BLOOD PRESSURE CONTROL BY FOREBRAIN & BRAINSTEM NEURONS

前脑控制血压

• 批准号: 3344981
• 负责人: SUSAN M BARMAN
• 金额: $ 11.92万
• 依托单位: MICHIGAN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-09-30 至 1995-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3344981
• 关键词: autonomic reflex; baroreceptors; brain electrical activity; brain mapping; brain stem; cardiovascular function; cats; efferent nerve; electrophysiology; histology; interneurons; neural information processing; neuroanatomy; neurogenic hypertension; prosencephalon; sympathetic nervous system

The long range goal of this research is to identify electrophysiologically CNS pathways that control sympathetic nerve discharge (SND) and cardiovascular function. The PI has studied these pathways in barbiturate- anesthetized cats in which SND is synchronized into bursts (slow waves) that are locked to the cardiac cycle via the baroreceptor reflex. After baroreceptor-denervation these sympathetic slow waves occur at frequencies varying mainly between 2 and 6 Hz. Others report that in some unanesthetized-decerebrate (UD), urethane-anesthetized, or conscious cats, a 10-Hz rhythm coexists with this 2- to 6-Hz activity. Recent studies in the PI's laboratory confirm the existence of a 10-Hz rhythm in SND of UD, baroreceptor-denervated cats. Key findings of these studies include the following. 1) 10-Hz activity coheres (correlates) strongly among each of the nerves studied (inferior cardiac, vertebral, and renal nerves). 2) Episodes of 10-Hz activity are often followed by increases in arterial pressure, suggesting that this rhythm regulates vasomotor tone. 3) 10-Hz but not 2- to 6-Hz activity is eliminated by a midline sagittal cut of the medulla (0-6 mm rostral to the obex). This occurs without a change in total power in SND, but blood pressure significantly decreases. This suggests that the pattern (10-Hz vs 2- to 6-Hz) rather than just total power in SND regulates the level of blood pressure. 4) The activity of some raphe neurons is synchronized to 10-Hz slow waves in SND. Although this 10-Hz rhythm was described ~ 25 yr ago, no one has yet established its region of origin, properties of central neurons mediating this rhythm, or pathways that relay this activity to sympathetic nerves. Data available suggest that the 10-Hz rhythm is generated in the brainstem. State-of-the- art electrophysiological techniques (spike-triggered averaging, antidromic mapping, and autospectral, coherence, and phase spectral analyses) will be used to address the following aims in experiments on UD cats: 1) to determine the site of origin of this activity, 2) to identify brainstem neurons whose activity is correlated to this rhythm in SND, 3) to determine interconnections of neurons responsible for the 10-Hz rhythm, 4) to assess the functional significance of this rhythm in regulating cardiovascular function, and 5) to assess the effects of central respiratory drive on the frequency of sympathetic nerve slow waves. These studies will determine if the 2- to 6-Hz and 10-Hz components in SND are generated by different brainstem networks, or if the two patterns reflect different physiological states of the same network. These studies will enhance our understanding of the central circuitry responsible for generating resting SND in the absence of the effects of anesthesia.

这项研究的长期目标是从电生理学角度识别 控制交感神经放电(SND)和 心血管功能。PI已经研究了巴比妥酸盐中的这些途径- SND同步成脉冲波(慢波)的麻醉猫 通过压力感受器反射锁定在心跳周期。之后 压力感受器去神经这些交感慢波在频率上发生 主要在2至6赫兹之间变化。其他人则报告说，在一些 未麻醉-去大脑(UD)、乌拉坦麻醉或清醒的猫， 10赫兹的节律与这种2至6赫兹的活动共存。最近的研究 PI的实验室证实UD的SND中存在10-Hz节律， 压力感受器失神经的猫。这些研究的主要发现包括 下面是。1)10-HZ活动在每一个之间存在强烈的相关性 所研究的神经(心下神经、椎神经和肾神经)。2) 10赫兹活动发作后往往伴随着动脉血流量的增加 压力，这表明这种节律调节血管舒缩张力。3)10赫兹 但2至6赫兹的活动不能通过中线矢状面切割来消除 髓质(距OBEX吻部0-6毫米)。这种情况发生时不会改变 SND的总功率，但血压显著下降。这 建议模式(10-HZ与2-6-HZ)而不仅仅是总和 SND中的能量调节血压水平。4)活跃性 在SND中，一些中缝神经元与10-Hz慢波同步。虽然 这种10赫兹的节奏是在大约25年前被描述的，至今还没有人建立起它 起源区域，调节这种节律的中枢神经元的特性，或 将这种活动传递给交感神经的通路。可用的数据 提示这种10赫兹的节律是在脑干产生的。最新情况- ART电生理技术(尖峰触发平均、反向 测绘、自谱、相干和相位谱分析) 用于解决UD猫实验中的以下目标：1) 确定这一活动的起源地，2)确定脑干 SND中活动与此节律相关的神经元，3)确定 负责10赫兹节律的神经元的相互连接，4)评估 这种节律在心血管调节中的功能意义 功能，以及5)评估中枢呼吸驱动对 交感神经慢波频率。这些研究将确定是否 SND中的2-6-HZ和10-HZ分量由不同的 脑干网络，或者如果这两种模式反映了不同的生理 同一网络中的国家。这些研究将增进我们对 负责产生静止SND的中央电路的 没有麻醉的效果。