> Research Disclaimer: Selank is a research peptide approved in Russia as an anxiolytic but not approved by the FDA or EMA for human therapeutic use. This article summarizes published scientific literature for educational and research purposes only. Not for human use.
What Is Selank?
Selank (developmental code: TP-7) is a synthetic heptapeptide with the amino acid sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a metabolically stabilized derivative of tuftsin — an endogenous tetrapeptide (Thr-Lys-Pro-Arg) naturally produced by spleen-derived cleavage of the immunoglobulin G Fc region.
With a molecular weight of approximately 751.9 Da, Selank retains and amplifies tuftsin's immunomodulatory properties while acquiring anxiolytic and nootropic activities conferred by the C-terminal Pro-Gly-Pro extension — the same metabolic stability motif used in Semax. This C-terminal addition dramatically extends Selank's half-life in plasma and cerebrospinal fluid compared to unmodified tuftsin, enabling more sustained biological activity.
Selank is approved in Russia as an anxiolytic nasal spray under the brand name Selank (0.15%), indicated for generalized anxiety disorder, adjustment disorder, and neurasthenia. It has been in clinical use in Russia since 2009.
Structural Basis
The Thr-Lys-Pro-Arg tetrapeptide core (tuftsin) mediates Selank's immunomodulatory and some anxiolytic effects, while the Pro-Gly-Pro C-terminal extension provides:
- •Resistance to enzymatic cleavage by carboxypeptidases and aminopeptidases
- •Enhanced metabolic stability in nasal mucosa and plasma
- •Possible independent bioactivity through Pro-Gly-Pro fragment effects
Selank's amphiphilic structure supports nasal absorption and nose-to-brain transport — making intranasal delivery the primary research and clinical administration route.
Mechanism of Action
Selank's pharmacology is complex and pleiotropic, operating through multiple neurotransmitter and immunological pathways:
GABAergic Modulation
The primary anxiolytic mechanism of Selank involves potentiation of GABAergic inhibitory neurotransmission. Research suggests Selank enhances GABA-A receptor function through an allosteric mechanism distinct from benzodiazepines — producing anxiolytic effects without the sedation, tolerance, and dependence liabilities associated with classical GABA-A positive allosteric modulators. This selectivity for anxiolytic over sedative effects has driven research interest in Selank as a non-sedating anxiolytic research tool.
The precise binding site and modulation mechanism at GABA-A receptors have not been fully characterized at the structural level, but behavioral and electrophysiological evidence consistently supports enhanced GABAergic tone as the primary anxiolytic mechanism.
Serotonergic Modulation
Selank modulates serotonin (5-HT) neurotransmission in limbic regions — particularly the hippocampus and amygdala. Research indicates enhanced serotonin turnover and modulation of 5-HT receptor expression under Selank administration, contributing to anxiolytic and mood-stabilizing effects. The serotonergic component distinguishes Selank from pure GABAergic anxiolytics and may account for its additional antidepressant-like properties in behavioral models.
Enkephalin Degradation Inhibition
Selank has been shown to inhibit enkephalinase — the enzyme responsible for degrading endogenous enkephalins (opioid peptides involved in pain modulation, anxiety regulation, and reward processing). Reduced enkephalin degradation elevates endogenous opioid tone, contributing to anxiolytic and stress-reducing effects through mu and delta opioid receptor pathways.
BDNF and Neurotrophin Effects
Similar to Semax, Selank modulates BDNF and other neurotrophins in the CNS, though with a less pronounced profile. The combination of GABAergic + serotonergic + neurotrophic mechanisms may underlie Selank's cognitive-enhancing effects alongside anxiolysis — a combination that differentiates it from purely symptomatic anxiolytics.
Immunomodulatory Mechanisms
Inheriting tuftsin's immunological properties, Selank modulates cytokine and chemokine gene expression in immune cells. Kolomin et al. (2011) characterized changes in gene expression for chemokines, cytokines, and their receptors in response to Selank administration (PMID: 21786679), demonstrating that Selank upregulates expression of IL-2, IL-6, and related immune signaling molecules while modulating T-cell and natural killer (NK) cell function. This dual CNS-immune activity profile makes Selank a research tool for psychoneuroimmunology investigations.
