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Short Communication

Exp Neurobiol 2019; 28(3): 320-328

Published online June 26, 2019

© The Korean Society for Brain and Neural Sciences

Basal Forebrain Cholinergic-induced Activation of Cholecystokinin Inhibitory Neurons in the Basolateral Amygdala

Seungho Lee, and Joung-Hun Kim*

Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea.

Correspondence to: *To whom correspondence should be addressed.
TEL: 82-54-279-2347, FAX: 82-54-279-5969

Received: April 22, 2019; Revised: May 28, 2019; Accepted: May 31, 2019

The basolateral amygdala (BLA) receives dense projections from cholinergic neurons of the basal forebrain. Acetylcholine can contributes to amygdala-dependent behaviors: formation and extinction of fear memory and appetitive instrumental learning. However, the cholinergic mechanism at the circuit level has not been defined yet. We demonstrated that cholinergic-induced di-synaptic inhibition of BLA pyramidal neurons exhibits a retrograde form of short-term synaptic inhibition, depolarization-induced suppression of inhibition (DSI). Activation of nicotinic receptors was sufficient to evoke action potentials in cholecystokinin (CCK)-positive inhibitory neurons, which strongly inhibit pyramidal neurons through their perisomatic synapses. Our cell type-specific monosynaptic retrograde tracing also revealed that CCK neurons are innervated by basal forebrain cholinergic neurons. Therefore, our data indicated that CCK inhibitory neurons mediate the cholinergic-induced di-synaptic inhibition of BLA pyramidal neurons.

Graphical Abstract

Keywords: Cholecystokinin, Acetylcholine, Di-synaptic inhibition, Basolateral amygdala, Iontophoresis, Retrograde tracing