Objective To observe the expression of glutamate (Glu) and γ-aminobutyric acid (GABA) in the retina of diabetic rats which were intervened later by insulin intensive therapy, and to investigate the mechanism of metabolic memory of hyperglycemia which induced the retina neuropathy in diabetic rats.Methods 60 Brown Norway rats were randomly divided into normal control (NC) group, diabetes mellitus (DM) group (6 weeks at DM1,12 weeks at DM2) and metabolic memory (MM) group, 15 rats in each group.Diabetes was induced by intraperitoneal injection of streptozocin.After 6 weeks, MM group was treated with insulin intensive therapy for 6 weeks.DM1 group was sacrificed at the end of 6 weeks and other groups were sacrificed at the end of 12 weeks.High performance liquid chromatography was used to detect the amount of Glu and GABA in the rat retina.Real-time polymerase chain reaction was applied to quantify the mRNA expressions of Glutamate decarboxylase (GAD).TdT mediated dUTP nick ending labelling was used to detect cell apoptosis.Results The concentration of Glu (t=6.963), GABA (t=4.385) and the ratio of Glu/GABA (t =4.163) in MM group were significantly higher than DM1 group, but the concentration of Glu (t=3.411) and GABA (t=3.709) were significantly lower than DM2 group (P＜0.05).And there was no significant difference in the ratio of Glu/GABA between MM and DM2 groups (t=1.199 ,P＞0.05).The level of expressions of GAD mRNA in MM group was significantly lower than DM1 group (t=3.496, P＜0.05), but higher than DM2 group (t=8.613, P＜0.05).The number of nerve cells apoptosis in MM group was significantly higher than DM1 group (t=2.584, P＜0.05), but lower than DM2 group (t-3.531, P＜0.05).Conclusions Intensive therapy later by insulin can partially reduce the content of Glu and GABA and the rate of nerve cells apoptosis, which cannot return to normal levels, and has no effect on the rise in the ratio of Glu/GABA caused by the hyperglycemia.The disorders of Glu and GABA may participate in the metabolic memory of hyperglycemia.%目的 观察后期胰岛素强化治疗后糖尿病(DM)大鼠视网膜组织中神经递质谷氨酸(Glu)、γ-氨基丁酸(GABA)表达,探讨高糖"代谢记忆"致DM大鼠视网膜神经病变发展机制.方法 SpragueDawley大鼠60只,随机数字表法分为实验组和正常对照组(NC组),分别为45、15只大鼠.实验组大鼠腹腔注射链脲佐菌素建立DM模型;NC组大鼠腹腔注射等体积柠檬酸-柠檬酸钠缓冲液.实验组再随机分为DM1组、DM2组、代谢记忆组(MM组),每组均为15只大鼠.建模后6周,MM组大鼠给予胰岛素强化治疗,连续6周.DM1组6周,DM2组、MM组、NC组12周处死大鼠,高效液相色谱法检测大鼠视网膜组织中Glu、GABA的含量;实时定量荧光聚合酶链反应检测大鼠视网膜组织中谷氨酸脱羧酶(GAD)mRNA的表达;原位末端标记法检测大鼠视网膜组织中神经细胞凋亡数.结果 MM组大鼠视网膜中Glu0=6.963)、GABA(t=4.385)含量及其Glu/GABA比值(t=4.163)较DM1组高,差异有统计学意义(P＜0.05).MM组大鼠视网膜中Glu(t=3.411)、GABA(t=3.709)含量较DM2组低,差异有统计学意义(P＜0.05);Glu/GABA比值与DM2组比较,差异无统计学意义(t=1.199,P＞0.05).MM组大鼠视网膜组织中GADmRNA表达较DM1组明显降低(t=3.496),较DM2组升高(t=8.613),差异有统计学意义(P＜0.05).MM组大鼠视网膜组织中神经细胞凋亡数较DM1组明显升高(t=2.584,P＜0.05),较DM2组降低(t=3.531,P＜0.05),差异有统计学意义.结论 后期胰岛素强化治疗可部分降低DM大鼠视网膜组织中Glu、GABA含量和神经细胞凋亡率,且对高血糖引起的Glu/GABA比值升高没有影响;Glu、GABA表达紊乱可能是高糖"代谢记忆"致DM视网膜神经病变发展的机制之一.
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