Retaux S, Caboche J, Rogard M, Julien J F, Penit-Soria J, Besson M J
Laboratoire de Neurochimie-Anatomie, CNRS URA 1488, Université Pierre et Marie Curie, Paris, France.
Brain Res. 1993 May 21;611(2):187-96. doi: 10.1016/0006-8993(93)90502-e.
In situ hybridization of mRNA encoding one isoform of glutamic acid decarboxylase (GAD67) was performed in the rat medial frontal cortex (MFC) to characterize GABA interneurons. Qualitatively, the labelling obtained with a [35S]cDNA probe was in register with neurons and was never associated with glial cells. No obvious differences in the density of labelled cells were observed between the different areas of the MFC examined (infralimbic, prelimbic, anterior cingulate and precentral medial) and between the various cortical layers. Grain counting was performed on single cells in the various layers of the prelimbic and the anterior cingulate area, two main areas of the MFC. According to their grain density, neurons were arbitrarily classified as low, high and very high GAD67 mRNA content. The neurons with the high GAD67 mRNA content corresponded to around 50% of the labelled cells in all the layers and in both areas. In the prelimbic area, the neuronal population with a low GAD67 mRNA content varied from 50% in layers I and II-III to 40% in layers V-VI whereas the very high GAD67 mRNA content neurons corresponded to around 5% of the labelled neurons in all layers. In the anterior cingulate area the neuronal population showing low GAD67 mRNA content varied from 35% in layers I and II-III to 20% in layers V-VI. In this area, neurons with a very high GAD67 mRNA content were more numerous than in the prelimbic area: they varied from 15% in layers I and II-III to 30% in layers V-VI. Parallel to the presence of very highly labelled cells, GAD enzymatic activity measured both in the presence and in the absence of pyridoxal 5'-phosphate was higher in the anterior cingulate area than in the prelimbic area. The heterogeneity of GAD67 mRNA content at the cellular level might underlie the existence of subpopulations of GABA interneurons in the MFC and suggests a higher GABAergic inhibitory control in the anterior cingulate area than in the prelimbic area.
为了对γ-氨基丁酸（GABA）中间神经元进行特征描述，我们在大鼠内侧前额叶皮质（MFC）中进行了编码谷氨酸脱羧酶（GAD67）一种同工型的mRNA的原位杂交。定性来看，用[35S]cDNA探针获得的标记与神经元对齐，且从未与神经胶质细胞相关联。在所检查的MFC不同区域（边缘下区、边缘前区、前扣带回和中央前内侧区）以及不同皮质层之间，未观察到标记细胞密度有明显差异。对MFC的两个主要区域即边缘前区和前扣带回区各层中的单个细胞进行了颗粒计数。根据其颗粒密度，神经元被任意分类为GAD67 mRNA含量低、高和非常高。GAD67 mRNA含量高的神经元在所有层和两个区域中约占标记细胞的50%。在边缘前区，GAD67 mRNA含量低的神经元群体在I层和II-III层中占50%，在V-VI层中占40%，而GAD67 mRNA含量非常高的神经元在所有层中约占标记神经元的5%。在前扣带回区，GAD67 mRNA含量低的神经元群体在I层和II-III层中占35%，在V-VI层中占20%。在该区域，GAD67 mRNA含量非常高的神经元比边缘前区更多：在I层和II-III层中占15%，在V-VI层中占30%。与存在标记非常高的细胞平行，在前扣带回区，无论有无磷酸吡哆醛5'-磷酸时测得的GAD酶活性均高于边缘前区。GAD67 mRNA含量在细胞水平的异质性可能是MFC中GABA中间神经元亚群存在的基础，并表明前扣带回区比边缘前区具有更高的GABA能抑制控制。
