Alpha-2 adrenergic receptor (central) (α2-adrenoceptor (central) or α2-AR (central))

Alpha-2 adrenergic receptors are a family of G protein-coupled receptors subdivided into α2A, α2B, and α2C, with α2A and α2C highly expressed in the central nervous system. Centrally, these receptors mediate inhibition of norepinephrine release via presynaptic negative feedback, decrease sympathetic neuroactivity, induce sedation, and provide analgesic effects. Activation of central alpha-2-adrenoceptors lowers blood pressure and heart rate, making them targets for antihypertensive drugs such as clonidine and methyldopa. They are also used in treatment of ADHD, opioid withdrawal, procedural sedation, and pain control. Safety concerns include hypotension, sedation, depression, and the risk of rebound hypertension if medications are stopped abruptly. The receptors are a central focus for drugs acting on the nervous system with widespread influence on cardiovascular, cognitive, and autonomic functions.

Other names

Alpha-2 adrenoceptorα2-ARCentral alpha-2 adrenergic receptorCentral alpha-2 adrenoceptorAlpha-2A adrenergic receptor (for the major central subtype)Central α2 receptor

Presynaptic inhibition: Stimulation inhibits release of norepinephrine, reducing sympathetic outflow. Central nervous system action: Stimulation induces sedation, analgesia, and reduces anxiety. Blood pressure lowering: Reduces heart rate and blood pressure by central action on the medullary vasomotor center. Attenuation of withdrawal symptoms in substance dependence.