Hajos N, Acsady L, Freund T F
Institute of Experimental Medicine, Hungarian Academy of Science, Budapest, POB 67, H-1450, Hungary.
Eur J Neurosci. 1996 Jul;8(7):1415-31. doi: 10.1111/j.1460-9568.1996.tb01604.x.
Vasoactive intestinal polypeptide (VIP) has been shown to be present in a morphologically heterogeneous subpopulation of interneurons in the dentate gyrus, but the relationship between their input and output characteristics and neurochemical features has not been established. Three types of VIP-immunoreactive cells have been identified on the basis of these criteria: (i) cells forming a dense axonal plexus in the hilus have always coexisted with the calcium binding protein calretinin (CR), but never with the neuropeptide cholecystokinin (CCK). The postsynaptic targets of these VIP-positive cells were neurons visualized by immunostaining for substance P receptor, which is known to label different hilar non-principal cells. (ii) VIP-immunoreactive basket cells, innervating predominantly the somata and proximal dendrites of granule cells, were found in the striatum moleculare and stratum granulosum. They contained CCK, but not CR. (iii) Cells projecting to the stratum moleculare were found to have dendrites and axons restricted to this layer. In 75% of these cells VIP coexisted with CR but not with CCK, and they established multiple contacts largely with non-principal cells. GABA was shown to be present but the calcium-binding proteins calbindin D28K and parvalbumin were absent in all three types of VIP-containing interneuron. On the basis of these observations we conclude that three different types of VIP-positive neuron are present in this area, and are likely to subserve different inhibitory functions, cells with a hilar projection as well as those projecting to the stratum moleculare may synchronize the activity of hilar and other interneurons, or disinhibit granule cells by specific interneuron-to-interneuron connections. In contrast, basket cells control the activity of granule cells directly, via perisomatic inhibition.
血管活性肠肽（VIP）已被证明存在于齿状回中间神经元形态学异质性亚群中，但其输入和输出特征与神经化学特征之间的关系尚未明确。基于这些标准，已鉴定出三种类型的VIP免疫反应性细胞：（i）在齿状回门区形成密集轴突丛的细胞总是与钙结合蛋白钙视网膜蛋白（CR）共存，但从不与神经肽胆囊收缩素（CCK）共存。这些VIP阳性细胞的突触后靶点是通过对P物质受体进行免疫染色而可视化的神经元，已知该受体可标记不同的门区非主要细胞。（ii）VIP免疫反应性篮状细胞主要支配颗粒细胞的胞体和近端树突，见于分子层和颗粒层。它们含有CCK，但不含CR。（iii）投射到分子层的细胞的树突和轴突局限于该层。在这些细胞中，75%的细胞VIP与CR共存，但不与CCK共存，并且它们主要与非主要细胞建立多个接触。已证明所有三种类型的含VIP中间神经元中都存在GABA，但不存在钙结合蛋白钙结合蛋白D28K和小白蛋白。基于这些观察结果，我们得出结论，该区域存在三种不同类型的VIP阳性神经元，可能发挥不同的抑制功能，具有门区投射的细胞以及投射到分子层的细胞可能通过特定的中间神经元到中间神经元的连接来同步门区和其他中间神经元的活动，或解除对颗粒细胞的抑制。相比之下，篮状细胞通过胞体周围抑制直接控制颗粒细胞的活动。
