BLOOD PRESSURE CONTROL BY FOREBRAIN & BRAINSTEM NEURONS

这项拨款支持的研究的长期目标是 从电生理学角度识别中枢神经系统 参与心血管控制的通路 功能。在当前的资助期内，我们使用了州- 最先进的电生理分析以识别主要传出信号 延髓吻侧腹外侧区(VLM)的传入联系 神经元可能解释了它们在控制 尿毒症患者的交感神经放电(SND) 麻醉的猫。本提案中描述的实验 将这些技术的使用扩展到下丘脑的研究 室旁核和下丘脑背内侧核(PVN- DMH)以及视前-下丘脑前区(PO- 啊哈)。这些下丘脑核团最近收到了 当参与控制的前脑区域受到相当大的关注 SND和血压。PVN神经元直接投射到 胸腰椎中间外侧(IML)自主神经核 脊髓以及脑干自主神经区域(例如， 孤束核、VLm吻侧核、桥脑核 蓝斑和臂旁复合体(LC/PB)，以及 中脑导水管周围灰质(PAG))。Po-AHA神经元 投射到PVN、LC/PB和PAG。一点儿 目前可获得的信息包括 PVN-DMH和PO-AHA神经元的电生理特性 包含在这些路径中。神经支配的脑干区域 PVN-DMH和PO-AHA神经元也为这些神经元提供输入 下丘脑核团。因此，反馈环路可能在 控制中枢交感神经回路的活动。 最近，我们实验室使用了尖峰触发技术 平均识别PVN和PO内两种类型的神经元 AHA，其自发活动与脑内活动相关 麻醉猫心下交感神经的实验研究。这个 1型神经元的自发放电与 心下神经活动中的棘波成分，而 2型神经元的活动被锁定在心脏相关的 组件在SND中。目前仍有待确定的是，这些 下丘脑神经元参与静息性SND的控制。 如果这两种神经元都控制心血管功能， 它们可能是通过将它们的影响施加于不同的 中央通道。这项提案中概述的实验包括 旨在确定PVN-DMH和PO-AHA神经元是 传出交感神经成分(兴奋性或抑制性) 压力感受器传入肢的通路或中间神经元 反射弧线。我们还将能够确定一些主要的 这些神经元的传出和传入联系。这个 将使用的电生理技术包括尖峰触发 SND平均、逆行标测和轴突试验 分支，以及单位减去或大于单位互相关 分析。

The long range goal of the research supported by this grant is to identify electrophysiologically the central nervous system pathways that are involved in the control of cardiovascular function. During the current funding period we have used state- of-the-art electrophysiological analyses to identify major efferent and afferent connections of rostral ventrolateral medullary (VLM) neurons that likely account for their role in the control of sympathetic nerve discharge (SND) in the Dial-urethane anesthetized cat. The experiments described in this proposal extends the use of these techniques to studies of the hypothalamic paraventricular nucleus and dorsomedial hypothalamus (PVN- DMH) as well as the preoptic-anterior hypothalamic area (PO- AHA). These hypothalamic nuclei have recently received considerable attention as forebrain regions involved in the control of SND and blood pressure. PVN neurons project directly to the intermediolateral (IML) autonomic nucleus in the thoracolumbar spinal cords well as to brainstem autonomic regions (e.g., the nucleus tractus solitarius, the rostral VLM, the pontine locus coeruleus and parabrachial complex (LC/PB), and the mesencephalic periaqueductal gray (PAG)). PO-AHA neurons project to the PVN and to the LC/PB and PAG. Little information is currently available concerning the electrophysiological properties of PVN-DMH and PO-AHA neurons contained in these pathways. The brainstem regions innervated by PVN-DMH and PO-AHA neurons also provide input to these hypothalamic nuclei. Thus, feedback loops may play a role in controlling the activity within central sympathetic circuits. Recently, our laboratory has used the technique of spike-triggered averaging to identify two types of neurons in the PVN and PO- AHA whose spontaneous activity is correlated to that in the inferior cardiac sympathetic nerve in anesthetized cats. The spontaneous discharges of Type 1 neurons are synchronized to a spike-like component in inferior cardiac nerve activity, whereas the activity of Type 2 neurons is locked to the cardiac-related component in SND. It remains to be determined whether these hypothalamic neurons are involved in the control of resting SND. If both of these neuronal types control cardiovascular function, they probably do so by exerting their effects over different central pathways. The experiments outlined in this proposal are designed to determine which PVN-DMH and PO-AHA neurons are elements of efferent sympathetic (excitatory or inhibitory) pathways or interneurons in the afferent limb of the baroreceptor reflex arc. We also will be able to identify some of the major efferent and afferent connections of these neurons. The electrophysiological techniques to be used include spike-triggered averaging of SND, antidromic mapping and tests for axonal branching, and unit minus or greater than unit crosscorrelation analysis.