The short version of Intranasal route fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-05-13 and is reviewed periodically as new material appears.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
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.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
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.
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.
India accounts for the bulk of the Indian subcontinent, lying atop the Indian tectonic plate, a part of the Indo-Australian Plate. India's defining geologic processes began approximately 70 million years ago, when the Indian Plate, then part of the southern supercontinent Gondwana, began a north-eastward drift caused by seafloor spreading to its south-west, and later, south and south-east. Simultaneously, the vast Tethyan oceanic crust, to its northeast, began to subduct under the Eurasian Plate. The Indian continental crust was obstructed and was sheared horizontally; while its lower crust and mantle slid beneath Eurasia, the upper layer piled up in sheets ahead of the subduction zone. This mountain-building orogeny created the Himalayas. The middle and stiffer layer continued to push into Tibet, causing crustal thickening of the Tibetan Plateau. Immediately south of the emerging Himalayas, plate movement created a vast crescent-shaped trough that rapidly filled with river-borne sediment and now constitutes the Indo-Gangetic Plain. The original Indian plate makes its first appearance above the sediment in the ancient Aravalli range, which extends from the Delhi Ridge in a southwesterly direction. To the west lies the Thar Desert, whose eastern spread is checked by the Aravallis.
==== Dercum's disease ==== Lipedema / Dercum's disease differentiation – these conditions may co-exist. Dercum's disease is a syndrome of painful growths in subcutaneous fat. Unlike lipedema, which occurs primarily in the trunk and legs, the fatty growths can occur anywhere on the body.
==== Luminal ions ==== In addition to NAADP gating the channel, there is evidence that the luminal pH also affects TPC channel activity, either TPC1 [1] or TPC2 [2][3]. However, a clear consensus on the effect of pH has not been reached with some suggesting that acidic pH favours TPC1 or TPC2 opening, whereas others report that a more alkaline pH favours TPC2 opening. Furthermore, luminal Ca2+ also promotes TPC1 and TPC2 opening (in the latter case, luminal Ca2+ also sensitizes TPCs to NAADP (analogous to luminal Ca2+ regulation of IP3Rs and RyRs), but this demands wider study across isoforms and species. This is one way by which cross-talk can occur between acidic Ca2+ stores and the ER i.e. Ca2+ release from the ER can 'prime' acidic Ca2+ stores and promote further NAADP-dependent Ca2+ responses [4].
Somalia is a federal parliamentary representative democratic republic. The president of Somalia is the head of state and commander-in-chief of the Somali Armed Forces and selects the prime minister to lead as head of government. The Federal Parliament of Somalia is the national parliament of Somalia. The bicameral National Legislature consists of the House of the People (lower house) and the Senate (upper house), whose members are elected to serve four-year terms. The parliament elects the President, Speaker of Parliament and Deputy Speakers. It also has the authority to pass and veto laws. The Judiciary of Somalia is defined by the Provisional Constitution of the Federal Republic of Somalia. Adopted on 1 August 2012 by a National Constitutional Assembly in Mogadishu, the document was formulated by a committee of specialists chaired by attorney and Speaker of the Federal Parliament, Mohamed Osman Jawari. It provides the legal foundation for the existence of the Federal Republic and source of legal authority.
Sources: en.wikipedia.org
== Early life and education == Susan Epstein (later changed to Leeman by marriage) was born on May 9, 1930, in Chicago, Illinois. Her mother was born in the United States and her father had emigrated from Russia to New York City. Her father was an academic metallurgist and her mother attended college at George Washington University at a time when few other women did. Susan also had one older brother named Henry. When Susan was six weeks old she and her family moved to Columbus, Ohio, and then to Bethlehem, Pennsylvania when she was six years old. There she grew up a part of a middle class Jewish family. She often faced discrimination in the form of antisemitism and sexism as she pursued a career in science. During her childhood Leeman attended Hebrew School and was a Girl Scout. She decided to attend Goucher College, which was an all-girls’ school at the time, from which she received a bachelor's degree in physiology in 1951. She then applied to and was accepted by Harvard Medical School, but her academic program was administered through Radcliffe College. Thus, Radcliffe College was where she received her master's degree and PhD from in 1954 and 1958 respectively. Leeman was the only woman in her class to make it through the graduate program and continue a career in science. During her time in graduate school she was introduced to the field of neuroendocrinology, within which she was able to explore her passion for how the mind connects to the body.
The outer layer is continuous with the pretracheal fascia, attaching the gland to the cricoid and thyroid cartilages via a thickening of the fascia to form the posterior suspensory ligament of thyroid gland, also known as Berry's ligament. This causes the thyroid to move up and down with the movement of these cartilages when swallowing occurs.
Corticotropin-releasing hormone (CRH), which regulates ACTH secretion from the anterior pituitary gland Somatostatin, which regulates growth hormone secretion from the anterior pituitary gland Thyrotropin-releasing hormone (TRH), which regulates TSH and prolactin secretion
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.