Alpha-3 nicotinic acetylcholine receptor (CHRNA3) (α3* nAChR)

The alpha-3 nicotinic acetylcholine receptor (α3* nAChR) is a subtype of ligand-gated ion channel primarily expressed in the autonomic ganglia, adrenal medulla, and specific regions of the central nervous system such as the medial habenula (UniProt: P32297). It typically functions as a heteromeric pentamer, most commonly composed of α3 and β4 subunits, which mediates fast excitatory synaptic transmission through the influx of cations like sodium and calcium (PubMed: 21840572). This receptor plays a pivotal role in regulating the autonomic nervous system, thereby influencing heart rate, blood pressure, and gastrointestinal motility. Clinically, the α3* nAChR is a major focus in addiction and oncology research, as genetic variations in the CHRNA3 gene cluster are strongly associated with nicotine dependence, lung cancer risk, and chronic obstructive pulmonary disease (PubMed: 18391951). Pharmacological targeting of this receptor involves agonists like nicotine and partial agonists like varenicline for smoking cessation, as well as antagonists like mecamylamine for autonomic research (PubChem: CID 89594). However, the development of α3*-selective drugs is challenging due to the risk of systemic autonomic side effects, including cardiovascular instability and gastrointestinal distress.

Other names

CHRNA3Neuronal acetylcholine receptor subunit alpha-3Cholinergic receptor nicotinic alpha 3 subunitL-nicotinic acetylcholine receptor alpha-3 subunit

Agonism (opening of the cation channel leading to depolarization), partial agonism (limited channel opening), and non-competitive antagonism (channel pore blockade) (PubMed: 21840572).