The electrical response of cerebellar Purkinje neurons to simulated ischaemia
The electrical response of cerebellar Purkinje neurons to simulated ischaemia
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DOI：
10.1093/brain/awh619
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发表时间：
2005-10-01
期刊：
影响因子：
14.5
通讯作者：
Attwell, D
中科院分区：
文献类型：
--
作者：
Hamann, M;Rossi, DJ;Attwell, D
尽管缺乏N-甲基-d-天冬氨酸受体，小脑浦肯野细胞是非常脆弱的缺血性损伤，这导致他们在α-氨基-3-羟基-5-甲基-异恶唑-4-丙酸（AMPA）受体依赖性的方式坏死。为了研究导致这种细胞死亡的电事件，我们在小脑切片中全细胞钳位浦肯野细胞。模拟缺血诱发浦肯野细胞初始超极化8.5 mV，随后再生的“缺氧去极化”（AD）至-14 mV。谷氨酸受体阻滞剂可预防AD。在电压钳模式中，我们使用细胞的谷氨酸受体来感知缺血引起的细胞外谷氨酸浓度的升高，GABA（a）和GABA（B）受体被阻断，Cs（+）作为主要的吸管阳离子。缺血在浦肯野细胞中诱导了缓慢发展的小（< 500 pA）内向电流，随后是突然的大内向“AD电流”（类似于6 nA），这在很大程度上被阻断AMPA受体所阻止。去除细胞外钙减少了大的谷氨酸介导的电流在早期（缺血10分钟后）的70%，但在以后的时间（15分钟）没有影响。通过用缓慢转运的谷氨酸类似物PDC（1-反式-吡咯烷-2，4-二羧酸酯）预加载细胞来阻断谷氨酸转运体的运作，在早期和后期分别将电流降低了88%和83%。在缺乏胶质谷氨酸转运蛋白GLAST或GLT-1的小鼠的浦肯野细胞切片中，缺血诱发的AD电流与野生型切片中的AD电流无法区分。这些数据表明，在小脑缺血，浦肯野细胞的电生理功能障碍的主要原因是浦肯野细胞AMPA受体的激活。激活这些受体的谷氨酸通过胞吐作用（早期）和谷氨酸转运体的逆转（显然在神经元中）释放。
Despite lacking N-methyl-d-aspartate receptors, cerebellar Purkinje cells are highly vulnerable to ischaemic insults, which lead them to die necrotically in an alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptor-dependent manner. To investigate the electrical events leading to this cell death, we whole-cell clamped Purkinje cells in cerebellar slices. Simulated ischaemia evoked an initial hyperpolarization of Purkinje cells by 8.5 mV, followed by a regenerative 'anoxic depolarization' (AD) to -14 mV. The AD was prevented by glutamate receptor blockers. In voltage-clamp mode, we used the cells' glutamate receptors to sense the rise of extracellular glutamate concentration induced by ischaemia, with GABA(a) and GABA(b) receptors blocked and Cs(+) as the main pipette cation. Ischaemia induced a small (< 500 pA) slowly developing inward current in Purkinje cells, followed by a sudden large inward 'AD current' (similar to 6 nA) which was largely prevented by blocking AMPA receptors. Removing extracellular calcium reduced the large glutamate-mediated current by similar to 70% at early times (after 10 min ischaemia), but had no effect at later times (15 min). Blocking the operation of glutamate transporters, by preloading cells with the slowly transported glutamate analogue PDC (l-trans-pyrrolidine-2,4-dicarboxylate), reduced the current by similar to 88% at early and 83% at later times. In Purkinje cells in slices from mice lacking the glial glutamate transporters GLAST or GLT-1, the ischaemia-evoked AD current was indistinguishable from that in wild-type slices. These data suggest that, in cerebellar ischaemia, the dominant cause of the electrophysiological dysfunction of Purkinje cells is an activation of Purkinje cell AMPA receptors. The glutamate activating these receptors is released both by exocytosis (at early times) and by reversal of a glutamate transporter, apparently in neurons.