Kolpakova Jenya, Li Liang, Hatcher Jeffrey T, Gu He, Zhang Xueguo, Chen Jin, Cheng Zixi Jack
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando FL, United States of America.
Department of Neurology, Henry Ford Hospital, Detroit, Michigan, United States of America.
PLoS One. 2017 Apr 6;12(4):e0169529. doi: 10.1371/journal.pone.0169529. eCollection 2017.
Previously, many different types of NTS barosensitive neurons were identified. However, the time course of NTS barosensitive neuronal activity (NA) in response to arterial pressure (AP) changes, and the relationship of NA-AP changes, have not yet been fully quantified. In this study, we made extracellular recordings of single NTS neurons firing in response to AP elevation induced by occlusion of the descending aorta in anesthetized rats. Our findings were that: 1) Thirty-five neurons (from 46 neurons) increased firing, whereas others neurons either decreased firing upon AP elevation, or were biphasic: first decreased firing upon AP elevation and then increased firing during AP decrease. 2) Fourteen neurons with excitatory responses were activated and rapidly increased their firing during the early phase of AP increase (early neurons); whereas 21 neurons did not increase firing until the mean arterial pressure changes (ΔMAP) reached near/after the peak (late neurons). 3) The early neurons had a significantly higher firing rate than late neurons during AP elevation at a similar rate. 4) Early neuron NA-ΔMAP relationship could be well fitted and characterized by the sigmoid logistic function with the maximal gain of 29.3. 5) The increase of early NA correlated linearly with the initial heart rate (HR) reduction. 6) The late neurons did not contribute to the initial HR reduction. However, the late NA could be well correlated with HR reduction during the late phase. Altogether, our study demonstrated that the NTS excitatory neurons could be grouped into early and late neurons based on their firing patterns. The early neurons could be characterized by the sigmoid logistic function, and different neurons may differently contribute to HR regulation. Importantly, the grouping and quantitative methods used in this study may provide a useful tool for future assessment of functional changes of early and late neurons in disease models.
此前，已鉴定出多种不同类型的孤束核（NTS）压力感受性神经元。然而，NTS压力感受性神经元活动（NA）对动脉血压（AP）变化的时间进程以及NA与AP变化的关系尚未得到充分量化。在本研究中，我们对麻醉大鼠降主动脉闭塞诱导的AP升高时单个NTS神经元放电进行了细胞外记录。我们的研究结果如下：1）35个神经元（共46个神经元）在AP升高时放电增加，而其他神经元在AP升高时放电减少，或呈双相变化：AP升高时先放电减少，AP下降时再放电增加。2）14个具有兴奋性反应的神经元在AP升高的早期阶段被激活并迅速增加放电（早期神经元）；而21个神经元直到平均动脉压变化（ΔMAP）达到峰值附近/之后才增加放电（晚期神经元）。3）在AP以相似速率升高期间，早期神经元的放电频率显著高于晚期神经元。4）早期神经元的NA-ΔMAP关系可以用最大增益为29.3的S形逻辑函数很好地拟合和表征。5）早期NA的增加与初始心率（HR）降低呈线性相关。6）晚期神经元对初始HR降低没有贡献。然而，晚期NA与晚期HR降低密切相关。总之，我们的研究表明，NTS兴奋性神经元可根据其放电模式分为早期和晚期神经元。早期神经元可用S形逻辑函数表征，不同神经元对HR调节的贡献可能不同。重要的是，本研究中使用的分组和定量方法可能为未来评估疾病模型中早期和晚期神经元的功能变化提供有用工具。
