Glutamate and GABA_B transmissions in lateral amygdala are involved in startle-like electromyographic (EMG) potentiation caused by activation of auditory thalamus

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• 作者：He ; Shuchang ; Huang ; Juan ; Wu ; Xihong ; Li ; Liang
• 关键词：Startle potentiation ; Lateral amygdala nucleus ; Medial geniculate nucleus ; Auditory association cortex ; Glutamate receptors ; GABA_B receptors
• 刊名：Neuroscience Letters
• 出版年：2005
• 出版时间：February 10, 2005
• 年：2005
• 卷：374
• 期：2
• 页码：113-118
• 全文大小：282 K

文摘

The lateral amygdala nucleus (LA) receives auditory inputs from both the auditory thalamus (medial geniculate nucleus, MGN) and auditory association cortex (AAC). These auditory inputs are closely linked with glutamate and GABA_B receptors in the LA. The LA has intra-amygdaloid connections with the central amygdala nucleus, which mediates auditory fear potentiation of startle (AFPS) via pathways to the startle circuits. The purpose of the present study was to establish an electromyographic (EMG) model for studying AFPS-related neural transmissions in the LA. Hind-limb startle-like EMG responses to single-pulse electrical stimulation of the trigeminal nucleus (TN) were recorded in anesthetized rats. These EMG responses were enhanced by single-pulse sub-threshold electrical stimulation of the MGN when the MGN stimulus led the TN stimulus at short inter-stimulus intervals (ISI). However, the EMG responses were not affected by single-pulse sub-threshold electrical stimulation of the AAC. Bilateral injection of the glutamate antagonist, kynurenic acid, into the LA decreased both the EMG enhancement caused by MGN stimulation at short ISIs and EMG responses to combined TN and AAC stimulation across various ISIs. Moreover, bilateral injection of the GABA_B antagonist, phaclofen, into the LA increased both EMG responses to combined TN and MGN stimulation across various ISIs, and EMG responses to combined TN and AAC stimulation at short ISIs. These results suggest that the auditory inputs to the LA from the MGN and those from the AAC are affected differently by glutamate and GABA_B receptors in the LA, and play differential roles in modulating startle responses.