PACEMAKER BEHAVIOR OF RESPIRATORY NEURONS IN MEDULLARY SLICES FROM NEONATAL RAT
PACEMAKER BEHAVIOR OF RESPIRATORY NEURONS IN MEDULLARY SLICES FROM NEONATAL RAT
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DOI：
10.1152/jn.1994.72.6.2598
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发表时间：
1994-12-01
影响因子：
2.5
通讯作者：
FELDMAN, JL
中科院分区：
文献类型：
--
作者：
JOHNSON, SM;SMITH, JC;FELDMAN, JL
1.我们假设前Botzinger复合体（前BotC）中的起搏神经元形成呼吸节律产生的核心。这一假说的一个预测是，在一些呼吸神经元的振荡行为可以持续在突触传递的情况下。在这项研究中，我们使用细胞外记录的神经元活动的切片制备从新生大鼠延髓，产生呼吸节律在体外，以确定1）是否起搏器的属性存在于pre-BotC和呼吸神经元独特的，2）起搏器的属性是否是共同的所有呼吸神经元，和3）起搏器神经元活动的时空模式。呼吸神经元的全细胞记录证实，低钙/高镁溶液（low-Ca 2 + solution）可消除内源性呼吸突触输入和电诱发的突触输入. 63个神经元在低Ca ~（2+）溶液中自发产生节律性动作电位。在我们切换到对照溶液以重新激活呼吸网络之后，这些神经元基于其与呼吸周期相关的尖峰放电模式被分类为：1）吸气（I）神经元（n = 41），2）强直呼气（强直E）神经元（n = 4），和3）强直神经元（n = 18）。在其他实验中，我们测试了I和紧张性E神经元在低Ca 2+溶液中的爆发行为，首先在对照溶液中识别。几个I神经元（n = 5/33），但没有一个紧张性E神经元（n = 0/13），继续有节奏地爆发。爆发性和非爆发性呼吸神经元分布在pre-BotC内的腹外侧网状结构中，以及在pre-BotC尾侧的腹侧呼吸组（VRG）中。我们的结论是，亚群的VRG神经元在体外有节奏的爆发性能时，突触传递被废除。呼吸神经元，特别是I神经元，是最普遍的一类爆发细胞。然而，只有一小部分呼吸神经元具有起搏特性。这些发现与呼吸振荡器包括具有内在振荡特性的专门神经元的假设一致。
1. We have hypothesized that pacemaker neurons in the pre-Botzinger complex (pre-BotC) form the kernel for respiratory rhythm generation. A prediction of this hypothesis is that oscillatory behavior in some respiratory neurons could persist in the absence of synaptic transmission. In this study we used extracellular recording of neuronal activity in slice preparations from neonatal rat medulla that generate respiratory rhythm in vitro to determine 1) whether pacemaker properties are present in pre-BotC and unique to respiratory neurons, 2) whether pacemaker properties are common to all respiratory neurons, and 3) the spatiotemporal patterns of pacemaker neuron activity.2. Whole cell recordings from respiratory neurons verified that bathing the slices in a low-Ca2+/high-Mg2+ solution (low-Ca2+ solution) eliminated endogenous respiratory synaptic inputs and electrically evoked synaptic inputs.3. Sixty-three neurons spontaneously generated rhythmic bursts of action potentials in low-Ca2+ solution. After we switched to control solution to reactivate the respiratory network, these neurons were classified on the basis of their spike discharge patterns relative to the respiratory cycle as: 1) inspiratory (I) neurons (n = 41), 2) tonic expiratory (tonic E) neurons (n = 4), and 3) tonic neurons (n = 18).4. In other experiments we tested I and tonic E neurons identified first in control solution for bursting behavior in low-Ca2+ solution. Several I neurons (n = 5 of 33), but none of the tonic E neurons (n = 0 of 13), continued to burst rhythmically.5. Bursting and nonbursting respiratory neurons were distributed throughout the ventrolateral reticular formation within the pre-BotC as well as in the ventral respiratory group (VRG) immediately caudal to the pre-BotC.6. We conclude that subpopulations of VRG neurons in vitro have rhythmic bursting properties when synaptic transmission is abolished. Respiratory neurons, especially I neurons, were the most prevalent class of bursting cells. Only a small percentage of respiratory neurons, however, had pacemaker properties. These findings are consistent with the hypothesis that the respiratory oscillator includes specialized neurons with intrinsic oscillatory properties.