谷氨酸诱导对鼠视网膜Müller细胞谷氨酸转运体的调控

目的 研究底物谷氨酸对视网膜Müller细胞L-谷氨酸和L-天门冬氨酸转运体(GLAST)的调控作用.方法 采用L-3H-谷氨酸摄取分析方法研究底物谷氨酸诱导对GLAST活性影响.并提取细胞总蛋白,采用免疫印迹法分析视网膜Miiller细胞GLAST蛋白质表达量的差异.结果 在培养的鼠视网膜Müller细胞中加入不同浓度的谷氨酸培养30 min后,发现随着底物谷氨酸浓度增加(5～1000 μmol/L),L-3H-谷氨酸的摄取量增加.平均摄取量分别为(3100.7±86.8)、(3247.0±84.2)、(3840.0±118.6)、(4493.7±229.2)、(6429.0±81.5)、(6305.3±31.0)、(6346.3±36.2)cpm·mg-1·ml-1.当谷氨酸浓度为100 μmol/L时,L-3H-谷氨酸摄取量最大.随着谷氨酸浓度的增加,谷氨酸转运体GLAST蛋白质的表达量增加,当谷氨酸浓度为100 μmol/L时,GLAST蛋白质表达量达最大.结论 谷氨酸的底物诱导可增加GLAST摄取活性,且上调GLAST蛋白质的表达.     

脑源性神经营养因子对鼠视网膜Müller细胞GLAST蛋白表达及功能的调控

目的 研究脑源性神经营养因子（BDNF）对鼠视网膜Müller细胞L-谷氨酸/L-天门冬氨酸转运体（GLAST）蛋白表达及功能的调控作用.方法 实验研究.取出生3～7 d的新生昆明小鼠视网膜组织进行Müller细胞培养,取传代后第3代Müller细胞进行后续试验.实验分为BDNF干预组和空白对照组：BDNF干预组小鼠视网膜Müller细胞分别加入50、75、100、125和150 ng/ml的BDNF培养24 h：空白对照组培养的Müller细胞不加BDNF.采用Western blot方法检测Müller细胞GLAST蛋白的表达.采用L-[3,4-H3]-谷氨酸检测100 ng/ml的BDNF干预组与空白对照组Müller细胞对谷氨酸的摄取功能的差异.对各组视网膜Müller细胞GLAST蛋白表达水平的比较采用单因素方差分析,100ng/ml的BDNF干预组与空白对照组对谷氨酸摄取量的比较采用独立样本t检验.结果 Western blot检测结果显示,空白对照组GLAST蛋白的相对表达量为0.151±0.025,50、75、100、125和150 ng/ml的BDNF干预组蛋白相对表达量分别为0.331±0.076、0.413±0.110、0.497±0.080、0.411±0.072、0.319±0.084,不同浓度的BDNF均能上调GLAST蛋白的表达水平（F=6.793,P=0.003）.当BDNF浓度为100 ng/ml时,CLAST蛋白表达量最大.100 ng/ml的BDNF组与空白对照组对谷氨酸的摄取量分别为（81 213±5982）和（68 743±2688）cpm/（mg·ml）,100 ng/ml的BDNF组能够增加Müller细胞对谷氨酸的摄取,两组差异有统计学意义（t=6.462,P=0.023）.结论 BDNF能够上调GLAST蛋白的表达,并增加细胞对谷氨酸的摄取.     

脑源性神经营养因子对小鼠视网膜Müller细胞谷氨酸转运体表达的调控

谷氨酸是视网膜主要的兴奋性神经递质,然而在病理性浓度升高时,对视网膜神经节细胞(RGC)具有兴奋毒性作用[1].L-谷氨酸/L-天门冬氨酸转运体(GLAST)是表达在视网膜Müller细胞上最主要的谷氨酸转运体[5],在维持谷氨酸平衡和保护RGC免受谷氨酸兴奋毒性作用中发挥着重要作用[3].     

