5HT PRESYNAPTIC INHIBITION OF RETINAL INPUT TO THE SCN

描述(申请人摘要)：这项研究的目的是提供一个 对复杂的神经底物的理解 昼夜节律振荡器位于下丘脑视交叉上核(SCN)， 它就像我们的生物钟。增加对功能的了解 下丘脑和昼夜节律系统的组织与 主要公共卫生问题，如睡眠障碍、睡眠中断(如 时差或倒班)，以及严重的情感障碍。光学信息 对于SCN生物钟的日常重置是必不可少的 通过视网膜下丘脑束从视网膜直接进入SCN。南华早报 也接受来自中脑中缝的密集的5-羟色胺能神经支配 和来自膝间小叶(IGL)的附加传入。在最近 多年来，多种5-羟色胺(5-羟色胺)受体亚型已被描述并 分成几个家族：5-HT1-5-HT7。在这份提案中，我们将测试 5-HT1B受体位于免疫球蛋白终末的假说 SCN内的传入和5-HT7受体存在于SCN神经元上。 脊髓核内的GABA能终末。此外，我们将检验这一假设 5-HT1B受体不位于视网膜神经节细胞亚群上 将轴突分支发送到SCN和IGL。电子显微镜 免疫细胞化学技术将被用来检验5-HT1B SCN内IGL终末上有突触前受体，5-HT7受体 位于SCN的神经元上和突触前的GABA终末上。在……里面 将使用原位杂交来检验IGL神经元表达的假设 5-HT1B受体基因。利用全细胞膜片钳技术，我们将测试 5-HT7受体激动剂抑制视神经刺激诱发的假说 野生型和5-HTlA受体基因敲除SCN神经元中的EPSCs 这些激动剂通过抑制小鼠脊髓核内GABA的释放 突触前机制。昼夜节律的行为药理学分析 轮子跑的活动将被用来补充体外分析。这个 行为、药理、形态和电生理的应用 方法将提供5-羟色胺受体亚型的综合分析 在SCN中的功能以及在SCN的传入上调节时钟功能。

DESCRIPTION (applicant's abstract): The goal of this research is to furnish an understanding of the complex neural substrates underlying the regulation of the circadian oscillator located in the hypothalamic suprachiasmatic nucleus (SCN), which functions as our biological clock. Increased knowledge of the functional organization of the hypothalamus and the circadian timing system is relevant to major public health concerns such as sleep disorders, sleep disruption (as in jet lag or shift work), and serious affective disorders. Photic information essential for the daily resetting of the SCN circadian clock is conveyed directly to the SCN from the retina via the retinohypothalamic tract. The SCN also receives a dense serotonergic innervation arising from the midbrain raphe and additional afferents from the intergeniculate leaflet (IGL). In recent years, multiple serotonin (5-HT) receptor subtypes have been described and grouped into several families: 5-HT1 - 5-HT7. In this proposal, we will test the hypotheses that 5-HT1B receptors are located on the terminals of IGL afferents in the SCN and that 5-HT7 receptors are present on SCN neurons and on GABAergic terminals in the SCN. Moreover, we will test the hypothesis that 5-HT1B receptors are not located on a subset of retinal ganglion cells that send axonal branches to the SCN and IGL. Electron microscopic immunocytochemical techniques will be used to test the hypotheses that 5-HT1B receptors are presynaptic on IGL terminals in the SCN and that 5-HT7 receptors are located on neurons and presynaptically on GABA terminals in the SCN. In situ hybridization will be used to test the hypothesis that IGL neurons express 5-HT1B receptor mRNA. Using whole-cell patch-clamp techniques, we will test the hypothesis that 5-HT7 receptor agonists inhibit optic nerve stimulation-evoked EPSCs in SCN neurons in vitro in wild-type and in 5-HTlA receptor knock-out mice and that these same agonists inhibit GABA release in the SCN via a presynaptic mechanism. Behavioral pharmacological analyses of circadian wheel-running activity will be used to complement the in vitro analysis. The use of behavioral, pharmacological, morphological, and electrophysiological approaches will provide an integrated analysis of 5-HT receptor subtype function in the SCN and on afferents to the SCN that regulate clock function.