Muscle nicotinic acetylcholine receptor (adult) (nAChR)

The adult muscle nicotinic acetylcholine receptor (nAChR) is a specialized pentameric ligand-gated ion channel located on the postsynaptic membrane of the neuromuscular junction (UniProt, 2024). It is composed of four distinct subunit types in a specific stoichiometry of two alpha-1, one beta-1, one delta, and one epsilon subunit (α1₂β1δε), which distinguishes it from the fetal isoform containing a gamma subunit (NCBI, 2023). Its primary biological role is to mediate fast excitatory transmission by converting chemical signals from the motor neuron into electrical signals in the muscle fiber. Upon binding of the neurotransmitter acetylcholine, the channel opens to allow the rapid influx of sodium ions, leading to membrane depolarization and subsequent muscle contraction (StatPearls, 2023). In clinical practice, this receptor is the primary target of neuromuscular blocking agents used to facilitate endotracheal intubation and provide muscle relaxation during surgical procedures. Pathologically, it is the major target of autoimmune attacks in Myasthenia Gravis, where autoantibodies block or lead to the degradation of the receptors, resulting in profound muscle weakness (NIH, 2023).

Other names

Muscle-type nicotinic acetylcholine receptorAdult muscle nAChRNeuromuscular nicotinic acetylcholine receptorCHRNAChR

Drugs targeting this receptor act as either depolarizing agonists (e.g., succinylcholine) that cause persistent activation and subsequent desensitization of the receptor, or non-depolarizing competitive antagonists (e.g., rocuronium) that block acetylcholine from binding to the alpha subunits, both of which result in the inhibition of neuromuscular transmission and skeletal muscle relaxation (StatPearls, 2023).