GABA-A modulation 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.
Updated 2025-10-15. 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.
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.
| 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 |
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.
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.
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.
=== In Europe === Chia is considered a novel food in Europe because it does not have "a significant history of consumption within the European Union before 15 May 1997", according to the Advisory Committee of Novel Foods and Processes. Under this rule, chia seeds may be 5% of total matter in bread products. Prepackaged chia seeds must carry additional labelling to inform the consumer that the daily intake is no more than 15 grams and pure chia oil only 2 grams daily. Chia seeds sold in the EU are imported mainly from South American and Central American countries and require inspections for levels of pesticides, contaminants, and microbiological criteria.
(2026) study the evolution of amphibious hearing in pinnipeds on the basis of data from extant and extinct representatives of the group and their relatives, link its evolution to the evolution of cavernous tissue in pinniped ear canal and middle ear, and report evidence of presence of amphibious hearing in the last common ancestor of "enaliarctines" and modern pinnipeds but not in more basal members of the pinniped stem group. The first pinniped fossil from Taiwan (a femur of a member of the genus Zalophus from the Pleistocene strata from the bottom of the Taiwan Strait) is described by Sun et al. (2026). Dewaele et al. (2026) study the long bone variability of extant earless seals, finding no evidence of consistently clear genus- or species-specific shapes, and note the need for reevaluation of validity of fossil taxa described on the basis of isolated long bones. Postcranial earless seal bones with distinctive morphology are reported from the Miocene strata from Hrytsiv (Ukraine; the type locality of Planopusa semenovi) by Otriazhyi et al. (2026). Dewaele (2026) revises the fossil record of earless seals from the Miocene strata of the Chesapeake Group (Maryland and Virginia, United States), reporting evidence of presence of three seal morphotypes in the studied fossil material.
Drilling is carried out after studies of structural geology (at the reservoir scale), sedimentary basin analysis, and reservoir characterisation (mainly in terms of the porosity and permeability of geologic reservoir structures). Wells are drilled into oil reservoirs to extract the crude oil. "Natural lift" production methods that rely on the natural reservoir pressure to force the oil to the surface are usually sufficient for a while after reservoirs are first tapped. In some reservoirs, such as in the Middle East, the natural pressure is sufficient over a long time. The natural pressure in most reservoirs, however, eventually dissipates. Then the oil must be extracted using "artificial lift" means. Over time, these "primary" methods become less effective and "secondary" production methods may be used. A common secondary method is "waterflood" or injection of water into the reservoir to increase pressure and force the oil to the drilled shaft or "wellbore". Eventually "tertiary" or "enhanced" oil recovery methods may be used to increase the oil's flow characteristics by injecting steam, carbon dioxide and other gases or chemicals into the reservoir. In the United States, primary production methods account for less than 40 percent of the oil produced on a daily basis, secondary methods account for about 50 percent, and tertiary recovery the remaining 10 percent.
== 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
On 8 December 1988, an A-10 Thunderbolt II attack jet of the United States Air Force crashed onto a residential area in the city of Remscheid, West Germany. The aircraft crashed into the upper floor of an apartment complex. In addition to the pilot, five people were killed. Fifty others were injured, many of them seriously. When the number of cancer cases in the vicinity of the accident rose disproportionately in the years after, suspicion rose that the depleted uranium ballast in the jet may have been the cause. This was denied by the US military. However, 70 tons of top soil from the accident scene was removed and taken away to a depot. Film material taken during the top-soil removal show radiation warning signs. 120 residents and rescue workers reported skin diseases. Medical diagnosis concluded that these symptoms related to toxic irritative dermatitis.
== Function == This protein is expressed largely in cells possessing a regulated secretory pathway, such as endocrine/neuroendocrine cells and neurons. The intact proSAAS protein, as well as the carboxyy-terminal peptide containing the inhibitory hexapeptide LLRVKR, functions as an inhibitor of prohormone convertase 1/3, which accomplishes the initial proteolytic cleavage of peptide precursors. ProSAAS is further processed at the N- and C-termini into multiple short peptides, leaving the central segment intact. This central, unprocessed portion of the protein may function as a neural- and endocrine-specific chaperone due to its potent ability to block the aggregation of beta amyloid and alpha synuclein in vitro, and to block oligomer cytotoxicity in cells. Recent data show that nigral proSAAS expression blocks the deterioration of the striatonigral pathway in a synuclein rat model of Parkinson's disease. ProSAAS also oligomerizes and undergoes liquid-liquid phase separation. Differential expression of this gene may be associated with obesity.
Heinz Kähler: Die Augustusstatue von Primaporta. Köln 1959. Erika Simon: Der Augustus von Prima Porta. Bremen, Dorn 1959. (Opus nobile 13) Hans Jucker: Dokumentationen zur Augustusstatue von Primaporta, in: Hefte des Archäologischen Seminars Bern 3 (1977) S. 16–37. Paul Zanker: Augustus und die Macht der Bilder. München, C. H. Beck 1987, ISBN 3-406-32067-8 Kaiser Augustus und die verlorene Republik, Ausstellung Berlin 1988. Mainz, Zabern 1988. S. 386 f. Nr. 215. Erika Simon: Altes und Neues zur Statue des Augustus von Primaporta, in: G. Binder (Hrsg.), Saeculum Augustum, Bd. 3, Darmstadt, WBG 1991, S. 204–233. Dietrich Boschung: Die Bildnisse des Augustus, Gebr. Mann Verlag, Berlin 1993 (Das römische Herrscherbild, Abt. 1, Bd. 2) ISBN 3-7861-1695-4 Thomas Schäfer: Der Augustus von Primaporta im Wechsel der Medien, in: H. J. Wendel u.a. (Hrsg.), Wechsel des Mediums. Zur Interdependenz von Form und Inhalt, Rostock 2001, S. 37–58. Vinzenz Brinkmann und Raimund Wünsche (eds.): Bunte Götter. Die Farbigkeit antiker Skulptur. Eine Ausstellung der Staatlichen Antikensammlungen und Glyptothek München in Zusammenarbeit mit der Ny Carlsberg Glyptotek Kopenhagen und den Vatikanischen Museen, Rom, Staatliche Antikensammlungen und Glyptothek, München 2004 ISBN 3-933200-08-3. In Italian
=== Spintronics === Large-area graphene created by chemical vapor deposition (CVD) and layered on a SiO2 substrate, can preserve electron spin over an extended period and communicate it. Spintronics varies electron spin rather than current flow. The spin signal is preserved in graphene channels that are up to 16 micrometers long over a nanosecond. Pure spin transport and precession extended over 16 μm channel lengths with a spin lifetime of 1.2 ns and a spin diffusion length of ≈6 μm at room temperature. Spintronics is used in disk drives for data storage and in magnetic random-access memory. Electronic spin is generally short-lived and fragile, but the spin-based information in current devices needs to travel only a few nanometers. However, in processors, the information must cross several tens of micrometers with aligned spins. Graphene is the only known candidate for such behavior.
{\displaystyle {\begin{aligned}{\frac {\partial f(t,j)}{\partial t}}&=2k_{+}m(t)f(t,j-1)-2k_{+}m(t)f(t,j)\\&+2k_{\rm {off}}f(t,j+1)-2k_{\rm {off}}f(t,j)\\&+k_{-}\sum _{i=j+1}^{\infty }f(t,i)-k_{-}(j-1)f(t,j)\\&+k_{1}m(t)^{n_{1}}\delta _{j,n_{1}}+k_{2}m(t)^{n_{2}}M(t)\delta _{j,n_{2}}\\\\\end{aligned}}}
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.