This is a working overview of GABA-A receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-04. Anything still debated is marked as such rather than presented as settled.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
=== Legal status === Zanidatamab was approved for medical use in the United States in November 2024. In April 2025, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a conditional marketing authorization for the medicinal product Ziihera, intended for the treatment of adults with unresectable locally advanced or metastatic HER2-positive biliary tract cancer. The applicant for this medicinal product is Jazz Pharmaceuticals Ireland Limited. Zanidatamab was authorized for medical use in the European Union in June 2025.
=== Analysis of protein expression === Protein microarrays and high throughput (HT) mass spectrometry (MS) can provide a snapshot of the proteins present in a biological sample. The former approach faces similar problems as with microarrays targeted at mRNA, the latter involves the problem of matching large amounts of mass data against predicted masses from protein sequence databases, and the complicated statistical analysis of samples when multiple incomplete peptides from each protein are detected. Cellular protein localization in a tissue context can be achieved through affinity proteomics displayed as spatial data based on immunohistochemistry and tissue microarrays.
=== Soviet Union === The Soviet Union was the other major ally of the Việt Minh, alongside the PRC. Moscow supplied GAZ-built trucks, truck engines and motor-parts, fuel, tyres, many different kinds of arms and weapons (including thousands of Škoda-manufactured light machine-guns of Czech origin), all kinds of ammunition (ranging from rifle to machine-gun ammunition), various types of anti-aircraft guns (such as the 37mm air-defense gun) and even cigarettes and tobacco products. During Operation Hirondelle, French Union paratroopers captured and destroyed many tonnes of Soviet-supplied material destined for Việt Minh use in the area of Ky Lua. According to General Giap, the chief military leader of all Việt Minh forces, the Việt Minh used about 400 Soviet-produced GAZ-51 trucks at the Battle of Dien Bien Phu. Because the trucks were concealed and hidden with the use of highly effective camouflage (consisting predominantly of thick vegetation), French Union reconnaissance aircraft were not able to notice them and take note of the effective Việt Minh supply-train. On May 6, 1954, during the siege against French forces at the valley of Dien Bien Phu, Soviet-supplied Katyusha MLRS were successfully fielded against French Union military outposts, destroying enemy troop formations and bases and lowering their morale levels. Together with the PRC, the Soviet Union sent up to 2,000 military advisors to provide training to the Việt Minh guerrilla troops and to turn it into a conventional army.
=== Chemical additives === Chemical additives are small chemical compounds that are added to the crystallization process to increase the yield of crystals. The role of small molecules in protein crystallization had not been well thought of in the early days since they were thought of as contaminants in most case. Small molecules are thought to help if/when they are incorporated as "packing bridges" in the crystal contact interfaces. It is currently not possible (as of 2017) to rationally determine what small molecules to use to improve chances of crystallization.
== Effects on Animals == Calciseptine has been examined in vivo and in vitro in all kinds of animals, but mostly in rats. Calciseptine relaxes precontracted rat (thoracic) aorta and decreases blood pressure drastically. The decrease in blood pressure shows a combination of short- and long-lasting effects. The early, acute onset took five minutes, and the effect could last for 120 minutes or longer. In addition, calciseptine had only a small effect on the heart rhythm, changing it only slightly. Furthermore, it can also relax the trachea rings in the lungs. These effects can be explained by the relaxing activity of calciseptine on various smooth muscle cells. The inhibitory effect of calciseptine results in a decreased or total disappearance of electric activity in these cells. The total inhibitory effect depends on the tissue: the cardiovascular system is the most vulnerable, while neuronal cells are less vulnerable and skeletal muscle cells are completely resistant. This difference in tissue sensitivity is probably caused by slight differences in the L-type calcium channels in these tissues. These effects can occur at low subjected amounts of 0.1 till 1 μM calciseptine. In mouse myotube the Ca2+ currents show higher amplitude after incubation in calciseptine (1 μM). This effect of calciseptine on the Ca2+ current develops relatively fast. Calciseptine changes the reversal potential of the Ca2+ current in mouse myotubes. In adult frog skeletal muscle fibers calciseptine also causes an increased Ca2+ current.
