REGION-SPECIFIC AGE EFFECTS ON AMPA SENSITIVITY - ELECTROPHYSIOLOGICAL EVIDENCE FOR LOSS OF SYNAPTIC CONTACTS IN HIPPOCAMPAL FIELD CA1
REGION-SPECIFIC AGE EFFECTS ON AMPA SENSITIVITY - ELECTROPHYSIOLOGICAL EVIDENCE FOR LOSS OF SYNAPTIC CONTACTS IN HIPPOCAMPAL FIELD CA1
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DOI：
10.1002/hipo.450020413
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发表时间：
1992-10-01
期刊：
影响因子：
3.5
通讯作者：
MCNAUGHTON, BL
中科院分区：
文献类型：
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作者：
BARNES, CA;RAO, G;MCNAUGHTON, BL
体外研究衰老对大鼠海马神经元对l -谷氨酸和AMPA离子吸附的反应性的影响。年龄对神经元对l -谷氨酸的反应没有影响；然而，老龄大鼠的CA1锥体细胞，而不是齿状筋膜中的颗粒细胞，在AMPA应用后，细胞外记录的突触反应减少较小（可能是由去极化介导的），细胞外“DC”场变小（通过减去AMPA在树突应用后树突和体细胞的DC电位来测量）。为了研究这种与年龄相关的AMPA敏感性改变的细胞基础，使用了两种额外的电生理方法：(1)测量细胞外EPSP和Schaffer侧侧- ca1反应的纤维电位组分的振幅比；(2)测量细胞内记录的单一epsp并对其波动进行定量分析。对这类实验的四种假设可能结果的解释进行了概述，并根据实验数据进行了评估。本实验获得的结果模式支持以下结论：在老年大鼠中，单个Schaffer侧突触似乎没有改变AMPA受体的特性，因为统一突触反应的平均大小和表观量子大小在年龄组之间都没有差异；然而，数据确实支持老年CA1锥体细胞中每个Schaffer侧支的突触少于年轻CA1锥体细胞的结论。
The effects of aging on the responsiveness of hippocampal neurons to iontophoretic application of L-glutamate and AMPA were studied in vitro. There were no effects of age on neuronal responses to L-glutamate; however, CA1 pyramidal cells of old rats, but not granule cells in the fascia dentata, showed both a smaller reduction in extracellularly-recorded synaptic responses following application of AMPA (presumably mediated by depolarization), and smaller extracellular "DC" fields (measured by subtracting the DC potentials at the dendrite and soma following AMPA application in the dendrites). To examine the cellular bases of this age-related alteration in AMPA sensitivity, two additional electrophysiological approaches were used: (1) measurement of the amplitude ratios of extracellular EPSP and fiber potential components of the Schaffer collateral-CA1 response; (2) measurement of intracellularly recorded unitary EPSPs and quantal analysis of their fluctuations. The interpretations that would be placed on four hypothetical possible outcomes of such experiments are outlined and assessed in relation to the experimental data. The pattern of results obtained in the present experiments supports the following conclusions: In old rats, individual Schaffer collateral synapses do not appear to have altered AMPA receptor properties, as neither the mean size of the unitary synaptic response nor the apparent quantal size differs between age groups; however, the data do support the conclusion that there are fewer synapses per Schaffer collateral branch in old versus young CA1 pyramidal cells.