RESUMO
Background Glaucoma is common blinding eye diseases characterized by chronic loss of retinal ganglion cells(RGCs).Currently glaucoma pathogenesis is not completely understood,heat shock protein 27 ( HSP27 )may be associated with the pathogenesis of glaucomatous optic neuropathy. Objective Through the establishment of a rat model of high intraocular pressure,detection of the expression of HSP27 antibody in serum and RGCs apoptosis to investigate the role of HSP27 in RGCs apoptosis. Methods Fifty-one clean Wistar rats were divided into high intraocular pressure group (34 rats)and sham operation group( 17 rats)using a random number table.An animal model of high intraocular pressure was established in the right eye by the application of bipolar underwater electrocoagulation on vein of sclera surface in the experimental group,and rats with conjunctiva incision only without electric coagulation were served as sham operation (control).The intraocular pressure of rats of the both groups including experimental and control rats was measured 1,2,4,6,8 weeks after operation and then the rats were sacrificed.1 ml serum was collected from these rats to determine the concentration of HSP27 antibody.The retinas of the rats were isolated and homogenated for the extraction and analysis of the retinal protein by Western blot.Apoptosis of RGCs were assayed by TUNEL.The use of the experimental animals followed the Regulations for the Administration of Affair Concerning Experimental Animals by Kunming Medical Collegc. Results Intraocular pressure was elevated significantly after modeling and remained a high value during the expcrimental duration,showing a significant difference among the different groups ( F =318.502,P＜0.01 ).However,no significant change in intraocular pressure before and after operation in the sham-operation group ( F =2.076,P ＞ 0.05 ).The serum concentration of HSP27 antibody was increased significantly overtime from 1,2,4,6 to 8 weeks after the surgery applied,with a significant difference among various time points( F =154.221,P＜0.01 ),but no obvious difference was seen in the shamoperation group( F =0.422,P＞0.05 ).Importantly,Apoptosis rate of RGCs in the experimental eyes was significant higher as the time prolong after intraocular elevated(x2=856.12,P＜0.05 ).The positive rate of RGCs apoptosis in the rats with high intraocular pressure group was elevated significantly compared to the rats in the sham operation group(P＜0.05). Conclusions High intraocular pressure induces the expressions of HSP27 in retina and the accumulation of HSP27 antibody in rats serum;the elevated HSP27 is associated with the increased cell death in RGCs.
RESUMO
Background As one of the most common microvascular complication of diabetes in eyes,diabetic retinopathy (DR) is one of the most important cause of blindness.Nuclear factor-kappa B (NF-κB) is involved in the occurrence and development of the disease through the activation of a series of inflammatory cytokines.Objective The present study was to investigate the effects of peroxisome proliferator-activated receptor-gamma (PPAR-γ) excitomotor,rosiglitazone,on NF-κB expression and apoptosis of the retinal ganglion cells (RGCs) in the retina with diabetes mellitus. Methods Ninety SPF male Wistar rats were randomized into normal control group,diabetic control group and rosiglitazone group.Diabetes mellitus was induced by intraperitoneal injection of 50 mg/kg streptozotocin(STZ).Then 3 mg/kg rosiglitazone was intragastricly administered once per day in the rosiglitazonegroup,and the same volume of saline solution was used at the same way in the normal control group and diabetic control group from 3 days after modeling.The rats were sacrificed and the eye cups specimen was made at 4,8 and 12 weeks after usage of drugs.Retinal histopathological examination was performed by hematine-eosin staining,and expression of NF-κB p65 protein in retina and apoptotic index(AI) of RGCs were detected by immunohistochemistry and TUNEL assay,respectively in different time points mentioned above.The use of the animals complied with the Regulations for the Administration of Affairs Concerning Experimental Animals by State and Technology Commission.Results The blood glucose level was significantly elevated at various time points in the diabetic control group and rosiglitazone group compared with normal control group (P＜0.01 ),and that of the rosiglitazone group was significantly declined in comparison to the diabetic control group (q =0.81,0.82,1.23,P＞ 0.05 ).Normal retinal structure was seen in the normal control group,and edema retinal cell and disorder of retinal layers were exhibited in the diabetic control group.Retinal structure was almost normal in the rosiglitazone group.The NF-κB p65 was expressed weakly in the retina of normal control group,but the expression of NF-κB p65 was significantly elevated in the diabetic control group and rosiglitazone group compared with the normal control group(P＜0.01 ).However,the expression of NF-κB p65(A value)was significantly decreased in the rosiglitazone group compared with diabetic control group at 8 weeks and 12 weeks( q=17.77,15.30,P＜0.01 ).There were a few apoptotic cells in rat retina of the normal control group.Compared with the normal control group,the AI of the diabetic control group and rosiglitazone group was significantly reduced(P＜0.01 ).However,the AI of RGCs in the rosiglitazone group was significantly lower than that of diabetic control group in various time points (q =19.28,27.39,49.92,P＜0.01 ). Conclusions As one of the PPAR-γexcitomotors,rosiglitazone can inhibit apoptosis of RGCs through downregulating the expression of NF-κB in rat retina with diabetes mellitus,indicating a protective effect of rosiglitazone on retina in diabetic rat.