CALRETININ IS PRESENT IN NONPYRAMIDAL CELLS OF THE RAT HIPPOCAMPUS .1. A NEW TYPE OF NEURON SPECIFICALLY ASSOCIATED WITH THE MOSSY FIBER SYSTEM
CALRETININ IS PRESENT IN NONPYRAMIDAL CELLS OF THE RAT HIPPOCAMPUS .1. A NEW TYPE OF NEURON SPECIFICALLY ASSOCIATED WITH THE MOSSY FIBER SYSTEM
复制标题
DOI：
10.1016/0306-4522(92)90334-x
复制
发表时间：
1992-05-01
期刊：
影响因子：
3.3
通讯作者：
FREUND, TF
中科院分区：
文献类型：
--
作者：
GULYAS, AI;MIETTINEN, R;FREUND, TF
用免疫细胞化学方法显示大鼠背侧海马结构内含Calretinin细胞。Calretinin免疫反应仅见于齿状回各层和CA1-3区的非锥体细胞。Calretinin阳性神经元和突起在齿状回的门区和CA3区的透明层最为丰富。在海马裂内有几个Calretinin免疫反应细胞。在颗粒细胞层的浅层和分子层的最低层有一条明显的钙维A免疫反应纤维带。近距离观察钙维A阳性细胞发现它们形成了两个不同的细胞群。其中一组细胞仅见于CA3区的透明层和齿状回的门部，上面覆盖着大量的棘细胞。它们的体细胞和树突仅局限于透明层和门部。另一组细胞具有光滑的、常呈静脉曲张的放射状树突，分布于海马体的所有区域和各层。2~3个粗大的初级树突从形状不规则的棘细胞胞体中长出，向远端(70-100亩-m)发出细小的次级分支，在那里形成一个丰富的网络。广泛的树状树状细胞在透明层内水平分布，横径和间隔距离均为400-600亩。这些细胞及其突起的特定层位表明，它们的大部分输入可能来自苔藓纤维。这一假设已被电子显微镜检查所证实。大量的非对称性突触覆盖于胞体、树突和细胞的棘突(4~6个突触/棘突)。突触大部分由突触形成，具有苔藓纤维终末的特征。3~6个初级树突由无棘细胞的多极、两极或锥体组成，比棘细胞的体细胞小。光滑且经常出现静脉曲张的树突向近端分支，主要呈放射状分布。树突通过几层向上或向下移动，接受非对称性和对称性突触。在CA1亚区，垂直排列的树突与其他无钙蛋白免疫反应的树突或胞体频繁接触。电子显微镜下可见2~3个Calretinin免疫反应阳性的树突附着超过100个或偶尔200个单位，其间可见多个点状粘连。这些细胞的轴突在各层均呈树枝状分布，有小的突起走行，并与树突建立对称性突触。综上所述，无脊钙维A免疫反应细胞在光镜和电子显微镜水平上都具有GABA能中间神经元的特征，颗粒细胞层浅层致密的钙维A免疫反应纤维网络的轴突终末与可能的颗粒细胞的树突和棘突形成突触。突触的特征性位置和特征，即突触后非常厚和密集的特化，表明这些纤维来自乳头上核，而不是来自海马区的Calretinin免疫反应神经元。
Calretinin-containing cells were visualized with immunocytochemistry in the rat dorsal hippocampal formation. Calretinin immunoreactivity was present exclusively in non-pyramidal cells in all layers of the dentate gyrus and the CA1-3 areas. Calretinin-positive neurons and processes were most abundant in the hilus of the dentate gyrus and in the stratum lucidum of the CA3 region. Several calretinin-immunoreactive cells were located within the hippocampal fissure. A distinct band of calretinin-immunoreactive fibres occupied the superficial part of the granule cell layer and the lowest part of the molecular layer.Closer examination of the calretinin-positive cells revealed that they formed two distinct cell groups. One group of cells, found exclusively in the stratum lucidum of the CA3 area and in the hilus of the dentate gyrus, was covered with numerous spines. Their somata and dendrites were restricted to stratum lucidum and to the hilus. Cells of the other group had smooth, often varicose, radially running dendrites, and were present in all areas and layers of the hippocampal formation.Two to three thick primary dendrites arose from the irregularly shaped cell body of spiny cells and emitted fine secondary branches only distally (70-100-mu-m) from the soma, where they formed a profuse network. The extensive dendritic tree of the cells spread horizontally within stratum lucidum and span a distance of 400-600-mu-m both in the septotemporal and in the transverse directions. The layer-specific location of these cells and their processes suggested that the majority of their input may derive from mossy fibres. This presumption has been confirmed by electron microscopic examination. A large number of asymmetrical synapses were found to cover the soma, the dendritic shafts and the spines (four to six synapses/spine) of the cells. A large proportion of the synapses were formed by boutons, which showed the distinctive features of mossy fibre terminals.Three to six primary dendrites arose from the multipolar, bipolar or pyramidal-shaped somata of spine-free cells, which were smaller than the somata of spiny cells. The smooth and frequently varicose dendrites branched proximally and ran primarily radially. Dendrites ascended or descended through several layers and received both asymmetrical and symmetrical synapses. In the CA1 subfield, the vertically running dendrites frequently contacted other calretinin-immunoreactive spine-free dendrites or cell bodies. Two or three calretinin-immunoreactive dendrites were often seen to be attached for over 100 or, occasionally, 200-mu-m and several puncta adherentia were observed between them using the electron microscope. The axons of the cells arborized in all layers, had small en passant varicosities, and were found to establish symmetrical synapses with dendritic shafts. In summary, spine-free calretinin-immunoreactive cells showed the characteristic features of GABAergic interneurons both at the light and the electron microscopic levels.Axon terminals of the dense calretinin-immunoreactive fibre network in the superficial part of the granule cell layer formed synapses with dendritic shafts and spines of putative granule cells. the characteristic location and features of the synapses, i.e. a very thick and dense postsynaptic specialization, suggest that these fibres derive from the supramammillary nucleus, rather than from calretinin-immunoreactive neurons in the hippocampus.