Machado B H, Mauad H, Chianca Júnior D A, Haibara A S, Colombari E
Departamento de Fisiologia, Faculdade de Medicina de Ribeiräo Preto, Universidade de São Paulo, Brasil.
Braz J Med Biol Res. 1997 Apr;30(4):533-43. doi: 10.1590/s0100-879x1997000400015.
The nucleus tractus solitarii (NTS) receives afferent projections from the arterial baroreceptors, carotid chemoreceptors and cardiopulmonary receptors and as a function of this information produces autonomic adjustments in order to maintain arterial blood pressure within a narrow range of variation. The activation of each of these cardiovascular afferents produces a specific autonomic response by the excitation of neuronal projections from the NTS to the ventrolateral areas of the medulla (nucleus ambiguous, caudal and rostal ventrolateral medulla). The neurotransmitters at the NTS level as well as the excitatory amino acid (EAA) receptors involved in the processing of the autonomic responses in the NTS, although extensively studied, remain to be completely elucidated. In the present review we discuss the role of the EAA L-glutamate and its different receptor subtypes in the processing of the cardiovascular reflexes in the NTS. The data presented in this review related to the neurotransmission in the NTS are based on experimental evidence obtained in our laboratory in unanesthetized rats. The two major conclusions of the present review are that a) the excitation of the cardiovagal component by cardiovascular reflex activation (chemo- and Bezold-Jarisch reflexes) or by L-glutamate microinjection into the NTS is mediated by N-methyl-D-aspartate (NMDA) receptors, and b) the sympatho-excitatory component of the chemoreflex and the pressor response to L-glutamate microinjected into the NTS are not affected by the NMDA receptors antagonist, suggesting that the sympatho-excitatory component of these responses is mediated by non-NMDA receptors.
孤束核（NTS）接收来自动脉压力感受器、颈动脉化学感受器和心肺感受器的传入投射，并根据这些信息进行自主调节，以将动脉血压维持在狭窄的变化范围内。这些心血管传入神经中的每一个的激活都会通过激发从NTS到延髓腹外侧区域（疑核、尾侧和头端腹外侧延髓）的神经元投射而产生特定的自主反应。尽管对NTS水平的神经递质以及参与NTS自主反应处理的兴奋性氨基酸（EAA）受体进行了广泛研究，但仍有待完全阐明。在本综述中，我们讨论了EAA L-谷氨酸及其不同受体亚型在NTS心血管反射处理中的作用。本综述中呈现的与NTS神经传递相关的数据基于我们实验室在未麻醉大鼠中获得的实验证据。本综述的两个主要结论是：a）心血管反射激活（化学反射和贝佐尔德-雅里什反射）或向NTS微量注射L-谷氨酸对心迷走神经成分的兴奋是由N-甲基-D-天冬氨酸（NMDA）受体介导的；b）化学反射的交感兴奋成分以及向NTS微量注射L-谷氨酸引起的升压反应不受NMDA受体拮抗剂的影响，这表明这些反应的交感兴奋成分是由非NMDA受体介导的。
