NPY INDUCED REGULATION SYMPATHETIC NEUROTRANSMISSION

NPY 诱导的交感神经传递调节

• 批准号: 2901389
• 负责人: Thomas C Westfall
• 金额: $ 27.68万
• 依托单位: SAINT LOUIS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2901389
• 关键词: PC12 cells; calcium channel; evoked potentials; laboratory rat; neural transmission; neuropeptide Y; neuropeptide receptor; neuropharmacology; neuroregulation; neurotransmitter biosynthesis; neurotransmitter transport; vascular smooth muscle nervous control; voltage /patch clamp; voltage gated channel

DESCRIPTION: (Adapted from the application) Neuropeptide Y (NPY) is known to be co-localized with norepinephrine (NE) and adenosine triphosphate (ATP) in vascular sympathetic neurons where it may play a role as a co-transmitter/co-modulator. Recent evidence has established that NPY plays a physiological role in sympathetic mediated vasoconstriction by acting on postjunctional Y1 receptors. NPY is also known to exert prejunctional effects leading to inhibition of NE, NPY and ATP release via Y2 receptors and inhibition of catecholamine (CA) synthesis via Y3 receptors. These results suggest that the process of CA synthesis and release may be differentially modulated by NPY suggesting an additional level of control in the prejunctional regulation of sympathetic neurotransmission; however, the physiological role of these actions has yet to be established. Our investigations into the mechanisms of these actions suggest that NPY receptor activation inhibits voltage-gated Ca2+ channels although direct evidence has not yet been obtained. The purpose of the present proposal is to investigate the physiological role (Aim 1 and 2) and the mechanism(s) of action (Aim 3) of the NPY-induced inhibition of CA synthesis and release. The rationale for studies proposed in Aim 1 is as follows: If NPY normally exerts an inhibitory autoregulation on transmitter release then an antagonist for the receptor in question should interrupt the feedback circuit and increase transmitter release. The prejunctional effects of both exogenously administered agonists and antagonists should vary with the biophase concentration of endogenous NPY. Furthermore, the response of the effector cell should be consistent with inhibition or stimulation of NPY release. Finally, it would seem necessary to demonstrate functional receptors in vivo as well as in vitro. A similar rationale exists for Aim 2. In Aim 1, the effect of a series of selective Y1 and Y2 agonists and antagonists will be examined on the release of NE, NPYir and sometimes ATP evoked by nerve stimulation, as well as measurements of perfusion pressure in the mesenteric arterial bed. This will be done before and after the endogenous NPY concentration is elevated by: 1) increasing the frequency of nerve stimulation or 2) decreasing the perfusion rate or after the NPY concentration has been reduced by depletion of tissue levels. The in vivo effect of agonists and antagonists will also be examined in the pithed rat preparation. In Aim 2, similar experiments will evaluate the effect of NPY analogs on the nerve stimulation evoked increase in NE synthesis as measured by DOPA accumulation after decarboxylase inhibition. In Aim 3, voltage-clamp recordings will be accomplished in NGF-differentiated PC12 cells to directly determine if activation of Y2 and Y3 receptors can decrease Ca2+ current. Whether this is mediated by inhibition of Ca2+ influx through N-type and L-type voltage activated Ca2+ channels will be assessed, as will whether inhibition of L-type Ca2+ channels also involves the action of PKC. These studies are designed to provide useful new information on the functional role and mechanism of action of NPY in the prejunctional regulation of sympathetic neurotransmission.

描述：（改编自申请）神经肽 Y (NPY) 是已知的 与去甲肾上腺素 (NE) 和三磷酸腺苷 (ATP) 共定位 在血管交感神经元中，它可能发挥作用 协同发射机/协同调制器。 最近的证据表明 NPY 发挥作用 通过作用于交感神经介导的血管收缩的生理作用 结后Y1受体。 NPY 也被认为可以发挥预结作用 通过 Y2 受体抑制 NE、NPY 和 ATP 释放的作用 以及通过 Y3 受体抑制儿茶酚胺 (CA) 合成。 这些 结果表明CA的合成和释放过程可能是 NPY 的差异调节表明额外的控制水平 交感神经传递的交界前调节；然而， 这些作用的生理作用尚未确定。 我们的 对这些作用机制的研究表明 NPY 受体激活抑制电压门控 Ca2+ 通道，尽管直接 尚未取得证据。 本提案的目的是 研究生理作用（目标 1 和 2）和机制 NPY 诱导的 CA 合成和释放抑制作用（目标 3）。 目标 1 中提出的研究的基本原理如下：如果 NPY 通常 对递质释放施加抑制性自动调节，然后 相关受体的拮抗剂应中断反馈 电路并增加发射器释放。 两者的预作用 外源性给药的激动剂和拮抗剂应随药物的不同而变化。 内源性NPY的生物相浓度。 此外，该机构的回应 效应细胞应与 NPY 的抑制或刺激一致 发布。 最后，似乎有必要证明功能性 体内和体外的受体。 Aim 也存在类似的理由 2. 在目标 1 中，一系列选择性 Y1 和 Y2 激动剂的作用和 将检查拮抗剂的 NE、NPYir 和有时 ATP 的释放情况 由神经刺激以及灌注压测量引起 在肠系膜动脉床。 这将在 内源性 NPY 浓度通过以下方式升高： 1) 增加频率 神经刺激或 2) 降低灌注速率或 NPY 之后 浓度因组织水平的消耗而降低。 体内 激动剂和拮抗剂的作用也将在髓大鼠中进行检查 准备。 在目标2中，类似的实验将评估NPY的效果 经测量，神经刺激的类似物引起 NE 合成增加 脱羧酶抑制后多巴积累。 在目标 3 中， 电压钳记录将在 NGF 分化的 PC12 中完成 细胞直接确定 Y2 和 Y3 受体的激活是否可以 减少Ca2+电流。 这是否是通过抑制 Ca2+ 介导的 通过 N 型和 L 型电压激活的 Ca2+ 通道的流入将 评估，L 型 Ca2+ 通道的抑制是否也涉及 PKC 的作用。 这些研究旨在提供有用的新 有关 NPY 的功能作用和作用机制的信息 交感神经传递的交界前调节。