脑源性神经营养因子对小鼠视网膜Müller细胞谷氨酸转运体表达的调控

谷氨酸是视网膜主要的兴奋性神经递质,然而在病理性浓度升高时,对视网膜神经节细胞(RGC)具有兴奋毒性作用[1].L-谷氨酸/L-天门冬氨酸转运体(GLAST)是表达在视网膜Müller细胞上最主要的谷氨酸转运体[5],在维持谷氨酸平衡和保护RGC免受谷氨酸兴奋毒性作用中发挥着重要作用[3].     

脑源性神经营养因子对小鼠视网膜Müller细胞谷氨酸转运体表达的调控

谷氨酸是视网膜主要的兴奋性神经递质,然而在病理性浓度升高时,对视网膜神经节细胞(RGC)具有兴奋毒性作用[1].L-谷氨酸/L-天门冬氨酸转运体(GLAST)是表达在视网膜Müller细胞上最主要的谷氨酸转运体[5],在维持谷氨酸平衡和保护RGC免受谷氨酸兴奋毒性作用中发挥着重要作用[3].     

缺氧对视网膜Müller细胞促红细胞生成素mRNA和蛋白表达的影响

目的 探讨缺氧条件下促红细胞生成素（EPO）mRNA及蛋白在体外培养的Müller细胞的表达情况。 方法 胰酶消化新生大鼠视网膜组织制成单细胞悬液，机械震荡、吹打法分离纯化视网膜Müller细胞，反转录-聚合酶链反应（RT-PCR）、免疫细胞化学方法对缺氧条件下视网膜Müller细胞EPO基因和蛋白的表达进行测定。 结果 成功获得视网膜Müller细胞，传代后95%以上的细胞呈神经胶质纤维酸性蛋白（GFAP）染色阳性。EPO蛋白的阳性染色位于视网膜Müller细胞的细胞浆及突起上。在正常的视网膜Müller细胞中仅见微弱的EPO mRNA和蛋白表达，而缺氧后表达明显上调，且呈时间依赖性。 结论 Müller细胞在缺氧条件下EPO mRNA和蛋白表达增强，EPO表达水平的升高可能是缺氧性视网膜病变的神经保护因素之一。 (中华眼底病杂志, 2006, 22: 196-199)     

糖尿病视网膜Müller细胞GLAST功能变化的研究进展

糖尿病引起的视网膜神经功能异常可能先于血管损伤,引起这一改变的最主要原因是视网膜细胞外谷氨酸的大量蓄积,持久激活谷氨酸受体以及损伤视网膜神经元。细胞外谷氨酸的蓄积可能与视网膜Müller细胞L-谷氨酸/L-天冬氨酸转运体(GLAST)功能下降有关,致使细胞外的谷氨酸不能及时转运到Müller细胞内。本文就Müller细胞GLAST的作用机制及在糖尿病状态下功能的变化进行综述。     

压力对体外培养大鼠视网膜Müller细胞的影响

目的　探讨压力作用下体外培养的大鼠Müller细胞形态、活性和谷氨酸代谢功能是否有改变,以明确Müller细胞在青光眼损伤过程中的作用。方法　将体外培养的大鼠Müller细胞随机分为对照组和加压处理组,加压组在50mmHg(1mmHg=0. 133kPa)压力下处理1h,然后两组细胞继续培养3d后,使用倒置显微镜和电镜观察细胞的形态,MTT比色法测定两组细胞的活性,RT PCR法检测两组细胞内谷氨酰胺合成酶mRNA表达,并用图像分析系统测定吸光度值。结果　体外培养的Müller细胞经压力处理后与对照组相比倒置显微镜下改变不明显,电镜下可见细胞内空泡增多,线粒体肿胀;MTT比色法显示细胞活性降低,差异有统计学意义(P<0 05); RT PCR法示细胞内谷氨酰胺合成酶mRNA表达减少,差异有统计学意义(P<0 .05)。结论　经压力处理后体外培养的Müller细胞有损伤的改变,细胞由于谷氨酸谷氨酰胺循环中的关键酶谷氨酰胺合成酶mRNA表达减少而代谢谷氨酸的能力下降,这可能是青光眼玻璃体中谷氨酸浓度升高的原因之一。     

视网膜Müller细胞谷氨酸转运体及其功能调节

谷氨酸的兴奋毒性是造成视网膜神经节细胞损伤和死亡的主要因素之一,而谷氨酸转运体对维持细胞外谷氨酸水平起重要作用.GLAST是表达在Müller细胞膜上的一种重要的谷氨酸转运体,其在分子和蛋白质水平上的调节方式可能为酶底物-诱导的负反馈调节.     

