食欲素A促进短暂性全脑缺血大鼠的海马CA1区谷氨酸摄取并抑制迟发性神经元死亡

Orexin A promotes glutamate uptake and inhibits delayed neuronal death in hippocampus CA1 region of transient global cerebral ischemic rats

目的探讨食欲素A(OX-A)对短暂性全脑缺血(tGCI)大鼠的海马CA1区胶质细胞谷氨酸转运体-1(GLT-1)的表达与功能以及迟发性神经元死亡(DND)的影响及机制。方法将大鼠分为假手术(sham)组、模型(model)组、OX-A组和OX-A+LY294002组。用[3H]-谷氨酸标记法检测海马CA1区GLT-1的结合能力和对谷氨酸的摄取能力;用谷氨酸定量试剂盒检测海马CA1区组织中谷氨酸含量;用Nissol、NeuN和Fluro-Jade C染色法观察海马CA1区神经元病理改变;用Western blot检测海马CA1区组织中GLT-1、p-PI3K和p-AKT的表达。结果OX-A能促进tGCI大鼠海马CA1区的GLT-1的结合能力和GLT-1对谷氨酸摄取能力、增加谷氨酸含量、GLT-1表达和PI3K/AKT信号活性并抑制DND(P<0.05);而LY294002能减弱OX-A的上述治疗效应(P<0.05)。结论OX-A能通过增强PI3K/AKT信号活性来增加tGCI大鼠海马CA1区GLT-1的表达与功能并减轻DND。

Objective To investigate the effect and mechanism of orexin-A(OX-A)on the expression and function of glial glutamate transporter-1(GLT-1)and delayed neuronal death(DND)in hippocampus CA1 region of transient global cerebral ischemia(tGCI)in rats.Methods The rats were randomized into sham group,model group,OX-A group and OX-A+LY294002 group.The binding and glutamate uptake of GLT-1 in hippocampal CA1 region were detected by the[3H]-glutamate labeling method.The content of glutamate in hippocampal CA1 region was determined by the glutamate quantitative kit.The pathological changes of neurons in hippocampal CA1 region were observed by Nissol,NeuN and Fluro-Jade C staining.The expressions of GLT-1,p-PI3K and p-Akt in hippocampal CA1 region were detected by Western blot.Results OX-A promoted the binding and glutamate uptake of GLT-1,increased glutamate content,GLT-1 expression and PI3K/AKT signaling activity,and inhibited DND in the hippocampal CA1 region of tGCI rats(P<0.05);However,LY294002 attenuated the above therapeutic effects of OX-A(P<0.05).Conclusions OX-A can increase the expression and function of GLT-1 and reduce DND in thehippocampal CA1 region of tGCI rats by enhancing the activity of I3K/AKT signal.