INDUCTION OF LONG-TERM POTENTIATION IS ASSOCIATED WITH AN INCREASE IN THE NUMBER OF AXOSPINOUS SYNAPSES WITH SEGMENTED POSTSYNAPTIC DENSITIES
INDUCTION OF LONG-TERM POTENTIATION IS ASSOCIATED WITH AN INCREASE IN THE NUMBER OF AXOSPINOUS SYNAPSES WITH SEGMENTED POSTSYNAPTIC DENSITIES
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DOI：
10.1016/0006-8993(91)91683-r
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发表时间：
1991-12-06
期刊：
影响因子：
2.9
通讯作者：
MORRELL, F
中科院分区：
文献类型：
--
作者：
GEINISMAN, Y;DETOLEDOMORRELL, L;MORRELL, F
长时程增强（LTP）的特点是突触功效的持久增强，这可能是由于突触数量的增加所致。 本研究旨在使用最近开发的无偏突触定量方法来验证该建议的有效性。 通过连续 4 天对内侧穿支路径进行高频刺激，在年轻成年大鼠中引发 LTP。 第四次刺激后1小时处死增强的动物。 受刺激但未增强和植入但未受刺激的大鼠作为对照。 在海马齿状回的中间（MML）和内部（IML）分子层检查突触。 使用体视解剖技术，对以下形态突触类型获得每个神经元突触数量的无偏估计：涉及树突轴的轴突突触，表现出连续突触后密度（PSD）的非穿孔轴棘突触和以有窗、马蹄形或分段PSD为特征的穿孔轴棘突触。 这项研究的一个主要发现是，LTP 的诱导伴随着分段 PSD 突触数量的选择性增加。 这种变化仅在增强突触区 (MML) 中检测到，但在紧邻突触区 (IML) 中未检测到，该突触区在 LTP 诱导过程中未直接受到刺激。 后一个发现强烈表明，表现出分段 PSD 的轴棘突触数量的增加与 LTP 相关。 这种高度选择性的连接修饰仅涉及增强突触场中一种特定的突触亚型，很可能代表 LTP 典型的突触功效持久增强的结构基础。
Long-term potentiation (LTP) is characterized by a long-lasting enhancement of synaptic efficacy which may be due to an increase in synaptic numbers. The present study was designed to verify the validity of this suggestion using recently developed unbiased methods for synapse quantitation. LTP was elicited in young adult rats by high-frequency stimulation of the medial perforant path carried out on each of 4 consecutive days. Potentiated animals were sacrificed 1 h after the fourth stimulation. Stimulated but not potentiated and implanted but not stimulated rats served as controls. Synapses were examined in the middle (MML) and inner (IML) molecular layer of the hippocampal dentate gyrus. Using the stereological disector technique, unbiased estimates of the number of synapses per neuron were differentially obtained for the following morphological synaptic types: axodendritic synapses involving dendritic shafts, non-perforated axospinous synapses exhibiting a continuous postsynaptic density (PSD) and perforated axospinous synapses distinguished by a fenestrated, horsehoe-shaped or segmented PSD. A major finding of this study is that the induction of LTP is accompanied by a selective increase in the number of synapses with segmented PSDs. This change was detected only in the potentiated synaptic field (MML), but not in an immediately adjacent one (IML) which was not directly stimulated during the induction of LTP. It is strongly suggested by the latter finding that the increase in the number of axospinous synapses exhibiting segmented PSDs is associated with LTP. Such a highly selective modification of connectivity, which involves only one particular subtype of synapses in the potentiated synaptic field, is likely to represent a structural substrate of the enduring augmentation of synaptic efficacy typical of LTP.