Amygdalic levels of dopamine and serotonin rise upon exposure to conditioned fear stress without elevation of glutamate
Amygdalic levels of dopamine and serotonin rise upon exposure to conditioned fear stress without elevation of glutamate
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DOI：
10.1016/j.neulet.2004.12.047
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发表时间：
2005-04
影响因子：
2.5
通讯作者：
M. Yokoyama;E. Suzuki;Taku Sato;Shuji Maruta;Shigeru Watanabe;H. Miyaoka
中科院分区：
文献类型：
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作者：
M. Yokoyama;E. Suzuki;Taku Sato;Shuji Maruta;Shigeru Watanabe;H. Miyaoka
条件性恐惧是一种人为的压力，由一种刺激(如音调)引起，在本质上不会引起恐惧。当音调与无条件刺激相结合时，这种恐惧反应是由实验动物获得的，比如脚部电击。杏仁核被认为是与获得、巩固和回忆恐惧有关的区域。之前的一系列药理学研究表明，多巴胺D1和D2、谷氨酸N-甲基-D-天冬氨酸和(±)-α-amino-3-hydroxy-5-methylisoxazole-4-propionic酸受体的拮抗剂可以防止获得条件性恐惧。然而，当条件性恐惧被习得和回忆起来时，人们对释放的神经递质类型知之甚少。本研究旨在利用体内微透析方法，连续监测杏仁核细胞外谷氨酸、多巴胺和5-羟色胺水平的变化，在第一天获得条件性恐惧时，以及在第二天对作为条件刺激的音调做出反应时，监测恐惧回忆的变化。谷氨酸只在第一天升高，而多巴胺和5-羟色胺在两天都上升。在第一天，多巴胺和5-羟色胺升高的时间比第二天更长。这些结果表明，与回忆条件性恐惧相比，获取更多的谷氨酸、多巴胺和5-羟色胺是必要的。
Conditioned fear is an artificial stress, induced by a stimulus, such as a tone, that does not elicit fear in nature. This fear response is acquired by experimental animals when tone is combined with an unconditioned stimulus, such as electrical foot shock. The amygdala is considered to be the area involved in acquisition, consolidation and recall of fear. A series of previous pharmacological studies showed antagonists of dopamine D1and D2, glutamate N-methyl-d-asparatate and (±)-α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors to prevent the acquisition of conditioned fear. However, little is known about the types of neurotransmitters released when conditioned fear is acquired and recalled. The present study was designed to continuously monitor changes in extracellular levels of glutamate, dopamine and serotonin in the amygdala, at the acquisition of conditioned fear on Day 1 and at fear recall in response to a tone as a conditioned stimulus on Day 2, using the in vivo microdialysis method. Glutamate was elevated only on Day 1, while dopamine and serotonin rose on both days. The periods of elevated dopamine and serotonin were longer on Day 1 than on Day 2. These results suggest that greater amounts of glutamate, dopamine and serotonin are necessary for acquisition than for recall of conditioned fear.