Differences in the distribution of GABA- and GAD-immunoreactive neurons in the anterior and posterior piriform cortex of rats
Differences in the distribution of GABA- and GAD-immunoreactive neurons in the anterior and posterior piriform cortex of rats
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DOI：
10.1016/s0006-8993(98)00488-0
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发表时间：
1998-07-27
期刊：
影响因子：
2.9
通讯作者：
Ebert, U
中科院分区：
文献类型：
--
作者：
Löscher, W;Lehmann, H;Ebert, U
越来越多的证据表明，梨状皮层对癫痫发作诱导和响应其他边缘脑区域引起的癫痫发作的功能改变的易感性存在前后差异，但梨状皮层前后轴上存在这种差异的原因尚不清楚。在本研究中，通过 GABA 和 GABA 合成酶谷氨酸脱羧酶的免疫细胞化学定位，在光镜水平上鉴定了大鼠梨状皮层中的 GABA 能神经元。为此目的，使用了针对 GABA 的单克隆抗体，以及用于比较的针对 GABA 和谷氨酸脱羧酶的多克隆抗体。在前梨状皮层和后梨状皮层中，第二层发现 GABA 免疫反应细胞的数量和密度最高。在 I 层和 III 层以及下面的内皮状皮质中发现了较低密度的 GABA 能细胞。当对梨状皮层的 19 个相应切片（覆盖该区域的大部分前后延伸部分）中的细胞进行定量时，在靠近前梨状皮层和后梨状皮层之间的过渡区内或附近的切片中，GABA 能神经元的密度似乎有所增加。对前梨状皮层和后梨状皮层以及两个部分之间的过渡区的 4 个切片水平进行的更详细的分析证实了过渡区中 GABA 能神经元的密度显着较高，这主要是由于 Lavers II 和 III 中的细胞数量增加所致。我们认为，前梨状皮层和后梨状皮层之间的过渡区是众多 GABA 能中间神经元调节邻近深层锥体细胞活动的位置，这些细胞同时接收来自梨状皮层更前部和后部的嗅球和远处锥体细胞的密集兴奋输入，从而增加了该限制区域内阵发性激活的风险。该提议与最近观察到的前梨状皮层和后梨状皮层之间的过渡区内对癫痫样激活和点燃引起的神经化学改变的敏感性增加的结果一致。 (C) 1998 Elsevier Science B.V. 保留所有权利。
There is accumulating evidence of anterior-posterior differences in the susceptibility of the piriform cortex to seizure induction and to functional alterations in response to seizures elicited from other limbic brain regions, but the reasons for such differences along the anterior-posterior axis of the piriform cortex are not clear. In the present study, GABAergic neurons have been identified in the piriform cortex of the rat at light microscopic level by immunocytochemical localization of GABA and the GABA-synthesizing enzyme glutamic acid decarboxylase. A monoclonal antibody to GABA and, for comparison, polyclonal antibodies to GABA and glutamic acid decarboxylase were used for this purpose. In both anterior and posterior piriform cortex, the highest number and density of GABA-immunoreactive cells was found in layer II. Lower density of GABAergic cells was found in layers I and III and the subjacent endopiriform cortex. When cells were quantified in 19 corresponding sections of the piriform cortex, covering most of anterior-posterior extension of this region, there appeared to be an increased density of GABAergic neurons in sections near to or within the transition zone between anterior and posterior piriform cortex. A more detailed analysis at 4 section levels in the anterior and posterior piriform cortex and the transition zone between the 2 parts substantiated a significantly higher density of GABAergic neurons in the transition zone, which was predominantly due to increased numbers of cells in lavers II and III. We propose that the transition zone between anterior and posterior piriform cortex is a location where numerous GABAergic interneurons regulate the activity of neighbouring deep pyramidal cells which receive dense excitatory input from both the olfactory bulb and distant pyramidal cells in the more anterior and posterior parts of the piriform cortex at the same time, thus increasing the risk of paroxysmal activation within this restricted area. This proposal is in line with recent observations of increased susceptibility to epileptiform activation and to kindling-induced neurochemical alterations within the transition zone between anterior and posterior piriform cortex. (C) 1998 Elsevier Science B.V. All rights reserved.