Alpha-2A and Alpha-2C adrenergic receptors (α2A and α2C adrenergic receptor)

Alpha-2A and Alpha-2C adrenergic receptors are subtypes of G protein-coupled receptors activated by the endogenous catecholamines norepinephrine (noradrenaline) and epinephrine, as well as by various drugs. These receptors are chiefly presynaptic, mediating inhibition of norepinephrine release through Gi protein-coupled signaling, which leads to decreased sympathetic outflow and cardiovascular effects including reduced blood pressure and heart rate. The alpha-2A subtype is the predominant form in the central nervous system, where it contributes to the antihypertensive actions of drugs such as clonidine and is also essential for feedback inhibition of neurotransmitter release. The alpha-2C subtype plays prominent roles in stress response, startle reflex, and control of neurotransmitter release at low levels of sympathetic activity; both subtypes are implicated in modulation of pain (nociception), glucose homeostasis, and several CNS and cardiovascular pathologies. Genetic variation in these receptors may influence individual responses to drugs targeting them and susceptibility to certain diseases

Other names

Noradrenaline alpha-2A and alpha-2C receptorNorepinephrine alpha-2A and alpha-2C receptorADRA2A (for alpha-2A adrenergic receptor)ADRA2C (for alpha-2C adrenergic receptor)Alpha-2 adrenergic receptor subtype AAlpha-2 adrenergic receptor subtype C

Agonist action: Inhibits adenylyl cyclase via Gi protein, reducing cAMP and leading to decreased norepinephrine release and lowered sympathetic tone Antagonist action: Blocks presynaptic inhibition, enhances norepinephrine release