Acsády L, Görcs T J, Freund T F
Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
Neuroscience. 1996 Jul;73(2):317-34. doi: 10.1016/0306-4522(95)00609-5.
The postsynaptic targets of three vasoactive intestinal polypeptide-containing GABAergic interneuron types were examined in the rat hippocampus. Two of them showed remarkable target selectivity for other GABAergic neurons, while the third contacted the somata and proximal dendrites of pyramidal cells. Vasoactive intestinal polypeptide-positive interneurons innervating the stratum oriens/alveus border in the CA1 region were shown to establish multiple contacts with horizontal GABAergic interneurons immunoreactive for type 1 metabotropic glutamate receptor. Similarly, identified axons of vasoactive intestinal polypeptide-positive interneurons projecting to stratum radiatum were found to establish symmetrical synapses largely on GABAergic dendrites. The majority of these postsynaptic GABAergic neurons were shown to contain calbindin or vasoactive intestinal polypeptide. In contrast to the first two vasoactive intestinal polypeptide-containing cell populations, vasoactive intestinal polypeptide-positive interneurons arborizing in stratum pyramidale formed baskets around pyramidal cells. These results revealed a new element in cortical microcircuits, interneurons which are specialized to innervate other GABAergic interneurons. The role of this new component may be the synchronization of dendritic inhibition, or an input-specific disinhibition of pyramidal cells in various dendritic domains. In contrast, vasoactive intestinal polypeptide-containing basket cells are likely to be involved in perisomatic inhibition of pyramidal neurons, and represents a new basket cell type different from that containing parvalbumin.
在大鼠海马体中，研究了三种含有血管活性肠肽的γ-氨基丁酸能中间神经元类型的突触后靶点。其中两种对其他γ-氨基丁酸能神经元表现出显著的靶点选择性，而第三种则与锥体细胞的胞体和近端树突相接触。在CA1区支配原层/肺泡边界的血管活性肠肽阳性中间神经元，被证明与对1型代谢型谷氨酸受体免疫反应的水平γ-氨基丁酸能中间神经元建立了多个接触点。同样，已确定的投射到辐射层的血管活性肠肽阳性中间神经元的轴突，被发现主要在γ-氨基丁酸能树突上形成对称性突触。这些突触后γ-氨基丁酸能神经元中的大多数被证明含有钙结合蛋白或血管活性肠肽。与前两个含有血管活性肠肽的细胞群体不同，在锥体层中分支的血管活性肠肽阳性中间神经元在锥体细胞周围形成篮状结构。这些结果揭示了皮质微回路中的一个新元素，即专门支配其他γ-氨基丁酸能中间神经元的中间神经元。这个新成分的作用可能是树突抑制的同步化，或对各种树突区域的锥体细胞进行输入特异性去抑制。相比之下，含有血管活性肠肽的篮状细胞可能参与锥体细胞的胞体周围抑制，并代表一种不同于含有小白蛋白的新的篮状细胞类型。
