The adenosine A3 receptor, also known as ADORA3, is an adenosine receptor, but also denotes the human gene encoding it.
The adenosine A3 receptor, also known as ADORA3, is an adenosine receptor, but also denotes the human gene encoding it.
Adenosine A3 receptors are G protein-coupled receptors that couple to Gi/Gq and are involved in a variety of intracellular signaling pathways and physiological functions. It mediates a sustained cardioprotective function during cardiac ischemia, it is involved in the inhibition of neutrophil degranulation in neutrophil-mediated tissue injury, it has been implicated in both neuroprotective and neurodegenerative effects, and it may also mediate both cell proliferation and cell death[ citation needed ]. Recent publications demonstrate that adenosine A3 receptor antagonists (SSR161421) could have therapeutic potential in bronchial asthma (17,18).
Multiple transcript variants encoding different isoforms have been found for this gene. [5]
An adenosine A3 receptor agonist (CF-101) is in clinical trials for the treatment of rheumatoid arthritis. [6] In a mouse model of infarction the A3 selective agonist CP-532,903 protected against myocardial ischemia and reperfusion injury. [7]
A number of selective A3 ligands are available. [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20]
The adenosine receptors (or P1 receptors) are a class of purinergic G protein-coupled receptors with adenosine as the endogenous ligand. There are four known types of adenosine receptors in humans: A1, A2A, A2B and A3; each is encoded by a different gene.
Nicotinic acetylcholine receptors, or nAChRs, are receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the central and peripheral nervous system, muscle, and many other tissues of many organisms. At the neuromuscular junction they are the primary receptor in muscle for motor nerve-muscle communication that controls muscle contraction. In the peripheral nervous system: (1) they transmit outgoing signals from the presynaptic to the postsynaptic cells within the sympathetic and parasympathetic nervous system, and (2) they are the receptors found on skeletal muscle that receive acetylcholine released to signal for muscular contraction. In the immune system, nAChRs regulate inflammatory processes and signal through distinct intracellular pathways. In insects, the cholinergic system is limited to the central nervous system.
Histamine H3 receptors are expressed in the central nervous system and to a lesser extent the peripheral nervous system, where they act as autoreceptors in presynaptic histaminergic neurons and control histamine turnover by feedback inhibition of histamine synthesis and release. The H3 receptor has also been shown to presynaptically inhibit the release of a number of other neurotransmitters (i.e. it acts as an inhibitory heteroreceptor) including, but probably not limited to dopamine, GABA, acetylcholine, noradrenaline, histamine and serotonin.
The adenosine A1 receptor (A1AR) is one member of the adenosine receptor group of G protein-coupled receptors with adenosine as endogenous ligand.
The 5-HT2A receptor is a subtype of the 5-HT2 receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor (GPCR). The 5-HT2A receptor is a cell surface receptor, but has several intracellular locations.
The nociceptin opioid peptide receptor (NOP), also known as the nociceptin/orphanin FQ (N/OFQ) receptor or kappa-type 3 opioid receptor, is a protein that in humans is encoded by the OPRL1 gene. The nociceptin receptor is a member of the opioid subfamily of G protein-coupled receptors whose natural ligand is the 17 amino acid neuropeptide known as nociceptin (N/OFQ). This receptor is involved in the regulation of numerous brain activities, particularly instinctive and emotional behaviors. Antagonists targeting NOP are under investigation for their role as treatments for depression and Parkinson's disease, whereas NOP agonists have been shown to act as powerful, non-addictive painkillers in non-human primates.
Dopamine receptor D2, also known as D2R, is a protein that, in humans, is encoded by the DRD2 gene. After work from Paul Greengard's lab had suggested that dopamine receptors were the site of action of antipsychotic drugs, several groups, including those of Solomon Snyder and Philip Seeman used a radiolabeled antipsychotic drug to identify what is now known as the dopamine D2 receptor. The dopamine D2 receptor is the main receptor for most antipsychotic drugs. The structure of DRD2 in complex with the atypical antipsychotic risperidone has been determined.
The adenosine A2A receptor, also known as ADORA2A, is an adenosine receptor, and also denotes the human gene encoding it.
