Dendritic origin of late events in optical recordings from salamander olfactory bulb.
Dendritic origin of late events in optical recordings from salamander olfactory bulb.
复制标题
蝾螈嗅球光学记录中晚期事件的树突起源。
DOI：
10.1152/jn.1992.68.3.786
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发表时间：
1992
影响因子：
2.5
通讯作者：
Salzberg,BM
中科院分区：
文献类型：
--
作者：
Cinelli,AR;Salzberg,BM
1.利用膜电位变化的光学记录，研究了火蜥蜴嗅球脑片中树突水平的电信号的来源和性质。2.光学事件与同时记录到的场势波相关联。这两种反应都表现出与其他物种相似的模式。3.顺行刺激在嗅神经纤维中诱发出一个复合动作电位，然后是两个额外的主波(N1和N2)。这些场电位波分别反映了初级二尖瓣/簇状和颗粒细胞树突的兴奋性突触后电位。4.用吡喃并氧杂环己烷染料RH-155染色的水平切片的外在光信号显示出一个特征的去极化和超极化事件序列。所有的信号都表现出对这种染料预期的波长依赖性，并且在镀液中存在高K+时被消除。5.根据时间进程，正常记录条件下的去极化反应可分为快和慢两种成分。顺序性刺激引起快速的突触前反应，代表来自嗅神经纤维的同步复合动作电位。在肾小球下水平，通常可在肾周/肾小球下水平和二尖瓣/簇状体节区域记录到额外的快速反应。这些突触后反应部分地与另一种去极化信号的上升阶段相一致，该信号是一种以延长时间为特征的慢成分。6.顺行刺激时，这种慢信号在肾小球和外丛状层(EPL)浅层之间的区域达到最大幅度。逆行刺激诱发的信号与顺行诱发的信号有一些相似之处，但起源于更深层次的EPL区域。7.慢组分的钙依赖性是其特征。低钙介质或钙通道阻滞剂抑制了这一光学成分，无论是顺向、逆行或直接刺激。此外，浴液中的Ba2+(2.5-3.6 mM)不能消除这些反应，这表明它们不反映细胞外K+浓度([K+]o)升高所引起的神经胶质细胞去极化。8.在5-10微米河豚毒素(TTX)或低Na+浓度([Na+]o)介质中，肾小球层旁局部施加刺激可引起上述信号，但逆行或顺行刺激在这些条件下均不能引起上述反应。对局部刺激的反应大小保持不变，但在河豚毒素或低[Na+]0.9中观察到其持续时间增加。伽马氨基丁酸(GABA)和巴氯芬以剂量依赖的方式减小慢成分的大小。
1. Optical recordings of membrane-potential changes were used to characterize the origin and properties of the electrical signals from the dendritic level in slices of the salamander olfactory bulb. 2. The optical events were correlated with field-potential waves recorded simultaneously. Both responses exhibited patterns similar to those found in other species. 3. Orthodromic stimulation evoked a compound action potential in the olfactory nerve fibers, followed by two additional principal waves (N1 and N2). These field-potential waves reflected excitatory postsynaptic potentials at the primary mitral/tufted and granule cell dendrites, respectively. 4. Extrinsic optical signals from horizontal slices stained with the pyrazo-oxonal dye RH-155 showed a characteristic sequence of depolarizing and hyperpolarizing events. All of the signals exhibited a wavelength dependence expected for this dye and were abolished in the presence of high K+ in the bath. 5. According to their time courses, depolarizing responses under normal recording conditions were divided into two components, fast and slow. Orthodromic stimuli evoked a fast presynaptic response that represents synchronous compound action potentials from olfactory nerve fibers. At subglomerular levels, additional fast responses could often be recorded at the peri/subglomerular level and in the mitral/tufted somata region. These postsynaptic responses partially coincided with the rising phase of a different depolarizing signal, a slow component characterized by its prolonged time course. 6. With orthodromic stimulation, this slow signal attained its largest amplitude in the zone between the glomeruli and the superficial part of the external plexiform layer (EPL). Antidromic stimuli evoked a signal with some similarities to the one evoked orthodromically, but originating in deeper EPL regions. 7. Slow components were characterized by their Ca dependence. Low Ca2+ medium, or calcium channel blockers, suppressed this optical component, whether evoked orthodromically, antidromically, or by direct stimulation. In addition, Ba2+ (2.5–3.6 mM) in the bath did not abolish these responses, suggesting that they do not reflect a glial depolarization in response to elevated extracellular K+ concentration ([K+]o). 8. Locally applied stimuli next to the glomerular layer elicited these signals in 5–10 microM tetrodotoxin (TTX) or in low extracellular Na+ concentration ([Na+]o) medium, but antidromic or orthodromic stimuli failed to evoke the response under these conditions. The sizes of the responses to local stimuli remained constant, but an increase in their duration was observed in either TTX or low [Na+]o. 9. gamma-Aminobutyric acid (GABA) and baclofen reduced the size of the slow components in a dose-dependent manner.(ABSTRACT TRUNCATED AT 400 WORDS)