The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon opening, the GABAA receptor is selectively permeable to chloride ions (Cl−) and, to a lesser extent, bicarbonate ions (HCO3−). Depending on the membrane potential and the ionic concentration difference, this can result in ionic fluxes across the pore. For instance, under physiological conditions Cl− will flow inside the cell if the membrane potential is higher than the equilibrium potential (also known as the reversal potential) for chloride ions if the receptor is activated. This causes an inhibitory effect on neurotransmission by diminishing the chance of a successful action potential occurring at the postsynaptic cell. The reversal potential of the GABAA-mediated inhibitory postsynaptic potential (IPSP) in normal solution is −70 mV, contrasting the GABAB IPSP (-100 mV).
The avermectins are a series of drugs and pesticides used to treat parasitic worms and insect pests. They are a group of 16-membered macrocyclic lactone derivatives with potent anthelmintic and insecticidal properties. These naturally occurring compounds are generated as fermentation products by Streptomyces avermitilis, a soil actinomycete. Eight different avermectins were isolated in four pairs of homologue compounds, with a major (a-component) and minor (b-component) component usually in ratios of 80:20 to 90:10. Other anthelmintics derived from the avermectins include ivermectin, selamectin, doramectin, eprinomectin, and abamectin.
DMCM is a drug from the β-carboline family. It acts as a negative allosteric modulator of GABAA receptors, meaning that it causes the opposite effects to the benzodiazepine class of drugs. As such, DMCM has anxiogenic and convulsant properties, and is used in scientific research to induce anxiety so that new anxiolytic medications can be tested, and to produce convulsions so that anticonvulsant medications can be tested. It has also been shown to produce analgesic effects in animals, thought to be because it produces panic which reduces the perception of pain.
γ-Amino-β-hydroxybutyric acid (GABOB), also known as β-hydroxy-γ-aminobutyric acid (β-hydroxy-GABA), and sold under the brand name Gamibetal among others, is an anticonvulsant which is used for the treatment of epilepsy in Europe, Japan, and Mexico. It is a GABA analogue, or an analogue of the neurotransmitter γ-aminobutyric acid (GABA), and has been found to be an endogenous metabolite of GABA.
Melanocortin 5 receptor is a protein that in humans is encoded by the MC5R gene. It is located on the chromosome 18 in the human genome. When the melanocortin 5 receptor was disrupted in transgenic mice, it induced disruption of their exocrine glands and resulted in decreased production of sebum.
Rivanicline is a drug which acts as a partial agonist at neural nicotinic acetylcholine receptors. It is subtype-selective, binding primarily to the α4β2 subtype. It has nootropic effects and was originally developed as a potential treatment for Alzheimer's disease, but a second action that was subsequently found was that it inhibits the production of Interleukin-8 and thus produces an antiinflammatory effect, and so it has also been developed as a potential treatment for ulcerative colitis. Rivanicline also has stimulant and analgesic actions which are thought to be mediated through stimulation of noradrenaline release, and so it could also have other applications.
Oxymorphazone is an opioid analgesic drug related to oxymorphone. Oxymorphazone is a potent and long acting μ-opioid agonist which binds irreversibly to the receptor, forming a covalent bond which prevents it from detaching once bound. This gives it an unusual pharmacological profile, and while oxymorphazone is only around half the potency of oxymorphone, with higher doses the analgesic effect becomes extremely long lasting, with a duration of up to 48 hours. However, tolerance to analgesia develops rapidly with repeated doses, as chronically activated opioid receptors are rapidly internalised by β-arrestins, similar to the results of non-covalent binding by repeated doses of agonists with extremely high binding affinity such as lofentanil.
ZK-93426 (ethyl-5-isopropoxy-4-methyl-beta-carboline-3-carboxylate) is a drug from the beta-carboline family. It acts as a weak partial inverse agonist of benzodiazepine receptors, meaning that it causes the opposite effects to the benzodiazepine class of drugs and has anxiogenic properties, although unlike most benzodiazepine antagonists it is not a convulsant and actually has weak anticonvulsant effects. In human tests it produced alertness, restlessness and feelings of apprehension, and reversed the effect of the benzodiazepine lormetazepam. It was also shown to produce nootropic effects and increased release of acetylcholine.
Bromantane, sold under the brand name Ladasten, is an atypical psychostimulant and anxiolytic drug of the adamantane family related to amantadine and memantine which is used in Russia in the treatment of neurasthenia. Although the effects of the bromantane have been determined to be dependent on the dopaminergic and possibly serotonergic neurotransmitter systems, its exact mechanism of action is unknown, and it is distinct in its properties relative to typical psychostimulants such as amphetamine. Because of its unique aspects, bromantane has sometimes been described instead as an adaptogen and actoprotector.
