Heterosynaptic enhancement of the excitability of hippocampal mossy fibers by long-range spill-over of glutamate
Heterosynaptic enhancement of the excitability of hippocampal mossy fibers by long-range spill-over of glutamate
复制标题
谷氨酸远程溢出对海马苔藓纤维兴奋性的异质突触增强
DOI：
10.1002/hipo.20885
复制
发表时间：
2012
期刊：
影响因子：
3.5
通讯作者：
Kamiya H.
中科院分区：
文献类型：
--
作者：
Uchida T.;Fukuda S.;Kamiya H.
已有报道几类离子型受体可使海马苔藓纤维轴突膜脱髓鞘。红藻氨酸受体和GABA A受体都位于轴突和/或突触前末梢上，并且已知这些受体被从突触裂隙溢出的突触释放的谷氨酸和GABA激活。然而，这两种受体在调节苔藓纤维轴突兴奋性中的相对作用目前还未见报道。在这项研究中，我们发现，谷氨酸溢出连合/联想突触诱发的便利化的逆行人口尖峰苔藓纤维。群体峰电位振幅的增加和潜伏期的减少表明，轴突膜的去极化增加了被招募的苔藓纤维的数量。应用非NMDA受体拮抗剂CNQX（10 μM）几乎消除了这种作用。谷氨酸转运体抑制剂TBOA（30 μM）可延长异突触易化的持续时间。这些结果表明，从远端连合/联合突触释放的谷氨酸从突触间隙溢出，激活CA 3区苔藓纤维上的红藻氨酸受体，在调节突触前兴奋性方面比GABA起主要作用。© 2010 Wiley Periodicals，Inc.
Several classes of ionotropic receptors have been reported to depolarize the axonal membrane of hippocampal mossy fibers. Both kainate receptors and GABAAreceptors are localized on axons and/or presynaptic terminals, and these receptors have been known to be activated by synaptically released glutamate and GABA which spill out from the synaptic clefts. However the relative contribution of these two receptors in modulating the excitability of mossy fiber axon was not reported so far. In this study, we revealed that glutamate spilled out from commissural/associational synapses evoked the facilitation of antidromic population spikes of mossy fibers. Increase in amplitude and decrease in latency of population spikes suggest that the number of recruited mossy fibers increases by depolarization of axonal membrane. Application of non‐NMDA receptor antagonist CNQX (10 μM) almost abolished this effect. TBOA (30 μM), an inhibitor of glutamate transporter, prolonged the duration of heterosynaptic facilitation. These results suggest that glutamate released from distant commissural/associational synapses spills out from synaptic cleft and activates the kainate receptors on the mossy fibers of CA3 region, and plays a major role in modulating presynaptic excitability than GABA. © 2010 Wiley Periodicals, Inc.