Heterogeneous presynaptic Ca2+ channel types triggering GABA release onto medial preoptic neurons from rat
Heterogeneous presynaptic Ca2+ channel types triggering GABA release onto medial preoptic neurons from rat
复制标题
触发大鼠内侧视前神经元释放 GABA 的突触前 Ca2+ 通道类型各不相同
DOI：
10.1111/j.1469-7793.1998.077bu.x
复制
发表时间：
1998-02-15
影响因子：
5.5
通讯作者：
Johansson, S
中科院分区：
文献类型：
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作者：
Haage, D;Karlsson, U;Johansson, S
1. 研究了电压依赖性 Ca2+ 通道触发大鼠内侧视前核神经元上 GABA 的释放。通过突触后细胞的紧密密封全细胞记录来研究具有贴壁功能性突触末梢的急性分离神经元。2．记录类似于微型突触后电流的自发电流事件。它们被荷包牡丹碱 (100 mu M) 阻断，显示出大致单峰振幅分布和与 Cl- 电流一致的反转电位，因此归因于突触释放的 GABA 激活的 GABA(A) 受体。3。应用 140 mM KCl 预计可以使突触前末梢去极化，引起的电流归因于 GABA 的更大量释放。 KCl 诱导的突触电流在不含 Ca2+ 的溶液中被消除，并与外部 Ca2+ 浓度呈大致双曲线关系，半饱和度为 0.15 mM。他们进一步依赖于高阈值 Ca2+ 通道所预期的 KCl 浓度。4． KCl诱发的突触电流被200μM Cd2+完全阻断，但被200μM Ni2+.5仅部分阻断。 KCl 诱发的突触电流对 L 型 Ca2+ 通道阻滞剂硝苯地平 (10 μM) 不敏感。然而，突触电流对 1 μM omega-芋螺毒素 GVIA、25 nM omega-芋螺毒素 IVA 或 1 μM omega-芋螺毒素 MVIIC.6 敏感。结论是，在许多突触前末梢，触发内侧视前神经元上的 GABA 释放的 Ca2+ 流入主要由一种主要类型的高阈值 Ca2+ 通道介导，该通道可能是 N-、P- 或 Q-型。 7．进一步得出结论，具有相似主要通道类型的终端通常聚集在同一突触后细胞上。
1. Voltage-dependent Ca2+ channels triggering GABA release onto neurons from the medial preoptic nucleus of rat were investigated. Acutely dissociated neurons with adherent functional synaptic terminals were investigated by tight-seal whole-cell recordings from the postsynaptic cells.2. Spontaneous current events similar to miniature postsynaptic currents were recorded. They were blocked by bicuculline (100 mu M), showed a roughly unimodal amplitude distribution and a reversal potential consistent with a Cl- current, and were therefore attributed to GABA(A) receptors activated by synaptically released GABA.3. Application of 140 mM KCl, expected to depolarize presynaptic terminals, evoked currents that were ascribed to a more massive release of GABA. The KCl-induced synaptic currents were abolished in Ca2+-free solutions and showed a roughly hyperbolic relation to external Ca2+ concentration with half-saturation at 0.15 mM. They further depended an the concentration of applied KCl in a way expected for high-threshold Ca2+ channels.4. The KCl-evoked synaptic currents were completely blocked by 200 mu M Cd2+, but only partially blocked by 200 mu M Ni2+.5. The KCl-evoked synaptic currents were insensitive to the L-type Ca2+ channel blocker nifedipine (10 mu M). However, the synaptic currents were sensitive to either 1 mu M omega-conotoxin GVIA, 25 nM omega-agatoxin IVA or 1 mu M omega-conotoxin MVIIC.6. It was concluded that, in many presynaptic terminals, the Ca2+ influx triggering GABA release onto medial preoptic neurons is mainly mediated by one predominant type of high-threshold Ca2+ channel that may be either of N-, P- or Q-type.7. It was further concluded that terminals with similar predominant channel types often were clustered on the same postsynaptic cell.