Calcium-permeable AMPA receptors mediate long-term potentiation in interneurons in the amygdala.
Fear conditioning is a paradigm that has been used as a model for emotional learning in animals. The cellular correlate of fear conditioning is thought to be associative N-methyl-D-aspartate (NMDA) receptor-dependent synaptic plasticity within the amygdala. Here we show that glutamatergic synaptic transmission to inhibitory interneurons in the basolateral amygdala is mediated solely by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. In contrast to AMPA receptors at inputs to pyramidal neurons, these receptors have an inwardly rectifying current-voltage relationship, indicative of a high permeability to calcium. Tetanic stimulation of inputs to interneurons caused an immediate and sustained increase in the efficacy of these synapses. This potentiation required a rise in postsynaptic calcium, but was independent of NMDA receptor activation. The potentiation of excitatory inputs to interneurons was reflected as an increase in the amplitude of the GABA(A)-mediated inhibitory synaptic current in pyramidal neurons. These results demonstrate that excitatory synapses onto interneurons within a fear conditioning circuit show NMDA-receptor independent long-term potentiation. This plasticity might underlie the increased synchronization of activity between neurons in the basolateral amygdala after fear conditioning.
The Neuroscience Group, Faculty of Medicine and Health Sciences, University of Newcastle, NSW, Australia.
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D000679:Amygdala / Q000166:cytology / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D003214:Conditioning, Classical / Q000502:physiology; D004594:Electrophysiology; D005071:Evoked Potentials; D005239:Fear / Q000502:physiology; D066298:In Vitro Techniques; D007395:Interneurons / Q000502:physiology*; D017774:Long-Term Potentiation / Q000502:physiology*; D009433:Neural Inhibition; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000737:chemistry / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D005680:gamma-Aminobutyric Acid; C104722:glutamate receptor ionotropic, AMPA 2; D011188:Potassium; D002118:Calcium