Characterization of spontaneous inhibitory postsynaptic currents in cultured rat retinal amacrine cells
Characterization of spontaneous inhibitory postsynaptic currents in cultured rat retinal amacrine cells
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DOI：
10.1016/j.neuroscience.2009.10.010
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发表时间：
2010-01
期刊：
影响因子：
3.3
通讯作者：
J.-B. Ke;Wen Chen;Xian-mei Yang;Zhongfeng Wang
中科院分区：
文献类型：
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作者：
J.-B. Ke;Wen Chen;Xian-mei Yang;Zhongfeng Wang
自发性突触后电流是神经递质自发释放的反映，在多种神经生物学活动中起着多种作用。在本研究中，我们记录了自发抑制性突触后电流（sIPSCs）的膜片钳技术在培养的大鼠视网膜GABA能无长突细胞（AC），提供抑制性输入的双极和神经节细胞在视网膜内层，并检查是否和如何Ca 2+参与诱导自发GABA释放从这些细胞的终端。应用10 μM荷包牡丹碱或10 μM gabazine可完全阻断sIPSCs，sIPSCs的逆转电位接近ECl−，表明这些事件仅由GABA A受体介导。增加外部Ca 2+浓度从2到5 mM显着提高的频率，但没有改变sIPSCs的振幅。与此相反，灌注无Ca 2+的外部溶液大大减少了sIPSC的事件，并降低了sIPSC的振幅。同样，非选择性电压门控钙通道阻滞剂CdCl 2（200 μM）显著抑制sIPSC的频率和振幅。此外，ryanodine受体（RyR）拮抗剂dantrolene（10 μM）未能影响sIPSC，而肌醇1，4，5-三磷酸（IP 3）受体拮抗剂2-氨基乙基二苯基硼酸酯（2-APB，20 μM）和xestospongin C（XeC，1 μM）显著降低了sIPSC的频率。在存在SKF 96365（10 μM）（一种非特异性瞬时受体电位通道（TRP）阻断剂）的情况下，2-APB持续显示其对sIPSC的影响。这些结果表明，GABA能AC末端的自发GABA释放是Ca 2+依赖性的，并且在我们的实验条件下，通过突触前钙通道的细胞外钙内流和通过激活IP 3敏感途径而不是ryanodine敏感途径从细胞内储存释放的Ca 2+是产生sIPSC的原因。
Spontaneous postsynaptic current is a reflection of spontaneous neurotransmitter release that plays multiple roles in a variety of neurobiological activities. In the present study, we recorded spontaneous inhibitory postsynaptic currents (sIPSCs) by patch-clamp techniques in cultured rat retinal GABAergic amacrine cells (ACs), which provide inhibitory inputs to both bipolar and ganglion cells in the inner retina, and examined if and how Ca2+was involved in the induction of spontaneous GABA release from the terminals of these cells. sIPSCs were completely blocked by application of either 10 μM bicuculline or 10 μM gabazine, and the reversal potential of sIPSCs was close to ECl−, indicating that these events were exclusively mediated by GABAAreceptors. Increase of external Ca2+concentrations from 2 to 5 mM significantly enhanced the frequency, but did not change the amplitude of sIPSCs. In contrast, perfusion of Ca2+-free external solution greatly reduced the events of sIPSCs and decreased the amplitude of sIPSCs. Consistently, the non-selective voltage-gated calcium channel blocker CdCl2(200 μM) considerably suppressed both the frequency and the amplitude of sIPSCs. Furthermore, the ryanodine receptor (RyR) antagonist dantrolene (10 μM) failed to affect sIPSCs, while the inositol 1,4,5-trisphosphate (IP3) receptor antagonists 2-aminoethyl diphenylborinate (2-APB, 20 μM) and xestospongin C (XeC, 1 μM) significantly decreased the frequency of sIPSCs. In the presence of SKF96365 (10 μM), a non-specific transient receptor potential channel (TRP) blocker, 2-APB persisted to show its effect on sIPSCs. These results suggest that spontaneous GABA release from the terminals of GABAergic ACs is Ca2+-dependent, and both extracellular calcium influx through presynaptic calcium channels and Ca2+release through activation of the IP3-sensitive pathway, but not the ryanodine-sensitive one, from intracellular stores are responsible for the generation of sIPSCs under our experimental conditions.