Neuronal nicotinic acetylcholine receptors (nAChRs)

Neuronal nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels composed of five subunits (alpha and beta) with four transmembrane domains each, arranged around a central pore. These receptors are found throughout the central and peripheral nervous systems and respond to acetylcholine binding by opening a cation-selective channel permeable to Na+, K+, and sometimes Ca2+. In the brain, they are typically located presynaptically or perisynaptically, modulating neuronal excitability, regulating neurotransmitter release, and influencing neuronal integration. Unlike muscle nAChRs, CNS neuronal nAChRs have subtle modulatory functions. Different subunit combinations (e.g., α4β2, α7, α3β4) form diverse receptor subtypes with varying distributions and functional properties, implicated in disorders such as Alzheimer's disease, schizophrenia, and autism spectrum disorders. This makes them important therapeutic targets, with ongoing development of drugs like partial agonists and positive allosteric modulators. Their pharmacology is complex, involving interactions with endogenous ligands, therapeutic drugs, and natural toxins like α-conotoxins and α-bungarotoxin.

Neuronal nAChRs function as ligand-gated ion channels that open a cation-selective pore upon acetylcholine binding, allowing Na+, K+, and in some cases Ca2+ to flow, generating electrical signals. In the CNS, they primarily modulate neurotransmission. Therapeutic strategies involve targeting these receptors with agonists, partial agonists, or positive allosteric modulators to influence channel activity and neuronal function.