巢蛋白和神经胶质纤维酸性蛋白在大鼠视网膜发育中的动态表达

目的 观察巢蛋白(nestin)和神经胶质纤维酸性蛋白(GFAP)在大鼠视网膜发育中的动态变化.方法 48只Wistar大鼠,其中24只大鼠分为出生后1 d,1、2、3、4、7、12、20周8组,每组3只.制作眼球矢状位冰冻切片,采用共聚焦激光显微镜观察nestin和谷氨酰胺合成酶(GS)以及GFAP和GS免疫荧光染色情况.18只大鼠分为出生后id,1、2、3、4、12周,每组3只.提取大鼠视网膜总RNA,实时定量逆转录聚合酶链反应(RT-PCR)检测nestin、GFAP和GS mRNA表达.选择6只出生后7～12 d新生鼠,取眼球体外培养Müller细胞,行GS和(或)nestin免疫荧光染色,共聚焦激光显微镜观察荧光染色情况.结果 出生后1 d,nestin免疫阳性细胞贯穿神经视网膜全层,主要定位于视网膜前体细胞放射状排列的细长纤维中,在视网膜内侧出现GFAP阳性的星形胶质细胞.出生后1周出现表达GS的Müller细胞,同时表达nestin,但不表达GFAP;GFAP阳性细胞仍然位于视网膜内侧.出生后2～12周,nestin在Mfiller细胞上的表达逐渐减少直至消失,GFAP在星形胶质细胞中的表达强度投有显著变化.体外培养的Müller细胞表达nestin,不表达GFAP.Nestin和GFAP mRNA在视网膜中的表达与免疫荧光染色结果相一致.结论 随大鼠视网膜不断发育,Müller细胞上nestin表达逐渐减少,成年大鼠视网膜Müller细胞不再表达nestin;新生鼠和成年鼠Müller细胞均不表达GFAP.     

缺氧对视网膜Müller细胞中谷氨酸转运体及未折叠蛋白相关因子XBP1、CHOP表达的影响

目的研究体外缺氧刺激后视网膜Müller细胞是否存在未折叠蛋白反应(unfol-dedprotein reaction,UPR),及其与L-谷氨酸/L-天门冬氨酸转运体(glutamate-aspartatetrans-porters,GLAST)的关系。方法出生3～7d大鼠视网膜组织采用胰蛋白酶消化法培养视网膜Müller细胞,氯化钴(CoCl2)200μmol·L-1对视网膜Müller细胞进行体外缺氧干预,干预时间为0h、3h、6h、12h、24h、48h、72h;UPR诱导剂二硫苏糖醇(DTT)2mmol·L-1刺激视网膜Müller细胞为阳性对照,干预时间为0h、3h、6h、12h、24h、48h、72h。采用实时荧光定量PCR检测GLAST与UPR相关因子X盒结合蛋白1、C/EBP同源蛋白的表达并分析其相关性。结果视网膜Müller细胞鉴定:细胞免疫荧光染色示90%以上细胞GS、GLAST表达阳性;流式细胞仪检测结果:Müller细胞的GLAST表达阳性率为(84.66±3.51)%。缺氧刺激后,GLAST与X盒结合蛋白1、C/EBP同源蛋白在Müller细胞上均有表达,缺氧早期呈上升趋势,干预后24h表达最强,后呈下降趋势。DTT干预组表达趋势与缺氧干预组一致。结论体外缺氧刺激后视网膜Müller细胞存在UPR,其相关因子的变化与GLAST的变化趋势一致,提示UPR可能是调控GLAST变化的原因之一。     

