ADORA2A (Adenosine A2A Receptor) is a member of the guanine nucleotide-binding protein (G protein)-coupled receptor (GPCR) superfamily. It is a receptor for adenosine and is also targeted by caffeine. ADORA2A amplifies intracellular cAMP levels after binding adenosine, and it is important for cardiac rhythm and circulation, cerebral and renal blood flow, immune function, pain regulation, and sleep. Furthermore, natural increases in ADORA2A over time may be relevant to age-related decline in memory, and abrogation of the protein results in memory enhancements in mice. Along these lines, it is relevant to long-term memory storage and loss, and is thought to play a role in memory loss and the pathogenesis of related neurodegenerative disorders and inflammatory diseases. Levels of expression of this receptor have been found to be upregulated in astrocytes in Alzheimer’s disease patients and also in the early stages of Parkinson’s disease. In immunohistochemistry of normal tissue, ADORA2A has selective membranous positivity in the caudate nucleus in the brain and on populations of cells in the thymus, and is also expressed in vasculature and on platelets.
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