We have previously shown that repetitive induction of long‐term potentiation (LTP) by glutamate (100 μM, 3 min, three times at 24‐hr intervals) provoked long‐lasting synaptic enhancement accompanied by synaptogenesis in rat hippocampal slice cultures, a phenomenon termed RISE (repetitive LTP‐induced synaptic enhancement). Here, we examined the role of Ca²⁺‐permeable (CP) AMPA receptors (AMPARs) in the establishment of RISE. We first found a component sensitive to the Joro‐spider toxin (JSTX), a blocker of CP‐AMPARs, in a field EPSP recorded from CA3‐CA1 synapses at 2–3 days after stimulation, but this component was not found for 9–10 days. We also observed that rectification of AMPAR‐mediated current appeared only 2–3 days after stimulation, using a whole‐cell patch clamp recording from CA1 pyramidal neurons. These findings indicate that CP‐AMPAR is transiently expressed in the developing phase of RISE. The blockade of CP‐AMPARs by JSTX for 24 hr at this developing phase inhibited RISE establishment, accompanied by the loss of small synapses at the ultrastructural level. These results suggest that transiently induced CP‐AMPARs play a critical role in synaptogenesis in the developing phase of long‐lasting hippocampal synaptic plasticity, RISE.

中文翻译：

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Ca2+ 可渗透的 AMPA 受体的瞬时出现对于培养海马切片中重复 LTP 诱导的突触增强 (RISE) 的产生至关重要。

我们之前已经表明，谷氨酸盐（100 μM，3 分钟，每 24 小时间隔 3 次）重复诱导长时程增强 (LTP) 会在大鼠海马切片培养物中引发持久的突触增强伴随突触发生，这种现象称为RISE（重复 LTP 诱导的突触增强）。在这里，我们检查了 Ca ²⁺的作用-渗透性（CP）AMPA受体（AMPARs）在RISE的建立中。我们首先在刺激后 2-3 天从 CA3-CA1 突触记录的 EPSP 场中首次发现了对 Joro-spider 毒素（JSTX）（CP-AMPAR 的阻滞剂）敏感的成分，但在 9 天后未发现该成分。 10天。我们还观察到，使用来自 CA1 锥体神经元的全细胞膜片钳记录，仅在刺激后 2-3 天出现 AMPAR 介导的电流的整流。这些发现表明 CP-AMPAR 在 RISE 的发展阶段瞬时表达。在这个发育阶段，JSTX 对 CP-AMPAR 的阻断 24 小时抑制了 RISE 的建立，伴随着超微结构水平的小突触的丧失。