,the morphology of retinal ganglion cells (RGCs) and retinal structure were similar between SCID mice and C57BL/6 mice.The differences in the numbers of RGCs and retinal thickness were insignificant between the two types of mice(P＞0.05).In the experimental mice,the surviving RGCs were strikingly increased in SCID mice (91%±5%) compared with C57BL/6 mice(78%±5%)(P=0.003).The thickness of the retinal inner nuclear layer was obviously thinner in the model eyes (22.44±1.70μm) compared to model control eyes (31.06±3.75μm) in C57BL/6 mice(P=0.004),but no statistically significant difference was found between the model eyes and model control eyes in SCID mice (33.52±2.13μm vs 34.06±3.00μm) 21 days after ischemia-reperfusion injury(P＞0.05).Conclusion T and B lymphocytes deficient mice show a better tolerance to acute intraocular hypertension than the wild type C57BL/6 mice.