If you have been reading about elevated plus maze and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-07-08. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 |
|---|---|---|
| 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 |
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.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
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, 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.
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.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
High-throughput DNA sequencing in the 2010s greatly expanded the scale of data in lichen systematics, allowing entire genomes to be analyzed and timelines of lichen evolution to be estimated. Researchers could sequence hundreds of genes or whole genomes, for both the fungal partner and, in some cases, the photobiont. Phylogenomics applies the same tree-building principles but with exponentially larger datasets, offering greater resolving power. A comparative review by Divakar and Crespo (2015) argues that genome‑scale datasets already outperform multigene matrices at resolving the deepest nodes in the lichen‑forming fungal tree and may be the only realistic route to a fully resolved backbone. For perspective, a typical fungal genome spans 30–50 Mbp; Sanger datasets averaged only 3–5 kb. The added scale lets researchers date major radiations, probe the genetics of symbiosis, and resolve ancient splits left ambiguous by small gene sets. Nelsen et al. (2020) assembled multi-locus data (largely mined from genomes and transcriptomes) for 3,300 lichenised fungi making up about a quarter of Lecanoromycetes and produced the largest time-calibrated phylogeny to date. Their tree suggests a Mesozoic ancestor that was a crustose microlichen with a Trebouxia partner. Foliose and fruticose forms evolved repeatedly, first appearing in the Jurassic–Early Cretaceous and diversifying further in the Cenozoic. The study also found evidence that lichen symbiosis is not a one-way evolutionary dead-end.
Secondary radionuclides in a decay chain will occur in proportion to their half-lives, so short-lived ones will be very rare. For example, polonium can be found in uranium ores at a concentration about 1 part 1010 of uranium (0.1 mg per metric ton) by calculating the ratio of half-lives of polonium-210 to uranium-238, its ultimate parent.
One of the strategies I used to become more neurotypical was to pick out a random person on the street and follow them around for the entire day, I would carefully log all of their movements and observations I made. I still try to do this from time to time, but I get recognized a lot which makes it hard. In December 2024, Peters crashed his white BMW driving home from a restaurant security job on Cape Cod in Massachusetts, posting that he had fallen asleep off baclofen, a muscle relaxer he had recommended his viewers use to reduce anxiety. On April 14, 2026, while streaming in public with fellow influencer Androgenic, Peters experienced a drug overdose and was hospitalized; he had been using a combination of Adderall, dextromethorphan, pregabalin, ketamine and 1,4-Butanediol, referred to as the "pentastack" by Androgenic. Of the incident, Peters later said, "I didn't overdose or anything. I mean I just, literally, had not eaten that day, consumed too much alcohol, and just knocked out a little bit." He regards the substances he uses as "just a cope trying to feel neurotypical while being in public, but obviously that isn't a real solution."
=== Cardiovascular system === Nicotine exerts several significant effects on the cardiovascular system. Primarily, it stimulates the sympathetic nervous system, leading to the release of catecholamines. This activation results in an increase in heart rate and blood pressure, as well as enhanced myocardial contractility, which raises the workload on the heart. Additionally, nicotine causes systemic vasoconstriction, including constriction of coronary arteries, which can reduce blood flow to the heart. Long-term exposure to nicotine may impair endothelial function, potentially contributing to atherosclerosis. Furthermore, nicotine has been associated with the development of cardiac arrhythmias, particularly in individuals who already have underlying heart disease. The effects of nicotine can be differentiated between short-term and long-term use. Short-term nicotine use, such as that associated with nicotine replacement therapy (NRT) for smoking cessation, appears to pose little cardiovascular risk, even for patients with known cardiovascular conditions. In contrast, longer-term nicotine use may not accelerate atherosclerosis but could contribute to acute cardiovascular events in those with pre-existing cardiovascular disease. Many severe cardiovascular effects traditionally associated with smoking may not be solely attributable to nicotine itself. Cigarette smoke contains numerous other potentially cardiotoxic substances, including carbon monoxide and oxidant gases.
