Signaling properties of stratum oriens interneurons in the hippocampus of transgenic mice expressing EGFP in a subset of somatostatin‐containing cells
Signaling properties of stratum oriens interneurons in the hippocampus of transgenic mice expressing EGFP in a subset of somatostatin‐containing cells
复制标题
在含有生长抑素的细胞子集中表达 EGFP 的转基因小鼠海马中定向层中间神经元的信号传导特性
作者：
F. Minneci;M. Janahmadi;M. Migliore;Nataša Dragičević;D. Avossa;E. Cherubini
GABA能中间神经元构成了一组异质细胞，它们对网络兴奋性施加强有力的控制，并负责对大脑中的信息处理至关重要的振荡行为。这些细胞已根据其形态学、神经化学和生理学特征进行了不同的分类。在此，全细胞膜片钳记录用于进一步表征在含有生长抑素的GABA能中间神经元亚群中表达EGFP的转基因小鼠（GIN小鼠）中，在从P8老年动物获得的切片培养物中，海马CA 1区定向层中EGFP阳性细胞的功能特性。这些细胞表现出被动和主动的膜特性，类似于在定向层中间神经元投射到腔隙-分子层中发现的特性。此外，它们表现出不同的放电模式，维持在膜去极化：不规则（48%），规则（30%），和集群（22%）。中间神经元中的动作电位序列在少数主细胞（3/45）中诱发小振幅GABA能电流，其在20 Hz下经历短期抑制。相比之下，主细胞和EGFP阳性中间神经元之间的兴奋性连接是高度可靠的（17/55），并表现出频率和使用依赖性的促进作用，特别是在γ波段。此外，来自成对互连的EGFP阳性细胞的记录显示，47%的病例存在电耦合，而甘珀酸（200 μM）可消除电耦合。平均而言，耦合系数为0.21 ± 0.07。当电耦合特别强时，它充当了一个强大的低通滤波器，从而有助于改变单个细胞的输出。总之，它出现的动态相互作用的细胞与不同的放电模式可能会不同地影响GABA能信号，导致，如模拟数据所示，在海马网络内的广泛的神经元间的通信。© 2007 Wiley利斯公司
GABAergic interneurons constitute a heterogeneous group of cells that exert a powerful control on network excitability and are responsible for the oscillatory behavior crucial for information processing in the brain. These cells have been differently classified according to their morphological, neurochemical, and physiological characteristics. Here, whole cell patch clamp recordings were used to further characterize, in transgenic mice expressing EGFP in a subpopulation of GABAergic interneurons containing somatostatin (GIN mice), the functional properties of EGFP‐positive cells in stratum oriens of the CA1 region of the hippocampus, in slice cultures obtained from P8 old animals. These cells showed passive and active membrane properties similar to those found in stratum oriens interneurons projecting to stratum lacunosum‐moleculare. Moreover, they exhibited different firing patterns that were maintained upon membrane depolarization: irregular (48%), regular (30%), and clustered (22%). Trains of action potentials in interneurons evoked in a minority of principal cells (3/45) small amplitude GABAergic currents that at 20 Hz underwent short‐term depression. In contrast, excitatory connections between principal cells and EGFP‐positive interneurons were highly reliable (17/55) and exhibited a frequency and use‐dependent facilitation particularly in the gamma band. In addition, recordings from paired of interconnected EGFP‐positive cells revealed in 47% of the cases electrical coupling, which was abolished by carbenoxolone (200 μM). On average, the coupling coefficient was 0.21 ± 0.07. When electrical coupling was particularly strong it acted as a powerful low‐pass filter, thus contributing to alter the output of individual cells. In conclusion, it appears that the dynamic interaction between cells with various firing patterns could differently affect GABAergic signaling, leading, as suggested by simulation data, to a wide range of interneuronal communication within the hippocampal network. © 2007 Wiley‐Liss, Inc.