Kaplan Michael P, Wilcox Karen S, Dichter Marc A
Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Synapse. 2003 Oct;50(1):41-52. doi: 10.1002/syn.10244.
Synaptic transmission is highly dynamic, especially during periods of repetitive activity. This short-term synaptic plasticity, elicited by either pairs or short trains of action potentials at moderate frequencies (1-10 Hz), may give rise to either depression or facilitation of synaptic transmission. We analyzed these processes in isolated, synaptically coupled pairs of inhibitory or excitatory neurons grown in low-density cultures of hippocampal neurons. Most inhibitory and excitatory synapses in these cultures displayed paired pulse depression, although the responses of excitatory synapses were more variable and occasionally facilitation was seen. With tetanic stimuli, inhibitory synapses showed depression, but excitatory synapses showed a much richer repertoire of behaviors, including depression and facilitation. While many inhibitory synapses showed posttetanic depression following short trains of action potentials, excitatory synapses instead showed posttetanic facilitation. This facilitation is accompanied by an increase in paired pulse ratio, suggesting that it is the result of presynaptic mechanisms. Finally, excitatory synapses often displayed paired pulse and tetanic facilitation of asynchronous release, a process not seen in inhibitory synapses in these cultures. These similarities and differences in short-term plasticity exhibited by inhibitory and excitatory cells are likely to be critical for information processing and the control of neuronal excitability, under both normal and pathological conditions, such as epilepsy.
突触传递具有高度动态性，尤其是在重复活动期间。由中等频率（1-10赫兹）的成对或短串动作电位引发的这种短期突触可塑性，可能导致突触传递的抑制或易化。我们在海马神经元低密度培养物中生长的分离的、突触耦合的抑制性或兴奋性神经元对中分析了这些过程。这些培养物中的大多数抑制性和兴奋性突触表现出成对脉冲抑制，尽管兴奋性突触的反应更具变异性，偶尔也会出现易化。强直刺激时，抑制性突触表现出抑制，但兴奋性突触表现出更丰富的行为模式，包括抑制和易化。虽然许多抑制性突触在短串动作电位后表现出强直后抑制，但兴奋性突触则表现出强直后易化。这种易化伴随着成对脉冲比率的增加，表明它是突触前机制的结果。最后，兴奋性突触经常表现出成对脉冲和强直刺激对异步释放的易化，这一过程在这些培养物中的抑制性突触中未见。抑制性和兴奋性细胞在短期可塑性方面的这些异同，在正常和病理条件下，如癫痫，对于信息处理和神经元兴奋性的控制可能至关重要。
