A comparison of spontaneous EPSCs in layer II and layer IV-V neurons of the rat entorhinal cortex in vitro
A comparison of spontaneous EPSCs in layer II and layer IV-V neurons of the rat entorhinal cortex in vitro
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DOI：
10.1152/jn.1996.76.2.1089
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发表时间：
1996-08-01
影响因子：
2.5
通讯作者：
Jones, RSG
中科院分区：
文献类型：
--
作者：
Berretta, N;Jones, RSG
1. 我们采用全细胞电压钳记录的方法，比较了大鼠内鼻皮层（EC）第IV-V层和第II层神经元的自发兴奋性突触后电流（sEPSCs）特征。两层sEPSCs的频率相似，但IV-V层事件的平均振幅更大，上升时间更快，衰减速度更快。振幅的差异可归因于IV-V层神经元中存在大量较大的事件，而这些事件在ii层中不存在。第二层神经元的电紧张长度更大，表明sEPSCs的动力学差异可能部分由电紧张衰减来解释。河豚毒素（TTX）降低了两层sEPSCs的频率，幅度相似（15-20%）。然而，第II层的振幅分布没有变化，而在第IV-V层，TTX消除了大部分较大振幅的sepsc。6-氰-7-硝基喹诺啉-2,3-二酮或6-硝基-7-磺胺基苯并(f)-喹诺啉-2,3-二酮可降解两层神经元中的大部分sEPSCs。然而，即使在负保持电位下，在这些拮抗剂的存在下，仍有一群时间进程较慢的sEPSCs存在。慢速sEPSCs在IV-V层更常见，但在两层中具有相似的特征，在更正的保持电位下或在无Mg2+的介质中振幅增加，并被2-氨基-5-磷酸戊酸酯（AP5）阻断7。单独使用AP5（即不添加α -氨基-3-羟基-5-甲基-4-异恶唑丙酸拮抗剂）可降低IV-V层神经元sEPSCs的峰值振幅和衰减期，但对ii层神经元sEPSCs的振幅影响不大，仅对衰减期有微弱影响。因此，EC的第IV-V层和第II层神经元都受到连续的自发兴奋。而IV-V层神经元则表现出更大振幅的sEPSCs，可能是由多量子神经递质释放介导的。此外，尽管这两种类型的神经元都表现出由n -甲基- d -天冬氨酸受体介导的自发兴奋，但这种成分在深层中更为明显。
1. We have compared the characteristics of spontaneous excitatory postsynaptic currents (sEPSCs) in neurons of layer IV-V and layer II of the rat entorhinal cortex (EC) using whole cell voltage-clamp recordings in a slice preparation.2. The frequency of sEPSCs was similar in the two layers, but the events in layer IV-V had a larger mean amplitude, faster rise time, and were faster to decay. The difference in amplitude could be attributed to the presence of a population of larger events in the layer IV-V neurons that were not present in layer II.3. Electrotonic length was greater in layer II neurons, suggesting that the difference in kinetics of the sEPSCs may be explained partly by electrotonic attenuation.4. The frequency of sEPSCs in both layers was reduced by tetrodotoxin (TTX) to a similar extent (15-20%). However, the amplitude distribution was unchanged in layer II, whereas in layer IV-V TTX abolished most of the larger amplitude sEPSCs.5. 6-cyano-7-nitroquinoxaline-2,3-dione or 6-nitro-7-sulphamoylbenzo (f)-quinoxaline-2,3-dione, abolished most of the sEPSCs in neurons of both layers. However, even at negative holding potentials, a population of slower time-course sEPSCs remained in the presence of these antagonists.6. The slow sEPSCs were more frequent in layer IV-V but had similar characteristics in both layers, being increased in amplitude at more positive holding potentials or in Mg2+-free medium, and blocked by 2-amino-5-phosphonovalerate (AP5).7. AP5 alone (i.e., without addition of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid antagonists) reduced the peak amplitude and decay phase of sEPSCs in layer IV-V neurons but appeared to have little effect on amplitude and only a weak effect on decay phase in layer II.8. Thus both layer IV-V and layer II neurons of the EC suffer continuous spontaneous excitation. However, layer IV-V neurons exhibit larger amplitude sEPSCs, probably mediated by release of multiple quanta of neurotransmitter. In addition, although both types of neurons display spontaneous excitation mediated by N-methyl-D-aspartate receptors, this component appears more pronounced in the deeper layers.