The short version of heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-07-27. Anything still debated is marked as such rather than presented as settled.
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.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
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.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
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.
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.
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.
The concentration of hormones required for plant responses are very low (10−6 to 10−5 mol/L). Because of these low concentrations, it has been very difficult to study plant hormones, and only since the late 1970s have scientists been able to start piecing together their effects and relationships to plant physiology. Much of the early work on plant hormones involved studying plants that were genetically deficient in one or involved the use of tissue-cultured plants grown in vitro that were subjected to differing ratios of hormones, and the resultant growth compared. The earliest scientific observation and study dates to the 1880s; the determination and observation of plant hormones and their identification was spread out over the next 70 years. Synergism in plant hormones refers to the how of two or more hormones result in an effect that is more than the individual effects. For example, auxins and cytokinins often act in cooperation during cellular division and differentiation. Both hormones are key to cell cycle regulation, but when they come together, their synergistic interactions can enhance cell proliferation and organogenesis more effectively than either could in isolation.
== Demographics == The homeland was set up to house Setswana-speaking peoples. In 1983, it had more than 1,430,000 inhabitants; in 1990, it had an estimated population of 2,352,296. Only 10% of Bophuthatswana's total land area was arable, and much of that was covered with scrub bush. Though the majority of its population was Tswana-speaking, Tswana, English, and Afrikaans were all designated as official languages by the Constitution of Bophuthatswana.
=== Mental health === The longitudinal study Excess Mortality from Suicide and other External Causes of Death Among Women with Cosmetic Breast Implants (2007), reported that women who sought breast implants are almost 3.0 times as likely to commit suicide as are women who have not sought breast implants. Compared to the standard suicide-rate for women of the general populace, the suicide-rate for women with augmented breasts remained alike until 10-years post-implantation, yet it increased to 4.5 times greater at the 11-year mark, and so remained until the 19-year mark, when it increased to 6.0 times greater at 20-years post-implantation. Moreover, additional to the suicide risk, women with breast implants also faced a 3 times greater death risk from alcoholism and drug abuse (prescription and recreational). Although seven studies have found correlation between undergoing a breast augmentation procedure to a greater suicide rate in women, the research indicates that augmentation surgery does not increase the suicide risk. It is the psychopathologically afflicted woman who is likelier to undergo breast augmentation. Moreover, the study Effects of Breast Augmentation Mammoplasty on Self-Esteem and Sexuality: A Quantitative Analysis (2007), reported that the women attributed their improved self-esteem, self-image, and increased, satisfactory sexual functioning to having undergone breast augmentation; the cohort, aged 21–57 years, averaged post-operative self-esteem increases ranging from 20.7 to 24.9 points on the 30-point Rosenberg self-esteem scale.
As a result of population growth in African-Caribbean regions of overseas France and immigration from North and sub-Saharan Africa to mainland France, sickle cell disease has become a major health problem in France. Sickle cell disease has become the most common genetic disease in the country, with an overall birth prevalence of one in 2,415 in mainland France, ahead of phenylketonuria (one in 10,862), congenital hypothyroidism (one in 3,132), congenital adrenal hyperplasia (one in 19,008) and cystic fibrosis (one in 5,014) for the same reference period.
Sources: en.wikipedia.org
In the life sciences, a contract research organization or clinical research organization (CRO) is a company that provides support to the pharmaceutical, biotechnology, and medical device industries in the form of research services outsourced on a contract basis. A CRO may provide such services as biopharmaceutical development, biological assay development, commercialization, clinical development, clinical trials management, pharmacovigilance, outcomes research, and real world evidence. CROs are designed to reduce costs for companies developing new medicines and drugs in niche markets. They aim to simplify entry into drug markets, and simplify development, as the need for large pharmaceutical companies to do everything ‘in house’ is now redundant. CROs also support foundations, research institutions, and universities, in addition to governmental organizations (such as the NIH, EMA, etc.). Many CROs specifically provide clinical-study and clinical-trial support for drugs and/or medical devices. However, the sponsor of the trial retains responsibility for the quality of the CRO's work. CROs range from large, international full-service organizations to small, niche specialty groups. CROs that specialize in clinical-trials services can offer their clients the expertise of moving a new drug or device from its conception to FDA/EMA marketing approval, without the drug sponsor having to maintain a staff for these services. Organizations who have had success in working with a particular CRO in a particular context (e.g.
=== Pharmacodynamics === Similarly to ketamine, norketamine acts as a noncompetitive NMDA receptor antagonist (Ki = 1.7 μM and 13 μM for (S)-(+)-norketamine and (R)-(–)-norketamine, respectively). Also, similarly again to ketamine, norketamine binds to the μ- and κ-opioid receptors. Relative to ketamine, norketamine is much more potent as an antagonist of the α7-nicotinic acetylcholine receptor, and produces rapid antidepressant effects in animal models which have been reported to correlate with its activity at this receptor. However, norketamine is about 1/5 as potent as ketamine as an antidepressant in mice as per the forced swim test, and this seems also to be in accordance with its 3–5-fold reduced comparative potency in vivo as an NMDA receptor antagonist. Norketamine's metabolites, dehydronorketamine (DHNK) and hydroxynorketamine (HNK), are far less or negligibly active as NMDA receptor antagonists in comparison, but retain activity as potent antagonists of the α7-nicotinic acetylcholine receptor. In 2024, norketamine was discovered to act as a highly potent positive allosteric modulator of the opioid receptors, including of the μ-opioid receptor (MOR). It shares this action with ketamine and hydroxynorketamine (HNK). They are all active in this action at very low concentrations, for instance 1 nM. Ketamine, norketamine, and HNK can potentiate the effects of endogenous opioids like met-enkephalin and exogenous opioids like morphine.
=== Atherosclerosis === Rapamycin can accelerate degradation of oxidized LDL cholesterol in endothelial cells, thereby lowering the risk of atherosclerosis. Oxidized LDL cholesterol is a major contributor to atherosclerosis.
Peitzmeier and colleagues conducted a study on partner violence; they found that transgender individuals are 3 times more likely than their counterparts to experience partner violence physical and sexual. Partner violence is a risk factor for numerous health outcomes like a decrease psychological well-being, a poor sexual health, etc. There is limited data regarding the impact of social determinants of health on transgender and gender non-conforming individuals' health outcomes. However, despite the limited data available, transgender and gender non-conforming individuals have been found to be at higher risk of experiencing poor health outcomes and restricted access to health care due to increased risk for violence, isolation, and other types of discrimination both inside and outside the health care setting. Despite its importance, access to preventive care is also limited by several factors, including discrimination and erasure. A study on young transgender women's access to HIV treatment found that one of the main contributors to not accessing care was the use of incorrect name and pronouns. A meta analysis of the National Transgender Discrimination Survey examined respondents who used the "gender not listed here" option on the survey and their experiences with accessing health care. Over a third of the people who chose that option said that they had avoided accessing general care due to bias and fears of social repercussions.
== External links == Media related to Earthworms at Wikimedia Commons Data related to Lumbricina at Wikispecies Chisholm, Hugh, ed. (1911). "Earthworm" . Encyclopædia Britannica (11th ed.). Cambridge University Press.
Sources: en.wikipedia.org
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.