Selank: Anxiolytic Peptide, Tuftsin Lineage, Single-Region Evidence

The short version

Selank is a synthetic heptapeptide — a seven-amino-acid chain with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed by extending the endogenous tetrapeptide tuftsin (an IgG heavy-chain fragment involved in immune signaling) at the C-terminus with Pro-Gly-Pro, which slows enzymatic breakdown and extends the molecule's useful life in the body. The added tail is why the research community also refers to it as TP-7 or tuftsin analogue TP-7.

In animal studies and a narrow set of Russian clinical trials, Selank produced anxiolytic effects without the sedation, cognitive clouding, or dependence potential associated with benzodiazepines ^[1][6]. The mechanism appears to center on the brain's inhibitory GABA system — Selank acts as a positive allosteric modulator of GABA receptors and shifts the expression of GABA-pathway genes in the frontal cortex ^[1][3].

Two things are important to state plainly. First, Selank is not FDA-approved for any indication; its regulatory registration as an anxiolytic exists essentially only in Russia. It is sold strictly as a research chemical outside that context, not intended for human consumption. Second, it is categorically distinct from Semax — another Russian research peptide — which is an ACTH(4-7) analogue with a different sequence, origin, and mechanism. These two are often confused online; they are not the same compound. This page describes research findings; it is not medical advice and lists no human dose.

What it is

Selank's parent sequence is tuftsin — Thr-Lys-Pro-Arg — an endogenous tetrapeptide released by enzymatic cleavage of the heavy chain of immunoglobulin G. Tuftsin is classically described as an immunostimulant: it activates macrophages and monocytes, promotes phagocytosis, and modulates cytokine release. Because tuftsin is rapidly degraded by plasma and tissue enzymes (half-life is seconds to minutes), researchers at the Institute of Molecular Genetics and the Zakusov Institute of Pharmacology in Moscow added the C-terminal extension Pro-Gly-Pro to create a metabolically more stable analogue.

The result is Selank (TP-7, sequence: Thr-Lys-Pro-Arg-Pro-Gly-Pro), a molecule that retains tuftsin's immunomodulatory properties while gaining measurable stability and additional CNS activity not seen with the parent tetrapeptide. The Pro-Gly-Pro tail is the same sequence found in some neuropeptide degradation products (including collagen-derived fragments), which may contribute to its central effects. It is a fully synthetic research compound, not a natural product extractable from any tissue.

How it works

Selank's anxiolytic and nootropic effects in animal and limited human research are attributed to two main, non-benzodiazepine mechanisms.

1. GABAergic modulation. The primary mechanism identified across multiple studies is positive allosteric modulation of GABA receptor binding. A 2018 review in Protein and Peptide Letters established that Selank enhances [³H]GABA binding in a concentration-dependent, subtype-selective fashion and can partially block the modulatory activity of diazepam and olanzapine, indicating distinct but overlapping binding sites ^[1]. This is not the same mechanism as a benzodiazepine: it operates allosterically (at a different site) rather than directly on the benzodiazepine binding pocket. A 2016 frontal-cortex study found that Selank administration changed the expression of 45 GABAergic-pathway genes at one hour and 22 at three hours, with those shifts correlating positively with what GABA itself produces ^[3]. A 2017 rat study found that combining Selank with diazepam in an unpredictable chronic mild stress model produced the greatest anxiety reduction of any single or combined treatment, further supporting GABAergic interaction ^[2].

2. Enkephalinase inhibition. Selank inhibits plasma enkephalin-degrading enzymes dose-dependently in human plasma in vitro, with an IC50 of approximately 15 µM ^[7]. Enkephalins are endogenous opioid peptides that naturally reduce anxiety when they engage their receptors; they are also rapidly degraded. By slowing that degradation, Selank could in principle extend the anxiety-buffering effect of the body's own enkephalins. This mechanism was proposed specifically to explain the anxiolytic effect in patients with generalized anxiety, where enkephalin half-life was found to be shortened ^[7].

Additional targets include BDNF expression in the rat hippocampus (increased by intranasal administration in Wistar rats ^[4]), serotonin and dopamine turnover modulation, and Th1/Th2 cytokine balance shifts that reflect its tuftsin ancestry and give it a distinct immunomodulatory profile ^[5].

What the research shows

GABAergic mechanism — binding and gene expression. The 2018 Protein and Peptide Letters review confirmed Selank's positive allosteric modulation of GABA receptor binding, distinguishing it from classical benzodiazepines by its subtype selectivity and its ability to partially interfere with diazepam's own modulatory activity ^[1]. The 2016 frontal-cortex microarray study added a gene-expression dimension, showing GABA-correlated shifts in 45 genes at one hour after administration in rats ^[3].

Synergy with diazepam in stress. In the 2017 unpredictable chronic mild stress (UCMS) rat model, Selank administered alongside diazepam produced the strongest reduction in anxiety-related behavior of any tested condition — including either drug alone — and restored behavior toward pre-stress baselines ^[2]. This is a preclinical, not a human, finding, but it is relevant context for understanding how Selank is thought to sit within the GABAergic landscape.

BDNF in the hippocampus. Intranasal Selank in Wistar rats increased BDNF (brain-derived neurotrophic factor) expression in the hippocampus in vivo ^[4]. BDNF is a neuroplasticity signal: the finding is offered as a mechanistic link for Selank's reported memory and learning effects in rodents, though whether intranasal delivery produces comparable CNS bioavailability in humans is unstudied.

