Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil.
Pflugers Arch. 2020 Jan;472(1):49-60. doi: 10.1007/s00424-019-02341-9. Epub 2019 Dec 28.
The nucleus of the solitary tract (NTS) is an important area of the brainstem that receives and integrates afferent cardiorespiratory sensorial information, including those from arterial chemoreceptors and baroreceptors. It was described that acetylcholine (ACh) in the commissural subnucleus of the NTS (cNTS) promotes an increase in the phrenic nerve activity (PNA) and antagonism of nicotinic receptors in the same region reduces the magnitude of tachypneic response to peripheral chemoreceptor stimulation, suggesting a functional role of cholinergic transmission within the cNTS in the chemosensory control of respiratory activity. In the present study, we investigated whether cholinergic receptor antagonism in the cNTS modifies the sympathetic and respiratory reflex responses to hypercapnia. Using an arterially perfused in situ preparation of juvenile male Holtzman rats, we found that the nicotinic antagonist (mecamylamine, 5 mM), but not the muscarinic antagonist (atropine, 5 mM), into the cNTS attenuated the hypercapnia-induced increase of hypoglossal activity. Furthermore, mecamylamine in the cNTS potentiated the generation of late-expiratory (late-E) activity in abdominal nerve induced by hypercapnia. None of the cholinergic antagonists microinjected in the cNTS changed either the sympathetic or the phrenic nerve responses to hypercapnia. Our data provide evidence for the role of cholinergic transmission in the cNTS, acting on nicotinic receptors, modulating the hypoglossal and abdominal responses to hypercapnia.
孤束核（NTS）是脑干的一个重要区域，接收和整合传入的心肺感觉信息，包括来自动脉化学感受器和压力感受器的信息。有研究描述，NTS 的连合亚核（cNTS）中的乙酰胆碱（ACh）促进膈神经活动（PNA）增加，而同一区域的烟碱受体拮抗剂减少了外周化学感受器刺激引起的呼吸急促反应的幅度，这表明 cNTS 内胆碱能传递在化学感觉控制呼吸活动中具有功能作用。在本研究中，我们研究了 cNTS 中的胆碱能受体拮抗是否会改变对高碳酸血症的交感和呼吸反射反应。使用幼年雄性霍尔茨曼大鼠的动脉灌注原位制备物，我们发现烟碱受体拮抗剂（美加明，5 mM），而不是毒蕈碱受体拮抗剂（阿托品，5 mM），进入 cNTS 可减弱高碳酸血症引起的舌下神经活动增加。此外，cNTS 中的美加明增强了高碳酸血症引起的腹神经晚期呼气（late-E）活动的产生。在 cNTS 中注射的任何一种胆碱能拮抗剂都没有改变交感神经或膈神经对高碳酸血症的反应。我们的数据为 cNTS 中的胆碱能传递作用提供了证据，作用于烟碱受体，调节对高碳酸血症的舌下神经和腹部反应。