Key Research Studies
Morphine Withdrawal Attenuation (2022)
Konstantinopolsky MA, Chernyakova IV, Kolik LG, "Selank, a Peptide Analog of Tuftsin, Attenuates Aversive Signs of Morphine Withdrawal in Rats," Bulletin of Experimental Biology and Medicine, 2022 (PMID: 36322304). This study demonstrated that Selank administration during morphine withdrawal significantly attenuated somatic withdrawal signs in rats — including wet dog shakes, ptosis, and weight loss — consistent with its GABAergic and opioid-modulating mechanisms. These findings have implications for research into opioid dependence and addiction models.
Ethanol-Induced Memory Protection (2019)
Kolik LG, Nadorova AV, Antipova TA, et al., "Selank, Peptide Analogue of Tuftsin, Protects Against Ethanol-Induced Memory Impairment," Bulletin of Experimental Biology and Medicine, 2019 (PMID: 31625062). This research demonstrated that Selank administration countered ethanol-induced spatial memory deficits in a Morris water maze paradigm, with protective effects attributed to preserved BDNF levels and enhanced GABAergic signaling. The study suggests Selank's neuroprotective properties extend to alcohol-related neurotoxicity models.
Cytokine and Chemokine Gene Expression (2011)
Kolomin TA, Shadrina MI, Slominsky PA, Limborskaya SA, Myasoedov NF, "Changes in gene expression for chemokines, cytokines, and receptors in response to Selank and its fragments," Genetika, 2011 (PMID: 21786679). This molecular study characterized Selank's immunomodulatory effects at the transcriptomic level, demonstrating that Selank upregulates expression of several immune mediators and modulates lymphocyte function — consistent with tuftsin's known immunomodulatory properties and providing mechanistic insight into Selank's anti-stress immune effects.
Anxiety and Depression Behavioral Studies (2008)
Sarkisova KYu, Kozlovsky II, Kozlovskaya MM, "Effects of Selank on depression-related behaviors in WAG/Rij rats, Wistar rats, and BALB/c mice," Zhurnal Vysshei Nervnoi Deyatelnosti, 2008 (PMID: 18661785). This multi-strain behavioral study evaluated Selank's antidepressant effects in rodent models, finding significant reductions in depression-related behaviors across genetically diverse subjects. The study provided evidence that Selank's antidepressant effects are robust across different genetic backgrounds — supporting a pharmacological rather than model-specific mechanism.
Long-Term Anxiolytic Studies (2006)
Czabak-Garbacz R, Cygan B, Wolanski L, Kozlovsky I, "Influence of long-term treatment with tuftsin analogue TP-7 on anxiety-phobic states and body weight," Pharmacological Reports, 2006 (PMID: 16963804). This early study characterized the effects of prolonged Selank (TP-7) administration on anxiety phenotypes, demonstrating sustained anxiolytic efficacy without the tolerance development characteristic of benzodiazepines — a key finding supporting Selank's non-habit-forming profile.
Research Applications
Generalized Anxiety Disorder Models
Selank's primary research application involves modeling and studying anxiolytic mechanisms without benzodiazepine-associated confounds. The compound allows investigation of GABAergic anxiolysis without sedation, muscle relaxation, or tolerance — isolating specific behavioral and molecular components of anxiety regulation.
Stress and Adaptation Research
Selank is used to study allostatic stress responses and the neurobiological mechanisms of stress adaptation, including the roles of GABA, serotonin, and enkephalin pathways in stress resilience.
Cognitive Neuroscience
Selank's combination of anxiolysis and cognitive enhancement makes it valuable for research distinguishing anxiety-driven cognitive impairment from primary cognitive deficits. By reducing anxiety-related performance disruption, Selank enables cleaner cognitive endpoint assessment in behavioral paradigms.
Psychoneuroimmunology Research
The dual CNS and immune system effects of Selank — inherited from tuftsin — make it a tool for investigating the bidirectional communication between the nervous and immune systems, including stress-induced immune modulation.
Addiction and Withdrawal Research
As demonstrated in the morphine withdrawal studies, Selank's effects on GABAergic and opioid signaling pathways make it relevant to preclinical addiction research — particularly studies of opioid and alcohol dependence models.
Neuroprotection Research
Like Semax, Selank's neurotrophin-modulating properties support its use in neuroprotection research, particularly in models combining cognitive impairment with anxiety — as seen in neurodegenerative disease contexts.
