Everything below concerns Pro-Gly-Pro. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-07-05. Numbers and descriptions here follow the published literature rather than marketing material.
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 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.
| 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 |
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 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.
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.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
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.
== History == Acrolein was first named and characterized as an aldehyde by the Swedish chemist Jöns Jacob Berzelius in 1839. He had been working with it as a thermal degradation product of glycerol, a material used in the manufacture of soap. The name is a contraction of 'acrid' (referring to its pungent smell) and 'oleum' (referring to its oil-like consistency). In the 20th century, acrolein became an important intermediate for the industrial production of acrylic acid and acrylic plastics.
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Sources: en.wikipedia.org
== Physiological function == The principal function of glycine is it acts as a precursor to proteins. Most proteins incorporate only small quantities of glycine, a notable exception being collagen, which contains about 35% glycine due to its periodically repeated role in the formation of collagen's helix structure in conjunction with hydroxyproline. In the genetic code, glycine is coded by all codons starting with GG, namely GGU, GGC, GGA and GGG.
Matrix Biology is a peer-reviewed scientific journal in the field of matrix biology. The journal is published 8 times per year by Elsevier. The journal was established in 1981 as Collagen and Related Research and renamed to Matrix: Collagen and Related Research in 1988, before obtaining its current name in 1994. It is an official journal of the American Society for Matrix Biology and the International Society for Matrix Biology. The current editor-in-chief is Renato V. Iozzo (Thomas Jefferson University).
Robert Martin Culp (August 16, 1930 – March 24, 2010) was an American actor and screenwriter widely known for his work in television. Culp earned an international reputation for his role as Kelly Robinson on I Spy (1965–1968), the espionage television series in which he and co-star Bill Cosby played secret agents. Before this, he starred in the CBS/Four Star Western series Trackdown as Texas Ranger Hoby Gilman in 71 episodes from 1957 to 1959. The 1980s brought him back to television as FBI Agent Bill Maxwell on The Greatest American Hero. Later, he had a recurring role as Warren Whelan on Everybody Loves Raymond, and was a voice actor for various video games, including Half-Life 2. Culp gave hundreds of performances in a career spanning more than 50 years.
The partisan section took care of the armed defense of the territory, women assisted men with provisions, and party cadres had to keep in touch with the party federation. The revolutionaries established a “People's Tribunal,” which was based in the town square and had the power to try “enemies of the people". An internment camp held many agrarians and notables. The revolutionary experience worried both conservatives and communist leaders, who pressed Cavallaro to calm tempers and end the revolution. The mayor became spokesman for the rebels and convinced most of them to return home and lay down their arms. Diehards refused and went into hiding. Finally, on March 9, the prefect of Reggio Calabria sent departments of carabinieri and police to Caulonia. They arrested 365 men, who were referred to the Locri court for constitution of an armed gang, murder, violence to private individuals and usurpation of public office. On April 15, Cavallaro resigned as mayor. British historian Jonathan Dunnage reported an "institutional continuity" of the civil servants who survived these regime changes Civil servants were not purged either after 1922 or 1943. The "institutional continuity" of the bureaucracy of Calabria were committed to preserving the social structure. On 2 June 1946 Calabria, like the rest of the Mezzogiorno, voted solidly to retain the monarchy. The traditional political system in Calabria continued after 1945. During the war, the already low living standards of Calabria declined further and the region was notorious as one of Italy's most violent areas.
Sources: en.wikipedia.org
== In popular culture == In Agatha Christie's 1937 mystery Cards on the Table, Hexobarbital is used in conjunction with Veronal to induce overdose. It is referred to by Hercule Poirot as both N-methyl-cyclo-hexenyl-methyl-malonyl urea and Evipan. It was also used in Graham Greene's The Heart of the Matter (1948) Evipan was prescribed for a main character in tablet form to use as a sleeping aid.
As the first woman since 1964 to win the Nobel Prize in chemistry, and the first since Dorothy Crowfoot Hodgkin, 45 years previously. She was also the fourth of eight women ever to win the Nobel Prize in chemistry. Although Yonath once remarked, “I am a scientist, not male or female. A scientist,” her 2009 award was noted as a highlight for female scientists. The Australian noted that Yonath's Nobel win was "crushing the lab's glass ceiling". Regarded as an influential Israeli scientist, Yonath helped established the first protein crystallography laboratory in Israel. In 2018, while interviewing Yonath, UNESCO noted that her scientific research has also been "key to understanding how antibiotics work". Following her death, The New York Times noted that Yonath's mapping of the ribosome led to new designs for antibiotics. Her work was noted as "boundary pushing" with it having "immediate and practical consequences" for medicine and in the "fight against infectious disease". President Isaac Herzog noted Yonath as "one of the leading researchers in the history of Israeli science". The Hindu also noted Yonath's academic impact, especially in India through her engagements in academic institutions in the country.
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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.
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.