Mechanism of biological clock in mammals: Analysis of regulatory mechanism of

我们在大鼠脑中发现了一种具有36个氨基酸残基的新型神经肽，作为孤儿G蛋白偶联受体mf -4/TGR-1的内源性配体，该受体迄今已被鉴定为神经质U （NMU）受体，并将该肽命名为“神经质S （NMS）”，因为它在下丘脑视交叉上核（SCN）中特异性表达。我们研究了NMU和NMS在生物节律中的作用。NMU mRNA的表达具有昼夜节律性，在CT4-8 h时在SCN中达到峰值。NMU和NMS的两个NMU结合受体（NMU- r1和NMU- r2）也在SCN脑室内注射（ICV）中表达，诱导SCN细胞中Fos蛋白的表达，并引起昼夜运动活动节律的相依赖相移。这种nmu和nms诱导的相移是非光型的。定量逆转录聚合酶链反应（RT-PCR）分析显示，SCN中c-fos、NGFI-A、NGFI-B和JunB等早期基因的表达增加。此外，ICV注射NMU增加了SCN中Per1的表达，但没有增加Per2的表达。这些结果表明，NMU和NMS可能在SCN中发挥自分泌或旁分泌作用，在昼夜节律振荡器中发挥重要作用。

We identified a novel neuropeptide of 36 amino-acid residues in rat brain as an endogenous ligand for the orphan G protein-coupled receptor FM-4/TGR-1, which was identified to date as the neuromedin U (NMU) receptor, and designate this peptide 'neuromedin S (NMS)' because it is specifically expressed in the suprachiasmatic nuclei (SCN) of the hypothalamus. We examined the role of NMU and NMS on the biological rhythm. The expression of NMU mRNA exhibited a circadian rhythm, with the peak expression in the SCN occurring at CT4-8 h. The two NMU-binding receptors (NMU-R1 and NMU-R2) were also expressed in the SCN Intracerebroventricular injection (ICV) of NMU and NMS induced the expression of Fos protein in the SCN cells and caused a phase-dependent phase shift of the circadian loco motor activity rhythm. This NMU-and NMS-induced phase shift was of the nonphotic type. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed increases in the expression in the SCN of immediate early genes, such as c-fos, NGFI-A, NGFI-B, and JunB. Furthermore, ICV injection of NMU increased the expression of Per1, but not Per2 in the SCN. These results indicate that NMU and NMS may play some important role in the circadian oscillator by exerting an autocrine or paracrine action in the SCN.