Mechanisms of circadian rhythm analyzed from transcription factor of mRNA in suprachiasmatic nucleus

哺乳动物的昼夜节律是由下丘脑视交叉上核（SCN）中的起搏器调节的。含有多种多肽的SCN。含argvasressin （AVP）的神经元是SCN向其他脑区输出昼夜节律信号的神经元之一。对于起搏器的牵引机制，血管活性肠肽（vasoactive intestinal peptide， VIP）、胃泌素释放肽被认为与之有关。而这些肽对AVP释放的作用是相互的；即我们发现VIP增加AVP的释放，而胃泌素释放肽降低AVP的释放。通过在一天中使用差异显示PCR发现了许多scn特异性mRNA。然而，只有少数产品出现在CT 20-23。主观白天SCN中AVP肽高于夜间。需要在单个动物中分析SCN中AVPmRNA的定性分析，以比较肽水平和其他昼夜节律指数。采用RT-PCR方法，结合特异性引物，对同一只大鼠两孔SCN中提取的AVPmRNA水平进行检测。PCR产物强度的昼夜变化模式与Northern blot分析结果相似。这些昼夜变化在持续的昏暗光照下自由运行，直到第21天。我们发现SCN（含有旁细胞AVP的神经元）和视上核（magunocellular）对GABA和皮质酮/地塞米松的不同反应。视网膜的光刺激诱导scn细胞c-fos的发育，c-fos的发育与相反应和其他昼夜节律指标相关。我们有理由推测，AVP编码基因可能在5′启动子区上游含有IEG （c-fos）结合位点。虽然，AVP编码DNA没有从视上核或其他脑区获得的基因组测序的AP-1结合位点。我们正在寻找编码源自SCN的AVPmRNA的特定基因组。

Mammalian circadian rhythm is regulated by a pacemaker in the suprachiasmatic nuclei (SCN) of hypothalamus. The SCN containing variety of peptides. Argvasopressin (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.e.we found that the VIP increased AVP release, while gastrin-releasing peptide decreased AVP release. Many SCN-specific mRNA from are found by using differential display PCR throughout a day. However, a few products appeared only at CT 20-23. AVP peptide in SCN is higher in subjective day than in night. The qualitative assay of AVPmRNA in SCN is desired to be analyzed in individual animals to compare the peptide levels and other circadian index. We could detect the AVPmRNA levels extracted from two punches of SCN in one rat by using RT-PCR with specific primers. The pattern of day-night variations in PCR product-intensity are similar with that analyzed by Northern blot. These day-night variations were free-run until 21st day under the constant dim light. We find the differential responses in SCN (parvocellular AVP containing neuron) and supraoptic nucleus (magunocellular) against to GABA and corticosterone/dexamethasone. Photic atimulation from retina induces c-fos development in SCN.c-fos development couples with the phase responses and other indexes of circadian rhythm. It is reasonable to speculate that the AVP coding gene might containing IEG (c-fos) binding site at the upstream of 5' promoter area. Although, the AVP coding DNA has no AP-1 binding site that was sequenced from the genome obtained from supraoptic nucleus or other brain area. We are searching the specific genome which code AVPmRNA originating from the SCN.