1-(1-Naphthyl)piperazine (1-NP) is a drug which is a phenylpiperazine derivative. It acts as a non-selective, mixed serotonergic agent, exerting partial agonism at the 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, and 5-HT1F receptors, while antagonizing the 5-HT2A, 5-HT2B, and 5-HT2C receptors. It has also been shown to possess high affinity for the 5-HT3, 5-HT5A, 5-HT6, and 5-HT7 receptors, and may bind to 5-HT4 and the SERT as well. In animals it produces effects including hyperphagia, hyperactivity, and anxiolysis, of which are all likely mediated predominantly or fully by blockade of the 5-HT2C receptor.
PNU-99,194(A) (or U-99,194(A)) is a drug which acts as a moderately selective D3 receptor antagonist with ~15-30-fold preference for D3 over the D2 subtype. Though it has substantially greater preference for D3 over D2, the latter receptor does still play some role in its effects, as evidenced by the fact that PNU-99,194 weakly stimulates both prolactin secretion and striatal dopamine synthesis, actions it does not share with the more selective (100-fold) D3 receptor antagonists S-14,297 and GR-103,691.
Ro5-4864 (4'-chlorodiazepam) is a drug which is a benzodiazepine derivative of diazepam. However unlike most benzodiazepine derivatives, Ro5-4864 lacks affinity for GABAA receptors and lacks typical benzodiazepine effects, instead being sedative yet also convulsant and anxiogenic in effects. Ro5-4864 was found to be a potent ligand for the "peripheral benzodiazepine receptor", later renamed to mitochondrial translocator protein 18kDa (TSPO). Despite its convulsant effects, at lower doses Ro5-4864 has proved to be neuroprotective and has become widely used for research into the role of the TSPO protein in neurotoxicity. In vitro studies and rodent models also suggest the possibility of analgesic, antidepressant, cardioprotective, and anti-cancer effects.
Nooglutyl is a nootropic agent that was studied at the Research Institute of Pharmacology, Russian Academy of Medical Sciences as a potential treatment for amnesia.
Alstonine is an indoloquinolizidine alkaloid and putative antipsychotic constituent of various plant species including Alstonia boonei, Catharanthus roseus, Picralima nitida, Rauwolfia caffra and Rauwolfia vomitoria. In preclinical studies alstonine attenuates MK-801-induced hyperlocomotion, working memory deficit and social withdrawal. It also possesses anxiolytic-like effects in preclinical studies, attenuates amphetamine-induced lethality and stereotypy as well as apomorphine-induced stereotypy, and attenuates haloperidol-induced catalepsy. These effects appear to be mediated by stimulation of the 5-HT2C receptor. In addition, alstonine, similarly to clozapine, indirectly inhibits the reuptake of glutamate in hippocampal slices. Unlike clozapine however, the effect of which is abolished by the D2 receptor agonist apomorphine, alstonine requires 5-HT2A and 5-HT2C receptors to produce this effect, as it is abolished by antagonists of these receptors. Also unlike clozapine, alstonine lacks pro-convulsant activity in mice.
Adapromine is an antiviral drug of the adamantane group related to amantadine (1-aminoadamantane), rimantadine, and memantine (1-amino-3,5-dimethyladamantane) that is marketed in Russia for the treatment and prevention of influenza. It is an alkyl analogue of rimantadine and is similar to rimantadine in its antiviral activity but possesses a broader spectrum of action, being effective against influenza viruses of both type A and B. Strains of type A influenza virus with resistance to adapromine and rimantadine and the related drug deitiforine were encountered in Mongolia and the Soviet Union in the 1980s.
In neuroscience, glutamate refers to the anion of glutamic acid in its role as a neurotransmitter: a chemical that nerve cells use to send signals to other cells. It is by a wide margin the most abundant excitatory neurotransmitter in the vertebrate nervous system. It is used by every major excitatory function in the vertebrate brain, accounting in total for well over 90% of the synaptic connections in the human brain. It also serves as the primary neurotransmitter for some localized brain regions, such as cerebellum granule cells.
Cortifen, also known as cortiphen or kortifen, as well as fencoron, is a synthetic glucocorticoid corticosteroid and cytostatic antineoplastic agent which was developed in Russia for potential treatment of tumors. It is a hydrophobic chlorphenacyl nitrogen mustard ester of 11-deoxycortisol (cortodoxone).
IPTBO (isopropylbicyclophosphate) is a bicyclic phosphate convulsant. It is an extremely potent GABA receptor antagonist that can cause violent convulsions in mice.
BIDN is a GABA receptor antagonist and convulsant.
1-(4-Chlorophenyl)silatrane is an extremely toxic organosilicon compound which was developed by M&T Chemicals as a single-dose rodenticide. It was never registered as rodenticide, except for experimental use. 1-(4-Chlorophenyl)silatrane was one of the chemicals studied in the Project Coast.
