Synaptic inhibition of pyramidal cells evoked by different interneuronal subtypes in layer v of rat visual cortex.
Synaptic inhibition of pyramidal cells evoked by different interneuronal subtypes in layer v of rat visual cortex.
复制标题
DOI：
10.1152/jn.2002.88.2.740
复制
发表时间：
2002-08
影响因子：
2.5
通讯作者：
Zixiu Xiang;J. Huguenard;D. Prince
中科院分区：
文献类型：
--
作者：
Zixiu Xiang;J. Huguenard;D. Prince
使用双全细胞记录检查了大鼠视觉皮层切片 V 层中间神经元的快速尖峰 (FS) 和低阈值尖峰 (LTS) 亚型诱发的锥体 (P) 细胞中 GABA(A) 受体介导的单一抑制性突触后电流 (uIPSC) 的特性。 FS 细胞诱发的 uIPSC 比 LTS 细胞诱发的 uIPSC 更大且上升更快，这与 FS 和 LTS 细胞轴突分别向 V 层锥体细胞的体周和远端树突区域的已知主要投射，以及由此产生的 LTS-P 突触事件的电紧张衰减一致。出乎意料的是，LTS-P 和 FS-P uIPSC 的衰减时间常数没有显着差异。建模结果与 LTS-P 和 FS-P 突触处 GABA(A) 受体介导的潜在电导差异一致。两个突触处均存在配对脉冲抑制（PPD），与失败率增加和变异系数降低相关，表明涉及突触前机制。此外，PPD 期间的第二个和第一个 uIPSC 振幅并非呈负相关，这表明两个突触处的 PPD 独立于先前的释放，并且可能不是由于突触小泡可释放池的耗尽所致。突触前中间神经元中短的 20 Hz 动作电位序列诱发了 uIPSC 序列，FS-P 和 LTS-P 突触的振幅呈指数递减。 FS-P uIPSC 振幅比 LTS-P uIPSC 下降得更慢。因此，FS 和 LTS 细胞在放电特性、与 V 层 P 细胞的突触连接以及短期突触动力学方面存在差异，可能在调节 P 细胞的输入输出关系中发挥不同的作用。
Properties of GABA(A) receptor-mediated unitary inhibitory postsynaptic currents (uIPSCs) in pyramidal (P) cells, evoked by fast spiking (FS) and low-threshold spike (LTS) subtypes of interneurons in layer V of rat visual cortex slices were examined using dual whole cell recordings. uIPSCs evoked by FS cells were larger and faster rising than those evoked by LTS cells, consistent with the known primary projections of FS and LTS cell axons to perisomatic and distal dendritic areas of layer V pyramidal cells, respectively, and the resulting electrotonic attenuation for LTS-P synaptic events. Unexpectedly, the decay time constants for LTS-P and FS-P uIPSCs were not significantly different. Modeling results were consistent with differences in the underlying GABA(A) receptor-mediated conductance at LTS-P and FS-P synapses. Paired-pulse depression (PPD), present at both synapses, was associated with an increase in failure rate and a decrease in coefficient of variation, indicating that presynaptic mechanisms were involved. Furthermore, the second and first uIPSC amplitudes during PPD were not inversely correlated, suggesting that PPD at both synapses is independent of previous release and might not result from depletion of the releasable pool of synaptic vesicles. Short, 20-Hz trains of action potentials in presynaptic interneurons evoked trains of uIPSCs with exponentially decreasing amplitudes at both FS-P and LTS-P synapses. FS-P uIPSC amplitudes declined more slowly than those of LTS-P uIPSCs. Thus FS and LTS cells, with their differences in firing properties, synaptic connectivity with layer V P cells, and short-term synaptic dynamics, might play distinct roles in regulating the input-output relationship of the P cells.