Serotonin modulates axo-axonal coupling between neurons critical for learning in the leech.
Serotonin modulates axo-axonal coupling between neurons critical for learning in the leech.
复制标题
血清素调节对水蛭学习至关重要的神经元之间的轴突耦合。
DOI：
10.1152/jn.00322.2005
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Burrell,BrianD
中科院分区：
文献类型：
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作者：
Moss,BrendaL;Fuller,AbbyD;Sahley,ChristieL;Burrell,BrianD
S细胞形成一个电耦合神经元链，延长水蛭CNS的长度，并在全身缩短期间的致敏中起关键作用。这一过程需要血清素，血清素的作用部分是通过改变S细胞网络的活动模式。在S-细胞电突触所在的Faivre神经中观察到含5-羟色胺的轴突和静脉曲张。为了确定是否5-羟色胺调节这些突触，S-细胞动作电位（AP）的传播进行了研究，在一个包含一个电突触的双神经节链。抽吸电极被放置在连接的切断端，以刺激一个S细胞，同时记录另一个耦合的S细胞的AP。低浓度的差距连接抑制剂辛醇增加了AP在两节链上的潜伏期，这种效应局限于包含电突触的轴突区域。在更高的浓度下，AP无法通过突触传播。5-羟色胺也增加了电突触的AP潜伏期，这表明5-羟色胺减少了S细胞之间的耦合。这种效果是独立的传播方向，并增加了越来越长的链中的电突触的数量。此外，5-羟色胺调制的瞬时AP频率时，AP启动在单独的S细胞和在计算模型的S细胞活动后mechanosensory输入。因此，S细胞电突触的多巴胺能调节可能有助于改变S细胞网络中的活动模式。
S cells form a chain of electrically coupled neurons that extends the length of the leech CNS and plays a critical role in sensitization during whole-body shortening. This process requires serotonin, which acts in part by altering the pattern of activity in the S-cell network. Serotonin-containing axons and varicosities were observed in Faivre's nerve where the S-to-S-cell electrical synapses are located. To determine whether serotonin modulates these synapses, S-cell action-potential (AP) propagation was studied in a two-ganglion chain containing one electrical synapse. Suction electrodes were placed on the cut ends of the connectives to stimulate one S cell while recording the other, coupled S cell's APs. A third electrode, placeden passant, recorded the APs near the electrical synapse before they propagated through it. Low concentrations of the gap junction inhibitor octanol increased AP latency across the two-ganglion chain, and this effect was localized to the region of axon containing the electrical synapse. At higher concentrations, APs failed to propagate across the synapse. Serotonin also increased AP latency across the electrical synapse, suggesting that serotonin reduced coupling between S cells. This effect was independent of the direction of propagation and increased with the number of electrical synapses in progressively longer chains. Furthermore, serotonin modulated instantaneous AP frequency when APs were initiated in separate S cells and in a computational model of S-cell activity after mechanosensory input. Thus serotonergic modulation of S-cell electrical synapses may contribute to changes in the pattern of activity in the S-cell network.