Reconstitution and Storage
For qualified researchers only. Not for human use.
Reconstitution: Lyophilized Selank is reconstituted in sterile 0.9% sodium chloride (normal saline) to the desired concentration. For intranasal research use, a 0.15% solution (1.5 mg/mL) is consistent with the approved Russian clinical formulation. Gently swirl to dissolve — avoid vigorous shaking.
Intranasal preparation: For nasal delivery in research models, the reconstituted solution is typically administered via calibrated nasal spray applicators or micropipettes. Each nostril delivers 50 µL per application, providing 75 µg per nostril at 0.15% concentration.
Storage: Lyophilized Selank is stable for 12–24 months at -20°C. Reconstituted solutions should be refrigerated (2–8°C) and used within 2–4 weeks. Protect from light throughout storage and use.
Sourcing Guide
When sourcing Selank for research, key quality markers include:
- •Third-party HPLC purity documentation (≥98% purity of the TKPRPGP sequence)
- •Mass spectrometry confirmation of molecular weight (751.9 Da) and sequence identity
- •Proper lyophilization quality (white/off-white powder, complete dissolution on reconstitution)
- •Cold-chain shipping with temperature monitoring
- •Documented batch-level analysis with CoA
Compare current Selank suppliers, pricing, purity tiers, and formulation options on the Peptides.SO Selank comparison page.
Researchers studying the nootropic and anxiolytic peptide space may wish to compare Selank with Semax (complementary neuroprotective and cognitive-enhancing profile), Dihexa, and P21. The Semax + Selank combination is frequently investigated for synergistic anxiolytic-cognitive effects in research contexts.
Frequently Asked Questions
What is the relationship between Selank and tuftsin?
Selank is a synthetic derivative of tuftsin — the endogenous immunostimulatory tetrapeptide produced in the spleen. Tuftsin itself has a very short half-life (minutes) due to rapid enzymatic degradation. Selank adds a Pro-Gly-Pro tripeptide to tuftsin's C-terminus, dramatically extending stability and adding CNS-active properties (anxiolytic, nootropic) not present in tuftsin itself. The resulting molecule retains tuftsin's immunomodulatory profile while gaining a distinct neurological pharmacology.
How does Selank differ from benzodiazepines?
Both Selank and benzodiazepines produce anxiolytic effects through GABAergic mechanisms, but they differ significantly in their receptor interactions and consequence profiles. Benzodiazepines act as positive allosteric modulators at a well-characterized binding site on GABA-A receptors, producing reliable anxiolysis, sedation, muscle relaxation, and amnestic effects — with significant tolerance and dependence liability. Selank appears to modulate GABA-A function through a distinct mechanism that produces anxiolysis without the sedative, amnestic, and dependence profiles of benzodiazepines, though the exact binding site remains under characterization.
Does Selank affect memory and cognition?
Yes. In addition to anxiolytic effects, Selank demonstrates nootropic properties in rodent models — improving spatial memory acquisition, recall, and attention performance. Importantly, the cognitive enhancement appears to occur alongside (not despite) anxiolysis — suggesting that reduced anxiety and improved cognition may be partially linked phenomena, and that Selank's cognitive benefits may involve both direct neurotrophic effects and anxiety-reduction-mediated performance improvement.
Is Selank addictive?
Current preclinical evidence suggests Selank does not produce physical dependence or tolerance with chronic administration — a key distinction from benzodiazepines. Long-term studies in rodents have not demonstrated rebound anxiety or withdrawal symptoms upon discontinuation, and Selank lacks the reinforcing opioid or dopaminergic reward properties associated with high abuse potential. However, systematic human dependence studies have not been conducted under Western regulatory standards.
Can Selank and Semax be used together in research?
Selank and Semax are frequently studied in combination in Russian research contexts, where the anxiolytic-predominant Selank and neuroprotective-predominant Semax are considered complementary. The combination targets both anxiety and cognitive performance through partially distinct mechanisms. Preclinical evidence supports additive effects, though formal interaction pharmacology studies are limited.
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This research profile is for educational purposes only. Selank is not approved by the FDA for human therapeutic use. All research should be conducted by qualified investigators following applicable institutional and regulatory guidelines.