Kannan H, Niijima A, Yamashita H
Department of Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan.
Brain Res Bull. 1988 Jun;20(6):779-83. doi: 10.1016/0361-9230(88)90091-3.
Effects of electrical and chemical stimulation of the paraventricular nucleus (PVN) of the hypothalamus on blood pressure were examined in rats anesthetized with urethane-chloralose. Focal electrical stimulation (10-25 microA, 50 Hz, 0.5 msec) within the PVN consistently decreased blood pressure. Microinjection of L-glutamate (0.5 M, 80 n1) into the PVN led to a decrease in blood pressure, while the same amount of saline injection had no effect. The depressor response was not affected by cervical vagotomy. In order to obtain direct evidence for involvement of sympathetic nerve activity in the PVN-induced depressor response, effects of PVN stimulation on renal sympathetic nerve activity were examined. Low intensity electrical stimulation of the PVN inhibited renal sympathetic nerve activity, whereas the high intensity stimulation evoked a transient excitation followed by long lasting inhibition in renal sympathetic nerve activity. Latencies of the inhibitory and the excitatory responses were about 200 msec and 50-100 msec, respectively, judged by peristimulus time histograms. The result suggests that activation of PVN neurons produces a decrease in blood pressure due to inhibition of sympathetic outflows.
在用乌拉坦-氯醛糖麻醉的大鼠中，研究了下丘脑室旁核（PVN）的电刺激和化学刺激对血压的影响。PVN内的局部电刺激（10 - 25微安，50赫兹，0.5毫秒）持续降低血压。向PVN内微量注射L-谷氨酸（0.5 M，80纳升）导致血压下降，而注射等量生理盐水则无作用。降压反应不受颈迷走神经切断术的影响。为了获得交感神经活动参与PVN诱导的降压反应的直接证据，研究了PVN刺激对肾交感神经活动的影响。PVN的低强度电刺激抑制肾交感神经活动，而高强度刺激则引起肾交感神经活动短暂兴奋，随后是长期抑制。根据刺激后时间直方图判断，抑制性和兴奋性反应的潜伏期分别约为200毫秒和50 - 100毫秒。结果表明，PVN神经元的激活由于抑制交感神经输出而导致血压下降。
