A practical reference on GABA-A receptor: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-12-28. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
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.
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.
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.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
adenylyl sulfate + 2 glutathione The 3 substrates of this enzyme are adenosine monophosphate, sulfite, and glutathione disulfide, whereas its two products are adenylyl sulfate and glutathione. This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with a disulfide as acceptor. The systematic name of this enzyme class is AMP,sulfite:glutathione-disulfide oxidoreductase (adenosine-5'-phosphosulfate-forming). Other names in common use include 5'-adenylylsulfate reductase (also used for, internal_xref(ec_num(1,8,99,2))), AMP,sulfite:oxidized-glutathione oxidoreductase, (adenosine-5'-phosphosulfate-forming), and plant-type 5'-adenylylsulfate reductase. In plants, APS is reduced by the plastidic enzyme APS reductase (APR; EC 1.8.4.9) in the presence of physiological concentrations of reduced glutathione (GSH), which acts as an electron donor.
==== MeSH E05.300.530 – injections ==== MeSH E05.300.530.370 – injections, intra-arterial MeSH E05.300.530.380 – injections, intra-articular MeSH E05.300.530.430 – injections, intralesional MeSH E05.300.530.440 – injections, intralymphatic MeSH E05.300.530.460 – injections, intramuscular MeSH E05.300.530.490 – injections, intraperitoneal MeSH E05.300.530.540 – injections, intravenous MeSH E05.300.530.550 – injections, intraventricular MeSH E05.300.530.580 – injections, spinal MeSH E05.300.530.580.300 – injections, epidural MeSH E05.300.530.580.300.145 – blood patch, epidural MeSH E05.300.530.620 – injections, subcutaneous MeSH E05.300.530.620.410 – injections, intradermal MeSH E05.300.530.620.570 – injections, jet MeSH E05.300.530.620.570.100 – biolistics MeSH E05.300.530.690 – microinjections
=== Intravenous administration === Serum vancomycin levels may be monitored in an effort to reduce side effects, but the value of such monitoring has been questioned. Peak and trough levels are usually monitored, and for research purposes the area under the concentration curve is also sometimes used. Toxicity is best monitored by looking at trough values. Immunoassays are commonly used to measure vancomycin levels. Common adverse drug reactions (≥1% of patients) associated with intravenous vancomycin include:
Sources: en.wikipedia.org
== Mechanism of action == Abatacept is a soluble CTLA-4 analog that prevents antigen-presenting cells (APCs) from delivering the co-stimulatory signal. This prevents the T cells from being fully activated, and even downregulates them. Simple signaling without co-stimulation allows the cell to recognize the primary signal as "self" and not ramp-up responses for future responses as well. In order for T cells to be activated and attack an antigen, that antigen must be presented to the T cell by an APC. That activation requires two signals (one of which is called co-stimulatory signal or signal 2): For signal 1, the APC must bind the antigen to a major histocompatibility complex (MHC) molecule, bring that complex to its surface, and present it to the T cell receptor on the surface of the T cell. For signal 2, the APC must present a B7 protein (CD80 or CD86) on its cell surface to a CD28 protein on the surface of the T cell. These two signals activate the T cell. Without signal 2, the T cell will not be activated, and will become anergic. Abatacept, which consists of a fusion protein of the extracellular domain of CTLA-4 and human IgG1, binds to the B7 protein on the APC and prevents it from delivering the co-stimulatory signal to the T cell.
"I believe that all the power of the supreme being is not enough to liberate that despicable country (Peru): only Bolívar, supported by force, can do it." It is also known that San Martín wanted the disputed territory of Upper Peru, administered since 1810 by the Viceroyalty of Peru, to be handed over to the United Provinces of the Río de la Plata, which, although it would be somewhat predictable on his part (because it was an Argentine) in the exercise of a realpolitik, on the other hand it would be a sign of anti-Peruvianism on his part in the face of vague promises that he made to warlords, like Andrés de Santa Cruz, over the territory. Given this, he was allegedly accused of being dishonest with his ambiguous promises that he gave to Peruvian politicians who supported his government, since the Protectorate of San Martín de facto controlled the Atacama Party and was also claiming part of the territories of the current La Paz and Pando. That ended up generating a climate of mistrust, where the praises and praise of the Peruvians to the Liberator would have been apparent, in the midst of hostilities towards the Argentine caudillo. In the secret session of the Peruvian Congress, on September 27, 1822, suspicion and fear were expressed that San Martín tried to seize the provinces of Upper Peru, Arequipa and Cuzco.
== Contraindications == Mohs surgery is generally contraindicated when the criteria summarized in the “Uses” section above are not met. For example, the tumor is small, low-risk, has well-defined margins, and is in a non-critical area. The standard protocol for Mohs surgery requires the surgeon to both remove the tissue and interpret the pathology. The procedure is not considered Mohs surgery if the removed tissue is sent and read by a pathologist instead of the surgeon performing the procedure. In this case, it is considered a standard excision and should be documented as such. Another doctor interpreting histopathology is incompatible with Mohs surgery. Relative contraindications include instances where the risks of surgery outweigh the benefits such as in patients with co-morbidities, in cases where the defect caused by surgery would need complex reconstruction beyond the scope of the surgery, or when patient factors such as severe bleeding predispositions or being unable to tolerate local anesthesia would affect the prognosis. Increased postoperative complications are associated with immunosuppressed patients (e.g. solid organ transplant recipients) and elderly patients. These are not absolute contraindications, but the risks of this procedure should be weighed against the benefits for each individual patient.
Kenney, Padraic. 1989: Democratic Revolutions at the Cold War's End: A Brief History with Documents (2009) covers Poland, the Philippines, Chile, South Africa, Ukraine, and China Leffler, Melvyn P. For the Soul of Mankind: The United States, the Soviet Union, and the Cold War (2007) pp 338–450. Mann, James. The Rebellion of Ronald Reagan: A History of the End of the Cold War (2010). popular Matlock, Jack F. Autopsy on an Empire (1995) online by US ambassador to Moscow Matlock, Jack F. Reagan and Gorbachev : how the Cold War ended (2004) online Powaski, Ronald E. The Cold War: The United States and the Soviet Union, 1917–1991 (1998) Romero, Federico. "Cold War historiography at the crossroads." Cold War History 14.4 (2014): 685–703. online Shultz, George P. Turmoil and Triumph: My Years as Secretary of State (1993), a primary source Wilson, James Graham. The Triumph of Improvisation: Gorbachev's Adaptability, Reagan's Engagement, and the End of the Cold War (2014) Wohlforth, William C. "Realism and the End of the Cold War." International Security 19.3 (1994): 91–129. online Zubok, Vladislav M. "Gorbachev and the End of the Cold War: Perspectives on History and Personality," Cold War History (2002) 2:2, 61–100, DOI: 10.1080/713999954 Zubok, Vladislav M. A failed empire: the Soviet Union in the Cold War from Stalin to Gorbachev (2009). online Archived 2020-09-19 at the Wayback Machine
Sources: en.wikipedia.org
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.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.