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

应用微离子诱捕应用方法，研究中缝髓核（即中缝苍白核、暗核和大核）的呼吸和循环调节机制，特别是其血清素能和GABA能机制。电刺激猫的中脑髓核会产生呼吸（膈神经）、肾神经和血压几乎平行的抑制，但是，当刺激电极进入核的更腹侧部分时，这些反应逐渐向兴奋性反应转移。这些反应是用中缝刺激引起的膈神经平均电位来分析的。该平均电位由最初的轻微兴奋电位和随后的长时间欲望抑制电位组成，前者随着刺激部位更靠近腹侧而变大，并通过重复刺激产生兴奋反应。甲基塞吉胺（5-HT_2拮抗剂）可降低前者的电位，而普萘洛尔（公认具有5-HT_1拮抗剂）可降低后者的电位。短潜伏期中缝刺激可抑制髓质呼吸神经元（吸气和呼气神经元）和吻侧腹侧髓质血管舒缩神经元，静脉或微离子注入微毒素、双管蛋白（GABA拮抗剂）和心得安可拮抗这些抑制反应，提示中缝核的5 -羟色胺能和GABA能系统投射到这些神经元上。5-HT_1 -和GABA拮抗剂可拮抗5-HT_1 -和GABA拮抗剂，使这些呼吸和血管舒缩神经元呈剂量依赖性抑制。但甲基塞吉胺的应用反而增强了血清素的抑制作用，提示除了5-HT_1受体外，还存在5-HT_2受体的共定位。中缝神经刺激以及5 -羟色胺能和氨基丁酸能药物所产生的这些作用在髓质非呼吸神经元和非血管舒缩神经元中也同样被观察到，这表明中缝神经核对髓质神经元有泛抑制控制。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