Role of nicotinic acetylcholine receptors for modulation of microcircuits in the agranular insular cortex

Abstract

Background: Acetylcholine (ACh) plays key roles in regulating neuronal excitability throughout the brain by acting muscarinic ACh receptors (mAChRs) and nicotinic ACh receptors (nAChRs). The insular cortex is an important brain region associated with sensory perception, self-awareness, cognitive function, motor control, and drug addiction. The insular cortex receives cholinergic inputs from the basal forebrain, the activation of which stimulates mAChRs and nAChRs in the insular cortex and modulates its microcircuits to perform various functions. Therefore, it is crucial to understand the cholinergic modulation of microcircuits in the insular cortex. To date, we have been focused on the role of nAChRs in modulating neural circuits in the mouse agranular insular cortex.

Highlight: In this review, we present data on cholinergic inputs to neocortical regions, including the insular cortex, and characteristics of mAChRs and nAChRs. In addition, we describe which type of neurons express functional nAChRs in layer III, V, and VI of the mouse agranular insular cortex and how activation of nAChRs regulates synaptic transmission and plasticity in the layer III, V, and VI pyramidal cells.

Conclusion: The activation of nAChRs layer specifically modulates synaptic transmission and plasticity in the mouse agranular insular cortex. These synaptic mechanisms are critical to understand the modulating effects of ACh or nicotine on physiological and pathophysiological functions associated with the insular cortex.

Keywords: insular cortex; long-term depression; long-term potentiation; nicotinic acetylcholine receptor; synaptic transmission.