GABA-A receptor is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-06-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
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.
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.
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.
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.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
In addition, there were hundreds of thousands of part-time employees and informers in various Syrian intelligence departments. According to estimates, there was one member of various branches of the Ba'athist secret police for every 158 citizens, which was said to be one of the largest ratios in the world. The general intelligence, political security, and military intelligence divisions of the Ba'athist secret police had several branches in all governorates controlled by the Assad regime, where they were all headquartered in Damascus. With state impunity granted by the Assad regime, officers of the Mukhabarat wielded pervasive influence over local bodies, civil associations and bureaucracy, where they played a major role in shaping Ba'athist administrative decisions. Additionally, intense factional rivalries and power struggles existed among various branches of the secret police. Several academics have described the military, bureaucratic, and secret police apparatus of the Ba'athist state as constituting a pyramidal socio-political structure with an Orwellian surveillance system designed to neutralize independent civic activities and political dissent from its very onset. During Ba'athist rule, Syria was one of the five countries listed on Reporters Without Borders' list of "State Enemies of the Internet" in March 2013, which was a list of countries ruled by governments that perpetrate pervasive surveillance of news providers that resulted in harsh restrictions on access to information and personal lives.
Mitochondria are self-replicating double membrane-bound organelles that occur in various numbers, shapes, and sizes in the cytoplasm of the cell. Aerobic respiration in the mitochondria generates the cell's energy by oxidative phosphorylation, using oxygen to release energy stored in cellular nutrients (typically pertaining to glucose) to generate adenosine triphosphate (ATP). Mitochondria are descended from bacteria that formed an endosymbiotic relationship with ancient prokaryotes. Mitochondria multiply by binary fission and have their own DNA contained in multiple small circular chromosomes. The mitochondrial DNA (mtDNA) is very small compared to nuclear DNA, but it codes for 13 proteins involved in mitochondrial energy production and specific transfer RNAs (tRNAs). Mitochondria also have their own ribosomes known as mitoribosomes.
In 1876, French engineer Charles Tellier bought the ex-Elder-Dempster 690 tons cargo ship Eboe and fitted a Methyl-ether refrigerating plant of his design. The ship was renamed Le Frigorifique and successfully imported a cargo of refrigerated meat from Argentina. However the machinery could be improved and in 1877 another refrigerated ship called Paraguay with a refrigerating plant improved by Ferdinand Carré was put into service on the South American run. In 1879, Henry Bell (1848–1931) and John Bell (1850–1929) of Scotland and Joseph James Coleman FRSE (1838–1888) of Scotland completed the Bell–Coleman dense-air machine on the Anchor liner Circassia, which successfully brought a cargo of chilled beef from the US to London. In 1880, Strathleven, equipped with a Bell–Coleman air machine and loaded with successfully shipped beef, mutton, butter and kegs, sailed from Melbourne, Australia, to London—a nine-week voyage of about 15,000 miles (24,000 km). In 1881, Alfred Seale Haslam (1844–1927) of England equipped the liner Orient with Haslam refrigeration compressors. He bought the Bell–Coleman dense-air patents in 1878 and eventually equipped four hundred plants and ships with Bell-Coleman machines. By 1899, refrigerated fruit ship traffic to the US reached 90,000 tons per year. By 1890, after acquiring the patent rights of Franz Windhausen's CO2-compression refrigeration system, the J & E Hall company installed the first marine CO2 refrigerator system on the Nelson Line ship Highland Chief.
Sources: en.wikipedia.org
=== Thyroxine, iodine and apoptosis === Thyroxine and iodine stimulate the apoptosis of the cells of the larval gills, tail and fins in amphibian metamorphosis, and stimulate the evolution of their nervous system transforming the aquatic, vegetarian tadpole into the terrestrial, carnivorous frog. In fact, amphibian frog Xenopus laevis serves as an ideal model system for the study of the mechanisms of apoptosis.
