PHYSIOLOGICAL SUBSTRATES OF A CIRCADIAN OSCILLATOR

下丘脑的视交叉上核（SCN）是内源性的 振荡器，在生成中起着明确的关键作用， 以及生理学的每日（昼夜）振荡的夹带， 哺乳动物的新陈代谢和行为。我们广泛的研究目标是 了解分子，细胞和神经生理机制， SCN保持24小时。拟研究的模式物种是 大鼠SCN起搏器在下丘脑脑切片中完整存活 在那里可以进行旨在解剖细胞的实验， 机制等我们的方法学方法将脑切片培养与 传统的神经生理学技术， 神经元活动节律和生化分析， 核苷酸水平、酶活性和磷酸化的蛋白质。 目前的建议自然地从我们的发现发展而来， 通过影响环磷酸腺苷的治疗可以重置大脑切片的节律，或者 cGMP途径。此外，起搏器基底正在改变， 在供体的日子里，cAMP和cGMP或高K+（o） 在捐赠者之夜我们的具体目标包括：A）更充分地 探讨cAMP在SCN功能中的作用）（通过检测cAMP水平 SCN内的作用，调节cAMP的酶的活性， 褪黑激素对cAMP作用的调节，cAMP的参与 刺激磷酸化的相移，并参与新的 cAMP刺激中的蛋白质合成）; B）检查 cGMP类似物在夜间的作用（通过检查cGMP的特异性 刺激，去极化刺激对cGMP水平的影响，以及 确定蛋白激酶抑制剂在夜间是否有效）; 和C）鉴定SCN潜在的其他第二信使途径 起搏器（通过探索潜在的，可能是相互作用的，Ca++ 和磷脂代谢物）。因为SCN整合了大多数昼夜节律 行为和代谢变化，这项研究具有基本的相关性， 了解许多大脑和代谢功能障碍，包括某些 各种形式的精神疾病。

The suprachiasmatic muclei (SCN) of the hypothalamus are endogenous oscillators that serve a well-defined, critical role in the generation and entrainment of the daily (circadian) oscillations of physiology, metabolism and behavior of mammals. Our broad research objective is to understand the molecular, cellular and neurophysiological mechanisms by which the SCN keep 24 hr time. The model species to be studied is the rat. The SCN pacemaker survives intact in the hypothalamic brain slice where it is accessible to experiments aimed at dissecting cellular mechanisms. Our methodological approach combines brain slice culture with conventional neurophysiological techniques that measure the circadian rhythm of neuronal activity nd biochemical analyses that measure cyclic nucleotide levels, enzyme activities and proteins phosphorylated. The present proposal develops naturally from our finding that the SCN rhythm can be reset in the brain slice by treatments affecting cAMP or cGMP pathways. Further, the pacemaker substrates are changing so that the rhythm is reset by cAMP in the donor's days, and by cGMP or high K+(o) during the donor's night. Our specific aims include: A) to more fully explore the role of cAMP in SCN function )(by examining the level of cAMP action within the SCN, the activity of enzymes regulating cAMP, regulation of the cAMP effect by melatonin, the involvement of cAMP stimulated phosphorylation in phase-shifting, and the involvement of new protein synthesis in cAMP stimulation); B) to examine the nature of the effect of cGMP analogs at night (by examining the specificity of cGMP stimulation, the effect of depolarizing stimuli on cGMP levels, and determining whether protein kinase inhibitors are effective at night); and C) to identify other second messenger pathways underlying the SCN pacemaker (by exploring potential, possibly interactive, roles for Ca++ and phospholipid metabolites). Because the SCN integrates most circadian behaviors and metabolic changes, this Study has basic relevance to understanding many brain and metabolic dysfunctions, including certain forms of mental illness.