Analysis of serotonergic system in the respiratory and circulatory regulation of the medullary raphe nuclei.

本研究采用微电泳技术，对延髓中缝核（即中缝苍白核、暗核和大核）的呼吸和循环调节机制进行了研究，重点探讨了它们的多巴胺能和GABA能机制.电刺激猫的延髓中缝核产生几乎平行的呼吸（膈神经），肾神经和血压的抑制，但当刺激电极推进到更腹侧的核，这些反应逐渐转移到兴奋的。该平均电位由最初的轻微兴奋电位和长时间的兴奋电位组成，前者随着刺激部位的腹侧而增大，并通过重复刺激产生兴奋反应。5-HT_2受体拮抗剂麦角新碱（methysergide，5-HT_2 antagonist，5- ...更多信息 而普萘洛尔（公认的5-HT_1拮抗剂）则可降低后者的作用.刺激中缝核可使延髓头端腹外侧区的呼吸神经元（吸气和呼气神经元）和血管神经元出现ghort潜伏期的抑制，而静脉注射或微电泳应用印防己毒素、荷包牡丹碱（GABA拮抗剂）和心得安可拮抗这些抑制反应，提示中缝核的GABA能和GABA能系统向这些神经元投射.这些呼吸和血管神经元的抑制呈剂量依赖性的5-羟色胺和GABA的离子电渗应用，这些抑制作用被拮抗5-HT_1 -和GABA拮抗剂同时应用。但麦角新碱的应用反而增强了5-羟色胺的抑制作用，提示除5-HT_1受体外，还有5-HT_2受体的共定位.在延髓非呼吸和非血管运动神经元中也观察到了由中缝核刺激和多巴胺能和GABA能药物产生的这些效应，这表明中缝核对延髓神经元的泛突触控制。少

Respiratory and circulatory regulation mechanisms of the medullary raphe nuclei, that is, nucleus raphe pallidus,obscurus and magnus, were investigated, especially concerning their serotonergic and GABA ergic mechanisms, using microiontophoretic application methods.1. Electrical stimulation of medullary raphe nuclei of the cat produced almost parallel depressions of respiration (phrenic nerve), renal nerve and blood pressure, but, when the stimulating electrode advanced in the more ventral part of the nuclei, these responses moved gradually to the excitatory ones.These responses were analyzed on the averaged potential of the phrenic nerve elicited by raphe stimulation. This averaged potential was composed of the initial slight excitatory potential and following long-lusting depressant one, the former becoming larger as the stimulating site was more ventral, and producing excitatory response by repetitive stimulation. The former potential was depressed by methysergide (5-HT_2 antagonist … More ) and the latter was reduced by propranolol (recognized as possessing 5-HT_1 antagonistic effect).2. Medullary respiratory neurons (inspiratory and expiratory neurons) and vasomotor neurons in the rostral ventrolateral medulla were depressed by raphe stimulation with ghort latency, and these depressant responses were antagonized by intravenous or microiontophoretic application of picrotoxin, bicuculin (GABA antagonists) and propranolol, suggesting projection of serotonergic and GABAnergic systems of raphe nuclei to these neurons.3. These respiratory and vasomotor neurons were depressed dose-dependently by iontophoretic application of serotonin and GABA, and these depressant effects were antagonized by simultaneous application of 5-HT_1 - and GABA antagonists. But, application of methysergide rather augmented the depressant effect of serotonin, suggesting co-localization of 5-HT_2 receptor in addition to 5-HT_1 receptor.4. These effects produced by raphe stimulation and serotonergic and GABAergic drugs were observed similarly in the medullary non-respiratory and non-vasomotorneurons, too, suggesting pan-depressant control of raphe nuclei to the medullary neurons. Less