Hornung J P, Celio M R
Institute of Anatomy, Faculty of Medicine, University of Lausanne, Switzerland.
J Comp Neurol. 1992 Jun 22;320(4):457-67. doi: 10.1002/cne.903200404.
The serotoninergic input to the mammalian cerebral cortex originates in the median and the dorsal raphe nuclei. Median raphe neurons have been previously shown to give rise to beaded varicose axons which form dense pericellular arrays (baskets) surrounding the soma and the proximal dendrites of certain cortical neurons. In the present study, we have searched for specific markers characterizing the neurons of the marmoset neocortex and hippocampus surrounded by these thick varicose serotonin-containing fibers. The non-pyramidal nature of these neurons, suggested by their dendritic arborization, was correlated, in immunocytochemical experiments with double-labelling to demonstrate their surrounding serotonin-containing basket and their content of glutamic acid decarboxylase (GAD) or of the calcium-binding protein calbindin. Another calcium-binding protein common in numerous non-pyramidal cortical neurons, parvalbumin, was never found in neurons surrounded by serotonin-containing baskets. This organization was found in all areas of the neocortex and of the hippocampus where serotonin-containing baskets were present. One of the serotoninergic cortical inputs which originates from the brainstem tegmentum, traditionally described as "diffuse," proves to be highly selective in that a subset of its axons terminates preferentially on a subpopulation of inhibitory interneurons of the cerebral cortex. It may be emphasized that this subset of cortical interneurons has now been shown to be characterized not only by its axonal and dendritic arborization and its neurotransmitter, but also by a specific type of input which can modulate cortical function in a unique manner.
哺乳动物大脑皮层的5-羟色胺能输入起源于中缝核和背侧中缝核。先前已表明，中缝核神经元可产生串珠状曲张轴突，这些轴突形成密集的细胞周阵列（篮状结构），围绕某些皮层神经元的胞体和近端树突。在本研究中，我们寻找了特异性标记物，以表征被这些粗大的含5-羟色胺曲张纤维所包围的狨猴新皮层和海马体神经元。通过免疫细胞化学实验中的双重标记，将这些神经元的非锥体性质（由其树突分支所暗示）与它们周围含5-羟色胺的篮状结构以及它们所含的谷氨酸脱羧酶（GAD）或钙结合蛋白钙结合蛋白的含量相关联。另一种在众多非锥体皮层神经元中常见的钙结合蛋白小白蛋白，在被含5-羟色胺篮状结构包围的神经元中从未发现。在存在含5-羟色胺篮状结构的新皮层和海马体的所有区域都发现了这种组织结构。传统上被描述为“弥散性”的源自脑干被盖的一种5-羟色胺能皮层输入，结果证明具有高度选择性，因为其一部分轴突优先终止于大脑皮层抑制性中间神经元的一个亚群上。需要强调的是，现已表明，这一皮层中间神经元亚群不仅以其轴突和树突分支以及神经递质为特征，而且还具有一种特定类型的输入，这种输入能够以独特的方式调节皮层功能。
