Structural-functional properties of identified excitatory and inhibitory interneurons within pre-Botzinger complex respiratory microcircuits.
Structural-functional properties of identified excitatory and inhibitory interneurons within pre-Botzinger complex respiratory microcircuits.
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DOI：
10.1523/jneurosci.4427-12.2013
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发表时间：
2013-02-13
期刊：
影响因子：
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通讯作者：
Smith JC
中科院分区：
文献类型：
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作者：
Koizumi H;Koshiya N;Chia JX;Cao F;Nugent J;Zhang R;Smith JC
我们比较分析了新生啮齿动物前BötC复合体（前BötC）呼吸微回路中识别出的节律性兴奋性和抑制性中间神经元的细胞和回路特性，该结构在脑干中产生吸气节律。我们结合高分辨率的结构功能成像，神经递质表型鉴定的分子测定结合电生理特性表型，和形态重建的新生大鼠和小鼠切片在体外的中间神经元。这种方法揭示了以前未分化的结构功能的特点，区分兴奋性和抑制性interneuronal群体。我们确定了前BötC谷氨酸能、甘氨酸能、GABA能和甘氨酸-GABA共表达的中间神经元的不同亚群。大多数连合前BötC吸气中间神经元是神经元能的，其中一个重要的子集表现出内在的振荡爆发特性。连合兴奋性中间神经元投射到对侧前BötC的近平面轨迹，许多还与轴突侧支含有吸气舌下神经（XII）前运动神经元和运动神经元的区域。本研究中表征的抑制性神经元不表现出固有的振荡爆发特性，但在电生理学上表现出更明显的尖峰频率适应特性。许多抑制性神经元的轴突投射同侧也包含吸气XII前运动神经元和运动神经元的区域，而少数抑制性神经元有连合轴突投射。兴奋性和抑制性中间神经元的树突呈树枝状不对称，主要是在冠状面。抑制性中间神经元的树突野在空间上比兴奋性中间神经元的树突野更紧凑。我们的研究结果是一致的隔室电路组织的概念，一个双边耦合的兴奋性rhythmogenic内核，和前BötC抑制神经元在塑造吸气模式以及协调吸气和呼气活动的作用。
We comparatively analyzed cellular and circuit properties of identified rhythmic excitatory and inhibitory interneurons within respiratory microcircuits of the neonatal rodent pre-Bötzinger complex (pre-BötC), the structure generating inspiratory rhythm in the brain-stem. We combined high-resolution structural–functional imaging, molecular assays for neurotransmitter phenotype identification in conjunction with electrophysiological property phenotyping, and morphological reconstruction of interneurons in neonatal rat and mouse slices in vitro. This approach revealed previously undifferentiated structural–functional features that distinguish excitatory and inhibitory interneuronal populations. We identified distinct subpopulations of pre-BötC glutamatergic, glycinergic, GABAergic, and glycine-GABA coex-pressing interneurons. Most commissural pre-BötC inspiratory interneurons were glutamatergic, with a substantial subset exhibiting intrinsic oscillatory bursting properties. Commissural excitatory interneurons projected with nearly planar trajectories to the contralateral pre-BötC, many also with axon collaterals to areas containing inspiratory hypoglossal (XII) premotoneurons and motoneurons. Inhibitory neurons as characterized in the present study did not exhibit intrinsic oscillatory bursting properties, but were electrophysiologically distinguished by more pronounced spike frequency adaptation properties. Axons of many inhibitory neurons projected ipsilaterally also to regions containing inspiratory XII premotoneurons and motoneurons, whereas a minority of inhibitory neurons had commissural axonal projections. Dendrites of both excitatory and inhibitory interneurons were arborized asymmetrically, primarily in the coronal plane. The dendritic fields of inhibitory neurons were more spatially compact than those of excitatory interneurons. Our results are consistent with the concepts of a compartmental circuit organization, a bilaterally coupled excitatory rhythmogenic kernel, and a role of pre-BötC inhibitory neurons in shaping inspiratory pattern as well as coordinating inspiratory and expiratory activity.