Effect Of β-estradiol On Acute Ocular Hypertention Model Of Rat's Microglia

Objective: Glaucoma is one of the most frequent growing blind oculopathies, and its pathogenesis is not clear. Now immunological pathogenesis of glaucoma is getting attention gradually.Retinal microglial cells has become the hot reach pot as the most representative immunocyte of the central nervous system . As the different secretion of microglias, they have nerve protection and neurotoxicity. Therefore, the drug research to RMC becomes an entry point for the treatment of glaucoma . Studies have shown thatβ-estradiol has a role in the regulation of apoptosis in immunocytes and neuroprotection.This experiment was that observe effects ofβ-estradiol on activation of retinal microglia, expression of inducible nitric oxide synthase(iNOS) and effects on the protection of retinal ganglion cells (RGC)through the establishment of rat acute ocular hypertention model in order to provide experimental basis for future treatment of glaucoma.Methods: 35 SD male rats without eye diseases , each weighing 200 to 220g, were divided into 3 groups: groupⅠ:normal group(5rats,10eyes),groupⅡ:β-estradiol solution treated group (15rats),groupⅢ:balanced disinfected olive solution treated group(15 rats).Rats in groupⅡandⅢwere induced in left eye byforcing perfusion of balanced disinfected olive solution into the anterior chamber as acute ocular hypertention model.Right eyes were self-control eyes.Not standard eyeballswere discard and 10 eyeballs were selected and fixed in each group.The RMS were detected by immunohistological technique to observe the expression of RMC and iNOS and the effects on the protection of RGCs.The apoptosis cells were detected by TdT-dUDP terminal nick end-labeling (TUNEL) technique.The computer image analysis system was used to analysis the expression of RMC , iNOS and the apoptosis cells of RGCs in retina after immunohistochemistry stain.SPSS 13.0 was used to analyse data of this study.Results: 1.The change of histopathology1.1 CD11b-positive microglias:in groupⅠand the self–control eyes of groupⅡand groupⅢ, the pale staining cells were brown and banching. The cell bodies were small and they had dendritic extensions. In the model eyes of groupⅡand groupⅢ,the cells number is more. Ramified microglias changed their morphology to reactive or amoeboid forms accumulating in the apoptosis RGCs and cells segments.1.2 RGCs: in groupⅠand the self–control eyes of groupⅡand groupⅢ,RGCs were in singl arrangement,and there was no positive cell. In the model eyes of groupⅡand groupⅢ, the number of RGCs reduced evidently,and the ganglion cells layer(GCL) became vacuolated change. In the model eyes of groupⅡ, the number of RGCs reduced,but the structure of GCL was normal.2. The immunohistochemistry analysis of retinal microglial cells(the activation of retinal microglial cells and the expression iNOS): CD11b, the surface marker of microglia, expressed in all the group. InⅠgroup ,iNOS-positive cells didn't express. .The CD11b -positive cells and iNOS-positive cells of model eyes in groupⅡandⅢwere more than that of group I and self-control eyes,there were significant diferences (P<0.05) .But the CD11b-positive cells and iNOS-positive cells of model eyes in groupⅡwere less than that of groupⅢ,there were significant diferences (P<0.05). In all,there was statistical difference between model and self-control eyes both in the 2 groups and the significant difference of the model eyes between the two groups was also found (P<0.05).3. The TUNEL test of RGCs: The TUNEL-positive cells expressed in all the group. The TUNEL-positive cells of self-control eyes in groupⅡandⅢare lest,so was groupⅠ.The TUNEL-positive cells of model eyes in groupⅡandⅢwere more than that of groupⅠand self-control eyes,there were significant diferences (P<0.05).But the TUNEL-positive cells of model eyes in groupⅡwere less than that of groupⅢ,there were significant diferences (P<0.05).Meanwhile confirmed that the expression of CD11b-positive microglias was assumed linear correlation,so did the expression of iNOS and the apoptosis of RGCs.Conclusion:1. By analyzing the expression of CD11b and iNOS of the model eyes of groupⅡ,Ⅲ, groupⅠand self-control eyes (P <0.05), the retinal microglial cells activate and express iNOS in acute ocular hypertention.2. The expression of CD11b and iNOS of the model eyes of groupⅡ,Ⅲwas significant,soβ-estradiol can inhibit the activation of microglias, reducing the expression of iNOS, thereby reducing the synthesis of NO nerve toxic substances.3. NO is nerotoxic.4. The test of RGCs'TUNEL showed thatβ-estradiol can reduce the apoptosis of RGCs, so it can protect.5. The expression of CD11b and iNOS of the three groups are both assumed linear correlation with the expression of RGCs'TNUEL,and confirmed that microglia cells played a regulatory role to apoptosis of RGCs in the high intraocular pressure.