BLOOD PRESSURE CONTROL BY FOREBRAIN & BRAINSTEM NEURONS

这项研究的长期目标是 从电生理学上识别中枢神经系统 参与心血管疾病控制的通路 功能 在当前的融资周期内，我们使用了国家- 最先进的电生理分析，以确定主要传出神经 延髓头端腹外侧（VLM）的传入联系 神经元，可能占他们的作用，在控制 Dial-尿烷中的交感神经放电（SND） 麻醉猫。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- AHA）。 这些下丘脑核团最近接受了 相当多的注意力作为前脑区域参与控制 SND和血压。 PVN神经元直接投射到 胸腰段自主神经中间外侧核 脊髓以及脑干自主区域（例如，的 孤束核、腹外侧核、脑桥 蓝斑和臂旁复合体（LC/PB）， 中脑导水管周围灰质（PAG））。 PO-AHA神经元 向PVN、LC/PB和PAG提交项目。 小 目前已有有关 PVN-DMH和PO-AHA神经元的电生理特性 包含在这些路径中。 脑干区域受 PVN-DMH和PO-AHA神经元也向这些神经元提供输入。 下丘脑核 因此，反馈回路可能在以下方面发挥作用： 控制中枢交感神经回路的活动 最近，我们的实验室使用了尖峰触发技术， 平均以识别PVN和PO中的两种类型的神经元， AHA，其自发活动与 麻醉猫的心下交感神经。 的 1型神经元的自发放电同步于 下心神经活动中尖峰样成分，而 2型神经元的活动被锁定在心脏相关的 在SND中。 还有待确定的是， 下丘脑神经元参与静息SND的控制。 如果这两种神经元都控制心血管功能， 它们可能是通过对不同的 中央通道。 该提案中概述的实验是 旨在确定哪些PVN-DMH和PO-AHA神经元是 传出交感神经成分（兴奋性或抑制性） 压力感受器传入肢中的通路或中间神经元 反射弧 我们还将能够确定一些主要的 这些神经元的传出和传入连接。 的 所使用的电生理技术包括尖峰触发的 SND平均值、逆向映射和轴突测试 分支和单位负或大于单位互相关 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.