Kannan H, Hayashida Y, Yamashita H
Department of Physiology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Am J Physiol. 1989 Jun;256(6 Pt 2):R1325-30. doi: 10.1152/ajpregu.1989.256.6.R1325.
Our previous studies demonstrated that stimulation of the hypothalamic paraventricular nucleus (PVN) in anesthetized rats evoked a depressor response accompanied with a decrease in sympathetic outflow (H. Kannan, A. Niijima, and H. Yamashita, J. Auton. Nerv. Syst. 19: 83-86, 1987; H. Yamashita, H. Kannan, M. Kasai, and T. Osaka, J. Auton. Nerv. Syst. 19: 229-234, 1987). Because anesthesia may alter cardiovascular responses, we examined in conscious rats the effects of PVN stimulation on arterial pressure, heart rate, and renal sympathetic nerve activity. Electrical stimulation through chronically implanted electrodes evoked increases in arterial pressure and renal sympathetic nerve activity with a slight decrease in heart rate. The magnitude of responses was dependent on the frequency and the intensity of the stimulus. Latency of the excitatory response of the renal sympathetic nerve activity was approximately 70 ms. Microinjection of L-glutamate (0.5 M, 200 nl) into the PVN area also elicited increases in blood pressure and renal sympathetic nerve activity. These results suggest that activation of PVN neurons in conscious rats produces pressor responses due to an increase in the sympathetic outflow. These findings contrast with those obtained previously in anesthetized rats.
我们之前的研究表明，在麻醉大鼠中刺激下丘脑室旁核（PVN）会引起降压反应，并伴有交感神经传出活动的减少（H. 坎南、A. 新岛和H. 山下，《自主神经系统杂志》19: 83 - 86, 1987；H. 山下、H. 坎南、M. 笠井和T. 大阪，《自主神经系统杂志》19: 229 - 234, 1987）。由于麻醉可能会改变心血管反应，我们在清醒大鼠中研究了PVN刺激对动脉血压、心率和肾交感神经活动的影响。通过长期植入的电极进行电刺激会引起动脉血压和肾交感神经活动增加，心率略有下降。反应的幅度取决于刺激的频率和强度。肾交感神经活动兴奋性反应的潜伏期约为70毫秒。向PVN区域微量注射L - 谷氨酸（0.5 M，200 nl）也会引起血压和肾交感神经活动增加。这些结果表明，清醒大鼠中PVN神经元的激活由于交感神经传出活动增加而产生升压反应。这些发现与之前在麻醉大鼠中获得的结果形成对比。
