MG132对早期糖尿病大鼠视网膜病变过程中NF-κB及IκB表达的影响

Effect of MG132 on expression of NF-κB and ⅠκB in early period diabetic retinopathy in rats

目的观察泛素蛋白酶体抑制剂MG132对大鼠早期糖尿病视网膜病变(diabetic retinopathy,DR)过程中核因子-κB(nuclear factor-κB,NF-κB)以及其抑制性信号蛋白IκB激酶的降解调控作用,探讨泛素蛋白酶体系统在DR中的作用机制。方法选择健康成年雄性Wistar大鼠40只,随机分为正常对照组、DR安慰剂组、DR+MG132低浓度干预组、DR+MG132高浓度干预组。DR+MG132低浓度干预组按0.05mg.kg-1每天1次腹腔注射MG132DMSO液,DR+MG132高浓度干预组按0.10mg.kg-1每天1次腹腔注射MG132DMSO液。分别于给药后6周和8周检测大鼠体质量、血糖,并制备视网膜石蜡切片,采用免疫组织化学法分析NF-κB以及其抑制性信号蛋白IκB在各组大鼠视网膜中的表达。结果NF-κB p65在DR安慰剂组的表达较正常对照组明显增强,在MG132高浓度干预组的表达强度较DR安慰剂组减弱;IκBα在DR安慰剂组的表达较正常对照组显著减弱,MG132高浓度干预组的表达强度较DR安慰剂组增强,差异均有统计学意义(均为P<0.01)。相反,MG132低浓度干预组中NF-κB p65以及IκBα的表达强度与DR安慰剂组相比较,差异均无统计学意义(均为P>0.05)。结论泛素蛋白酶体系统通过调控NF-κB及IκBα的表达而影响DR的发生、发展。泛素蛋白酶体抑制剂MG132通过抑制IκB的泛素化降解,阻断NF-κB的激活,从而能早期干预DR。

Objective To investigate the regulation of ubiquitin-proteasome inhibitor MG132 on nuclear factor-κB（NF-κB）and its inhibitory signal protein IκB kinase degradation in earlier period diabetic retinopathy（DR）,and explore the mechanism of ubiquitin-proteasome system in DR in rats.Methods Forty healthy adult male Wistar rats were divided into normal control group,DR placebo group,DR＋low-MG132 treated group and DR＋high-MG132 treated group randomly.In DR＋low-MG132 treated group,the rats were intraperitoneally injected with 0.05 mg·kg-1 MG132 DMSO once a day,in DR＋high-MG132 treated group were intraperitoneally injected with 0.10 mg·kg-1 MG132 DMSO once a day.The results of body masses and fasting blood glucose were detected,the expression of NF-κB and IκB in retina of every group were analyzed by immunohistochemistry.Results The expression of NF-κB p65 was obviously up-regulated in DR placebo group compared with control group,but the expression was down-regulated in DR＋high-MG132 treated group compared with DR placebo group;The expression of IκBα was markedly down-regulated in DR placebo group compared with control group,but the expression was up-regulated in DR＋high-MG132 treated group compared with DR placebo group,there were all significant differences（all P0.01）.But there was no statistical difference on the expression of NF-κB p65 and IκBα between DR＋low-MG132 treated group and DR placebo group（all P0.05）.Conclusions Ubiquitin-proteasome system can influence the occurrence and development of DR by regulating NF-κB and IκBα expression.Application of ubiquitin-proteasome inhibitor MG132 can inhibit the ubiquitination of IκB degradation,and block the activation of NF-κB,which may play an early intervention role in DR.