The novel roles of the area postrema and NTS in cardiovascular regulation

1.最后区在大鼠动脉压力感受性反射中的作用本课题研究了最后区（AP）与孤束核（NTS）的突触联系。本实验观察了谷氨酸受体拮抗剂对孤束核神经元对AP刺激反应的影响。以0.2 Hz刺激AP产生NTS的动作电位。这些动作电位可被低Ca^2+、高Mg^2+溶液或10 μ M的6-氰基-7-硝基喹喔啉-2，3-二酮（CNQX）阻断<-5>，但不被10 μ M的DL-2-氨基-5-膦戊酸（AP-5）<-5>阻断。从反应时间判断，部分NTS神经元可能直接受AP神经元的神经末梢支配。这些结果表明，加压素介导的V1受体对AP神经元的兴奋作用是通过NMDA和非NMDA受体，或仅通过非NMDA受体，由谷氨酸传递到孤束核的.最后区在呕吐中的作用。呕吐反应是一种极其复杂的防御机制。呕吐是一种在呕吐中枢整合内脏传入和传出通路的反射，呕吐中枢被认为位于延髓。利用免疫组织化学技术，含有P物质的神经纤维参与呕吐在大鼠和人类的存在已被证明。在雪貂体内，我们用^3H-P物质作为结合配体进行了受体结合的放射自显影研究，观察到速激肽NK-1受体在这些区域的定位。AP内微量注射NK-1受体拮抗剂HSP-117（1.0 μg）和CP-99，994（7.5 μg）均能抑制吗啡或硫酸铜引起的呕吐反应。上述结果提示，AP、NTS和迷走神经背核的NK-1受体可能参与了呕吐的发生机制。

1. Role of the area postrema in the arterial baroreceptor reflex of ratsIn this project, we examined the synaptic connection to the nucleus tractus solitarius (NTS) from the area postrema (AP). We examined that the effects of glutamate receptor antagonists on the responses of NTS neurons to AP stimulation. The action potentials in the NTS were produced by AP stimulation at 0.2 Hz. These action potentials were blocked by a low Ca^<2+> and a high Mg^<2+> solution or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) at 10^<-5> M, but not by DL-2-amino-5-phsphonovaleric acid (AP-5) at 10^<-5> M.Judging from the response time, some NTS neurons may be innervated directly by nerve terminals of AP neurons. These results indicate that the excitation by vasopressin of AP neurons mediated V1 receptors is conveyed to NTS by glutamate via NMDA and non-NMDA receptors, or non-NMDA receptors only.2. Role of the area postrema in emesis.The emetic response is a defense mechanism which is extremely complicated. Vomiting is a reflex that integrates the visceral afferent and efferent pathways at the vomiting center, which is considered to be situated in the medulla oblongata. Using immunohistochemical techniques, the presence of substance P-containing nerve fibers involved in emesis in the rats and humans has been demonstrated. We observed the localization of tachykininNK-1 receptors in these areas in an auto radiographic receptor binding study using ^3H-substance P as a binding ligand in ferrets. The emetic response induced by either morphine or copper sulphate was suppressed by the microinjection of NK-1 receptor antagonists, HSP-117 (1.0 μg) and CP-99,994 (7.5 μg), into the AP of ferrets. These results show that the NK-1 receptors in the AP, NTS and the dorsal motor nucleus of the vagus may be involved in the mechanisms of emesis.