The mineralocorticoid receptor (MR) belongs to the nuclear receptor superfamily and is expressed in the retina and choroid. MR antagonist (MRA) has a long history of application in non-ophthalmic clinical practice. Various cellular and animal models indicated that inappropriate activation of MR participated in pathological angiogenesis, oxidative stress, inflammation, disturbance of ion/water homeostasis and neurodegenerative changes, while the application of MRA can reduce or reverse these pathological processes. After using MRA in central serous chorioretinopathy (CSC) patients, improved visual function, less subretinal fluid and reduced sub-foveal choroidal thickness were observed. Single nucleotide polymorphisms in MR and plasma aldosterone levels were significantly different between chronic CSC patients and CSC patients with spontaneous remission. Novel formulation for sustained-release MRA and the mechanisms involving inflammation may become the new focus of MR study. This review summarizes the research status of MR and MRA in order to provide a reference for future basic research and clinical treatment.
In order to study the expression change of insulin-like growth factor-1 (IGF-1) and its receptor genes in different generations of tendon cell in culture, Dig-labeled synthesized oligonucleotide probes were used to detect the mRNA expression in primary, 6th and 13th generation of tendon cell. The results showed that IGF-1 receptor mRNA was expressed in all of the 3 above generation tendon cells. IGF-1 mRNA was expressed only in primary and 6th generation cells. Tendon cell of 13th generation did not express IGF-1 mRNA. It might suggest that the absence of IGF-1 mRNA expression be one of the causes which led to the decrease of reproductive ability of 13th generation tendon cell.
ObjectiveTo investigate the effects and mechanisms of G protein-coupled receptor 91 (GPR91) on blood-retinal barrier (BRB) in diabetic rats. MethodsA lentiviral vector of shRNA targeting rat GPR91 and scrambled shRNA were constructed. Healthy male Sprague-Dawley (SD) rats were selected in this study. The 60 rats were randomized into 4 groups and treated as follows:(1) control group (Group A, n=15), the rats received injections of an equal volume of 0.1% citrate buffer; (2) streptozocin (STZ) group (Group B, n=15), the rats received injections of STZ; (3) LV.shScrambled group (Group C, n=15), diabetic rats received an intravitreal injection of 1 μl 1×108 TU/ml scrambled shRNA lentiviral particles at 2 weeks after the induction of diabetes; (4) LV.shGPR91 group (Group D, n=15), diabetic rats received an intravitreal injection of 1 μl 1×108 TU/ml pGCSIL-GFP-shGPR91 lentiviral particles. At 12 weeks after intravitreal injection, immunohistochemistry and Western blot were used to assess the expression of GPR91, p-extracellular signal-regulated kinase(ERK)1/2, t-ERK1/2, p-Jun N-terminal kinase (JNK), t-JNK, p-p38 mitogen-activated protein kinase (MAPK) and t-p38 MAPK. Haematoxylin and eosin (HE) staining and Evans blue dye were used to assess the structure and function of the retinal vessel. Immunohistochemistry enzyme-linked immunosorbent assay (ELISA) was used to test the protein level of VEGF. ResultsImmunohistochemistry staining showed that GPR91 was predominantly localized to the cell bodies of the ganglion cell layer. Western blot showed that GPR91 expression in Group D decreased significantly compared with Group C (F=39.31, P < 0.01). HE staining showed that the retina tissue in Group B and C developed telangiectatic vessels in the inner layer of retina, while the telangiectatic vessels attenuated in Group D. It was also demonstrated in Evans blue dye that the microvascular leakage in Group D decreased by (33.8±4.11)% compared with Group C and there was significant difference (F=30.35, P < 0.05). The results of ELISA showed the VEGF secretion of Group B and C increased compared with Group A and the VEGF expression in Group D was significantly down regulated after silencing GPR91 gene (F=253.15, P < 0.05).The results of Western blot indicated that compared with Group A, the expressions of p-ERK1/2, p-JNK and p-p38 MAPK were significantly upregulated (q=6.38, 2.94, 3.45;P < 0.05). Meanwhile, the activation of ERK1/2 was inhibited by GPR91 shRNA and the difference was statistically significant (F=22.50, P < 0.05). ConclusionsThe intravitreal injection of GPR91 shRNA attenuated the leakage of BRB in diabetic rats. GPR91 regulated the VEGF release and the leakage of BRB possibly through the ERK1/2 signaling pathway.
