Alpha-2A adrenergic receptor, Alpha-2B adrenergic receptor, Alpha-2C adrenergic receptor (ADRA2A, ADRA2B, ADRA2C)

The alpha-2A, alpha-2B, and alpha-2C adrenergic receptors are three closely related subtypes of G protein-coupled receptors that respond to catecholamines such as norepinephrine and epinephrine. They mediate their effects by coupling to inhibitory Gi/o proteins, resulting in decreased cyclic AMP levels and neuronal inhibition. The receptors are distributed in different tissues: alpha-2A and alpha-2C are mainly found in the central nervous system, mediating sedation, analgesia, and sympatholysis, while alpha-2B is more prominent in vascular smooth muscle, promoting vasoconstriction. These receptors are important therapeutic targets, underpinning the clinical use of drugs for hypertension, sedation, anesthesia, and psychiatric disorders. Their functions are shaped by genetic variation, tissue expression, and drug subtype selectivity, which influence therapeutic efficacy and side effect risk.

Other names

Alpha-2A adrenoceptorAlpha-2B adrenoceptorAlpha-2C adrenoceptorα2A-adrenergic receptorα2B-adrenergic receptorα2C-adrenergic receptorADRA2AADRA2BADRA2Cα2A ARα2B ARα2C AR

Agonists: Bind and activate α2 adrenergic receptor, coupling to Gi/o, inhibit adenylyl cyclase, lead to reduced cAMP, neuronal hyperpolarization, decreased neurotransmitter release, sympatholytic, sedative, and analgesic effects. Antagonists: Bind and block receptor, prevent negative feedback on norepinephrine release or other catecholamines, lead to increased neurotransmitter availability and smooth muscle relaxation. Subtype selectivity can mediate specific therapeutic/safety profiles.