NPY INDUCED REGULATION 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， 共发射器/共调制器。 最近的证据表明， 在交感神经介导的血管收缩中的生理作用， 连接后Y1受体。 众所周知，神经肽Y还可以发挥交界前的作用 通过Y2受体抑制NE、NPY和ATP释放 和通过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 差异调制的神经肽Y表明一个额外的控制水平， 交感神经传递的连接前调节;然而， 这些行动的生理作用尚未确定。 我们 对这些作用机制的研究表明， 受体激活抑制电压门控Ca2+通道，尽管直接 尚未取得证据。 本建议的目的是 研究的生理作用（目的1和2）和机制， 目的3：抑制NPY诱导的CA合成和释放。 目标1中提出的研究的基本原理如下：如果NPY正常 对递质释放产生抑制性自动调节， 受体拮抗剂的问题应该中断反馈 电路和增加变送器释放。 两者的结合前效应 外源性给予的激动剂和拮抗剂应随 内源性NPY的生物相浓度。 此外， 效应细胞应该与NPY抑制或刺激一致 release. 最后，似乎有必要证明功能性 受体在体内以及体外。 Aim也有类似的理由 2. 在目的1中，研究了一系列选择性Y1和Y2激动剂和 将检查拮抗剂对NE、NPYr和有时ATP释放的影响 通过神经刺激诱发，以及灌注压的测量 在肠系膜动脉床。 这将是之前和之后， 内源性NPY浓度通过以下方式升高：1）增加 神经刺激或2）降低灌注率或在NPY 浓度已通过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去髓大鼠中检查 准备. 在目标2中，类似的实验将评估NPY的作用。 神经刺激的类似物引起NE合成的增加， 通过脱羧酶抑制后的多巴积累。 在目标3中， 电压钳记录将在NGF分化的PC12中完成 细胞直接确定是否激活Y2和Y3受体， 降低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Ca 2+通道的流入将被 评估，以及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的 信息的功能作用和作用机制的神经肽Y在 交感神经传递的连接前调节。

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.