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.
Mahanty
N K
NK
The Neuroscience Group, Faculty of Medicine and Health Sciences, University of Newcastle, NSW, Australia.
Sah
P
P
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