Tanaka J, Ushigome A, Hori K, Nomura M
Department of Human Development, Naruto University of Education, Tokushima, Japan.
Brain Res Bull. 1998;45(3):315-8. doi: 10.1016/s0361-9230(97)00371-7.
The subfornical organ (SFO) is an important central site of action of circulating angiotensin II (ANG II). Although neuroanatomical tracing studies have identified the efferent pathways from the SFO to the midbrain raphe nucleus (RN), the functional role of the pathways is unknown. The present study was carried out to examine the responses of SFO neurons projecting to the dorsal RN (DRN) to microiontophoretic application or intracarotid injection of ANG II in male rats under urethane anesthesia. Twenty-three neurons in the SFO were antidromically identified by electrical stimulation of the midbrain DRN. Of these identified units, 13 were excited by ANG II applied iontophoretically, while 10 were unresponsive. ANG II-induced excitation was prevented by the ANG II antagonist saralasin (Sar) applied iontophoretically. The activity of seven out of 10 units that displayed this excitation to iontophoretically applied ANG II was also enhanced by intracarotid injection of ANG II. These results suggest that SFO neurons projecting to the DRN may monitor the circulating level of ANG II and carry the information to the DRN.
穹窿下器官（SFO）是循环血管紧张素II（ANG II）作用的一个重要中枢位点。尽管神经解剖追踪研究已确定了从SFO到中脑缝核（RN）的传出通路，但这些通路的功能作用尚不清楚。本研究旨在检查在乌拉坦麻醉下雄性大鼠中，投射至背侧缝核（DRN）的SFO神经元对微量离子电泳施加或颈内注射ANG II的反应。通过电刺激中脑DRN，逆向鉴定出SFO中的23个神经元。在这些已鉴定的单位中，13个被离子电泳施加的ANG II兴奋，而10个无反应。离子电泳施加ANG II拮抗剂沙拉新（Sar）可阻止ANG II诱导的兴奋。颈内注射ANG II也增强了10个对离子电泳施加的ANG II表现出这种兴奋的单位中7个的活性。这些结果表明，投射至DRN的SFO神经元可能监测ANG II的循环水平，并将信息传递至DRN。