牛磺酸对高糖刺激大鼠视网膜Müller细胞GLAST和GS表达的影响

目的:通过检测牛磺酸对高糖刺激大鼠视网膜Müller细胞谷氨酸转运蛋白(glutamate-aspartate transporters,GLAST)和谷氨酰胺合成酶(glutamine synthetase,GS)表达的影响,探讨牛磺酸保护糖尿病引起视网膜损伤的机制。方法:高糖培养大鼠视网膜Müller细胞,分正常对照组(NC)、高糖组(high glucose,HG,25mmol/L)、高糖+0.1mmol/L牛磺酸(taurine,T)干预组(HG+0.1T)、高糖+1mmol/L牛磺酸干预组(HG+1T)、高糖+10mmol/L牛磺酸干预组(HG+10T)。用免疫荧光化学法和Western-blotting检测大鼠视网膜Müller细胞中GLAST和GS的表达。结果:高糖培养后,大鼠视网膜Müller细胞中GLAST和GS的表达明显减少(P<0.05),与高糖组相比,1mmol/L和10mmol/L牛磺酸干预可明显增加GLAST和GS的表达(P<0.05)。结论:牛磺酸增加Müller细胞中GLAST和GS的表达抑制糖尿病引起的视网膜Müller细胞功能改变。     

Regulation of brain-derived neurotrophic factor on the expression of GLAST protein and its function in retinal Müller cells of mice

Objective To study the effect of brain-derived neurotrophic factor (BDNF)on the expression of L-glutamate/L-aspartate transporter (GLAST) protein and its function in the retinal mice at 3 to 7 days postnatal were cultured by an enzymatic digestion method, and the third passage different concentrations of recombinant human BDNF (50, 75, 100, 125 and 150 ng/ml) for 24 h in group and the control group. The expression of GLAST protein was analyzed with one-way analysis of variance (ANOVA) and L-[3,4-3H]-glutamic acid uptake was analyzed with independent samples t test. Results The expression of GLAST protein in the control group was 0.151±0.025 and the expression in the BDNF group (50, 75, 100, 125 and 150 ng/ml) was 0.331±0.076, 0.413±0.110, 0.497±0.080, 0.411±0.072, and 0.319±0.084, respectively. Different concentrations of BDNF could up-regulate the expression of GLAST protein compared to the control group (F=6.793, P=0.003).The expression of GLAST protein reached a maximum when the concentration of BDNF was 100 ng/ml.L-[3,4-3H]-glutamic acid uptake for the 100 ng/ml BDNF group and control group was 81 213±significantly higher than for the control group (t=6.462, P=0.023). Conclusion BDNF can up-regulate the expression of GLAST protein and increase extracellular glutamate uptake.     

花色苷对高糖培养的视网膜Müller细胞L-谷氨酸/L-天门冬氨酸转运体表达的影响

目的 观察花色苷对体外高糖培养的视网膜Müller细胞L-谷氨酸/L-天门冬氨酸转运体(GLAST)表达的影响.方法 取出生后10 d的雄性Sprague-Dawley(SD)大鼠视网膜组织,体外原代培养Müller细胞.第2～4代细胞用于实验.将实验分为正常对照组(A组)、高糖对照组(B组)、高糖+30 μmol/L花色苷组(C组)、高糖+60 μmol/L花色苷组(D组)、高糖+100μmol/L花色苷组(E组)进行.采用噻唑蓝比色法(MTT)测定波长570 nm处的吸光度[A,旧称光密度(OD)]值,以各组A值计算细胞相对存活率.采用免疫蛋白印迹法(Western blot)检测各组大鼠视网膜Müller细胞上GLAST的蛋白表达.结果 MTT检测显示,A、B、C、D、E组A值分别为0.450 8±0.020 4、0.270 1±0.031 4、0.332 0±0.023 2、0.428 3±0.017 2、0.361 9±0.027 0,细胞相对存活率分别为100.0%、59.9%、73.6%、95.0%、80.3%.其中,C、D、E组A值均较B组增高,差异有统计学意义(F=32.25,P＜0.05);D组A值较C、E组显著增高,差异也有统计学意义(F=21.07,P＜0.05).Western blot检测显示,B组大鼠视网膜Müller细胞的GLAST蛋白表达较A组降低,差异有统计学意义(t=5.25,P＜0.05);A、C、D、E组间大鼠视网膜Müller细胞的GLAST蛋白表达无明显变化,差异无统计学意义(F=2.979,P＞0.05).结论 花色苷可逆转高糖引起的Müller细胞GLAST蛋白表达下降.

