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.
Epibatidine is a chlorinated alkaloid that is secreted by the Ecuadoran frog Epipedobates anthonyi and poison dart frogs from the Ameerega genus. It was discovered by John W. Daly in 1974, but its structure was not fully elucidated until 1992. Whether epibatidine is the first observed example of a chlorinated alkaloid remains controversial, due to challenges in conclusively identifying the compound from the limited samples collected by Daly. By the time that high-resolution spectrometry was used in 1991, there remained less than one milligram of extract from Daly's samples, raising concerns about possible contamination. Samples from other batches of the same species of frog failed to yield epibatidine.
Attention deficit hyperactivity disorder predominantly inattentive, is one of the three presentations of attention deficit hyperactivity disorder (ADHD). In 1987–1994, there were no subtypes and thus it was not distinguished from hyperactive ADHD in the Diagnostic and Statistical Manual (DSM-III-R).
Desformylflustrabromine (dFBr) is a monomethyltryptamine derivative which was first isolated as a secondary metabolite of the marine bryozoan Flustra foliacea.
A nicotinic agonist is a drug that mimics the action of acetylcholine (ACh) at nicotinic acetylcholine receptors (nAChRs). The nAChR is named for its affinity for nicotine.
The alpha-4 beta-2 nicotinic receptor, also known as the α4β2 receptor, is a type of nicotinic acetylcholine receptor implicated in learning, consisting of α4 and β2 subunits. It is located in the brain, where activation yields post- and presynaptic excitation, mainly by increased Na+ and K+ permeability.
The alpha-7 nicotinic receptor, also known as the α7 receptor, is a type of nicotinic acetylcholine receptor implicated in long-term memory, consisting entirely of α7 subunits. As with other nicotinic acetylcholine receptors, functional α7 receptors are pentameric [i.e., (α7)5 stoichiometry].
Ispronicline is an experimental drug which acts as a partial agonist at neural nicotinic acetylcholine receptors. It progressed to phase II clinical trials for the treatment of dementia and Alzheimer's disease, but is no longer under development.
Tebanicline is a potent synthetic nicotinic (non-opioid) analgesic drug developed by Abbott. It was developed as a less toxic analog of the potent poison dart frog-derived compound epibatidine, which is about 200 times stronger than morphine as an analgesic, but produces extremely dangerous toxic side effects. Like epibatidine, tebanicline showed potent analgesic activity against neuropathic pain in both animal and human trials, but with far less toxicity than its parent compound. It acts as a partial agonist at neuronal nicotinic acetylcholine receptors, binding to both the α3β4 and the α4β2 subtypes.
Dianicline (SSR-591,813) is a drug developed by Sanofi-Aventis which acts as a partial agonist at neural nicotinic acetylcholine receptors. It is subtype-selective, binding primarily to the α4β2 subtype. It is being developed as a medication for the treatment of nicotine dependence to assist in smoking cessation. Dianicline is very similar to the already marketed drug varenicline and it is unclear what advantages it will have over the older drug, although it may have an improved side effect profile. It has been through human trials up to Phase II, although results have not yet been reported. Drug development has been discontinued after reporting of unfavourable results during Phase III trials.
ABT-418 is a drug developed by Abbott, that has nootropic, neuroprotective and anxiolytic effects, and has been researched for treatment of both Alzheimer's disease and ADHD. It acts as an agonist at neural nicotinic acetylcholine receptors, subtype-selective binding with high affinity to the α4β2, α7/5-HT3, and α2β2 nicotinic acetylcholine receptors but not α3β4 receptors ABT-418 was reasonably effective for both applications and fairly well tolerated, but produced some side effects, principally nausea, and it is unclear whether ABT-418 itself will proceed to clinical development or if another similar drug will be used instead.
GTS-21 is an investigational drug that has been studied for its potential therapeutic uses, particularly in the treatment of neurodegenerative diseases and psychiatric disorders.
Sazetidine A (AMOP-H-OH) is a drug which acts as a subtype selective partial agonist at α4β2 neural nicotinic acetylcholine receptors, acting as an agonist at (α4)2(β2)3 pentamers, but as an antagonist at (α4)3(β2)2 pentamers. It has potent analgesic effects in animal studies comparable to those of epibatidine, but with less toxicity, and also has antidepressant action.
A-84543 is a drug developed by Abbott, which acts as an agonist at neural nicotinic acetylcholine receptors with high selectivity for the α4β2 subtype. It is widely used in scientific research into the structure and function of this receptor subtype and has been the lead compound for the development of a large family of related derivatives.
UB-165 is a drug which acts as an agonist at neuronal nicotinic acetylcholine receptors being a full agonist of the α3β2 isoform and a partial agonist of the α4β2* isoform. It is used to study the role of this receptor subtype in the release of dopamine and noradrenaline in the brain, and has also been used as a lead compound to derive a number of other selective nicotinic receptor ligands.
Altinicline is a drug which acts as an agonist at neural nicotinic acetylcholine receptors with high selectivity for the α4β2 subtype. It stimulates release of dopamine and acetylcholine in the brain in both rodent and primate models, and progressed as far as Phase II clinical trials for Parkinson's disease, where "no antiparkinsonian or cognitive-enhancing effects were demonstrated", although its current status is unclear.
The alpha-3 beta-4 nicotinic receptor, also known as the α3β4 receptor and the ganglion-type nicotinic receptor, is a type of nicotinic acetylcholine receptor, consisting of α3 and β4 subunits. It is located in the autonomic ganglia and adrenal medulla, where activation yields post- and/or presynaptic excitation, mainly by increased Na+ and K+ permeability.
The alpha-3 beta-2 nicotinic receptor, also known as the α3β2 receptor, is a type of nicotinic acetylcholine receptor, consisting of α3 and β2 subunits.
6-Chloronicotine is a drug which acts as an agonist at neural nicotinic acetylcholine receptors. It substitutes for nicotine in animal studies with around twice the potency, and shows antinociceptive effects.
The alpha-5 nicotinic acetylcholine receptor(α5 nAChR) also known as the α5 receptor is a type of ligand gated nicotinic acetylcholine receptor involved in pain regulation. One of the 5 transmembrane subunits of this receptor is the α5 subunit and is transcribed by the CHRNA5 gene. This receptor is commonly associated with nicotine addiction, immunotherapy, cancer, pain and attention.
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