Dopamine receptor D1, also known as DRD1. It is one of the two types of D1-like receptor family — receptors D1 and D5. It is a protein that in humans is encoded by the DRD1 gene.
G protein-coupled receptor 35 also known as GPR35 is a G protein-coupled receptor which in humans is encoded by the GPR35 gene. Heightened expression of GPR35 is found in immune and gastrointestinal tissues, including the crypts of Lieberkühn.
The adenosine A2B receptor, also known as ADORA2B, is a G-protein coupled adenosine receptor, and also denotes the human adenosine A2b receptor gene which encodes it.
P2Y purinoceptor 6 is a protein that in humans is encoded by the P2RY6 gene.
The cannabinoid receptor 2(CB2), is a G protein-coupled receptor from the cannabinoid receptor family that in humans is encoded by the CNR2 gene. It is closely related to the cannabinoid receptor 1 (CB1), which is largely responsible for the efficacy of endocannabinoid-mediated presynaptic-inhibition, the psychoactive properties of tetrahydrocannabinol (THC), the active agent in cannabis, and other phytocannabinoids. The principal endogenous ligand for the CB2 receptor is 2-Arachidonoylglycerol (2-AG).
8-Cyclopentyl-1,3-dipropylxanthine (DPCPX, PD-116,948) is a drug which acts as a potent and selective antagonist for the adenosine A1 receptor. It has high selectivity for A1 over other adenosine receptor subtypes, but as with other xanthine derivatives DPCPX also acts as a phosphodiesterase inhibitor, and is almost as potent as rolipram at inhibiting PDE4. It has been used to study the function of the adenosine A1 receptor in animals, which has been found to be involved in several important functions such as regulation of breathing and activity in various regions of the brain, and DPCPX has also been shown to produce behavioural effects such as increasing the hallucinogen-appropriate responding produced by the 5-HT2A agonist DOI, and the dopamine release induced by MDMA, as well as having interactions with a range of anticonvulsant drugs.
Metabotropic glutamate receptor 7 is a protein that in humans is encoded by the GRM7 gene.
The 5-HT7 receptor is a member of the GPCR superfamily of cell surface receptors and is activated by the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) The 5-HT7 receptor is coupled to Gs (stimulates the production of the intracellular signaling molecule cAMP) and is expressed in a variety of human tissues, particularly in the brain, the gastrointestinal tract, and in various blood vessels. This receptor has been a drug development target for the treatment of several clinical disorders. The 5-HT7 receptor is encoded by the HTR7 gene, which in humans is transcribed into 3 different splice variants.
P2Y purinoceptor 4 is a protein that in humans is encoded by the P2RY4 gene.
PSB-10 is a drug which acts as a selective antagonist for the adenosine A3 receptor (ki value at human A3 receptor is 0.44 nM), with high selectivity over the other three adenosine receptor subtypes (ki values at human A1, A2A and A2B receptors are 4.1, 3.3 and 30 μM). Further pharmacological experiments in a [35S]GTPγS binding assay using hA3-CHO-cells indicated that PSB-10 acts as an inverse agonist (IC50 = 4 nM). It has been shown to produce antiinflammatory effects in animal studies. Simple xanthine derivatives such as caffeine and DPCPX have generally low affinity for the A3 subtype and must be extended by expanding the ring system and adding an aromatic group to give high A3 affinity and selectivity. The affinity towards adenosine A3 subtype was measured against the radioligand PSB-11.
UK-432,097 is a drug developed by Pfizer for the treatment of chronic obstructive pulmonary disease, which acts as a potent and selective agonist of the adenosine A2A receptor. It was discontinued from clinical trials following poor efficacy results, but its high selectivity has made it useful for detailed mapping of the internal structure of the A2A receptor.
25CN-NBOH is a compound indirectly derived from the phenethylamine series of hallucinogens, which was discovered in 2014 at the University of Copenhagen. This compound is notable as one of the most selective agonist ligands for the 5-HT2A receptor yet discovered, with a pKi of 8.88 at the human 5-HT2A receptor and with 100x selectivity for 5-HT2A over 5-HT2C, and 46x selectivity for 5-HT2A over 5-HT2B. A tritiated version of 25CN-NBOH has also been accessed and used for more detailed investigations of the binding to 5-HT2 receptors and autoradiography.