Sources: en.wikipedia.org
Other approaches ("metabolism-first" hypotheses) focus on how catalysis on the early Earth might have provided the precursor molecules for self-replication. The 1952 Miller–Urey experiment demonstrated that amino acids can be synthesized from inorganic compounds under conditions like early Earth's. Subsequently, amino acids have been found in meteorites, comets, asteroids, and star-forming regions of space. While the last universal common ancestor of all modern organisms (LUCA) existed millions of years after the origin of life, its study can guide research into early universal characteristics. A genomics approach has sought to characterize LUCA by identifying the genes shared by Archaea and Bacteria, major branches of life. It appears there are 60 proteins common to all life and 355 prokaryotic genes that trace to LUCA; their functions imply that LUCA was anaerobic with the Wood–Ljungdahl pathway, deriving energy by chemiosmosis, and used DNA, the genetic code, and ribosomes. Earlier cells might have had a leaky membrane and been powered by a naturally occurring proton gradient near a deep-sea white smoker hydrothermal vent; or, life may have originated inside the continental crust or in water at Earth's surface. Although Earth is the only place known to harbor life, astrobiologists assume that life exists and came into being by similar processes on other planets. Geochemical and fossil evidence informs most studies. The Earth was formed at 4.54 Gya, and the earliest evidence of life on Earth dates from 3.8 Gya from Western Australia.
Oxycodone, a semi-synthetic opioid, is a highly selective full agonist of the μ-opioid receptor (MOR). This is the main biological target of the endogenous opioid neuropeptide β-endorphin. Oxycodone has low affinity for the δ-opioid receptor (DOR) and the κ-opioid receptor (KOR), where it is an agonist similarly. After oxycodone binds to the MOR, a G protein-complex is released, which inhibits the release of neurotransmitters by the cell by decreasing the amount of cAMP produced, closing calcium channels, and opening potassium channels. Opioids like oxycodone are thought to produce their analgesic effects via activation of the MOR in the midbrain periaqueductal gray (PAG) and rostral ventromedial medulla (RVM). Conversely, they are thought to produce reward and addiction via activation of the MOR in the mesolimbic reward pathway, including in the ventral tegmental area, nucleus accumbens, and ventral pallidum. Tolerance to the analgesic and rewarding effects of opioids is complex and occurs due to receptor-level tolerance (e.g., MOR downregulation), cellular-level tolerance (e.g., cAMP upregulation), and system-level tolerance (e.g., neural adaptation due to induction of ΔFosB expression). Taken orally, 20 mg of immediate-release oxycodone is considered to be equivalent in analgesic effect to 30 mg of morphine, while extended release oxycodone is considered to be twice as potent as oral morphine. Similarly to most other opioids, oxycodone increases prolactin secretion, but its influence on testosterone levels is unknown.
According to the International Energy Agency (IEA), the global natural gas market has been significantly affected by geopolitical disruptions in the Middle East, resulting in a short-term supply shock and reduced availability of liquefied natural gas (LNG) in global markets. The agency reported that these developments have tightened global gas balances and increased price volatility. While global LNG supply growth is expected to continue in the medium term, the market is projected to remain tight through 2026 and 2027, depending on geopolitical conditions and infrastructure recovery.
In addition, the Kanji of the Year (kotoshi no kanji) has been selected since 1995, and both the kanji and the word/phrase of the year often reflect current Japanese events and attitudes. For example, in 2011, following the Fukushima nuclear disaster, the frustratingly enigmatic phrase used by Japanese officials before the explosion regarding the possibility of a meltdown - "the possibility of recriticality is not zero" (Sairinkai no kanōsei zero de wa nai) - became the top phrase of the year. In the same year, the kanji for "bond" (i.e., family ties or friendship) became the kanji of the year, expressing the importance of collectiveness in the face of disaster. Liechtenstein: Word of the year (Liechtenstein) since 2002. In Norway, the Word of the year poll has been carried out since 2012. In Portugal, the Word of the year poll has been carried out since 2009. In Russia, the Word of the year poll has been carried out since 2007. In Slovenia, the word of the year poll has been carried out since 2016. Each year, it is announced in January together with the SSL (Slovenian Sign Language) gesture of the year. In Spain, a Word of the year has been selected by Fundéu since 2013. Switzerland: Word of the year (Switzerland), since 2003. In Ukraine, the Word of the year poll has been carried out since 2013. In The Netherlands, a word of the year poll is carried out by dictionary publisher Van Dale since 2007.
The accepted treatment for affected boys presenting with the cerebral childhood form of the disease is a bone marrow transplant, a procedure which carries significant risks. However, because most affected males will demonstrate adrenal insufficiency, early discovery and treatment of this symptom could potentially prevent complications and allow these patients to be monitored for other treatment in the future, depending on the progression of their disease. The Loes score is a rating of the severity of abnormalities in the brain found on MRI. It ranges from 0 to 34, based on a point system derived from the location and extent of disease and the presence of atrophy in the brain, either localized to specific points or generally throughout the brain. A Loes score of 0.5 or less is classified as normal, while a Loes score of 14 or greater is considered severe. It was developed by neuroradiologist Daniel J. Loes MD and is an important tool in assessing disease progression and the effectiveness of therapy.
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.
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.