Romijn H J, Sluiter A A, Pool C W, Wortel J, Buijs R M
Netherlands Institute for Brain Research, Amsterdam.
Eur J Neurosci. 1997 Dec;9(12):2613-23. doi: 10.1111/j.1460-9568.1997.tb01691.x.
The rat suprachiasmatic nucleus (SCN) consists of several classes of neurons which can be identified by their transmitter content. Knowledge of putative interaction between these different cell types is essential in order to understand the possibilities of information processing within the SCN. The aim of the present study was therefore to obtain more information about the mutual innervation between the main cell classes in the rat SCN, viz. those containing the neuropeptides arginine vasopressin (AVP), vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI), gastrin-releasing peptide (GRP) and somatostatin respectively. For this purpose, vibratome sections were double-immunolabelled for seven different peptide combinations and subsequently analysed by high-resolution confocal laser scanning fluorescence microscopy. Attention was focused on axosomatic appositions, the occurrence and frequency of which were quantitatively estimated. Our analysis of double-immunolabelled sections demonstrated that some of the VIP- and some of the GRP-immunoreactive nerve cells and endings showed colocalization. Assuming, on the basis of literature data, that VIP and PHI are always colocalized at the cellular level, the five main cell classes in the SCN appeared to be interconnected, at least axosomatically, in the following reciprocal way: AVP <--> VIP/PHI, AVP <--> GRP, AVP <--> somatostatin, somatostatin <--> VIP/PHI, somatostatin <--> GRP, VIP/PHI <--> GRP, VIP/PHI/GRP <--> GRP, VIP/PHI/GRP <--> VIP/ PHI. In addition to this heterologous axosomatic innervation, these cell groups also showed substantial homologous innervation. Supported by electron microscope data from the literature showing the existence of axodendritic synapses for some of these peptide combinations, our findings strongly suggest that the rat SCN comprises a complex synaptic network with strong interactive capabilities, which is probably a requisite for its biological clock function.
大鼠视交叉上核（SCN）由几类神经元组成，这些神经元可通过其递质含量来识别。了解这些不同细胞类型之间可能存在的相互作用对于理解SCN内信息处理的可能性至关重要。因此，本研究的目的是获取更多关于大鼠SCN中主要细胞类群之间相互神经支配的信息，即分别含有神经肽精氨酸加压素（AVP）、血管活性肠肽（VIP）、肽组氨酸异亮氨酸（PHI）、胃泌素释放肽（GRP）和生长抑素的细胞类群。为此，使用振动切片机对切片进行了七种不同肽组合的双重免疫标记，随后通过高分辨率共聚焦激光扫描荧光显微镜进行分析。研究重点关注轴体突触，对其出现情况和频率进行了定量估计。我们对双重免疫标记切片的分析表明，一些VIP免疫反应性神经细胞和终末以及一些GRP免疫反应性神经细胞和终末显示出共定位。根据文献数据假设VIP和PHI在细胞水平上总是共定位，SCN中的五个主要细胞类群似乎至少在轴体水平上以以下相互方式相互连接：AVP <--> VIP/PHI，AVP <--> GRP，AVP <--> 生长抑素，生长抑素 <--> VIP/PHI，生长抑素 <--> GRP，VIP/PHI <--> GRP，VIP/PHI/GRP <--> GRP，VIP/PHI/GRP <--> VIP/PHI。除了这种异源性轴体神经支配外，这些细胞群还显示出大量的同源性神经支配。文献中的电子显微镜数据表明这些肽组合中的一些存在轴树突触，我们的研究结果强烈表明大鼠SCN包含一个具有强大相互作用能力的复杂突触网络，这可能是其生物钟功能的必要条件。
