Dale N, Kandel E R, Schacher S
J Neurosci. 1987 Jul;7(7):2232-8. doi: 10.1523/JNEUROSCI.07-07-02232.1987.
When isolated and grown in cell culture, the sensory and motor neurons of the gill withdrawal reflex of Aplysia readily form synaptic connections. Repeated exposures to 5-HT cause facilitation of the synaptic connections between co-cultured sensory and motor neurons lasting at least 24 hr. As a first step toward understanding the locus and the mechanisms underlying this long-term synaptic facilitation, we have examined the membrane excitability of the isolated presynaptic sensory neurons grown alone in dissociated cell culture. Four repeated applications of 1 microM 5-HT caused a significant increase in the excitability of sensory neurons, lasting at least 24 hr. This resembles the short-term changes in excitability seen in response to a single application of 5-HT. Unlike the short-term effect, this long-lasting change was blocked by exposure of the cells during the 5-HT treatment to 10 microM anisomycin, an inhibitor of protein synthesis. Thus, like the synaptic facilitation, the long-term change in excitability of the isolated presynaptic neurons differs from the short-term in requiring the synthesis of new protein. This finding suggests that the sensory neuron uses gene products to modulate membrane currents in its long-term response to repeated external stimuli that are not required in its short-term response to a single stimulus.
当分离出来并在细胞培养中生长时，海兔鳃收缩反射的感觉神经元和运动神经元很容易形成突触连接。反复暴露于5-羟色胺（5-HT）会导致共培养的感觉神经元和运动神经元之间的突触连接增强，持续至少24小时。作为理解这种长期突触增强的位点和机制的第一步，我们研究了在解离细胞培养中单独生长的分离的突触前感觉神经元的膜兴奋性。四次重复应用1微摩尔/升的5-HT会导致感觉神经元的兴奋性显著增加，持续至少24小时。这类似于单次应用5-HT时观察到的兴奋性短期变化。与短期效应不同，这种长期变化在5-HT处理期间通过将细胞暴露于10微摩尔/升茴香霉素（一种蛋白质合成抑制剂）而被阻断。因此，与突触增强一样，分离的突触前神经元兴奋性的长期变化与短期变化不同，它需要合成新的蛋白质。这一发现表明，感觉神经元利用基因产物来调节膜电流，以应对反复的外部刺激，而短期对单个刺激的反应则不需要这些基因产物。
