BDNF raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
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.
There are many physiological mechanisms that control starting and stopping a meal. The control of food intake is a physiologically complex, motivated behavioral system. Hormones such as cholecystokinin, bombesin, neurotensin, anorectin, calcitonin, enterostatin, leptin and corticotropin-releasing hormone have all been shown to suppress food intake. Eating rapidly leads to obesity and overeating, probably because the feelings of satiety can be slower.
The largest and most famous sphinx is the Great Sphinx of Giza, situated on the Giza Plateau adjacent to the Great Pyramids of Giza on the west bank of the Nile River and facing east (29°58′31″N 31°08′15″E). The sphinx is located southeast of the pyramids. While the date of its construction is not known for certain, the consensus among Egyptologists is that the head of the Great Sphinx bears the likeness of the pharaoh Khafre, dating it to between 2600 and 2500 BC. However, a fringe minority of late 20th century geologists have claimed evidence of water erosion in and around the Sphinx enclosure which would prove that the Sphinx predates Khafre, at around 10,000 to 5000 BC, a claim that is sometimes referred to as the Sphinx water erosion hypothesis but which has little support among Egyptologists and contradicts other evidence. What names their builders gave to these statues is unknown. At the Great Sphinx site, a 1400 BC inscription on a stele belonging to the 18th dynasty pharaoh Thutmose IV lists the names of three aspects of the local sun deity of that period, Khepera–Rê–Atum. Many pharaohs had their heads carved atop the guardian statues for their tombs to show their close relationship with the powerful solar deity Sekhmet, a lioness. Besides the Great Sphinx, other famous Egyptian sphinxes include one bearing the head of the pharaoh Hatshepsut, with her likeness carved in granite, which is now in the Metropolitan Museum of Art in New York, and the alabaster Sphinx of Memphis, currently located within the open-air museum at that site.
=== Self-propelled artillery === Sexton (artillery) – Saw service until 1956 FV433 Abbot SPG – Main light SPG M109 howitzer – Main heavy SPG M270 Multiple Launch Rocket System – acquired late in the Cold War
== Further reading == Aziz, Nusrate; Asadullah, M Niaz (2017). "Military spending, armed conflict and economic growth in developing countries in the post–Cold War era" (PDF). Journal of Economic Studies. 44 (1): 47–68. doi:10.1108/JES-01-2015-0021. Bartel, Fritz (2022). The Triumph of Broken Promises: The End of the Cold War and the Rise of Neoliberalism. Harvard University Press. ISBN 9780674976788. Henriksen, Thomas H. (2017). Cycles in US Foreign Policy Since the Cold War. Palgrave Macmillan. Jones, Bruce D.; Stedman, Stephen John (2017). "Civil Wars & the Post–Cold War International Order". Dædalus. 146 (4): 33–44. Menon, Rajan; Rumer, Eugene B., eds. (2015). Conflict in Ukraine: The Unwinding of the Post–Cold War Order. MIT Press. Peterson, James W. (2017). Russian-American relations in the post–Cold War world. Oxford UP. Sakwa, Richard (2017). Russia against the Rest: The Post–Cold War Crisis of World Order. Cambridge UP. p. 362. Wood, Luke B. (2017). "The politics of identity and security in post–Cold War Western and Central Europe". European Politics and Society. 18 (4): 552–556. doi:10.1080/23745118.2017.1376444.
Sources: en.wikipedia.org
==== Microsomal triglyceride transfer protein (MTTP) ==== Microsomal triglyceride transfer protein (MTTP) is an endoplasmic reticulum lipid transfer protein involved in the biosynthesis and lipid loading of apolipoprotein B. MTTP is also involved in the late stage of CD1d trafficking in the lysosomal compartment, CD1d being the MHC I-like lipid antigen presenting molecule.
In 1027 and 1044, Patriarch Poppo of Aquileia, who rebuilt the cathedral of Aquileia, entered and sacked neighbouring Grado, and, though the Pope reconfirmed the Patriarch of the latter in his dignities, the town never fully recovered, though it continued to be the seat of the Patriarchate until its formal transference to Venice in 1450. In the fourteenth century, the Patriarchal State reached its largest extension, stretching from the Piave river to the Julian Alps and northern Istria. The seat of the Patriarchate of Aquileia had been transferred to Udine in 1238, but returned to Aquileia in 1420 when Venice annexed the territory of Udine. In 1445, the defeated patriarch Ludovico Trevisan acquiesced in the loss of his ancient temporal estate in return for an annual salary of 5,000 ducats allowed him from the Venetian treasury. Henceforth only Venetians were allowed to hold the title of Patriarch of Aquileia. The Patriarchal State was incorporated into the Republic of Venice with the name of Patria del Friuli, ruled by a provveditore generale or a luogotenente living in Udine.
Biocatalysis refers to the use of living (biological) systems or their parts to speed up (catalyze) chemical reactions. In biocatalytic processes, natural catalysts, such as enzymes, perform chemical transformations on organic compounds. Both enzymes that have been more or less isolated and enzymes still residing inside living cells are employed for this task. Modern biotechnology, specifically directed evolution, has made the production of modified or non-natural enzymes possible. This has enabled the development of enzymes that can catalyze novel small molecule transformations that may be difficult or impossible using classical synthetic organic chemistry. Utilizing natural or modified enzymes to perform organic synthesis is termed chemoenzymatic synthesis; the reactions performed by the enzyme are classified as chemoenzymatic reactions.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
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.