Mick G, Maeno H, Kiyama H, Tohyama M
INSERM Unité 94, Bron, France.
Brain Res Mol Brain Res. 1994 Jan;21(1-2):157-61. doi: 10.1016/0169-328x(94)90388-3.
Neurons expressing the substance P (SP) receptor (NK1 receptor) in the suprachiasmatic nucleus of the hypothalamus (SCN) have been topographically identified using radioactive in situ hybridization histochemistry. In the anterior hypothalamic area, clustered labeled neurons of small size and exhibiting low levels of gene expression are observed exclusively at the dorsolateral margin of the SCN, straddling cytoarchitectural boundaries of the nucleus. The marginal topography of neurons putative target of a SP-containing retinal input to the ventral SCN indicates that their dendrites bearing the receptor extend towards the retinorecipient part of the nucleus, where they can be modulated by overlapping inputs from the intergeniculate leaflet and the raphe. Eventual interactions between glutamatergic and putative tachykininergic retinal pathways for a coherent photic control of circadian rhythms may therefore occur mainly via intrinsic neuronal connections between their distinct target populations. In addition, since glutamate and SP induce electrophysiological responses in ventrolateral neurons with no interactive effect, neurons integrating both chemical signals, subsequently to their modulation by several influences, may be not located within the ventrolateral SCN. Alternatively but not exclusively, marginal neurons could be a target of SP-containing neurons within the SCN or nearby the nucleus, or from ascending projections from the raphé where serotonin and SP colocalize. The marginal topography of neurons expressing the SP receptor supports the view of the involvement of neurons located in the vicinity of the nucleus in the regulation of circadian rhythms.
利用放射性原位杂交组织化学技术，已在地形学上鉴定出下丘脑视交叉上核（SCN）中表达P物质（SP）受体（NK1受体）的神经元。在前下丘脑区域，仅在SCN的背外侧边缘观察到成簇的、小尺寸且基因表达水平低的标记神经元，跨越该核的细胞构筑边界。向腹侧SCN输入含SP的视网膜输入的假定目标神经元的边缘地形表明，其带有受体的树突向该核的视网膜接受部分延伸，在那里它们可受到来自膝间小叶和中缝的重叠输入的调节。因此，谷氨酸能和假定的速激肽能视网膜通路之间最终的相互作用，以实现对昼夜节律的连贯光控，可能主要通过其不同目标群体之间的内在神经元连接发生。此外，由于谷氨酸和SP在腹外侧神经元中诱导电生理反应且无交互作用，整合这两种化学信号的神经元，在受到多种影响调节之后，可能并不位于腹外侧SCN内。或者但不仅限于此，边缘神经元可能是SCN内或该核附近含SP神经元的目标，或者是来自5-羟色胺和SP共定位的中缝的上行投射的目标。表达SP受体的神经元的边缘地形支持了位于该核附近的神经元参与昼夜节律调节的观点。
