Duan Y F, Kopin I J, Goldstein D S
Clinical Neurochemistry Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1620, USA.
Am J Physiol. 1999 Aug;277(2):R403-11. doi: 10.1152/ajpregu.1999.277.2.R403.
The present study assessed whether the baroreflex inhibition elicited by electrical stimulation of the hypothalamic paraventricular nucleus (PVN) involves altered activity in the nucleus of the solitary tract (NTS). Unit recordings were made from 107 neurons in the NTS in anesthetized rabbits. Intravenous phenylephrine was used to induce a pressor response and to activate baroreflexes. Of the neurons that responded to pressor responses, two-thirds were excited and one-third was inhibited. Stimulation of the PVN inhibited 70% of the phenylephrine-responsive NTS neurons, with or without concurrent baroreceptor stimulation. When PVN stimulation was delivered concurrently with phenylephrine injection, more NTS neuronal inhibition and less excitation occurred than with phenylephrine alone. Usually PVN stimulation inhibited NTS neurons that were excited by pressor responses; less commonly, PVN stimulation excited NTS neurons that were inhibited by pressor responses. The findings are consistent with the view that PVN activation during the defense reaction inhibits baroreflexes by altering firing of NTS neurons.
本研究评估了下丘脑室旁核（PVN）电刺激引发的压力反射抑制是否涉及孤束核（NTS）活动的改变。在麻醉兔的NTS中对107个神经元进行了单位记录。静脉注射去氧肾上腺素以诱导升压反应并激活压力反射。在对升压反应有反应的神经元中，三分之二被兴奋，三分之一被抑制。无论有无同时进行压力感受器刺激，PVN刺激均抑制了70%的对去氧肾上腺素有反应的NTS神经元。当PVN刺激与去氧肾上腺素注射同时进行时，与单独使用去氧肾上腺素相比，NTS神经元的抑制更多，兴奋更少。通常PVN刺激抑制因升压反应而兴奋的NTS神经元；较少见的是，PVN刺激兴奋因升压反应而被抑制的NTS神经元。这些发现与以下观点一致，即防御反应期间PVN的激活通过改变NTS神经元的放电来抑制压力反射。
