Sun Z Y, Schacher S
Center for Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, and New York State Psychiatric Institute, New York, New York 10032, USA.
J Neurosci. 1998 Jun 1;18(11):3991-4000. doi: 10.1523/JNEUROSCI.18-11-03991.1998.
Long-term changes in the efficacy of Aplysia sensorimotor synapses accompany nonassociative and associative forms of behavioral plasticity. This synapse expresses long-term facilitation either with repeated applications of 5-hydroxytryptamine (5-HT) or with a single pairing of tetanus in the sensory neuron (SN) and bath application of 5-HT. We examined whether structural changes in the SN accompany all forms of long-term synaptic enhancement and the locations at which 5-HT must bind receptors to evoke long-term functional and/or structural changes. Pairing tetanus with one application of 5-HT evoked both functional and structural changes after 24 hr only when 5-HT application was temporally paired with the tetanus and activated receptors on both the SN cell body and terminal region. Repeated application of 5-HT to the terminal region alone failed to evoke any long-term change. Repeated applications of 5-HT to the SN cell body alone evoked a change in synaptic efficacy at 24 hr but failed to increase SN varicosities. Repeated applications of 5-HT to both the SN cell body and the terminal region evoked increases in both synaptic efficacy and the number of SN varicosities at 24 hr. The results indicate that different external stimuli can evoke equivalent forms of long-term synaptic facilitation with or without structural changes in the SNs. Changes in the number of SN varicosities can accompany different forms of long-term facilitation and require the activation of 5-HT receptors at multiple sites.
海兔感觉运动突触效能的长期变化伴随着非联合性和联合性形式的行为可塑性。该突触在重复应用5-羟色胺(5-HT)或在感觉神经元(SN)中单次配对强直刺激并在浴液中应用5-HT时表现出长期易化。我们研究了SN中的结构变化是否伴随着所有形式的长期突触增强,以及5-HT必须结合受体以引发长期功能和/或结构变化的位置。仅当5-HT的应用在时间上与强直刺激配对并激活SN细胞体和终末区域的受体时,将强直刺激与一次5-HT应用配对在24小时后才会引起功能和结构变化。仅对终末区域重复应用5-HT未能引发任何长期变化。仅对SN细胞体重复应用5-HT在24小时时引起突触效能的变化,但未能增加SN曲张体。对SN细胞体和终末区域都重复应用5-HT在24小时时引起突触效能和SN曲张体数量的增加。结果表明,不同的外部刺激可以引发等效形式的长期突触易化,无论SN中是否有结构变化。SN曲张体数量的变化可以伴随着不同形式的长期易化,并且需要在多个位点激活5-HT受体。