Amygdalar NMDA Receptors are Critical for New Fear Learning in Previously Fear-Conditioned Rats
Amygdalar NMDA Receptors are Critical for New Fear Learning in Previously Fear-Conditioned Rats
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DOI：
10.1523/jneurosci.18-20-08444.1998
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发表时间：
1998-10
期刊：
影响因子：
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通讯作者：
Hongjoo J. Lee;J. J. Kim-J.
中科院分区：
文献类型：
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作者：
Hongjoo J. Lee;J. J. Kim-J.
杏仁核中的NMDA受体似乎对幼年大鼠的恐惧条件作用至关重要。最近的空间学习研究表明，先前的学习保护动物免受NMDA拮抗剂对新学习(类似行为任务)的遗忘效应的影响。因此，本研究调查了阻断杏仁基底外侧核(BLA)的NMDA受体是否阻止了先前恐惧条件下大鼠的新恐惧学习，这是通过冰冻行为来衡量的。在白血球体内注射NMDA受体拮抗剂1-2-氨基-5-磷酸丙戊酸(APV)，完全阻断了先前对光刺激产生恐惧条件的动物对音调刺激的恐惧条件反射。在对不同环境产生恐惧的大鼠进行情境恐惧条件化之前，在白血球内注射APV，也得到了类似的结果。其他实验表明，白血球内注射APV实质上干扰了对音调、光线和背景刺激的条件性恐惧的表达和消退。综上所述，这些结果表明，BLA中的NMDA受体对于编码新的恐惧记忆(即形成特定的条件刺激-无条件刺激联想)、表达条件恐惧反应和消除获得性恐惧是至关重要的。
NMDA receptors in the amygdala seem to be critical for fear conditioning in naive rats. Recent spatial-learning studies suggest that previous learning protected animals from the amnesic effect of NMDA antagonists on new learning (of a similar behavioral task). Therefore, the present study examined whether blocking of NMDA receptors in the basolateral nucleus of the amygdala (BLA) prevents new fear learning in previously fear-conditioned rats, as measured by freezing behavior. Intra-BLA infusions of the NMDA receptor antagonistdl-2-amino-5-phosphonovaleric acid (APV) completely blocked fear conditioning to a tone stimulus in animals that had previously been fear-conditioned to a light stimulus. Similar results were obtained with intra-BLA infusions of APV before contextual fear conditioning in rats that had been fear-conditioned to a different context. Additional experiments showed that intra-BLA APV infusions substantially interfere with the expression and extinction of conditioned fear to tone, light, and context stimuli. Together, these results indicate that NMDA receptors in the BLA are crucial for the encoding of new fear memories (i.e., the formation of specific conditioned stimulus–unconditioned stimulus association), the expression of conditioned fear responses, and the extinction of acquired fear.