A practical reference on GABA-A receptor: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-12-04. Anything still debated is marked as such rather than presented as settled.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
=== Pregnancy === Pregnancy can cause major complications when trying to properly dose the nutrient mixture. Because all of the fetus' nourishment comes from the mother's blood stream, the doctor must properly calculate the dosage of nutrients to meet both recipients' needs and have them in usable forms. Incorrect dosage can lead to many adverse, hard-to-guess effects, such as death, and varying degrees of deformation or other developmental problems. It is recommended that parenteral nutrition administration begins after a period of natural nutrition so doctors can properly calculate the nutritional needs of the fetus. Otherwise, it should only be administered by a team of highly skilled doctors who can accurately assess the fetus' needs.
The Moscow Jewelry Factory and the Jewellerprom produce jewelry. Other industries are located just outside Moscow, and some microelectronic industries are located in Zelenograd, including the company Ruselectronics. Gazprom, the world's largest extractor of natural gas and the largest Russian company, is headquartered in Moscow, along with other oil, gas, and electricity companies. Moscow contains the headquarters of many telecommunications and technology companies, including 1C, ABBYY, Beeline, Kaspersky Lab, Mail.Ru Group, MegaFon, MTS, Rambler&Co, Rostelecom, Yandex, and Yota. Some industry is being transferred out of Moscow to improve the city's ecological condition.
=== Exercise and muscle soreness === A 2017 review showed that taking antioxidant dietary supplements before or after exercise is unlikely to produce a noticeable reduction in muscle soreness after a person exercises.
Sources: en.wikipedia.org
Monoamines are connected to the pathophysiology of depression. Symptoms may occur because concentrations of neurotransmitters, such as norepinephrine and serotonin, are insufficient, leading to downstream changes. Medications for depression affect the transmission of serotonin, norepinephrine, and dopamine. Older and less selective antidepressants like TCAs and MAOIs inhibit the reuptake or metabolism of norepinephrine and serotonin in the brain, which results in higher concentrations of neurotransmitters. Antidepressants that have dual mechanisms of action inhibit the reuptake of both serotonin and norepinephrine and, in some cases, inhibit with weak effect the reuptake of dopamine. Antidepressants affect variable neuronal receptors such as muscarinic cholinergic, α1- and α2-adrenergic, H1-histaminergic, and sodium channels in the cardiac muscle, leading to decreased cardiac conduction and cardiotoxicity associated particularly with TCAs, and to a lesser extent with SSRIs. Selectivity of antidepressant agents are based on the neurotransmitters that are thought to influence symptoms of depression. Drugs that selectively block the reuptake of serotonin and norepinephrine effectively treat depression and are better tolerated than TCAs. TCAs have comprehensive effects on various neurotransmitters receptors, which leads to lack of tolerability and increased risk of toxicity. SNRIs primarily work by binding to and thus inhibiting the serotonin transporter (SERT) and norepinephrine transporter (NET).
It was later determined that the Act-1 monoclonal antibody reacted with an α4β7 integrin that was subsequently shown to interact with a gut-associated addressin, MadCAM. Early work with Dr. Bruce Yacyshyn showed differential expression in inflammatory bowel disease. Dr. Lazarovits isolated the antibody to produce the murine homologue MLN0002 which he licensed with the Massachusetts General Hospital to Millennium Pharmaceuticals of Boston for further development. Scientists at LeukoSite realized the potential of this antibody to treat inflammatory bowel disease, and this company was eventually acquired by Millennium which took an exclusive license to the cell line from Massachusetts General Hospital. In vivo proof of concept ultimately led to the decision to humanize the antibody and move it into clinical trials as "Vedolizumab". In addition to its reactivity to gut-associated lymphoid tissues, Act-1 antibody also stains large numbers of lymphocytes in rheumatoid synovium, and has been shown by Dr. A. A. Ansari of Emory University to prevent or delay onset of AIDS in a monkey-model of Simian Immunodeficiency Virus-induced AIDS. Thus, reactivity with this antibody may show widespread applicability in inflammatory processes of diverse etiologies.
==== Biophysics of AMPA receptor trafficking ==== The movement of AMPA receptors within the neuronal membrane is commonly modeled as Brownian diffusion, reflecting their lateral mobility across the lipid bilayer. However, at synaptic sites— particularly the postsynaptic density (PSD)—this motion is modulated by retention forces that can transiently stabilize receptors. These forces do not completely immobilize AMPARs but instead permit a dynamic exchange with receptors in the perisynaptic domain. The molecular basis for this stabilization is believed to involve nanodomain organization within the PSD, including anchoring interactions with scaffolding proteins such as PSD-95 and transmembrane AMPA receptor regulatory proteins (TARPs). Recent evidence suggests that this compartmentalization may arise through liquid-liquid phase separation (LLPS), a biophysical process by which biomolecular condensates form via weak, multivalent interactions. LLPS may contribute to the formation of synaptic nanodomains that selectively retain or enrich AMPARs at functional sites within the PSD.
