Alpha-2A, Alpha-2B, and Alpha-2C adrenergic receptors (α2A-AR, α2B-AR, α2C-AR)

The alpha-2A, alpha-2B, and alpha-2C adrenergic receptors are closely related G protein-coupled receptor subtypes that mediate many actions of the endogenous catecholamines norepinephrine and epinephrine in the central and peripheral nervous systems. Alpha-2A is the predominant subtype in the brain, controlling sympathetic outflow and mediating antihypertensive effects; alpha-2B is important in peripheral vascular responses; alpha-2C modulates stress, startle, and locomotion, and is involved in longer-term suppression of neurotransmitter release. Drugs that target these receptors are used to treat hypertension, attention-deficit disorders, pain syndromes, anxiety, and withdrawal states, and provide sedation during surgical procedures. Despite therapeutic benefits, adverse effects like excessive sedation, hypotension, and risk of withdrawal symptoms must be managed carefully.

Other names

α2A adrenoceptorα2B adrenoceptorα2C adrenoceptorα2-adrenoceptor subtypesAlpha-2-AR subtypesAlpha-2 adrenergic receptor subtypes

Agonists stimulate presynaptic α2 adrenergic receptors in the CNS and peripheral nervous system, inhibiting norepinephrine release and lowering sympathetic tone. Decrease in blood pressure and heart rate by reducing sympathetic outflow. Analgesia and sedation via CNS modulation. Reversal of effects (Antagonists, e.g., atipamezole) restores normal sympathetic outflow.