Immunomodulation in patients. A 2008 human study involving patients with anxiety-asthenic disorders found that Selank shifted the Th1/Th2 cytokine ratio and modulated peripheral-blood IL-6 expression, leading the authors to characterize it as a novel immunomodulator with a dual anxiolytic-immune action ^[5]. This was a small, uncontrolled study, but it is one of the few human-tissue data points in the record.

Russian clinical trial in generalized anxiety disorder. A 2008 clinical study reported that intranasal Selank in patients with generalized anxiety disorder produced anxiolytic and mildly activating effects comparable to a benzodiazepine comparator, without sedation, cognitive impairment, or withdrawal on stopping ^[6]. The authors concluded it was a viable peptide anxiolytic. Important context: this study was conducted in Russia under medical supervision, published in a Russian-language journal with an English abstract, and has not been independently replicated in controlled Western trials. It should be read as supporting hypothesis, not as established efficacy.

Enkephalinase inhibition. The in vitro human plasma data confirmed dose-dependent inhibition of enkephalin-degrading enzymes at pharmacologically plausible concentrations ^[7], giving biochemical plausibility to the proposed opioid-adjacent mechanism, though this has not been demonstrated to translate to meaningful enkephalin stabilization in a living human nervous system.

Reported effects, cautions & safety

A note on this section. The following two blocks — community-reported effects and safety cautions — serve different purposes and must be read as such. Community reports are explicitly anecdotal, not clinical evidence. They describe what people say they notice; they do not establish that Selank caused any effect, that any effect was real rather than expectation-driven, or that use was safe. Safety cautions are drawn from mechanism and the cited literature; they represent what is genuinely not known, not a list of documented harms.

---

What people report (anecdotal, not clinical evidence):

The most consistent community account — spanning nootropic forums, biohacker blogs, and peptide-user guides — is calm without sedation: a softening of background anxiety that does not feel like being drugged or slowed. People commonly describe it as the volume on anxious thought being turned down while mental clarity and energy hold steady. This is explicitly and frequently contrasted with the heavy, foggy sedation of benzodiazepines or the emotional flatness of SSRIs.

Situational and social anxiety before high-pressure events — presentations, exams, interviews — is a very commonly reported use case. People describe markedly fewer nerves and less anticipatory build-up, with social interaction feeling less effortful and draining. These are subjective community reports, not a demonstration that Selank treats any anxiety disorder.

Users of the intranasal route commonly report noticing a shift within roughly 20 to 40 minutes, which is why many use it situationally rather than on a fixed daily schedule. Many also describe a gradual mood lift and greater stress resilience that builds over one to two weeks of regular use — though this kind of slow accumulation is especially hard to separate from expectation effects.

Not everyone responds. A recurring honest counterpoint in these same communities is people finishing an entire vial and feeling nothing, or finding the effect so subtle they were uncertain it was real. This non-response is a real and commonly voiced part of the picture.

Adverse signals: a minority report mild drowsiness or a sense of being over-calm, especially with more frequent use. Nasal irritation (dryness, burning, stinging) is very commonly mentioned with the intranasal route and is generally attributed to the liquid carrier. Occasional mild headache is reported. Scattered, unverified anecdotes of hair thinning exist but are rare and unconfirmed.

A widely stated point is the apparent absence of dependence, tolerance escalation, or rebound anxiety on stopping — which users contrast sharply with benzodiazepines and phenibut. This is anecdotal and rests on short-term, informal experience, not long-term human safety trials.

---

Safety cautions (drawn from the literature):

• Unregulated research-chemical supply. Selank outside Russia is sold as a research chemical, not a pharmaceutical product. Identity, purity, sterility, and actual peptide content vary by supplier and are not independently guaranteed. Impurities carry their own risks independent of any peptide pharmacology ^[6].
• Long-term human safety is not established. Human data are largely confined to a small set of Russian clinical studies over courses of a few weeks, with no Western replication and no long-term safety follow-up. Favorable short-term tolerability is not a long-term safety clearance ^[6].
• Interaction unknowns across multiple systems. Selank acts on GABA receptors, inhibits enkephalin-degrading enzymes (engaging opioid pathways), modulates serotonin and dopamine turnover, and shifts immune cytokine balance. The potential for additive or unpredictable interactions with GABAergic sedatives, opioids, serotonergic and dopaminergic drugs is real and essentially unstudied in people ^[1][2][7][5].
• Self-treating anxiety is not a substitute for care. Persistent or impairing anxiety is a medical condition with established, evidence-based treatments and clinical oversight. An unapproved research peptide is not a substitute for evaluation by a qualified professional. Even the Russian clinical studies were conducted under medical supervision in diagnosed patients ^[6].
• Pregnancy and pre-existing conditions are wholly unstudied. No human safety data exist for Selank in pregnancy, breastfeeding, or in people with significant medical conditions ^[5][6].

Where it fits in this desk

Among the two peptides on Peptivio Peptides, Selank is the lead — and the one with the more substantiated mechanism and the stronger (if still narrow) human evidence. Its GABAergic modulation, enkephalinase inhibition, and limited clinical data represent a reasonably coherent anxiolytic story, even if that story was written mostly in one research community, in one country, in a small number of trials. It stands in useful contrast to DSIP, whose mechanism remains genuinely unknown and whose sleep-promoting evidence is inconsistently replicated. Read both; then see the comparison page for how they line up.