NPY INDUCED REGULATION SYMPATHETIC NEUROTRANSMISSION

描述：(改编自应用)已知神经肽Y(NPY) 与去甲肾上腺素(NE)和三磷酸腺苷(ATP)共同定位 在血管交感神经元中，它可能扮演着一个 共发送器/共调制器。最近的证据表明，NPY发挥作用 交感神经在交感神经介导的血管收缩中的作用 节后Y1受体。神经肽Y也是已知的使用前置连接词 通过Y2受体抑制去甲肾上腺素、神经肽Y和ATP的释放 通过Y3受体抑制儿茶酚胺(CA)的合成。这些 结果表明，CA的合成和释放过程可能是 受NPY的差异调制，表明在 交感神经传递的节前调节；然而， 这些行为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钙通道，尽管直接 目前还没有获得证据。本提案的目的是 探讨其生理作用(目标1和目标2)及其作用机制(S) NPY抑制CA合成和释放的作用(目标3)。 目标1中提出的研究的理由如下：如果NPY正常 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 电路和增加发射器释放。两种语言的前言效应 外源性给药的激动剂和拮抗剂应随 内源NPY的生物相浓度。此外，美国政府的反应 效应细胞应与NPY的抑制或刺激相一致 放手。最后，似乎有必要演示功能 体内和体外的受体。AIM也有类似的理由 2.在目标1中，一系列选择性Y1和Y2激动剂和 拮抗剂将检测NE、NPYir的释放，有时还包括ATP的释放 由神经刺激诱发，以及灌流压力的测量 在肠系膜动脉床上。这将在之前和之后完成 内源性NPY浓度的升高是通过：1)增加频率 神经刺激或2)降低灌注率或NPY后 由于组织水平的耗尽，浓度已经降低。活体内 激动剂和拮抗剂的效果也将在脊髓损伤的大鼠身上进行检测。 准备工作。在目标2中，类似的实验将评估NPY的效果 神经刺激引起的NE合成增加的类似物 通过抑制脱羧酶后的DOPA积聚。在《目标3》中， 电压钳位记录将在NGF区分的PC12中完成 直接确定Y2和Y3受体的激活是否可以 降低钙电流。这是否通过抑制钙离子来调节 通过N型和L型电压激活的钙通道内流 评估，以及抑制L型钙通道是否也涉及 PKC的作用。这些研究旨在提供有用的新的 NPY的功能作用和作用机制的信息 交感神经传递的节前调节。

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.