The so-called "border war" of the 1970s and 1980s was not actually a war at all by classic standards. At the same time it eludes exact definitions. The core of it was a protracted insurgency in South West Africa, later South-West Africa/Namibia and still later Namibia. At the same time it was characterised by the periodical involvement of the SADF in the long civil war taking place in neighbouring Angola, because the two conflicts could not be separated from one another. The South West African People's Organisation (SWAPO) has described the South African Border War as the Namibian War of National Liberation and the Namibian Liberation Struggle. In the Namibian context, it is also commonly referred to as the Namibian War of Independence. However, these terms have been criticised for ignoring the wider regional implications of the war and the fact that most of the fighting took place in countries other than Namibia.
Sources: en.wikipedia.org
Tourism is a significant contributor to the Romanian economy, generating around 5% of GDP. The number of tourists has been rising steadily, reaching 9.33 million foreign tourists in 2016, according to the Worldbank. Tourism in Romania attracted €400 million in investments in 2005. More than 60% of the foreign visitors in 2007 were from other EU countries. The popular summer attractions of Mamaia and other Black Sea Resorts attracted 1.3 million tourists in 2009. Among Romania's spa towns and resorts are Buziaș, Băile Călacea, Moneasa, Băile Lipova, Călimănești, Amara, and Geoagiu-Băi. At the same time, seaside resorts such as Eforie, Mangalia, Saturn, Venus, Neptun, Olimp, and Mamaia (sometimes also called the Romanian Riviera) are among the main tourist attractions during the summer. Most popular skiing resorts are along the Valea Prahovei, Muntele Mic, Semenic, Straja and Poiana Brașov. Wine tourism is represented by areas such as Recaș, Silagiu, Odobești, Drăgășani, and Podgoria Aradului. Castles, fortifications, or strongholds as well as preserved medieval Transylvanian cities or towns such as Timișoara, Cluj-Napoca, Sibiu, Brașov, Alba Iulia, Baia Mare, Bistrița, Mediaș, Cisnădie, Sebeș, or Sighișoara also attract a large number of tourists. Bran Castle, near Brașov, is one of the most famous attractions in Romania, drawing hundreds of thousands of tourists every year as it is often (falsely) advertised as being Dracula's Castle. Other attractions include the Danube Delta or the Sculptural Ensemble of Constantin Brâncuși at Târgu Jiu.
In Chile, state-run universities are less expensive than private ones but are not tuition-free. Chile spends only four percent of its GDP on education, compared to the 7% recommended by the United Nations for developed nations. As a result, students and their families must cover 75 percent of tuition costs for attending both public and private universities. The most prestigious universities are the state-run Universidad de Chile and the private with state funding Pontificia Universidad Católica de Chile, Universidad de Concepción, and Universidad Técnica Federico Santa María. The Universidad de Chile is the country's leading research institution.
== Gene expression == The gene from which this enzyme is synthesized is mostly expressed in the liver, with some expression in the kidneys, skeletal muscle, and brain. It is also expressed in melanocytes, synovium, placenta, breasts, fetal liver and heart.
THC, referred to as dronabinol in the pharmaceutical context, is approved in the United States as a capsule or solution to relieve chemotherapy-induced nausea and vomiting and HIV/AIDS-induced anorexia. THC is an active ingredient in nabiximols (Sativex), a specific extract of Cannabis that was approved as a botanical drug in the United Kingdom in 2010 as a mouth spray for people with multiple sclerosis to alleviate neuropathic pain, spasticity, overactive bladder, and other symptoms. Nabiximols (as Sativex) is available as a prescription drug in Canada. In 2021, nabiximols was approved for medical use in Ukraine. THC is sometimes prescribed off-label to treat glaucoma, Crohn's disease, and post-traumatic stress disorder (PTSD).
The peptide sequence tag approach developed at the EMBL was one of the first methods for the identification of peptides based on mass spectra and genome data. Nano-electrospray (an electrospray technique with very low flow rates) was the first method that allowed femtomole sequencing of proteins from polyacrylamide gels. A recently developed metabolic labeling technique called SILAC (stable isotope labeling with amino acids in cell culture) is widely used in quantitative proteomics.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.