Abstract：

Objective To observe the effect of cyanin on the expression of L-glutamate/ L-aspartate transporter (GLAST) in high glucose cultured retina Müller cells. Methods The retinal tissue of SpragueDawley (SD) rats was collected at postnatal 10 day, and Müller cells were isolated and cultured according to literature. The Müller ceils (2nd-4th generations) were treated with five different medium as normal group (group A), high glucose control group (group B), high glucose+30 μmol/L cyanin group (group C), high glucose+60 μmol/L cyanin group (group D) and high glucose+100 μmol/L cyanin group (group E). Cell relative survival rates (A value) were measured by MTT assay at 570 nm. The GLAST protein expression in M011er cells was observed by Western blot. Results MTT assay showed that the A value of the five group were 0. 450 8±0. 020 4, 0. 270 1±0. 031 4, 0. 332 0±0. 023 2, 0. 428 3±0. 017 2, 0. 361 9±0. 027 0,the cell relative survival rate were 100. 0%, 59. 9%, 73.6%, 95%, 80.3% respectively. The A value of group C, D, E were significantly higher than that of group B (F=32.25, P<0.05), the A value of group D were significantly higher than that of group C and E (F=21.07, P<0. 05). Western blot showed that the GLAST protein expression of group B was lower than that of group A (t=5.25, P<0. 05) ; there was no obvious changes of GLAST protein expression in group A, C, D and E (F= 2. 979, P>0.05).Conclusion Cyanin can rescue high glucose-induced GLAST reduction.     

碱性成纤维细胞生长因子在糖基化终产物作用下视网膜Müller细胞中的表达及对血管内皮生长因子影响

目的 观察糖基化终产物(AGEs)作用下兔视网膜Müller细胞中碱性成纤维细胞生长因子(bFGF)的表达,以及bFGF对该细胞表达血管内皮生长因子(VEGF)的影响,探讨AGEs对于糖尿病视网膜病变(DR)发生发展的可能作用机制.方法 制备牛血清白蛋白AGEs(AGEs-BSA)及其对照物并将其作用于体外培养的兔视网膜Müller细胞,采用免疫细胞化学(ICC)方法 半定量检测不同时间点(1d、3d、6d、9d)Müller细胞bFGF表达变化.利用外源性bFGF(0.1、1.0、10.0、50.0、100.0)ng/mL干预Müller 细胞,采用ICC方法 半定量检测不同时间点(1d、3d、6d、9d)M üller细胞VEGF的表达变化.结果 AGEs作用下兔视网膜M üller细胞bFGF的表达增高(P<0.05或P<0.01)且具有一定的时间和浓度依赖性.外源性bFGF可上调视网膜M üller细胞VEGF的表达,且具有一定的浓度依赖性及时限性.结论 AGEs可以上调视网膜Mü ller细胞表达bFGF,而bFGF可以上调Müller细胞表达VEGF,推测AGEs可能通过增加bFGF的表达,以及通过分泌的bFGF间接促进VEGF的表达,从而在DR形成过程中起重要作用.

