Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil.
Auton Neurosci. 2010 Jan 15;152(1-2):27-34. doi: 10.1016/j.autneu.2009.08.016. Epub 2009 Sep 23.
Chemoreflex afferent fibers terminate in the nucleus tractus solitarii (NTS), but the specific location of the NTS neurons excited by peripheral chemoreflex activation remains to be characterized. Here, the topographic distribution of chemoreflex sensitive cells at the commissural NTS was evaluated. To reach this goal, Fos-immunoreactive neurons (Fos-ir) were accounted in rostro-caudal levels of the intermediate and caudal commissural NTS, after intermittent chemoreflex activation with intravenous injection of potassium cyanide [KCN (80microg/kg) or saline (0.9%, vehicle), one injection every 3min during 30min]. In response to intermittent intravenous injections of KCN, a significant increase in the number of Fos-ir neurons was observed specifically in the lateral intermediate commissural NTS [(LI)NTS (82+/-9 vs. 174+/-16, cell number mean per section)] and lateral caudal commissural NTS [(LC)NTS (71+/-9 vs. 199+/-18, cell number mean per section)]. To evaluate the influence of baroreceptor-mediated inputs following the increase in blood pressure during intermittent chemoreflex activation, we performed an intermittent activation of the arterial baroreflex by intravenous injection of phenylephrine [1.5microg/kg iv (one injection every 3min during 30min)]. This procedure induced no change in Fos-ir in (LI)NTS (64+/-6 vs. 62+/-12, cell number mean per section) or (LC)NTS (56+/-15 vs. 77+/-12, cell number mean per section). These data support the involvement of the commissural NTS in the processing of peripheral chemoreflex, and provide a detailed characterization of the topographical distribution of activated neurons within this brain region.
化学感受反射传入纤维终止于孤束核（NTS），但外周化学感受反射激活兴奋的 NTS 神经元的具体位置仍有待描述。在这里，评估了 NTS 连合部化学感受敏感细胞的拓扑分布。为了达到这个目的，在中间和尾部连合部 NTS 的头尾部水平上计算了 Fos-免疫反应性神经元（Fos-ir）。在静脉注射氰化钾[KCN（80μg/kg）或生理盐水（0.9%，载体）后，每隔 3 分钟进行一次间歇性化学感受反射激活，持续 30 分钟]后，记录 Fos-ir 神经元。对 KCN 静脉内间歇性注射的反应，在中间连合部 NTS 的外侧部[（LI）NTS（82±9 与 174±16，每个节段的细胞数平均值）]和尾部连合部 NTS 的外侧部[（LC）NTS（71±9 与 199±18，每个节段的细胞数平均值）]中，Fos-ir 神经元的数量显著增加。为了评估在间歇性化学感受反射激活期间血压升高引起的压力感受器介导输入的影响，我们通过静脉内注射苯肾上腺素间歇性激活动脉压力感受器[1.5μg/kg iv（每隔 3 分钟注射一次，持续 30 分钟）]。这一过程在（LI）NTS（64±6 与 62±12，每个节段的细胞数平均值）或（LC）NTS（56±15 与 77±12，每个节段的细胞数平均值）中均未引起 Fos-ir 的变化。这些数据支持连合部 NTS 参与外周化学感受反射的处理，并提供了该脑区激活神经元的拓扑分布的详细特征。