Objective To observe the expression of erythropoietin (EPO) and EPO receptor (EPOR) in detached retina in rat model. Methods Fourty-eight male SD rats were randomly divided into control group and retinal detachment (RD) groups (1 hour, 3, 6, 12, 24, 48, and 72 hours group) with 6 rats (12 eyes) in each group. 1.4% hyaluronic acid was slowly injected into the subretinal space to induce the detachment of the upper retina to set up the RD model. The expression levels of mRNA and protein of EPO and EPOR were measured by RT-PCR and western-blotting analysis. Meanwhile, the locations of EPO and EPOR in retina were checked by immunohistochemistry. Results Both of the mRNA and protein levels of EPO and EPOR increased after RD, and reached the peak at the 48th hour after RD. The mRNA levels of EPO and EPOR were significantly higher in the 6 and 12 hours group than that in the control group（Plt;0.05）. The protein levels of EPO and EPOR were significantly higher in 3 hours group than that in the control group（Plt;0.05）. Immunohistochemistry indicated weak expression of EPO from ganglion cell layer to inner and outer segment of photoreceptor cells, and b expression in the corresponding location was found 48 hours after RD. Expression of EPOR from ganglion cell layer to inner segment of photoreceptor cells in the normal retina was detected, and b expression in the corresponding location was found 48 hours after RD. Conclusion The expression of EPO and EPOR in retina increases gradually after RD, and reaches the peak at the 48th hour; most of the layers of neural retina can express EPO and EPOR.
Proliferative vitreoretinopathy (PVR) is a common complication and major cause of blindness of ocular trauma. Many cytokines, including vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF), participate in the process of the pathogenesis of traumatic PVR. VEGF competitively inhibits binding of PDGF to its receptor (PDGFRα), enables indirect activation of PDGFRα by non-PDGF ligands, resulting in reduced p53 expression, cell proliferation and migration, which is a key point in the pathogenesis of traumatic PVR.
Objective To investigate the activation and role of signal transduction pathway of epidermal growth factor (EGF)-epidermal growth factor receptor (EGFR)-mitogen activated protein kinase (MAPK) in proliferation of human retinal pigment epithelial (RPE) cells. Methods Human RPE cells were stimulated with 0.1%，10% foetal calfserum (FCS) and EGF(0.1, 1, 10, 50 and 100 ng/ml)in 0.1% FCS Dulbeco′s modified Eagle′s medium (DMEM) and in 10% FCS DMEM for 3 days, respectively. Immunohistochemical staining and in situ hybridization were used to observe the expressions of EGFR protein and EGFR mRNA，respectively. Activation of MAPK was detected by immunohistochemical method with specific anti-phosphorylated ERK 1/2 antibody. Results The optimal concentrations of EGF were 10 ng/ml in 0.1% FCS DMEM and 1 ng/ml in 10% FCS DMEM. After 3 days of stimulation with EGF, phosphorylated ERK 1/2 staining was detectable in nucleus of RPE cells, whereas cells presented immunostaining for phosphorylated ERK 1/2 in the cytoplasm before stimulation. Conclusions EGF may improve the expression of EGFR protein and EGFR mRNA of RPE cells, and induced MAPK nuclear translocation in a concentration-dependent manner. EGF-EGFR-MAPK signal transduction pathway may play a key role in RPE cells proliferation, and serum exerts an important acceclerating function in the process. (Chin J Ocul Fundus Dis，2004，20：67-132)
Objective To investigate the expression of eotaxin-1, eotaxin-2 and eotaxin-3 in ARPE-19 human RPE cells after exposure to light. Methods Cultured human RPE cells (5th~10th generations) were divided into lightinduced group and control group. Cells light-induced group were exposed to the blue light at the intensity of (600plusmn;100) Lux for 12 h to establish the light damaged model. Eotaxin-1, eotaxin-2 and eotaxin-3 mRNA and protein were determined by real time polymerase chain reaction and Western blot at 0, 3, 6, 12, 24 hours after light-induced. Results In light-induced groups, mRNA levels of eotaxin-1 and eotaxin-2 were increased at 0 h (t1=6.05.t2=12.561) and 3 h （t1=2.95.t2=3.67） significantly(P＜0.05), but the mRNA level of eotaxin-3 had not changed （t3=1.57 and 1.00 respectively，P＞0.05） at that time. At 6 h （t1=4.73，t2=18.64，t3=28.48）, 12 h （t1=3.11，t2=20.62，t3=18.50）, 24 h （t1=8.25，t2=38.27，t3=18.60）, mRNA levels of eotaxin-1, 2, 3 were increased significantly （P＜0.05）. Except for the eotaxin-3 protein had not changed at 3 h （t3=1.28，P＞0.05）, protein expression of eotaxin-1, 2, 3 were increased significantly （P＜0.05） at 0 h （t1=4.85，t2=5.45，t3=6..21）, 3 h （t1=5.64，t2=4.55）, 6 h （t1=31.60，t2=6.63，t3=7.15）, 12 h （t1=14.09，t2=18.22，t3=15.76）, 24 h （t1=6.96，t2=10.47，t3=12.85）. Conclusion Eotaxin-1, eotaxin-2 and eotaxin-3 expression were increased after Light-damage, corresponding to the time after light exposure. Eotaxin-3 was the most prominent isoform.