Abstract：

Objective To investigate the effect of advanced glycosylation end products (AGEs) on expression of basic fibroblast growth factor (bFGF) in rabbit retinal Müller cells, also the effect ofbFGF on expression of vascular endothelial growth factor (VEGF) in rabbit retinal Müller cells in vitro. Methods Rabbit retinal Müller cells were cultured first, then AGEs-BSA and its control were prepared. Müller cells were treated with 5 different concentration series of AGEs-BSA and AGEs-BSA control for 1, 3, 6 and 9 days, while blank control group was incubated without any intervention. Then bFGF expression in Müller cells was half-quantitatively identified by immunocytochemistry (ICC). Cultured rabbit Müller cells were also treated with bFGF of 5 concentrations (0.1, 1.0, 10.0, 50.0, 100.0) ng/mL for 1, 3, 6, 9 days, while blank control group was incubated without any intervention. Then VEGF expression in Müller cells was half-quantitatively identified by ICC. Results Comparing with control group, AGEs-BSA evoked a time and concentration-dependent increase ofbFGF expression on cultured retinal Müller cells (P ＜0. 05 or P ＜0. 01). And comparing with blank control group, bFGF also evoked a time and concentration-dependent increase of VEGF expression on retinal Mi ller cells in a certain range. Conclusions AGEs up-regulates the expression ofbFGF, which can up-regulate the expression of VEGF in Müller cells. These results indicate that AGEs might promote the progress of DR.     

色素上皮衍生因子对糖尿病大鼠视网膜谷氨酸代谢的影响

目的 观察色素上皮衍生因子(PEDF)对糖尿病大鼠视网膜谷氨酸代谢的影响.方法 Sprague_Dawley大鼠78只,分为模型组、模型对照组、PEDF干预组(干预组)、干预对照组,实验结束时去除血糖恢复鼠和实验期间死亡鼠,每组以12只大鼠作为统计样本.模型组、干预组、干预对照组大鼠采用链脲佐菌素诱导糖尿病大鼠模型.模型组大鼠不作任何干预,模型对照组为相同月龄的正常大鼠.干预组大鼠左眼玻璃体腔注射0.1 μg/μl的PEDF 5.0μl,干预对照组大鼠左眼玻璃体腔注射相同容积的磷酸盐缓冲液.采用蛋白免疫印迹法(Western bolt)和实时荧光聚合酶链式反应(PCR)法检测视网膜L-谷氨酸-L-门冬氨酸转运体(GLAST)表达的变化,高压液相色谱法(HPLC)观察视网膜谷氨酸的含量变化.将体外培养的大鼠视网膜Müller细胞随机分为对照组、实验组、PEDF干预组(干预组)和干预对照组,荧光免疫法和实时荧光PCR法检测Müller细胞GLAST表达的改变,根据[3H]标记的D,L-谷氨酸摄入量判断Müller细胞的摄取功能.结果 实时荧光PCR法和Western bolt检测结果显示,相对于模型对照组大鼠,模型组大鼠视网膜GLAST表达降低(实时荧光PCR法:t=8.86,P＜0.01;Western blot:t=3.42,P＜0.05),视网膜谷氦酸含量升高(t=4.01,P＜0.05);干预组大鼠视网膜GLAST表达与干预对照组视网膜GLAST表达比较,干预组大鼠视网膜GLAST的表达升高(实时荧光PCR法:t=3.56,P＜0.05;Western blot:t=3.52,P＜O.05);视网膜谷氨酸含量下调(t=4.36,P＜0.05).实时荧光PCR法和荧光免疫法检测结果显示,高糖可以降低视网膜Müller细胞GLAST的表达(实时荧光PCR法:t=3.48,P＜O.05;荧光免疫法:t=4.72,P＜O.05);[3H]标记的D,L-谷氨酸摄人量结果显示,高糖可以下调视网膜Mü1ler细胞GIAST的功能(t=3.81,P＜0.05);经PEDF处理后,可以明显改善高糖状态下视网膜Müller细胞GLAST的表达(实时荧光PCR法:t=6.82,P＜O.01;荧光免疫法:t=3.72,P＜0.05)和对谷氨酸的摄取功能(t=4.14,P＜0.05).结论 PEDF可通过改善糖尿病大鼠视网膜Müller细胞中GLAST功能从而改善谷氨酸循环,抑制神经节细胞的死亡.

