This is a working overview of GABA-A receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-11 and is reviewed periodically as new material appears.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
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.
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.
| 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 |
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
== Volunteers == CLSI relies on more than 2,000 volunteers. Volunteers and mentors also collaborate with CLSI's Global Health Partnerships to help establish laboratory quality management systems in resource-limited countries.
=== β-Adrenergic receptor antagonism === Stimulation of β1 receptors by epinephrine and norepinephrine induces a positive chronotropic and inotropic effect on the heart and increases cardiac conduction velocity and automaticity. Stimulation of β1 receptors on the kidney causes renin release. Stimulation of β2 receptors induces smooth muscle relaxation, induces tremor in skeletal muscle, and increases glycogenolysis in the liver and skeletal muscle. Stimulation of β3 receptors induces lipolysis. Beta blockers inhibit these normal epinephrine- and norepinephrine-mediated sympathetic actions, but have minimal effect on resting subjects. That is, they reduce the effect of excitement or physical exertion on heart rate and force of contraction, and also tremor, and breakdown of glycogen. Beta blockers can have a constricting effect on the bronchi of the lungs, possibly worsening or causing asthma symptoms. Since β2 adrenergic receptors can cause vascular smooth muscle dilation, beta blockers may cause some vasoconstriction. However, this effect tends to be small because the activity of β2 receptors is overshadowed by the more dominant vasoconstricting α1 receptors. By far the greatest effect of beta blockers remains in the heart. Newer, third-generation beta blockers can cause vasodilation through blockade of alpha-adrenergic receptors. Accordingly, nonselective beta blockers are expected to have antihypertensive effects.
== Presentation == Blastic plasmacytoid dendritic cell neoplasm occurs in children, including neonates, but is more common in adults, particularly those between the ages 60–80. BPDCN usually (i.e. 61% to 90% of cases) presents with skin lesions, i.e. nodules, tumors, red or purple papules, bruise-like patches, and/or ulcers that most often occur on the head, face, and upper torso. The lesions are due to diffuse infiltrations of the skin by malignant pDC. In one large study, this presentation was accompanied by swollen lymph nodes, usually in the neck, due to malignant pDC infiltrations (~50% of cases); enlarged liver (~16% of cases) and/or spleen (26% of cases), also due to malignant pDC infiltrations; increased levels of malignant pDC in blood (i.e. >2% of nucleated cells) (~40% of cases), bone marrow (~65% of cases) and cerebrospinal fluid (47% of childhood cases but less often detected in adult cases). More advanced or severe cases may present with extreme organ and/or lymph node enlargements, skin lesions in virtually any site, and clinical evidence of malignant pDC infiltrations in the breasts, eyes, kidneys, lungs, gastrointestinal tract, bone, sinuses, ears, or testes. About 10% of individuals with BPDCN present with a leukemia-like disease, i.e. they exhibit circulating malignant pDC, anemia, thrombocytopenia, and/or leukopenia due to extensive malignant pDC infiltrations in the bone marrow. A leukemic phase of the disease is a common feature of end stage and post-therapy relapsing BPDCN.
=== Policy on Scouting America === In November 2025, Hegseth in a draft memo proposed eliminating the promotion for Eagle Scouts who join the Army and other services due to the lack of "masculine values" and "promoting gender confusion." He also threatened to cut all support from the Department of Defense to Scouting America. The proposal in the draft memo would eliminate support to the National Jamboree as well as ban military bases from hosting or sponsoring scout units. He claimed that the organization was attacking "boy-friendly" spaces by allowing girls to join the organization in 2018. Military families and retired military have criticized the possible actions by Hegseth, stating it will harm military dependent children who depend on the organization as a stabilizing force. Other critics stated that this proposal would harm the military, as 20 percent of military academy students are former scouts and a number of scouts go directly into the military due to the partnership. Navy Secretary John Phelan wrote a memo of his own, stating, "Passive support to Scouting America through access to military installations and educational opportunities aboard said installations serve as a crucial recruiting and community engagement tool for the [Navy]". On February 27, 2026, Scouting America announced that they would immediately drop the Citizenship in the Society merit badge, will create a military service merit badge and waive registration fees for dependent children of active duty military, National Guard and reserve families.
Grammatophyllum speciosum, also called giant orchid, tiger orchid, sugar cane orchid or queen of the orchids, is a species of orchid native to Laos, Myanmar, Thailand, Vietnam, Borneo, Indonesia (Sumatra, Java, Sulawesi) and Malaysia. It has also been recorded in the Philippines, New Guinea and the Solomon Islands.
Sources: en.wikipedia.org
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==== Telomerase Vaccines ==== Two telomerase vaccines have been developed: GRNVAC1 and GV1001. GRNVAC1 isolates dendritic cells and the RNA that codes for the telomerase protein and puts them back into the patient to make cytotoxic T cells that kill the telomerase-active cells. GV1001 is a peptide from the active site of hTERT and is recognized by the immune system that reacts by killing the telomerase-active cells.
Comprehensive two-dimensional gas chromatography, or GC×GC, is a multidimensional gas chromatography technique that was originally described in 1984 by J. Calvin Giddings and first successfully implemented in 1991 by John Phillips and his student Zaiyou Liu. GC×GC utilizes two different columns with two different stationary phases. In GC×GC, all of the effluent from the first dimension column is diverted to the second dimension column via a modulator. The modulator quickly traps, then "injects" the effluent from the first dimension column onto the second dimension. This process creates a retention plane of the 1st dimension separation x 2nd dimension separation. The oil and gas industry was an early adopter of the technology for the complex oil samples to determine the many different types of hydrocarbons and their isomers. In these types of samples, over 30000 different compounds could be identified in a crude oil with this comprehensive chromatography technology (CCT). The CCT evolved from a technology only used in academic R&D laboratories into a more robust technology used in many different industrial labs. Comprehensive chromatography is used in forensics, food and flavor, environmental, metabolomics, biomarkers and clinical applications. Some of the most well-established research groups in the world that are found in Australia, Italy, the Netherlands, Canada, United States, and Brazil use this analytical technique.
Other biologists dispute this conception and emphasize the community metabolism theme, the idea that early living communities would comprise many different entities to extant cells, and would have shared their genetic material more extensively than current microbes.
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.
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.