Paré D, Smith Y
Département de Physiologie, Faculté de Médecine, Université Laval, Québec, Canada.
J Comp Neurol. 1994 Jun 1;344(1):33-49. doi: 10.1002/cne.903440104.
The intercalated cell masses (ICMs) are dense clusters of small GABAergic cells interposed between the basolateral and centromedial nuclear groups of the amygdala. Until now, the ICMs have been largely ignored in anatomical studies of the amygdaloid complex. Thus, this study was undertaken to identify some of their targets by means of tract-tracing methods combined with immunohistochemical techniques. Wheat-germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) was injected into numerous cortical areas and dorsal thalamic nuclei, in the anterior commissure and/or stria terminalis nuclei, and in the caudate nucleus, as well as into lateral and preoptic hypothalamic areas. Very few retrogradely labeled cells were seen in the ICMs following these injections. In contrast, massive retrograde labeling was found in the rostral groups of ICMs after WGA-HRP injections involving the substantia innominata and horizontal limb of the diagonal band. Furthermore, these retrogradely labeled intercalated cells were also GABA-immunoreactive. Results of iontophoretic injections of Phaseolus vulgaris-leucoagglutinin (PHA-L) in the rostral ICMs confirmed that they contribute a massive projection to the entire extent of the substantia innominata and horizontal limb of the diagonal band. Electron microscopic observations of ultrathin sections prepared for postembedding GABA or glutamate immunocytochemistry revealed that the ICM terminals labeled with PHA-L displayed GABA, but not glutamate immunoreactivity, and formed symmetric synapses with dendritic profiles. The present findings constitute the first direct demonstration of an amygdalofugal GABAergic projection to the basal forebrain. Considering that the basal forebrain contains a group of cholinergic and GABAergic neurons collectively projecting to the entire cortical mantle, this GABAergic projection of the ICMs could allow the amygdaloid complex to influence the activity of widespread cortical regions to which it is not directly connected, at least in the cat.
闰细胞群（ICMs）是位于杏仁核基底外侧核群和中央内侧核群之间的密集小群GABA能细胞。到目前为止，在杏仁复合体的解剖学研究中，ICMs在很大程度上被忽视了。因此，本研究采用示踪法结合免疫组织化学技术来确定其一些靶点。将与辣根过氧化物酶结合的小麦胚芽凝集素（WGA-HRP）注入多个皮质区域、背侧丘脑核、前连合和/或终纹床核、尾状核，以及外侧和视前下丘脑区域。在这些注射后，在ICMs中很少见到逆行标记的细胞。相反，在涉及无名质和斜带水平支的WGA-HRP注射后，在ICMs的嘴侧群中发现了大量逆行标记。此外，这些逆行标记的闰细胞也呈GABA免疫反应性。在嘴侧ICMs中进行菜豆白细胞凝集素（PHA-L）离子导入注射的结果证实，它们向无名质和斜带水平支的整个范围发出大量投射。对用于包埋后GABA或谷氨酸免疫细胞化学的超薄切片进行电子显微镜观察发现，用PHA-L标记的ICM终末显示GABA免疫反应性，但不显示谷氨酸免疫反应性，并与树突形成对称突触。本研究结果首次直接证明了杏仁核向基底前脑的GABA能投射。鉴于基底前脑包含一组共同投射到整个皮质被盖的胆碱能和GABA能神经元，ICMs的这种GABA能投射可能使杏仁复合体影响其至少在猫中未直接连接的广泛皮质区域的活动。
