Hypothermia protects against oxygen–glucose deprivation-induced neuronal injury by down-regulating the reverse transport of glutamate by astrocytes as mediated by neurons
Hypothermia protects against oxygen–glucose deprivation-induced neuronal injury by down-regulating the reverse transport of glutamate by astrocytes as mediated by neurons
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DOI：
10.1016/j.neuroscience.2013.01.056
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发表时间：
2013-05
期刊：
影响因子：
3.3
通讯作者：
D. Wang;Y. Zhao;Y. Zhang;T. Zhang;X. Shang;J. Wang;Y. Liu;Q. Kong;B. Sun;M. L.;X. Liu;G. Wang;H. Li
中科院分区：
文献类型：
--
作者：
D. Wang;Y. Zhao;Y. Zhang;T. Zhang;X. Shang;J. Wang;Y. Liu;Q. Kong;B. Sun;M. L.;X. Liu;G. Wang;H. Li
谷氨酸是脑缺血后兴奋毒性神经元死亡的主要介质。在严重的缺血条件下，谷氨酸转运体可以功能逆转释放谷氨酸，从而诱导进一步的神经元损伤。低温已被证明可以保护神经元免受脑缺血。然而，所涉及的机制仍不清楚。因此，本研究旨在探讨低温条件下脑缺血再灌注损伤时谷氨酸释放的机制。将神经元/星形胶质细胞共培养物在不同温度下暴露于氧-葡萄糖剥夺（OGD）2 h，并在复氧后12 h测定细胞活力。PI和MAP-2染色显示低温可明显减轻神经元的损伤。此外，[3 H]-谷氨酸摄取测定表明，低温保护大鼠原代皮层培养对OGD再氧诱导的损伤。还发现主要负责细胞外谷氨酸清除的星形胶质细胞谷氨酸转运蛋白GLT-1的蛋白水平以温度依赖性方式降低。相比之下，发现在添加维持在37°C的神经元条件培养基后，星形胶质细胞富集培养物中GLT-1的表达显著增加，并且在33°C的神经元条件培养基中GLT-1的表达程度较小。总之，低温对脑缺血再灌注损伤的神经保护作用涉及下调星形胶质细胞GLT-1，其介导谷氨酸的反向转运。此外，这一过程可能受到应激神经元分泌的分子的调节。
Glutamate is the major mediator of excitotoxic neuronal death following cerebral ischemia. Under severe ischemic conditions, glutamate transporters can functionally reverse to release glutamate, thereby inducing further neuronal injury. Hypothermia has been shown to protect neurons from brain ischemia. However, the mechanism(s) involved remain unclear. Therefore, the aim of this study was to investigate the mechanism(s) mediating glutamate release during brain ischemia–reperfusion injury under hypothermic conditions. Neuron/astrocyte co-cultures were exposed to oxygen–glucose deprivation (OGD) at various temperatures for 2h, and cell viability was assayed 12h after reoxygenation. PI and MAP-2 staining demonstrated that hypothermia significantly decreased neuronal injury. Furthermore, [3H]-glutamate uptake assays showed that hypothermia protected rat primary cortical cultures against OGD reoxygenation-induced injury. Protein levels of the astrocytic glutamate transporter, GLT-1, which is primarily responsible for the clearance of extracellular glutamate, were also found to be reduced in a temperature-dependent manner. In contrast, expression of GLT-1 in astrocyte-enriched cultures was found to significantly increase following the addition of neuron-conditioned medium maintained at 37°C, and to a lesser extent with neuron-conditioned medium at 33°C. In conclusion, the neuroprotective effects of hypothermia against brain ischemia–reperfusion injury involve down-regulation of astrocytic GLT-1, which mediates the reverse transport of glutamate. Moreover, this process may be regulated by molecules secreted by stressed neurons.