Glutamate-induced exocytosis of glutamate from astrocytes
Glutamate-induced exocytosis of glutamate from astrocytes
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DOI：
10.1074/jbc.m700452200
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发表时间：
2007-08-17
影响因子：
4.8
通讯作者：
Kang, Jian
中科院分区：
文献类型：
--
作者：
Xu, Jun;Peng, Hong;Kang, Jian
最近的研究表明，星形胶质细胞可以发挥更积极的作用，在神经元回路比以前认为，通过释放神经递质，如谷氨酸和ATP。在这里，我们报告说，局部应用谷氨酸或谷氨酰胺合成酶抑制剂诱导星形胶质细胞释放谷氨酸，激活一个缓慢衰减的短暂内向电流（SIC）在CA 1锥体神经元和短暂内向电流在海马切片星形胶质细胞。SICs的发生伴随着大泡周围的膨化吸管的外观。SICs的频率与[谷氨酸]（0）呈正相关。抗胶质细胞磷脂酸蛋白标记的星形胶质细胞的EM成像显示谷氨酸诱导的大星形胶质细胞囊泡。使用双光子激光扫描显微镜成像FM 1- 43荧光检测谷氨酸诱导的大囊泡的形成和融合，其被鉴定为FM 1- 43阴性结构。通过囊泡膜中具有高强度FM 1- 43染色的囊泡塌陷监测的大囊泡融合与SICs一致。谷氨酸诱导的两种类型的大囊泡具有高和低的囊泡内[Ca 2（+）]。高[Ca 2（+）]囊泡在星形胶质细胞释放谷氨酸中起主要作用。注入Ca 2（+）螯合剂1，2-双（2-氨基苯氧基）乙烷- N，N，N '，N '-四乙酸或SNARE阻断剂破伤风毒素可阻断囊泡融合，提示Ca 2（+）和SNARE依赖性融合.输注囊泡谷氨酸转运抑制剂虎红，减少星形胶质细胞谷氨酸释放，表明囊泡谷氨酸转运参与囊泡谷氨酸转运。我们的研究结果表明，局部[谷氨酸]（0）增加诱导含谷氨酸的大星形胶质细胞囊泡的形成和胞吐融合。这些大的囊泡在神经元回路的反馈控制和癫痫发作中可能发挥重要作用。
Recent studies indicate that astrocytes can play a much more active role in neuronal circuits than previously believed, by releasing neurotransmitters such as glutamate and ATP. Here we report that local application of glutamate or glutamine synthetase inhibitors induces astrocytic release of glutamate, which activates a slowly decaying transient inward current (SIC) in CA1 pyramidal neurons and a transient inward current in astrocytes in hippocampal slices. The occurrence of SICs was accompanied by an appearance of large vesicles around the puffing pipette. The frequency of SICs was positively correlated with [ glutamate] (0). EM imaging of anti-glial fibrillary acid proteinlabeled astrocytes showed glutamate-induced large astrocytic vesicles. Imaging of FM 1- 43 fluorescence using two- photon laser scanning microscopy detected glutamate- induced formation and fusion of large vesicles identified as FM 1- 43- negative structures. Fusion of large vesicles, monitored by collapse of vesicles with a high intensity FM 1- 43 stain in the vesicular membrane, coincided with SICs. Glutamate induced two types of large vesicles with high and low intravesicular [ Ca2(+) ]. The high [ Ca2 (+)] vesicle plays a major role in astrocytic release of glutamate. Vesicular fusion was blocked by infusing the Ca2 (+) chelator, 1,2- bis( 2-aminophenoxy) ethane- N, N, N ', N '-tetraacetic acid, or the SNARE blocker, tetanus toxin, suggesting Ca2 (+)-and SNARE- dependent fusion. Infusion of the vesicular glutamate transport inhibitor, Rose Bengal, reduced astrocytic glutamate release, suggesting the involvement of vesicular glutamate transports in vesicular transport of glutamate. Our results demonstrate that local [glutamate] (0) increases induce formation and exocytotic fusion of glutamate-containing large astrocytic vesicles. These large vesicles could play important roles in the feedback control of neuronal circuits and epileptic seizures.