. Even for a simple homogeneous sphere of radius a whose refractive index, n, is very nearly the same as the refractive index "n0" of the suspending fluid, i.e. Rayleigh–Gans approximation, the scattering function in the scattering plane is the relatively complex quantity
The synthesis of an mRNA display library starts from the synthesis of a DNA library. A DNA library for any protein or small peptide of interest can be synthesized by solid-phase synthesis followed by PCR amplification. Usually, each member of this DNA library has a T7 RNA polymerase transcription site and a ribosomal binding site at the 5' end. The T7 promoter region allows large-scale in vitro T7 transcription to transcribe the DNA library into an mRNA library, which provides templates for the in vitro translation reaction later. The ribosomal binding site in the 5'-untranslated region (5' UTR) is designed according to the in vitro translation system to be used. There are two popular commercially available in vitro translation systems. One is E. coli S30 Extract System (Promega) that requires a Shine-Dalgarno sequence in the 5' UTR as a ribosomal binding site; the other one is Red Nova Lysate (Novagen), which needs a ΔTMV ribosomal binding site. Once the mRNA library is generated, it will be Urea-PAGE purified and ligated using T4 DNA ligase to the DNA spacer linker containing puromycin at the 3' end. In this ligation step, a piece of mRNA is ligated with a single stranded DNA with the help from T4 DNA ligase. This is not a standard T4 DNA ligase ligation reaction, where two pieces of double stranded DNA are ligated together. To increase the yield of this special ligation, a single stranded DNA splint may be used to aid the ligation reaction.
Carbon fibers are filaments of carbon that can be used to make very strong yarns and textiles. Carbon fiber items are often produced by spinning and weaving the desired item from fibers of a suitable polymer, and then pyrolyzing the material at a high temperature (from 1,500–3,000 °C or 2,730–5,430 °F). The first carbon fibers were made from rayon, but polyacrylonitrile has become the most common starting material. For their first workable electric lamps, Joseph Wilson Swan and Thomas Edison used carbon filaments made by pyrolysis of cotton yarns and bamboo splinters, respectively. Pyrolysis is the reaction used to coat a preformed substrate with a layer of pyrolytic carbon. This is typically done in a fluidized bed reactor heated to 1,000–2,000 °C or 1,830–3,630 °F. Pyrolytic carbon coatings are used in many applications, including artificial heart valves.
Sources: en.wikipedia.org
== Operation Atlantic Resolve == On 29 March 2017, the Department of Defense reported that Green Berets from 1st Battalion 10th SFG were deployed to Europe to take part in exercise Allied Spirit VI-a multinational training exercise involving military personnel from Canada, Czech Republic, Estonia, Finland, France, Hungary, Germany, Italy, Macedonia, Kosovo, Latvia, the Netherlands, Slovenia, UK and US at the JMRC in Germany, the exercise involved special operations and conventional forces with the aim to increase their effectiveness and/particularly to increase the effectiveness of special operations forces in working together while bolstering the capabilities of partner nations within US European Command's area of responsibility. The Green Berets provided their advise and assist training/skills, whilst working with Estonian Special Operations Task Group troops and Macedonian special operations troops. US Army Major Robert Temple, the special operations force cell planner at the JMRC said that “The primary purpose of this exercise is providing a venue for the 1st Latvian Brigade to train in a Joint Task Force environment and increase their interoperability with both U.S. units as well as other multinational forces.” The exercise is being conducted as part of Operation Atlantic Resolve.
==== Extramural researchers and scientists ==== Important stakeholders of the NIH funding policy include researchers and scientists. Extramural researchers differ from intramural researchers in that they are not employed by the NIH but may apply for funding. Throughout the history of the NIH, the amount of funding received has increased, but the proportion to each IC remains relatively constant. The individual ICs then decide who will receive the grant money and how much will be allotted. Policy changes on who receives funding significantly affect researchers. For example, the NIH has recently attempted to approve more first-time NIH R01 applicants or the research grant applications of young scientists. To encourage the participation of young scientists, the application process has been shortened and made easier. In addition, first-time applicants are being offered more funding for their research grants than those who have received grants in the past.
== See also == Anthropogenic metabolism – Material and energy turnover of human society Antimetabolite – Chemical that inhibits the use of a metabolite Battery theory Calorimetry – Determining heat transfer in a system by measuring its other properties Isothermal microcalorimetry – Measuring versus elapsed time the net rate of heat flow Inborn errors of metabolism – Class of genetic diseases Iron–sulfur world hypothesis – Hypothetical scenario for the origin of life, a "metabolism first" theory of the origin of life Metabolic disorder – Any disease hindering the body's ability to process and distribute nutrients Microphysiometry Primary nutritional groups – Group of organisms Proto-metabolism – Chemical reactions which turn into modern metabolism Respirometry – Estimation of metabolic rates by measuring heat production Stream metabolism Sulfur metabolism – Set of chemical reactions involving sulfur in living organisms Thermic effect of food – Energy expenditure for processing food Urban metabolism – Model of the flows of materials and energy in cities Water metabolism – Aspect of homeostasis concerning control of the amount of water in an organism Overflow metabolism – Cellular phenomena Oncometabolism Reactome – Database of biological pathways KEGG – Collection of bioinformatics databases
Sources: en.wikipedia.org
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
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.