Objective To investigate the role of adenosine A2A receptor plays in retinal pathological neovascularization in mice. Methods A total of 202 mice were divided into room-air group (n=66) and oxygen induced retinopathy (OIR) group (n=136). Among room-air group, there were 18 A2A knock-out (KO) mice (KO subgroup) and 24 C57BL/6 mice as wide type (wide type subgroup). OIR group were divided into OIR control subgroup (n=48), A2A-OIR subgroup (n=24) and Caffeine-OIR subgroup (n=64). The retinal neovascularization of OIR group was induced by oxygen. The pathological neovascularization was determined by retinal sections. Fluorescent quantitative polymerase chain reaction (PCR) was used to measure the mRNA expression of A2A and vascular endothelial growth factor (VEGF). 0.1, 0.3, 1.0 g/L Caffeine was dissolve in drinking water of lactating females in Caffeine-OIR subgroup, non-perfusion areas of retina in mice at the age of 0 - 17, 0 - 7, 7- 17, 7-12, and 12- 17 days were analyzed in different dosage and when the dosage as 1.0 g/L. Results Compared with OIR control subgroup, the retinal non-perfusion areas and the numbers of endothelial cell nuclei breaking through the internal limiting membrane in A2A- OIR subgroup were reduced significantly (t=7.694, 7.747;P＜0.001). Compared with wide type subgroup, the level of A2A and VEGF mRNA in OIR control subgroup increased significantly (t=4.036, 2.230;P＜0.05). Compared with OIR control subgroup, the level of VEGF mRNA in A2A- OIR subgroup decreased significantly (t=3.122,P＜0.01). Compared with OIR control subgroup, the retinal non-perfusion areas in mice at the dosage of 0.1 and 1.0 g/L (t=2.397, 4.533) and at the age of 0 -17, 0 -7 days when the dosage as 1.0 g/L (t=4.070, 2.399) were reduced significantly (P＜0.05). Conclusions The expression of adenosine A2A receptor increases in oxygen-induced retinal pathological neovascularization. Adenosine A2A receptor may regulate the expression of VEGF. A2A receptor inactivation can inhibit oxygen-induced retinal pathological neovascularization.
Objective To investigate the polymorphism of the vitamin D receptor gene (VDR)TaqⅠin relation to diabetic retinopathy. Method Fragment length discrepant allele specific PCR(FLDAS-PCR) were used to determine VDR genetypes in 158 patients with diabetic retinopathy and in 198 normal subjects. Results The frequency distribution of VDR genotypes in diabetic retinopathy patients was 106 (67.1%) in TT, 33(20.9%) in Tt, 19(12.0%) in tt; and in normal persons was 165 (83.3%) in TT, 23(11.6%) in Tt, 10 (5.1%) in tt. There was a significant difference between diabetic retinopathy patients and normal persons in distribution of VDR gene TaqⅠgenotypes(Plt;0.05). Conclusions There is some distribution alterations of VDR gene polymorphism in diabetic retinopathy patients. (Chin J Ocul Fundus Dis, 2006, 22: 94-96)
Retinal neuronal cells are crucial in the formation of vision. Injury or death of these cells may lead to irreversible damage to visual function due to their low regenerative capacity. The P2X7 receptor is a trimeric adenosine triphosphate (ATP)-gated cation channel. Recent studies have shown that P2X7 receptor plays a role in retinal neuronal death. In a series of animal models, when exposed to conditions of hypoxia or ischemia, elevated ocular pressure, trauma and exogenous agonists, P2X7 receptor activated by extracellular ATP can cause death of retinal neuronal cells such as retinal ganglion cells and photoreceptor cells through direct or indirect pathways. Blocking the expression and function of P2X7 receptor by its specific antagonist and gene knocking-out, the loss of retinal neuronal cells is significantly attenuated. P2X7 receptor may become a potential novel neuroprotective target for diseases related to the loss of retinal neurons.