Molecular mechanisms of development of circadian rhythm in relation to transcription factor of peptide synthesis.

哺乳动物的昼夜节律由下丘脑视交叉上核(SCN)的起搏器调节。含有多种多肽的SCN。精氨酸加压素(AVP)神经元是SCN向其他脑区传递昼夜节律信号的输出神经元之一。起搏器的携带机制主要有血管活性肠肽(VIP)、胃泌素释放肽等。而这些多肽对AVP释放的作用是相互作用的，即VIP促进AVP释放，而胃泌素释放肽减少AVP释放。光信息是携带的最重要的因素，它通过含有谷氨酸的神经元传递给SCN。虽然在暗期，SCN的谷氨酸含量较高，但谷氨酸表现为暗脉冲型相位响应曲线。光脉冲诱导SCN腹外侧区谷氨酸的增加，因此，我们现在正在使用一种生物传感器来研究SCN释放谷氨酸的机制，该传感器是可连续测量的，并且对谷氨酸具有特异性。此外，几乎所有的SCN神经元都含有抑制氨基酸的GABA。GABA的释放呈现出昼夜节律，暗期高于光期。然而，GABA的功能目前还不清楚。因此，我们使用切片培养系统检测了GABA对AVP释放的影响。GABA的直接作用不明显，但GABAA受体激动剂Muscimol增加AVP水平，GABAA受体拮抗剂荷包牡丹碱减少AVP释放，而GABAB受体激动剂和/或拮抗剂没有明显作用。在从多肽转录因子分析起搏机制之前，我们利用差异显示PCR法筛选了SCN特异的mRNA。然而，少数产品只出现在CT 20-23上。我们正在分析与AP-1和cAMP水平的关系。

Mammalian circadian rhythum is regulated by a pacemaker in the suprachiasmatic nuclei (SCN) of hypothalamus. The SCN containing variety of peptides. Arg-vasopressin (AVP) containing neuron is one of the output neuron of circadian signal from the SCN to the other brain area. For the entraining mechanism of pacemaker, vasoactive intestinal peptide (VIP), gastrin-releasing peptide are considered to be concerned. While the function of these peptides on the AVP release is reciprocal ; i.s.we found that the VIP increased AVP release, while gastrin-releasing peptide decreased AVP release. Photic information is the most important factor for the entrainment, which is conveyed to SCN by glutamate containing neuron. Although the glutamate is higher in SCN during the dark period, glutamate plays dark pulse type phase response curve. Light pulse induces increment of glutamate at the ventrolateral area of SCN.So, we are examining now the mechanism of glutamate release from the SCN using a biosensor, which is continuously measurable and specific to glutamate.Beside, almost all of the SCN neuron containing GABA for an inhibitory amino-acid. GABA release shows diurnal rhythm that is higher at dark period than in light period. However the function of GABA is not clear yet. Therefore, we examined the effect of GABA on the AVP release using a slice culture system. The direct effect of GABA is not obvious, but the muscimol (GABAa-receptor agonist) increased the AVP level and bicuculline (GABAa antagonist) decreased AVP release, while the GABAb receptor agonist and/or antagonist did not show a significant effect.In preceding to analyze the pacemaking mechanism from the transcription factor of peptides, we are screening a SCN-specific, mRNA using differential display PCR.Many mRNA from SCN found to be expressed at a constant rate throughout a day. However, a few products appeared only at CT 20-23. We are analyzing the relationship with AP-1 and cAMP levels with them.