Department of Physiology, Health Sciences Institute, Federal University of Bahia, 40110-100 Salvador, Bahia, Brazil.
Life Sciences Department, Bahia State University, 41195-001 Salvador, Bahia, Brazil.
Auton Neurosci. 2014 Apr;181:55-68. doi: 10.1016/j.autneu.2014.01.003. Epub 2014 Jan 15.
Serotonin is widely distributed throughout the brain and is involved in a multiplicity of visceral, cognitive and behavioral responses. It has been previously shown that injections of different doses of ondansetron, a 5-HT3 receptor antagonist, into the medial septum/vertical limb of the diagonal band complex (MS/vDB) induce a hypertensive response in rats. On the other hand, administration of m-CPBG, a 5-HT3 agonist, into the MS/vDB inhibits the increase of blood pressure during restraint stress. However, it is unclear which neuronal circuitry is involved in these responses. The present study investigated Fos immunoreactive nuclei (Fos-IR) in different brain areas following the blockade of 5-HT3 receptors located in the MS/vDB in sham and in sinoaortic denervated (SAD) rats. Ondansetron injection into the MS/vDB increases Fos-IR in different brain areas including the limbic system (central amygdala and ventral part of the bed nucleus of the stria terminalis), hypothalamus (medial parvocellular parts of the paraventricular nucleus, anterodorsal preoptic area, dorsomedial hypothalamic nucleus), mesencephalon (ventrolateral periaqueductal gray region) and rhombencephalon (lateral parabrachial nucleus) in sham rats. Barodenervation results in higher Fos expression at the parvocellular and magnocellular part of the paraventricular nucleus, the lateral parabrachial nucleus, the central nucleus of amygdala, the locus coeruleus, the medial part of the nucleus of the solitary tract, the rostral ventrolateral medulla and the caudal ventrolateral medulla following 5-HT3receptor blockade in the MS/vDB. Based on the present results and previous data showing a hypertensive response to ondansetron injected into the MS/vDB, it is reasonable to suggest that 5-HT3receptors in the MS/vDB exert an inhibitory drive that may oscillate as a functional regulatory part of the complex central neuronal network participating in the control of blood pressure.
5-羟色胺广泛分布于大脑，并参与多种内脏、认知和行为反应。先前的研究表明，向中隔/斜角带垂直支（MS/vDB）的内侧注射不同剂量的昂丹司琼（一种 5-HT3 受体拮抗剂）会引起大鼠的高血压反应。另一方面，向 MS/vDB 中注射 m-CPBG（一种 5-HT3 激动剂）会抑制束缚应激时血压的升高。然而，目前尚不清楚哪种神经元回路参与了这些反应。本研究探讨了 5-HT3 受体在 MS/vDB 中的阻断后，在假手术和去窦神经（SAD）大鼠不同脑区的 Fos 免疫反应核（Fos-IR）。向 MS/vDB 中注射昂丹司琼会增加包括边缘系统（中央杏仁核和终纹床核腹侧部）、下丘脑（室旁核的小细胞部分、前背侧视前区、背内侧下丘脑核）、中脑（导水管周围灰质腹外侧区）和延髓（外侧臂旁核）在内的不同脑区的 Fos-IR。去窦神经会导致假手术大鼠的室旁核的小细胞和大细胞部分、外侧臂旁核、杏仁中央核、蓝斑、孤束核的中间部分、延髓腹外侧头端和尾端对 5-HT3 受体阻断的 Fos 表达更高，MS/vDB 中的神经元。基于目前的结果和先前的数据表明，向 MS/vDB 注射昂丹司琼会引起高血压反应，因此可以合理地假设 MS/vDB 中的 5-HT3 受体发挥抑制性驱动作用，可能作为参与血压控制的复杂中枢神经网络的功能性调节部分进行振荡。
