This is a working overview of GABA-A modulation, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-12 and is reviewed periodically as new material appears.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
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. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
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.
| Property | Value | Notes |
|---|---|---|
| Principal proposed target | GABA-A receptor complex | Hypothesis derived mainly from animal pharmacology |
| Common behavioral assay | Elevated plus maze | Rodent test for anxiety-like behavior |
| Reported molecular marker | Hippocampal BDNF expression | Measured by immunoassay or mRNA quantification |
| Typical dosing route | Intranasal | Chosen to reduce first-pass metabolism |
| Reported plasma half-life | Minutes | Based on limited peptide stability data |
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.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
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.
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.
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.
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.
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.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
== In plants == Approximately 30 GRX isoforms are described in the model plant Arabidopsis thaliana and 48 in Oryza sativa L. According to their redox-active centre, they are subgrouped in six classes of the CSY[C/S]-, CGFS-, CC-type and 3 groups with additional domains of unknown function. The CC-type GRXs are only found in higher plants. In Arabidopsis, GRXs are involved in flower development and Salicylic acid signalling.
Maurice Loyal Huggins (September 19, 1897, Berkeley, California – December 17, 1981) was a scientist who independently conceived the idea of hydrogen bonding and who was an early advocate for their role in stabilizing protein secondary structure. An important polymer theory, Flory–Huggins theory, is also named after him.
=== United Kingdom === A Chick-fil-A operated in Edinburgh during the Spring of 2018. On October 10, 2019, Chick-fil-A returned to Europe, with the opening of a store at The Oracle shopping centre in Reading, UK. The store closed in March 2020 after The Oracle opted not to continue the lease of the location beyond the six-month pilot period in the face of continued protests over the chain's anti-LGBTQ stance. In February 2019, Chick-fil-A opened a store on a 12-month pilot scheme in Aviemore, Scotland. The store was closed in January 2020 amidst protests and controversy from locals and customers regarding the chain's former donations to charities supporting anti-LGBT rights causes. Chick-fil-A said that they had always planned a short-term stay at the location. Later, the company changed some policies, appointing its first head of diversity in 2020, and focused its charitable activities on education and hunger alleviation rather than opponents of same-sex marriage. In September 2023, the company planned to open five restaurants in the UK from early 2025, investing over $100M over the following ten years in the UK. The chain said that it would apply its charitable policies, including a $25,000 donation to a local organization on opening a Chick-fil-A restaurant and donation of surplus food to local charitable causes, to its UK branches too.
Their mission, in their words "for the purpose of mutual aid in cases of sickness, accident and death of its members or their families". In 1923 it had 8,000 members in 60 subordinate societies; that year it had a capital of over $500,000, with a further $100,000 in sick benefit funds held by local societies. All policy decisions are determined by a "Central Society" made up of the officers, founders, and representatives of the subordinate lodges. A central society meets at stated intervals to elect officers to administer the group and make needed changes. Membership is open to men 18–50, of good moral character who have passed medical exams, regardless of religious or political creeds. Germania stated that it "is not a secret society. No pass-words or grips feature its work. In fact, any man is welcome to join its meetings." German Order of Harugari Greater Beneficial Union of Pittsburgh - Incorporated April 14, 1892 in Allegheny County, Pennsylvania, as the Deutscher Unter-stuetzungs-Bund, within a month had 243 members in 6 districts. Began the periodical, Union Reporter, the next year, now known as GBU Reporter. Rituals include the candidate signing an application and the president of the local lodge giving an address about the privileges of membership and how one should enter the lodge. Union claimed to be non-sectarian and had no secrets; open to all "well-meaning persons"; non-members accompanied by members allowed at meeting.
The American Academy of Allergy, Asthma & Immunology (AAAAI); American Board of Allergy & Immunology (ABAI) International Society of Internal Medicine Internal Medicine Society of Australia and New Zealand Archived 2016-08-31 at the Wayback Machine The American Board of Internal Medicine Canadian Society of Internal Medicine The American College of Osteopathic Internists American College of Physicians
Sources: en.wikipedia.org
As mentioned above, the naturally occurring nucleotides (nucleoside-3'- or 5'-phosphates) and their phosphodiester analogs are insufficiently reactive to afford an expeditious synthetic preparation of oligonucleotides in high yields. The selectivity and the rate of the formation of internucleosidic linkages is dramatically improved by using 3'-O-(N,N-diisopropyl phosphoramidite) derivatives of nucleosides (nucleoside phosphoramidites) that serve as building blocks in phosphite triester methodology. To prevent undesired side reactions, all other functional groups present in nucleosides have to be rendered unreactive (protected) by attaching protecting groups. Upon the completion of the oligonucleotide chain assembly, all the protecting groups are removed to yield the desired oligonucleotides. Below, the protecting groups currently used in commercially available and most common nucleoside phosphoramidite building blocks are briefly reviewed:
=== Pharmacodynamics === Citalopram contains two pharmacodynamically distinct enantiomers: (S)-citalopram (escitalopram) and (R)-citalopram. (S)-citalopram is a highly selective serotonin reuptake inhibitor and is thought to be responsible for most of the SRI activity of citalopram. (R)-citalopram, by comparison, is a 20-fold less potent SERT inhibitor and antagonizes the actions of (S)-citalopram at this site. The mechanism of antagonism is uncertain, but may involve kinetic interactions between the two; it has been proposed that the long-lasting inhibited state of SERT induced by (S)-citalopram may be attenuated by (R)-citalopram binding. Citalopram has a ~6-fold higher affinity for H1 histamine receptors than (S)-citalopram (Ki = 257nM vs 1500nM), though the clinical significance of this difference is unknown. Both citalopram and escitalopram have similar affinities for the σ1 receptor (Ki = 50nM).
