Synaptic relationships between axon terminals from the mediodorsal thalamic nucleus and γ-aminobutyric acidergic cortical cells in the prelimbic cortex of the rat
Synaptic relationships between axon terminals from the mediodorsal thalamic nucleus and γ-aminobutyric acidergic cortical cells in the prelimbic cortex of the rat
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DOI：
10.1002/cne.20249
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发表时间：
2004-09-13
影响因子：
2.5
通讯作者：
Price, JL
中科院分区：
文献类型：
--
作者：
Kuroda, M;Yokofujita, J;Price, JL
虽然前额叶皮质和丘脑内侧背侧核之间的相互联系是众所周知的，但抑制性皮质中间神经元在神经回路中的参与还没有完全确定。为了解决这个问题，我们对大鼠的大脑进行了三项联合神经解剖学研究。首先，用高尔基体染色皮质细胞和丘脑损毁后丘脑皮质终末变性的方法鉴定重建的非锥体神经元树突形成的突触的频率和空间分布。发现MD的终末与高尔基体浸染的非锥体细胞的树突或棘突发生突触接触，树突棘非常稀疏。其次，用菜豆亮氨酸凝集素顺行转运(PHA-L)和包埋后γ-氨基丁酸(GABA)免疫细胞化学的联合研究表明，MD的PHA-L标记终末与GABA免疫反应阳性的树突和棘突形成突触连接。用PHA-L标记的未标记树突棘既接受MD的轴突输入，也接受GABA能细胞的轴突输入。此外，在树突和轴突终末之间也发现了突触，它们都是GABA免疫反应阳性的。第三，用辣根过氧化物酶标记的小麦胚凝集素和包埋后的GABA免疫细胞化学方法，研究了投射到MD和GABA能终末的皮质丘脑神经元之间的突触联系。大脑皮层的GABA能终末与逆行标记的皮质丘脑神经元与MD形成对称性突触联系。突触均位于胞体和粗大的树突干上。这些结果首次证实了前额叶皮质中的突触接触不仅存在于MD和GABA能中间神经元的丘脑皮质终末之间，而且还存在于GABA能终末和投射到MD的皮质丘脑神经元之间。解剖结果表明，GABA能中间神经元对MD和前额叶皮质之间的兴奋性混响具有调制作用。(C)2004年Wiley-Liss公司
Although the reciprocal interconnections between the prefrontal cortex and the mediodorsal nucleus of the thalamus (MD) are well known, the involvement of inhibitory cortical interneurons in the neural circuit has not been fully defined. To address this issue, we conducted three combined neuroanatomical studies on the rat brain. First, the frequency and the spatial distribution of synapses made by reconstructed dendrites of nonpyramidalneurons were identified by impregnation of cortical cells with the Golgi method and identification of thalamocortical terminals by degeneration following thalamic lesions. Terminals from MD were found to make synaptic contacts with small dendritic shafts or spines of Golgi-impregnated nonpyramidal cells with very sparse dendritic spines. Second, a combined study that used anterograde transport of Phaseolus vulgaris leucoagglutinin (PHA-L) and postembedding gamma-aminobutyric acid (GABA) immunocytochemistry indicated that PHA-L-labeled terminals from MD made synaptic junctions with GABA-immunoreactive dendritic shafts and spines. Nonlabeled dendritic spines were found to receive both axonal inputs from MD with PHA-L labelings and from GABAergic cells. In addition, synapses were found between dendritic shafts and axon terminals that were both immunoreactive for GABA. Third, synalitic connections between corticothalamic neurons that project to MD and GABAergic terminals were investigated by using wheat germ agglutinin conjugated to horseradish peroxidase and postembedding GABA immunocytochemistry. GABAergic terminals in the prelimbic cortex made symmetrical synaptic contacts with retrogradely labeled corticothalamic neurons to MD. All of the synapses were found on cell somata and thick dendritic trunks. These results provide the first demonstration of synaptic contacts in the prelimbic cortex not only between thalamocortical terminals from MD and GABAergic interneurons but also between GABAergic terminals and corticothalamic neurons that project to MD. The anatomical findings indicate that GABAergic interneurons have a modulatory influence on excitatory reverberation between MD and the prefrontal cortex. (C) 2004 Wiley-Liss, Inc.