Cell surface domain specific postsynaptic currents evoked by identified GABAergic neurones in rat hippocampus in vitro
Cell surface domain specific postsynaptic currents evoked by identified GABAergic neurones in rat hippocampus in vitro
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DOI：
10.1111/j.1469-7793.2000.t01-3-00091.x
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发表时间：
2000-04-01
影响因子：
5.5
通讯作者：
Somogyi, P
中科院分区：
文献类型：
--
作者：
Maccaferri, G;Roberts, JDB;Somogyi, P
1.在CAI锥体细胞（n = 46）中由位于定向束中的经鉴定的中间神经元（n = 43）诱发的抑制性突触后电流（IPSC）被记录，以比较它们的功能特性并确定突触位置对表观IPXC动力学的影响，如使用体细胞电压钳在-70 mV和几乎对称的[Cl-]下记录的。通过免疫细胞化学和/或光镜和电镜下的突触定位，将突触前神经元分为五种类型：定向-陷窝（O-LMC）、篮状（BC）、轴-轴（AAC）、双层（BiC）和定向-双层（O-BiC）细胞.生长抑素免疫反应O-LMCs，支配最远端的树突轴和棘，诱发最小的振幅（26 +/- 10 pA，S.E.M.，n = 8）和最慢的IPSC（10-90%上升时间，6.2 +/- 0.6 ms;衰减，20.8 +/- 1.7 ms，n = 8），在100 ms尖峰间期没有第二IPXC的配对脉冲调制（93 +/- 4%）。相比之下，小清蛋白阳性的AAC诱发更大幅度（308 +/- 103 pA，n = 7）和动力学更快（上升时间，0.8 +/- 0.1 ms;衰减11.2 +/- 0.9 ms，n = 7）的IPSC，显示成对脉冲抑制（至68 +/-5%，n = 6）。小清蛋白或CCK阳性BC（n = 9）终止于索马/树突，BiCs（n = 4）和O-BiCs（n = 7）支配树突诱发具有中间动力学参数的IPSC。IPSCs的特性及对荷包牡丹碱的敏感性表明，IPSCs的活性是由GABA（A）受体介导的.在三种情况下，由记录的篮状细胞中的动作电位诱发的动力学复杂的多相IPSC表明，耦合的中间神经元可能通过电紧张性连接聚集在同一突触后神经元上。本研究中表征的O-BiC群体（4/4生长抑素阳性）具有限于定向束/肺泡的水平树突以及受神经支配的放射层和定向层。其他BiC具有如前所述的放射状树突。BiCs和O-BiCs诱发的IPSC参数显示，细胞间差异最大，单个中间神经元既能诱发小而慢的IPSC，也能诱发大而相对快的IPSC.体细胞记录的突触后电流的动力学特性与受神经支配的细胞表面结构域相关。整体单一IPSC的上升和衰减时间的显著相关性表明，远端反应的电紧张过滤是单一IPSC的位置和细胞类型特异性差异的主要因素，但突触后GABA（A）受体的分子异质性也可能有助于观察到的动力学差异。此外，在突触后反应的短期可塑性的特定领域的差异表明，在活动依赖性反应的interneurons的分化。
1. Inhibitory postsynaptic currents (IPSCs) evoked in CAI pyramidal cells (n = 46) by identified interneurones (n = 43) located in str. oriens were recorded in order to compare their functional properties and to determine the effect of synapse location on the apparent IPXC kinetics as recorded using somatic voltage clamp at -70 mV and nearly symmetrical [Cl-].2. Five types of visualised presynaptic interneurone, oriens-lacunosum moleculare (O-LMC), basket (BC), axo-axonic (AAC), bistratified (BiC) and oriens-bistratified (O-BiC) cells, were distinguished by immunocytochemistry and/or synapse location using light and electron microscopy.3. Somatostatin immunoreactive O-LMCs, innervating the most distal dendritic shafts and spines, evoked the smallest amplitude (26 +/- 10 pA, S.E.M., n = 8) and slowest IPSCs (10-90% rise time, 6.2 +/- 0.6 ms; decay, 20.8 +/- 1.7 ms, n = 8), with no paired-pulse modulation of the second IPXC (93 +/- 4%) at 100 ms interspike interval. In contrast, parvalbumin-positive AACs evoked larger amplitude (308 +/- 103 pA, n = 7) and kinetically faster (rise time, 0.8 +/- 0.1 ms; decay 11.2 +/- 0.9 ms, n = 7) IPSCs showing paired-pulse depression (to 68 +/- 5%, n = 6). Parvalbumin- or CCK-positive BCs (n = 9) terminating on soma/dendrites, BiCs (n = 4) and O-BiCs (n = 7) innervating dendrites evoked IPSCs with intermediate kinetic parameters. The properties of IPSCs and sensitivity to bicuculline indicated that they were mediated by GABA(A) receptors.4. In three cases, kinetically complex, multiphasic IPSCs, evoked by an action potential in the recorded basket cells, suggested that coupled interneurones, possibly through electrotonic junctions, converged on the same postsynaptic neurone.5. The population of O-BiCs (4 of 4 somatostatin positive) characterised in this study had horizontal dendrites restricted to str. oriens/alveus and innervated stratum radiatum and oriens. Other BiCs had radial dendrites as described earlier. The parameters of IPSCs evoked by BiCs and O-BiCs showed,the largest cell to cell variation, and a single interneurone could evoke both small and slow as well as large and relatively fast IPSCs.6. The kinetic properties of the somatically recorded postsynaptic current are correlated with the innervated cell surface domain. A significant correlation of rise and decay times for the overall population of unitary IPSCs suggests that electrotonic filtering of distal responses is a major factor for the location and cell type specific differences of unitary IPSCs, but molecular heterogeneity of postsynaptic GABA(A) receptors may also contribute to the observed kinetic differences. Furthermore, domain specific differences in the short-term plasticity of the postsynaptic response indicate a differentiation of interneurones in activity-dependent responses.