Abstract：

Objective To observe the effect of pigment epithelium-derived factor(PEDF)on glutamate metabolism in diabetic rat retina.Methods 78 Sprague-Dawley rats were randomly divided into the model group,model control group,PEDF intervention group and intervention control group.There were some dead and euglycemia rats at the end of experiment,so only 12 rats in each group were included in the statistical analysis.The diabetic retinopathy rat model of the model,PEDF intervention and intervention control group were induced with streptozotocin injection.The rats in the model group were not intervened.The monthly-age matched normal rats of model group were in the model control group.The left eyes of rats were received intravitreal injection with 5μl(0.1μg/μl)PEDF(PEDF intervention group)or 5μlphosphate buffer solution(intervention control group).The expressions of L-glutamate/L-aspartate transporter in retina were analyzed by western blot and real time RT-PCR techniques and glutamate content in retina was analyzed by high-pressure liquid chromatography(HPLC).Cultured rat Mailer cells were divided into the control,experimental,PEDF intervention and intervention control group,GLAST expressions were detected by fluorescence immunofluorescence and real-time RT-PCR techniques.The glutamate up-take activity of Müller cells was determined by intracellular[3H] labeled D,L-glutamate concentration with scintillation counting.Results Western blot and real-time RT-PCR showed that GLAST expression decreased(real-time RT-PCR:t=8.86,P＜0.01;Western blot:t=3.42,P＜0.05).glutamate content increased(t=4.01,P＜0.05)in model group compared with the model control group:GLAST expression increased(real-time RT-PCR:t=3.56,P＜0.05;Western blot:t=3.52,P＜0.05),glutamate content decreased(y=4.36,P＜0.05)in the PEDF intervention group compared with the intervention control group.Real-time RT-PCR and fluorescence immunofluorescenee showed that high glucose down-regulate GLAST expressions in Müller cells(real-time RT-PCR:t=3.48,P＜0.05;fluorescence immunofluoreseence:t=4.72,P＜0.05)and impair glutamate up-take activity of Müller cells(t=3.81,P＜0.05).Under high glucose conditions,PEDF up-regulated GLAST expression significantly(real-time RT-PCR:t=6.82,P＜0.01;fluorescence immunofluorescence:t=3.72,P＜0.05)and ameliorated the glutamate up-take activitv of Mailer cells(t=4.14,P＜0.05).Conclusions In diabetic rats,PEDF may improve the activitv of GLAST in Müller cells,thus ameliorate retinal glutamate metabolism and inhibit death of retinal ganglion cells.     

Role of interleukin-1β in hypoxia-induced depression of glutamate uptake in retinal Müller cells

Background

It is suggested that hypoxic–ischemic retinal diseases induce loss of retinal ganglion cells. Excess glutamate release is involved in these conditions. A predominant function of Müller cells is to regulate glutamate levels, but in these diseases the function is compromised. The present study was performed to investigate the role of interleukin-1β(IL-1β)on the glutamate uptake in retinal Müller cells under hypoxia and to study the possible mechanism.

Methods

The levels of IL-1β,Kir4.1, and GLAST in retinal Müller cells under hypoxia were analyzed by Western blotting and realtime-RT-PCR, and glutamate uptake assay was undertaken to investigate the activity of GLAST. After being treated with IL-1βunder normoxia, these proteins (Kir4.1 and GLAST) and their mRNAs, and glutamate uptake activity in Müller cells were investigated. To confirm the effect of IL-1βon glutamate uptake activity in Müller cells, addition of IL-1ra was used.

Results

Under hypoxia, Müller cells glutamate uptake, Kir4.1 and GLAST expressions were decreased significantly; however, IL-1βexpression was increased. IL-1βtreatment induced depression of glutamate uptake, decrease of Kir4.1 and GLAST expressions in retinal Müller cells under normoxia. Moreover, addition of IL-1ra significantly ameliorated decreases in Kir4.1 and GLAST expressions, and compromise of glutamate uptake activity in retinal Müller cells under hypoxia.

Conclusions

These findings indicated that decreases in Kir4.1 and GLAST expressions and depression of glutamate uptake in retinal Müller cells under hypoxia may be induced by the inflammatory cytokine IL-1β.