Adenosine receptors

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Adenosine receptors AR are a family of G-protein coupled receptors, comprised of four members, named A 1 , A 2A , A 2B , and A 3 receptors, found widely distributed in almost all human body tissues and organs. To date, they are known to participate in a large variety of physiopathological responses, which include vasodilation, pain, and inflammation. In particular, in the central nervous system CNS , adenosine acts as a neuromodulator, exerting different functions depending on the type of AR and consequent cellular signaling involved. In the CNS, A 1 receptors are widely distributed in the cortex, hippocampus, and cerebellum, A 2A receptors are localized mainly in the striatum and olfactory bulb, while A 2B and A 3 receptors are found at low levels of expression. In addition, AR are able to form heteromers, both among themselves e.

Adenosine receptors

Federal government websites often end in. The site is secure. To date, four AR subtypes have been cloned and identified in different tissues. These receptors have distinct localization, signal transduction pathways and different means of regulation upon exposure to agonists. This review will describe the biochemical characteristics and signaling cascade associated with each receptor and provide insight into how these receptors are regulated in response to agonists. Recent observations of oligomerization of these receptors into homo- and heterodimers will be discussed. In addition, the importance of these receptors in the regulation of normal and pathological processes such as sleep, the development of cancers and in protection against hearing loss will be examined. Adenosine is produced primarily from the metabolism of adenosine triphosphate ATP and exerts pleiotropic functions throughout the body. In the central nervous system CNS , adenosine plays important functions such as modulation of neurotransmitter release [ 1 ], synaptic plasticity [ 2 ] and neuroprotection in ischemic, hypoxic and oxidative stress events [ 3 — 5 ]. In addition, adenosine plays different roles in a large variety of tissues. In the cardiovascular system, adenosine produces either vasoconstriction or vasodilation of veins and arteries [ 6 ]. Adenosine regulates T cell proliferation and cytokine production [ 7 ].

Hettinger-Smith B. Sex differences in animal models: focus on addiction. Zajonc, D.

Nucleoside transporters. The adenosine receptors or P1 receptors [1] are a class of purinergic G protein-coupled receptors with adenosine as the endogenous ligand. The adenosine receptors are commonly known for their antagonists caffeine , theobromine , and theophylline , whose action on the receptors produces the stimulating effects of coffee , tea and chocolate. Each type of adenosine receptor has different functions, although with some overlap. Most older compounds acting on adenosine receptors are nonselective, with the endogenous agonist adenosine being used in hospitals as treatment for severe tachycardia rapid heart beat , [9] and acting directly to slow the heart through action on all four adenosine receptors in heart tissue, [10] as well as producing a sedative effect through action on A 1 and A 2A receptors in the brain. Xanthine derivatives such as caffeine and theophylline act as non-selective antagonists at A 1 and A 2A receptors in both heart and brain and so have the opposite effect to adenosine, producing a stimulant effect and rapid heart rate. Newer adenosine receptor agonists and antagonists are much more potent and subtype-selective, and have allowed extensive research into the effects of blocking or stimulating the individual adenosine receptor subtypes, which is now resulting in a new generation of more selective drugs with many potential medical uses.

Federal government websites often end in. The site is secure. To date, four AR subtypes have been cloned and identified in different tissues. These receptors have distinct localization, signal transduction pathways and different means of regulation upon exposure to agonists. This review will describe the biochemical characteristics and signaling cascade associated with each receptor and provide insight into how these receptors are regulated in response to agonists. Recent observations of oligomerization of these receptors into homo- and heterodimers will be discussed. In addition, the importance of these receptors in the regulation of normal and pathological processes such as sleep, the development of cancers and in protection against hearing loss will be examined. Adenosine is produced primarily from the metabolism of adenosine triphosphate ATP and exerts pleiotropic functions throughout the body. In the central nervous system CNS , adenosine plays important functions such as modulation of neurotransmitter release [ 1 ], synaptic plasticity [ 2 ] and neuroprotection in ischemic, hypoxic and oxidative stress events [ 3 — 5 ]. In addition, adenosine plays different roles in a large variety of tissues.

Adenosine receptors

Adenosine, beside its role in the intermediate metabolism, mediates its physiological functions by interacting with four receptor subtypes named A 1 , A 2A , A 2B and A 3. All these receptors belong to the superfamily of G protein-coupled receptors that represent the most widely targeted pharmacological protein class. Since adenosine receptors are widespread throughout the body, they are involved in a variety of physiological processes and pathology including neurological, cardiovascular, inflammatory diseases and cancer. At now, it is ascertained that the biological responses evoked by the activation of a single receptor are the result of complex and integrated signalling pathways targeted by different receptor proteins, interacting each other. These pathways may in turn control receptor responsiveness over time through fine regulatory mechanisms including desensitization-internalization processes. The knowledge of adenosine receptor structure as well as the molecular mechanisms underlying the regulation of receptor functioning and of receptor-receptor interactions during physio and pathological conditions represent a pivotal starting point to the development of new drugs with high efficacy and selectivity for each adenosine receptor subtype.

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Drug Targets 11, — Download citation. Shows that colon and breast carcinoma tissues have higher A 3 AR expression in the tumour versus adjacent non-neoplastic tissue or normal tissue, which provided a basis for the use of A 3 AR agonists in cancer therapy. His research interests include the development of new computational tools fortire evaluation, analysis, and comparison of new DNA and protein sequence data. Baumann, M. Drug Targets 7 , — CC and SM edited and reviewed the final version of the article. In instrumental conditioning, the external stimulus that signals a particular relationship between the instrumental response and the reinforcer. Expression of A1 and A3 adenosine receptors in human breast tumors. Adenosine A 2A receptor modulation of nicotine-induced locomotor sensitization. Issue Date : September Yao, L.

Adenosine is a naturally occurring nucleoside that is distributed ubiquitously throughout the body as a metabolic intermediary.

XAC has been utilized by Nakata with rat brain and by Olah et al. The A3 adenosine receptor is the unique adenosine receptor which facilitates release of allergic mediators in mast cells. Autocorrelation of molecular electrostatic potential surface properties combined with partial least squares analysis as new strategy for the prediction of the activity of human A3 adenosine receptor antagonists. Nature Neurosci. An alignment of both adenosine receptor subtypes and some other G-protein-linked receptors is shown in Fig. Bryant G. Trincavelli M. Influence of adenosine receptor agonists and antagonists on amphetamine-induced stereotypy in rats. Hatsukami, D. Sign up for Nature Briefing. Cocaine exposure modulates dopamine and adenosine signaling in the fetal brain. Anticancer Drugs 13 , — Lebon, G. Fernandez-Ruiz J. Koob, G.