Neural control of swimming in Aplysia brasiliana. III. Serotonergic modulatory neurons.
Neural control of swimming in Aplysia brasiliana. III. Serotonergic modulatory neurons.
复制标题
巴西海兔游泳的神经控制。
DOI：
10.1152/jn.1991.66.4.1366
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发表时间：
1991
影响因子：
2.5
通讯作者：
Blankenship,JE
中科院分区：
文献类型：
--
作者：
McPherson,DR;Blankenship,JE
1.我们描述了一组在足神经节的巴西龙蜥，并描述其对运动神经元输入的parapodia游泳肌肉的调制作用。每个足神经节在其背内侧表面附近包含一簇大型神经元，这些神经元与旁足的开放（下行程）同步发射;这些被指定为旁足开放相（POP）细胞。2. POP细胞很大，每个神经节有15-20个，在足旁神经中有外周轴突，具有独特形状的动作电位，并在虚构的游泳过程中，在足旁运动的开放或下行部分期间与运动神经元相性地爆发。用细胞内电流激发单个POP细胞表明它们对肌肉没有直接可检测的影响，既不引起连接电位也不引起收缩。3. 5，7-二羟色胺（5，7-DHT）染色，使用5-羟色胺（5-HT）抗体的免疫细胞化学，和直接的生化测量显示POP细胞是多巴胺能的。足旁肌内也可见5-羟色胺能神经末梢。4.同时细胞内记录和使用改变的二价浓度显示，POP细胞和运动神经元之间不存在可检测的直接突触相互作用。5.当在测量肌肉收缩的同时记录POP细胞和运动神经元时，发现POP细胞活性使运动神经元诱导的张力增强120- 900%，平均约300%。个别POP细胞功效的变异性表明它们可能影响特定区域或肌纤维群。6. POP细胞的活动也显著增加了足旁肌收缩的松弛率，平均减少了约40%的时间，需要放松到一半的峰值张力。松弛率的增加意味着肌肉行为的突触后变化。7. POP细胞增加收缩张力和舒张速率的有效性与POP细胞锋电位频率呈正相关。这些影响是缓慢的（秒）在发病和持久性有机污染物发射停止后，可以持续一分钟或更长时间。并发运动神经元的活动是不需要的调制POP细胞。8.同时从POP细胞，运动神经元和肌纤维的细胞内记录显示，POP细胞的活动增强运动神经元诱导的兴奋性连接电位（EJPs）的幅度。POP细胞的活动不会改变肌纤维膜电位，但实验留下了EJP增强是突触前、突触后或两者结合的可能性。（摘要截短至400字）
1. We describe a group of serotonergic neurons in the pedal ganglia of Aplysia brasiliana and characterize their modulatory effects on the motoneuron input to swimming muscles of the parapodia. Each pedal ganglion contains one cluster of large neurons near its dorsomedial surface that fires in phase with opening (downstroke) of the parapodia; these have been designated parapodial opener-phase (POP) cells. 2. POP cells are large, number 15-20 per ganglion, have peripheral axons in parapodial nerves, have distinctively shaped action potentials, and fire in bursts phasically with motoneurons during the opening, or downstroke portion, of parapodial movement during fictive swimming. Firing individual POP cells with intracellular current indicates that they have no direct detectable effect on muscle, causing neither junction potentials nor contractions. 3. 5,7-Dihydroxytryptamine (5,7-DHT) staining, immunocytochemistry using serotonin (5-HT) antibodies, and direct biochemical measurements revealed that POP cells are serotonergic. Serotonergic nerve endings were also seen in parapodial muscle. 4. Simultaneous intracellular recordings and use of altered divalent concentrations revealed that no detectable direct synaptic interactions exist between POP cells and motor neurons. 5. When POP cells and motoneurons were simultaneously recorded while measuring muscle contractions, it was found that POP cell activity enhances motoneuron-induced tension by 120-900%, averaging around 300%. Variability in the efficacy of individual POP cells suggests that they may influence specific regions or groups of muscle fibers. 6. POP cell activity also significantly increased the rate of relaxation of parapodial muscle contractions, averaging about a 40% reduction in the time required to relax to one-half peak tension. Increased relaxation rate implies a postsynaptic change in muscle behavior. 7. The effectiveness of POP cells to increase contraction tension and relaxation rate was positively correlated with POP cell spike frequency. These effects were slow (seconds) in onset and could persist for a minute or more after cessation of POP firing. Concurrent motoneuron activity is not required for modulation by POP cells. 8. Simultaneous intracellular recording from a POP cell, motoneuron, and muscle fiber revealed that POP cell activity enhanced the amplitude of motoneuron-induced excitatory junction potentials (EJPs). Activity of POP cells did not alter muscle fiber membrane potential, but the experiments left open the possibility that EJP enhancement is presynaptic, postsynaptic, or a combination.(ABSTRACT TRUNCATED AT 400 WORDS)