Arai A, Lynch G
Center for the Neurobiology of Learning and Memory, University of California, Irvine 92717-3800, USA.
Brain Res. 1996 Apr 15;716(1-2):202-6. doi: 10.1016/0006-8993(96)00030-3.
Patches excised from fields CA1 and CA3 of the hippocampus were used to study AMPA receptor responses to repetitive application of brief pulses of agonist. AMPA receptors in field CA1 exhibited a larger degree of paired-pulse depression and a slower recovery rate from desensitization than those from CA3 patches. Responses became progressively smaller during a train of short pulses (4 at 100 Hz), an effect that was greater in CA1 than CA3 patches and that was blocked by a drug (cyclothiazide) that slows desensitization. Cyclothiazide also increased steady state currents during a long pulse of glutamate and had a lower EC50 for CA3 than CA1 AMPA receptors. These results suggest (i) that differences in the relative balance of flip vs. flop subunits affect the kinetic and pharmacological properties of AMPA receptors in vivo, and (ii) that the rate of recovery from desensitization may influence responses to the bursts of afferent activity commonly used to induce long-term potentiation.
从海马体CA1区和CA3区切除的脑片用于研究AMPA受体对重复施加短暂激动剂脉冲的反应。与CA3脑片相比，CA1区的AMPA受体表现出更大程度的双脉冲抑制以及从脱敏状态恢复的速率更慢。在一串短脉冲（100 Hz下4个）期间，反应逐渐变小，这种效应在CA1脑片中比在CA3脑片中更明显，并且被一种减缓脱敏的药物（环噻嗪）所阻断。环噻嗪还增加了谷氨酸长脉冲期间的稳态电流，并且对于CA3区的AMPA受体，其半数有效浓度（EC50）低于CA1区。这些结果表明：（i）翻转亚基与翻转-反向亚基相对平衡的差异影响体内AMPA受体的动力学和药理学特性；（ii）脱敏恢复速率可能影响对常用于诱导长时程增强的传入活动爆发的反应。
