Neurogliaform cells of amygdala: a source of slow phasic inhibition in the basolateral complex.

Mirosława Mańko, Thomas C.M. Bienvenu, Yannis Dalezios, Marco Capogna
The Journal of Physiology. 2012-10-19; 590(22): 5611-5627
DOI: 10.1113/jphysiol.2012.236745

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Synaptic inhibition in the amygdala actively participates in processing emotional
information. To improve the understanding of interneurons in amygdala networks it
is necessary to characterize the GABAergic cell types, their connectivity and
physiological roles. We used a mouse line expressing a green fluorescent protein
(GFP) under the neuropeptide Y (NPY) promoter. Paired recordings between
presynaptic NPY-GFP-expressing (+) cells and postsynaptic principal neurons (PNs)
of the basolateral amygdala (BLA) were performed. The NPY-GFP+ neurons displayed
small somata and short dendrites embedded in a cloud of highly arborized axon,
suggesting a neurogliaform cell (NGFC) type. We discovered that a NPY-GFP+ cell
evoked a GABA(A) receptor-mediated slow inhibitory postsynaptic current (IPSC) in
a PN and an autaptic IPSC. The slow kinetics of these IPSCs was likely caused by
the low concentration and spillover of extracellular GABA. We also report that
NGFCs of the BLA fired action potentials phase-locked to hippocampal theta
oscillations in anaesthetized rats. When this firing was re-played in NPY+-NGFCs
in vitro, it evoked a transient depression of the IPSCs. Presynaptic GABA(B)
receptors and functional depletion of synaptic vesicles determined this
short-term plasticity. Synaptic contacts made by recorded NGFCs showed close
appositions, and rarely identifiable classical synaptic structures. Thus, we
report here a novel interneuron type of the amygdala that generates volume
transmission of GABA. The peculiar functional mode of NGFCs makes them unique
amongst all GABAergic cell types of the amygdala identified so far.


Auteurs Bordeaux Neurocampus