多巴胺 D1/D5 受体的激活促进了海马传出突触的突触前长时程增强诱导。
Activation of dopamine D1/D5 receptors facilitates the induction of presynaptic long-term potentiation at hippocampal output synapses.
机构信息
Department of Psychiatry and Psychotherapy, Charité- Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany.
出版信息
Eur J Neurosci. 2010 Aug;32(4):598-605. doi: 10.1111/j.1460-9568.2010.07312.x. Epub 2010 Jul 14.
Encoding of novel information has been proposed to rely on the time-locked release of dopamine in the hippocampal formation during novelty detection. However, the site of novelty detection in the hippocampus remains a matter of debate. According to current models, the CA1 and the subiculum act as detectors and distributors of novel sensory information. Although most CA1 pyramidal neurons exhibit regular-spiking behavior, the majority of subicular pyramidal neurons fire high-frequency bursts of action potentials. The present study investigates the efficacy of dopamine D1/D5 receptor activation to facilitate the induction of activity-dependent long-term potentiation (LTP) in rat CA1 regular-spiking and subicular burst-spiking pyramidal cells. Using a weak stimulation protocol, set at a level subthreshold for the induction of LTP, we show that activation of D1/D5 receptors for 5-10 min facilitates LTP in subicular burst-spiking neurons but not in CA1 neurons. The results demonstrate that D1/D5 receptor-facilitated LTP is NMDA receptor-dependent, and requires the activation of protein kinase A. In addition, the D1/D5 receptor-facilitated LTP is shown to be presynaptically expressed and relies on presynaptic Ca(2+) signaling. The phenomenon of dopamine-induced facilitation of presynaptic NMDA receptor-dependent LTP in subicular burst-spiking pyramidal cells is in accordance with observations of the time-locked release of dopamine during novelty detection in this brain region, and reveals an intriguing mechanism for the encoding of hippocampal output information.
新信息的编码被认为依赖于新奇检测过程中海马结构中多巴胺的时锁释放。然而,海马体中新奇检测的部位仍然存在争议。根据当前的模型,CA1 和 subiculum 充当新奇感觉信息的检测器和分配器。虽然大多数 CA1 锥体神经元表现出规则放电行为,但大多数 subicular 锥体神经元发射高频动作电位爆发。本研究调查了多巴胺 D1/D5 受体激活对促进大鼠 CA1 规则放电和 subicular 爆发放电锥体神经元的活动依赖性长时程增强(LTP)诱导的效果。使用弱刺激方案,设置在诱导 LTP 的阈下水平,我们表明,D1/D5 受体的激活 5-10 分钟可促进 subicular 爆发放电神经元中的 LTP,但不能促进 CA1 神经元中的 LTP。结果表明,D1/D5 受体促进的 LTP 依赖于 NMDA 受体,需要蛋白激酶 A 的激活。此外,D1/D5 受体促进的 LTP 是突触前表达的,并依赖于突触前 Ca2+信号。多巴胺诱导的 subicular 爆发放电锥体神经元中突触前 NMDA 受体依赖性 LTP 的易化现象与该脑区新奇检测过程中多巴胺时锁释放的观察结果一致,并揭示了一种令人着迷的海马体输出信息编码机制。