Majumdar Sriparna, Heinze Liane, Haverkamp Silke, Ivanova Elena, Wässle Heinz
Department of Neuroanatomy, Max-Planck-Institute for Brain Research, Frankfurt/Main, Germany.
Vis Neurosci. 2007 Jul-Aug;24(4):471-87. doi: 10.1017/S0952523807070174. Epub 2007 May 29.
A-type ganglion cells of the mouse retina represent the visual channel that transfers temporal changes of the outside world very fast and with high fidelity. In this study we combined anatomical and physiological methods in order to study the glycinergic, inhibitory input of A-type ganglion cells. Immunocytochemical studies were performed in a transgenic mouse line whose ganglion cells express green fluorescent protein (GFP). The cells were double labeled for GFP and the four alpha subunits of the glycine receptor (GlyR). It was found that most of the glycinergic input of A-type cells is through fast, alpha1-expressing synapses. Whole-cell currents were recorded from A-type ganglion cells in retinal whole mounts. The response to exogenous application of glycine and spontaneous inhibitory postsynaptic currents (sIPSCs) were measured. By comparing glycinergic currents recorded in wildtype mice and in mice with specific deletions of GlyRalpha subunits (Glra1spd-ot, Glra2-/-, Glra3-/-), the subunit composition of GlyRs of A-type ganglion cells could be further defined. Glycinergic sIPSCs of A-type ganglion cells have fast kinetics (decay time constant tau = 3.9 +/- 2.5 ms, mean +/- SD). Glycinergic sIPSCs recorded in Glra2-/- and Glra3-/- mice did not differ from those of wildtype mice. However, the number of glycinergic sIPSCs was significantly reduced in Glra1spd-ot mice and the remaining sIPSCs had slower kinetics than in wildtype mice. The results show that A-type ganglion cells receive preferentially kinetically fast glycinergic inputs, mediated by GlyRs composed of alpha1 and beta subunits.
小鼠视网膜的 A 型神经节细胞代表了一个视觉通道，它能够非常快速且高保真地传递外界的时间变化。在本研究中，我们结合了解剖学和生理学方法，以研究 A 型神经节细胞的甘氨酸能抑制性输入。在一种转基因小鼠品系中进行了免疫细胞化学研究，该品系的神经节细胞表达绿色荧光蛋白（GFP）。对细胞进行 GFP 和甘氨酸受体（GlyR）的四个α亚基的双重标记。结果发现，A 型细胞的大多数甘氨酸能输入是通过快速的、表达α1 的突触进行的。在视网膜全层标本中记录 A 型神经节细胞的全细胞电流。测量对外源性施加甘氨酸的反应以及自发抑制性突触后电流（sIPSCs）。通过比较在野生型小鼠和具有 GlyRα亚基特异性缺失的小鼠（Glra1spd-ot、Glra2-/-、Glra3-/-）中记录的甘氨酸能电流，可以进一步确定 A 型神经节细胞 GlyR 的亚基组成。A 型神经节细胞的甘氨酸能 sIPSCs 具有快速动力学（衰减时间常数 tau = 3.9 +/- 2.5 毫秒，平均值 +/- 标准差）。在 Glra2-/-和 Glra3-/-小鼠中记录的甘氨酸能 sIPSCs 与野生型小鼠的没有差异。然而，在 Glra1spd-ot 小鼠中，甘氨酸能 sIPSCs 的数量显著减少，并且剩余的 sIPSCs 动力学比野生型小鼠中的更慢。结果表明，A 型神经节细胞优先接受由α1 和β亚基组成的 GlyR 介导的动力学快速的甘氨酸能输入。
