Depolarization-secretion coupling

去极化-分泌耦合

• 批准号: 9247876
• 负责人: JOSE R LEMOS
• 金额: $ 38.14万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9247876
• 关键词: ATP Receptors; Action Potentials; Adenosine; Adult; Affect; Aggressive behavior; Alzheimer' s Disease; Autistic Disorder; Biological Assay; Birth; Buffers; Calcium; Calcium Channel; Coupling; Disease; Drug Addiction; Dyes; Electric Capacitance; Electric Stimulation; Feedback; Frequencies; GPR39 gene; Genetic; Goals; Hypothalamic structure; Image; In Situ; In Vitro; Ion Channel; Knock-out; Measurement; Mediating; Memory Loss; Molecular; Monitor; Mus; Nerve; Neuraxis; Neurons; Neuropeptides; Neurosecretory Granule; Oxytocin; Pattern; Peptides; Perfusion; Pharmaceutical Preparations; Phase; Physiological; Posterior Pituitary Gland; Preparation; Purines; Purinoceptor; Rattus; Regulation; Research; Role; Site; Social Behavior; Synapses; Synaptic Vesicles; Synaptic plasticity; System; Therapeutic; Transgenic Animals; Vasopressins; Zinc; autocrine; biophysical properties; controlled release; fluorescence imaging; magnocellular; neurotransmission; novel; paracrine; patch clamp; public health relevance; receptor; suckling; tool; voltage

 DESCRIPTION (provided by applicant): Depolarization-secretion coupling is thought to occur via electrical activity leading to the entry of calcium and the subsequent secretion of transmitters. The molecular details of how such patterns of activity control the release of neuropeptides from nerve terminals in the intact central nervous system (CNS), however, remain undetermined. Vasopressin (AVP) and oxytocin (OT) are synthesized by magnocellular neurons of the hypothalamus and secreted from neurohypophysial (NH) terminals; together they comprise the Hypothalamic-Neurohypophysial System (HNS). OT neurons are characterized by a high frequency discharge during suckling or parturition which leads to the pulsatile release of OT. AVP neurons are characterized by their asynchronous phasic activity during maintained AVP release. In both cases, it is the clustering of spikes (bursting) which facilitates neuropeptid release. We have discovered that there are different calcium-channel subtypes in AVP vs. OT terminals, but that their biophysical properties alone cannot explain the differential facilitationof release by such burst patterns. Conversely, we have demonstrated that autocrine/paracrine purinergic feedback effects help determine the efficacy of different bursting patterns of electrica activity in facilitating release of AVP vs. OT. Along with ATP, Zinc is also co-released with the HNS peptides. Zn2+ interacts with many effectors on neurons, leading to a variety of effects. It is not known, however, at what specific sites these effects occur at synapses in the CNS. The HNS now affords the unique opportunity of unraveling the complicated effects of endogenous Zinc in the CNS by comparing such effects on isolated terminals vs. the intact, whole system. The goal of the research proposed here is to determine molecular mechanisms that mediate endogenous Zinc-induced facilitation of neuropeptide secretion during physiological patterns of electrical stimulation. To achieve these objectives, recordings of ATP- and calcium-currents will be made from identified (as AVP vs. OT), isolated nerve terminals vs. intact preparations of the HNS of adult rats and mice. Selective fluorescent-indicator dyes will monitor intracellular Ca2+ and Zn2+ changes in NH terminals. Effects on neuropeptide release will be compared between the intact HNS and isolated NH terminals by the use of well-defined in vitro perfusion assays and capacitance measurements. This proposal takes advantages of newly available genetic tools that facilitate the elucidation of the function of novel Zinc receptors with greater specificty than is possible with traditional antagonist drugs. These receptor knockout studies will provide a unique opportunity to determine if endogenous Zinc feedback regulation occurs at the terminals of CNS neurons. Furthermore, since synaptic vesicles/neurosecretory granules appear to contain ATP and Zn2+, these feedback mechanisms could be physiologically important at many other synapses in the CNS.

 描述（通过应用程序提供）：认为通过电活动导致钙进入和随后的发射机分泌，可以认为去极化 - 分泌耦合。但是，这种活性模式如何控制完整中枢神经系统（CNS）中神经终末神经肽的释放的分子细节仍未确定。血管加压素（AVP）和氧加毒素（OT）由下丘脑的大细胞神经元合成，并从神经型物理（NH）末端分泌；它们共同组成下丘脑 - 神经型物理系统（HNS）。 OT神经元的特征是在哺乳或分娩期间高频排出，这导致OT的脉动释放。 AVP神经元的特征是它们在维持的AVP释放过程中的异步阶段活性。在这两种情况下，神经肽释放的设施是尖峰（爆发）的聚类。我们已经发现，AVP与OT终端有不同的钙通道亚型，但是仅它们的生物物理特性无法解释这种爆发模式释放的差异设施。相反，我们已经证明了自分泌/旁分泌嘌呤能反馈效应有助于确定电动活动不同爆发模式在开发AVP和OT释放中的有效性。与ATP一起，锌还与HNS Pepperides共同发行。 Zn2+与对神经元的许多影响相互作用，从而导致各种作用。但是，在中枢神经系统中突触时，这些效果发生在哪些特定位置。 HNS现在提供了独特的机会，可以通过比较对孤立终端与完整的整体系统进行这种影响，从而揭示中枢神经系统中内源性锌的复杂作用。这里提出的研究的目的是确定在电刺激物理模式下介导内源性锌诱导的神经肽分泌的促进的分子机制。为了实现这些目标，将通过识别（作为AVP与OT），孤立的神经末端与成年大鼠和小鼠的HNS的完整制剂制定ATP和钙 - 电流的记录。选择性荧光指示剂染料将监测NH末端中的细胞内Ca2+和Zn2+变化。通过使用明确定义的体外灌注分析和电容测量，将比较完整的HN和分离的NH末端对神经肽释放的影响。该建议利用了新近可用的遗传工具，这些工具促进了具有比传统拮抗剂药物更特异性的新型锌受体功能。这些受体敲除研究将为确定内源性锌反馈调节是否发生在CNS神经元的末端。此外，由于突触蔬菜/神经分泌颗粒似乎包含ATP和Zn2+，因此这些反馈机制在CNS中的许多其他突触中可能在物理上很重要。