Adenosine A1 receptor and Adenosine A2 receptor (A1AR and A2AR)

Adenosine A1 and A2 receptors are closely related but distinct members of the adenosine (P1) purinergic G protein-coupled receptor family. Both receptors are widely distributed throughout the body and play key roles in integrating extracellular adenosine signaling into intracellular cAMP-mediated pathways. A1 receptors (A1AR) typically couple to Gi/o proteins, leading to inhibition of adenylate cyclase, decreased cAMP, and effects such as negative chronotropic and dromotropic action on the heart, inhibition of neurotransmitter release, and cytoprotection during metabolic stress. A2 receptors (primarily A2AAR and A2BAR) couple to Gs proteins, stimulating adenylate cyclase, increasing cAMP, and promoting vasodilation, anti-inflammatory effects, and modulation of immune cell activity. The receptors are prominent in the central nervous system, cardiovascular system, and immune system. Both subtypes are actively investigated as therapeutic targets for a broad range of diseases, but drug development is challenged by their widespread expression and the narrow therapeutic index for some effects[1][2][3][6][7]. The query lists "Adenosine A1/A2 receptors" as a single target; however, these are two formally distinct receptor subtypes (A1 adenosine receptor and A2 adenosine receptor, specifically A2A and A2B). They should ideally be handled as separate targets for structured data, as they differ significantly in pharmacology, function, and clinical implications[1][2][3].

Other names

Adenosine receptor A1 (A1AR)Adenosine receptor A2A (A2AAR)Adenosine receptor A2B (A2BAR) [related family]Adenosine A1 receptorAdenosine A2 receptor

A1AR agonists: decrease cAMP via Gi protein, reduce heart rate, inhibit neurotransmitter/hormone release. A2AR agonists: increase cAMP via Gs protein, vasodilation, immunosuppression, anti-inflammatory effects. Antagonists: block effects of endogenous adenosine, resulting in increased neurotransmitter release, wakefulness, and others. Pharmacological modulation of G protein-coupled signaling pathways.