Sources: en.wikipedia.org
== See also == Artificial Intelligence Act — 2024 European Union regulation Privacy laws of the United States Use of artificial intelligence by the United States Department of Defense Americans for Responsible Innovation - nonprofit advocacy group
NMR spectroscopy has been utilized for the analysis of biological samples since the 1980s, and can be used as an effective technique for the identification and quantification of both known and unknown metabolites. For details on the principles of this technique, see NMR spectroscopy. In pharmacometabolomics analyses, NMR is advantageous because minimal sample preparation is required. Isolated patient samples typically include blood or urine due to their minimally-invasive acquisition, however, other fluid types and solid tissue samples have also been studied with this approach. Due to the minimal preparation of samples before analysis, samples can be potentially fully recovered following NMR analysis (If samples are kept refrigerated to avoid degradation). This permits samples to be repeatedly analysed with extremely high levels of reproducibility, as well as maintaining precious patient samples for an alternative analysis. The high reproducibility and precision of NMR, coupled with relatively fast processing time (greater than 100 samples per day), makes this process a relatively high-throughput form of sample analysis. One disadvantage of this technique is the relatively poor metabolite detection sensitivity compared to MS-based analysis, leading to a requirement for greater initial sample volume. Furthermore, the initial instrument costs are extremely high, for both NMR and MS equipment.
=== Norway === Reports from Norway have shown carisoprodol has addictive potential as a prodrug of meprobamate and/or potentiator of hydrocodone, oxycodone, codeine, and similar drugs. In May 2008 it was taken off the market in Norway.
== Medical career == Coatsworth is a Fellow of the Royal Australasian College of Physicians. His specialties are respiratory medicine and infectious diseases. He is currently director of infectious diseases at Canberra Hospital. His other roles have included executive director at the National Critical Care and Trauma Response Centre in Darwin. He has also lectured in medicine at the Australian National University. Coatsworth led humanitarian teams in the Congo and the Darfur region of Sudan for Medicins Sans Frontiers when he was 25, a task that he says left him with PTSD. He told the Today programme: "I think everyone has their limits in life and I kind of reached that, the security situation there was really difficult. There was the threat of assassination of people in the place where we were." After returning home, Coatsworth became anxious: "I felt like I was having these heart palpitations ... At the end of 2019 it got to the point one weekend I couldn't leave the house." He took anxiety medication to resolve the issue. He was elected to the board of Medicins Sans Frontiers in Australia in 2008. He served as the board's president in 2010 and 2011. He also led the second Australian Medical Assistance Team to the Philippines after Typhoon Haiyan in 2013. His other deployments with the Australian Medical Assistance Team include Vanuatu after Cyclone Pam in 2015 and Fiji following Cyclone Winston in 2016. In 2023, Coatsworth joined Patients Australia as Ambassador for Health Reform.
=== Cyclodextrin (CD) chiral stationary phases === Cyclodextrin (CD) chiral stationary phase is produced by partial degradation of starch by the enzyme cyclodextrin glycosyltransferase, followed by enzymatic coupling of the glucose units, forming a toroidal structure. CDs are cyclic oligosaccharides consisting of six (α CDs), seven (β CDs) and eight (γ CDs) glucopyranose units. The chiral recognition mechanism is based on a sort of inclusion complexation. Complexation involves the interaction of the hydrophobic portion of an analyte enantiomer with the non-polar interior of the cavity, while the polar functional groups can form a hydrogen bond with the polar hydroxyl chiral cavity space. The most important factor that determines whether the analyte molecule will fit into the cyclodextrin cavity is its size. The α-CD consists of 30 stereo-selective centers, β-CD consists of 35 stereo-selective centers and γ-CD consists of 40 stereo-selective centers. When the hydrophobic portion of the analyte is larger or smaller than the toroid's cavity size, inclusion will not occur.
Sources: en.wikipedia.org
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.