2 ENDOGENOUS NEUROPEPTIDES MODULATE THE GILL AND SIPHON WITHDRAWAL REFLEX IN APLYSIA BY PRESYNAPTIC FACILITATION INVOLVING CAMP-DEPENDENT CLOSURE OF A SEROTONIN-SENSITIVE POTASSIUM CHANNEL
2 ENDOGENOUS NEUROPEPTIDES MODULATE THE GILL AND SIPHON WITHDRAWAL REFLEX IN APLYSIA BY PRESYNAPTIC FACILITATION INVOLVING CAMP-DEPENDENT CLOSURE OF A SEROTONIN-SENSITIVE POTASSIUM CHANNEL
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DOI：
10.1073/pnas.81.24.7956
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发表时间：
1984-01-01
期刊：
影响因子：
--
通讯作者：
LLOYD, PE
中科院分区：
文献类型：
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作者：
ABRAMS, TW;CASTELLUCCI, VF;LLOYD, PE
两种内源性神经肽，小心脏活性肽SCPA和SCPB，促进虹吸机械感觉神经元的突触传递，并增强这些感觉神经元介导的防御性退缩反射。单通道记录显示，这些肽关闭一个特定的K+通道，S通道，这是敏感的cAMP。这些肽增加了这些感觉神经元中的cAMP水平。这种K+电流的减少减缓了这些细胞中动作电位的复极化，从而增加了递质的释放。在这些行为中，SCP既类似于增强反射的伤害性敏化刺激，也类似于血清素。腹神经节提取物的HPLC [高效液相色谱法]组分和免疫细胞化学的生物测定表明SCP和5-羟色胺都存在于神经节中，并在靠近虹吸感觉神经元的过程中发现，这表明这些递质可能参与行为敏化。最近的证据表明，一组确定的易化中间神经元，L29细胞，似乎不包含SCP或5-羟色胺，但可能使用另一种易化递质。几种递质可以会聚在防御性退缩反射的感觉神经元中产生突触前易化。这里研究的所有递质，SCP和5-羟色胺，都通过相同的分子级联起作用：cAMP依赖性关闭S-K+通道，扩大突触前动作电位，促进递质释放。
Two endogenous neuropeptides in Aplysia, the small cardioactive peptides SCPA and SCPB, facilitate synaptic transmission from siphon mechanosensory neurons and enhance the defensive withdrawal reflex that these sensory neurons mediate. Single-channel recording revealed that these peptides close a specific K+ channel, the S channel, which is sensitive to cAMP. The peptides increase cAMP levels in these sensory neurons. This reduction in K+ current slows the repolarization of the action potential in these cells, which increases transmitter release. In these actions, the SCP resemble both noxious sensitizing stimuli, which enhance the reflex, and serotonin. Bioassay of HPLC [high-performance liquid chromatography] fractions of abdominal ganglion extracts and immunocytochemistry indicate that both the SCP and serotonin are present in the ganglion and are found in processes close to the siphon sensory neurons, suggesting that these transmitters may be involved in behavioral sensitization. Recent evidence suggests that one group of identified facilitatory interneurons, the L29 cells, does not appear to contain either the SCP or serotonin but may use yet another facilitatory transmitter. Several transmitters can converge to produce presynaptic facilitation in the sensory neurons of the defensive withdrawal reflex. All of the transmitters studied here, the SCP and serotonin, act via an identical molecular cascade: cAMP-dependent closure of the S-K+ channel, broadening of the presynaptic action potential, and facilitation of transmitter release.