GABAergic excitation in the basolateral amygdala.
GABA-containing interneurons are a diverse population of cells whose primary mode of action in the mature nervous system is inhibition of postsynaptic target neurons. Using paired recordings from parvalbumin-positive interneurons in the basolateral amygdala, we show that, in a subpopulation of interneurons, single action potentials in one interneuron evoke in the postsynaptic interneuron a monosynaptic inhibitory synaptic current, followed by a disynaptic excitatory glutamatergic synaptic current. Interneuron-evoked glutamatergic events were blocked by antagonists of either AMPA/kainate or GABA(A) receptors, and could be seen concurrently in both presynaptic and postsynaptic interneurons. These results show that single action potentials in a GABAergic interneuron can drive glutamatergic principal neurons to threshold, resulting in both feedforward and feedback excitation. In interneuron pairs that both receive glutamatergic inputs after an interneuron spike, electrical coupling and bidirectional GABAergic connections occur with a higher probability relative to other interneuron pairs. We propose that this form of GABAergic excitation provides a means for the reliable and specific recruitment of homogeneous interneuron networks in the basal amygdala.
Woodruff
Alan R
AR
Queensland Brain Institute and School of Biomedical Sciences, University of Queensland, 4072 Brisbane, Australia.
Monyer
Hannah
H
Sah
Pankaj
P
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000679:Amygdala / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D005246:Feedback / Q000502:physiology; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists; D018698:Glutamic Acid / Q000378:metabolism; D007395:Interneurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D009415:Nerve Net / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009924:Organ Culture Techniques; D010320:Parvalbumins / Q000378:metabolism; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D058787:GABA-A Receptor Antagonists; D010320:Parvalbumins; D018091:Receptors, AMPA; D011963:Receptors, GABA-A; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid