Excitatory Synaptic Transmission in the Lateral and Central Amygdala

Abstract

The amygdala plays a major role in the acquisition and expression of fear conditioning. NMDA receptor‐dependent synaptic plasticity within the basolateral amygdala has been proposed to underlie the acquisition and possible storage of fear memories. Here the properties of fast glutamatergic transmission in the lateral and central nuclei of the amygdala are presented. In the lateral amygdala, two types of neurons, interneurons and projection neurons, could be distinguished by their different firing properties. Glutamatergic inputs to interneurons activated AMPA receptors with inwardly rectifying current‐voltage relations (I‐Vs), whereas inputs to projection neurons activated receptors that had linear I‐Vs, indicating that receptors on interneurons lack GluR2 subunits. Inputs to projection neurons formed dual component synapses with both AMPA and NMDA components, whereas at inputs to interneurons, the contribution of NMDA receptors was very small. Neurons in the central amygdala received dual component glutamatergic inputs that activated AMPA receptors with linear I‐Vs. NMDA receptor‐mediated EPSCs had slow decay time constants in the central nucleus. Application of NR2B selective blockers ifenprodil or CP‐101,606 blocked NMDA EPSCs by 70% in the central nucleus, but only by 30% in the lateral nucleus. These data show that the distribution of glutamatergic receptors on amygdalar neurons is not uniform. In the lateral amygdala, interneurons and pyramidal neurons express AMPA receptors with different subunit compositions. Synapses in the central nucleus activate NMDA receptors that contain NR1 and NR2B subunits, whereas synapses in the lateral nucleus contain receptors with both NR2A and NR2B subunits.

Chronic ethanol ingestion modulates proanxiety factors expressed in rat central amygdala

“…In addition, if one assumes approximately equivalent efficiencies for the various subunit PCR reactions, the C T values for each subunit ( Table 1) would suggest that the relative abundance of NR subunit mRNAs in the central amygdala would be NR1 = NR2B >NR2A >> NR2C = NR3A > NR3B > NR2D. This is consistent with recent reports suggesting the NR2B-containing receptors contribute significantly to adult central amygdala NMDA receptor-mediated synaptic responses (Sah & Lopez De Armentia, 2003). The differences between subunit C T values in the central amygdala samples (Table 1) would further suggest that NR2A, NR2C, and NR3A subunit mRNAs are relatively less abundant in the central amygdala compared to their expression in the forebrain.…”

Lack of the presynaptic RhoGAP protein oligophrenin1 leads to cognitive disabilities through dysregulation of the cAMP/PKA signalling pathway

“…Whole-cell current-and voltage-clamp recordings were obtained from LA principal neurons located in the dorsal subdivision of the LA [26][27][28]. Monosynaptic EPSCs or EPSPs at thalamo-LA and cortico-LA synapses were elicited by stimulating fibres from the internal capsule, containing thalamic afferents or from the external capsule, containing cortical afferents (figure 2a) [29].…”

A remote and highly conserved enhancer supports amygdala specific expression of the gene encoding the anxiogenic neuropeptide substance-P

“…76,77 The serotonin and dopamine receptors are also known to be expressed in neurones of the CeA and MeA and have been shown to mediate their effects through a cAMP/ PKA signal transduction pathway. Modulation of ECR1 activity may also be subject to control via aminergic pathways such as glutamate that is known to influence mood through NMDA receptors that are expressed in the CeA (NR1 and NR2B) 78 and which are also known to influence fear related learning 79 via the cAMP/PKA signal transduction pathway. 80 In addition, the amygdala contains the receptors of various endocrine compounds such as glucocorticoids and epinephrine that are known to be elevated during the stress response and bind to members of the glucocorticoid receptor family and the adrenoceptors.…”