Biden campaigned heavily for Democrats in the 2010 midterm elections, maintaining an attitude of optimism in the face of predictions of large-scale losses for the party. After big Republican gains in the elections and Emanuel's departure, Biden's past relationships with Republicans in Congress became more important. He led the successful administration effort to gain Senate approval for the New START treaty. In December 2010, Biden's advocacy for a middle ground, followed by his negotiations with Senate minority leader Mitch McConnell, were instrumental in producing the administration's compromise tax package that included a temporary extension of the Bush tax cuts. The package passed as the Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010. Obama delegated Biden to lead negotiations with Congress during the 2011 U.S. debt ceiling crisis. Biden's relationship with McConnell brought about the Budget Control Act of 2011 that solved the crisis. Some reports suggest that Biden opposed proceeding with the May 2011 U.S. mission to kill Osama bin Laden, lest failure adversely affect Obama's reelection prospects. In 2012, Biden made the case for Obama's reelection: "Osama bin Laden is dead and General Motors is alive." Obama named Biden to head the Gun Violence Task Force, created to address the causes of school shootings and consider possible gun control measures in the aftermath of the Sandy Hook Elementary School shooting, in December 2012.
=== As a fumigant === In the beginning of the 20th century sulfur dioxide was used in Buenos Aires as a fumigant to kill rats that carried the Yersinia pestis bacterium, which causes bubonic plague. The application was successful, and the application of this method was extended to other areas in South America. In Buenos Aires, where these apparatuses were known as Sulfurozador, but later also in Rio de Janeiro, New Orleans and San Francisco, the sulfur dioxide treatment machines were brought into the streets to enable extensive disinfection campaigns, with effective results.
Sources: en.wikipedia.org
This material comprises coordinatively saturated Zn4O nodes and fully complexed BDC struts (see above for abbreviation); yet it apparently catalyzes the Friedel–Crafts tert-butylation of both toluene and biphenyl. Furthermore, para alkylation is strongly favored over ortho alkylation, a behavior thought to reflect the encapsulation of reactants by the MOF.
A third, only marginally related concept was proposed in 1923 by Gilbert N. Lewis, which includes reactions with acid–base characteristics that do not involve a proton transfer. A Lewis acid is a species that accepts a pair of electrons from another species; in other words, it is an electron pair acceptor. Brønsted acid–base reactions are proton transfer reactions while Lewis acid–base reactions are electron pair transfers. Many Lewis acids are not Brønsted–Lowry acids. Contrast how the following reactions are described in terms of acid–base chemistry:
== Hertzian theory of non-adhesive elastic contact == The classical theory of contact focused primarily on non-adhesive contact where no tension force is allowed to occur within the contact area, i.e., contacting bodies can be separated without adhesion forces. Several analytical and numerical approaches have been used to solve contact problems that satisfy the no-adhesion condition. Complex forces and moments are transmitted between the bodies where they touch, so problems in contact mechanics can become quite sophisticated. In addition, the contact stresses are usually a nonlinear function of the deformation. To simplify the solution procedure, a frame of reference is usually defined in which the objects (possibly in motion relative to one another) are static. They interact through surface tractions (or pressures/stresses) at their interface. As an example, consider two objects which meet at some surface
=== Biological activities === β-thymosin repeat proteins resemble the monomeric forms in being able to bind to actin, but sequence differences in one example studied, a three-repeat protein Ciboulot of the fruit fly Drosophila, allow binding to ends of actin filaments, an activity which differs from monomer sequestration. These proteins became of interest in neurobiology with the finding that in the nudibranch (sea slug) Hermissenda crassicornis, the protein Csp24 (conditioned stimulus pathway phosphoprotein-24), with 4 repeats, is involved in simple forms of learning: both one-trial enhancement of the excitability of sensory neurons in the conditioned stimulus pathway, and in multi-trial Pavlovian conditioning. The phosphorylation of Csp24, in common with post-translational modifications of a number of cytoskeleton-related proteins may contribute to actin-filament dynamics underlying structural remodeling of responsive cells.
Vitamins are essential for the normal growth and development of a multicellular organism. Using the genetic blueprint inherited from its parents, a fetus develops from the nutrients it absorbs. It requires certain vitamins and minerals to be present at certain times. These nutrients facilitate the chemical reactions that produce among other things, skin, bone, and muscle. If there is serious deficiency in one or more of these nutrients, a child may develop a deficiency disease. Even minor deficiencies may cause permanent damage.
Sources: en.wikipedia.org
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.
Behavioral endpoints include time spent in open arms of the elevated plus maze and avoidance latencies. Biochemical endpoints include BDNF concentration, cytokine levels, and monoamine metabolite ratios in brain tissue.
Most published studies are small, originate from a limited number of laboratories, and lack independent replication. Dose-response relationships, measured brain exposure, and long-term outcomes are not well characterized.
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.