Bonham A C, Hasser E M
Department of Internal Medicine, University of California, Davis 95616.
Am J Physiol. 1993 May;264(5 Pt 2):H1674-85. doi: 10.1152/ajpheart.1993.264.5.H1674.
Area postrema neurons enhance baroreflex function, perhaps by augmenting baroreceptor afferent processing in the nucleus tractus solitarius (NTS). If so, NTS neurons should receive convergent excitatory inputs from area postrema neurons and baroreceptors. The aims of this study were to record extracellular activity of NTS neurons to determine whether 1) area postrema and aortic baroreceptor afferents converged in NTS, 2) area postrema and vagal afferents converged in NTS, and 3) the convergent inputs were facilitative. Studies were performed in pentobarbital sodium- or alpha-chloralose-anesthetized rabbits. Forty-six of 194 NTS neurons received inputs from the area postrema and aortic depressor nerve. Twelve of the 23 inputs showed facilitative summation; unit response rate evoked by paired inputs (79%) doubled the predicted (calculated) response rate for simple addition (37%). Fifty-eight of 114 NTS neurons received excitatory inputs from the area postrema and vagus. Eleven of the 13 inputs showed facilitative summation; unit response to paired inputs (87%) doubled the predicted response (44%). Area postrema neurons may augment the processing of aortic and vagal inputs by NTS neurons and, hence, enhance the reflex output of these afferent pathways.
最后区神经元可能通过增强孤束核（NTS）中压力感受器传入信号的处理来增强压力感受性反射功能。如果是这样，NTS神经元应该接收来自最后区神经元和压力感受器的汇聚性兴奋性输入。本研究的目的是记录NTS神经元的细胞外活动，以确定：1）最后区和主动脉压力感受器传入信号是否在NTS中汇聚；2）最后区和迷走神经传入信号是否在NTS中汇聚；3）汇聚性输入是否具有易化作用。研究在戊巴比妥钠或α-氯醛糖麻醉的家兔中进行。194个NTS神经元中有46个接收来自最后区和主动脉减压神经的输入。23个输入中有12个显示出易化性总和；配对输入诱发的单位反应率（79%）是简单相加预测（计算）反应率（37%）的两倍。114个NTS神经元中有58个接收来自最后区和迷走神经的兴奋性输入。13个输入中有11个显示出易化性总和；对配对输入的单位反应（87%）是预测反应（44%）的两倍。最后区神经元可能增强NTS神经元对主动脉和迷走神经输入的处理，从而增强这些传入通路的反射输出。
