Selank: Anxiolytic Heptapeptide

Selank is a synthetic heptapeptide analog of the endogenous immunomodulator tuftsin. Developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, Selank has been investigated primarily for anxiolytic and cognitive-enhancing effects, with additional research into immune modulation and neuroprotection.

What Is Selank?

Selank is a synthetic heptapeptide with the 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 modified analog of tuftsin, an endogenous tetrapeptide fragment of the immunoglobulin G heavy chain. The addition of three proline-glycine-proline residues to the tuftsin core sequence was designed to improve metabolic stability and enable central nervous system activity.

Although tuftsin itself is studied primarily for its immunomodulatory activity, Selank's modifications shifted the peptide's profile toward the central nervous system. In Russia, Selank has been investigated in clinical research for decades as a potential anxiolytic and cognitive-modulating agent, and it remains approved for certain indications in the Russian Federation while remaining a research compound elsewhere.

Key Identifier

Peptide Profile

Full Name: Selank (Tuftsin analog)
Sequence: Thr-Lys-Pro-Arg-Pro-Gly-Pro
Molecular Weight: 751.88 g/mol
CAS Number: 129954-34-3
Classification: Synthetic heptapeptide, anxiolytic

Mechanism of Action

The mechanism by which Selank produces its observed anxiolytic and cognitive effects is multi-faceted and remains under active investigation. Research has identified several pathways through which Selank appears to exert its biological activity.

GABAergic Modulation

Preclinical research has observed that Selank influences the GABAergic system, a central inhibitory neurotransmitter pathway associated with anxiolytic activity. Unlike benzodiazepines, which act directly at the GABA-A receptor, Selank appears to exert its effects indirectly, potentially through modulation of GABA receptor expression and signaling rather than direct receptor binding.

Enkephalinase Inhibition

Studies have suggested that Selank can inhibit the activity of enkephalinase, an enzyme responsible for degrading endogenous enkephalins. By extending the half-life of endogenous opioid peptides, this activity may contribute to Selank's observed analgesic and anxiolytic effects in preclinical models.

Serotonergic and Dopaminergic Influence

Research has examined Selank's influence on monoamine neurotransmitter systems, with studies reporting modulatory effects on serotonin and dopamine turnover in select brain regions. These findings have contributed to investigation of Selank as a potential cognitive and mood-modulating compound in preclinical research.

BDNF and Neuroplasticity

Research has observed that Selank administration may influence the expression of brain-derived neurotrophic factor (BDNF) and other neuroplasticity-related signaling molecules. These effects have been linked to observations of cognitive enhancement in preclinical rodent learning and memory models.

Immunomodulation

As a tuftsin analog, Selank retains some of the parent peptide's immunomodulatory profile. Research has reported effects on cytokine expression, T-cell activity, and inflammatory signaling, though these applications are secondary to the peptide's central nervous system research focus.

Research Overview

Selank has been investigated for several decades, with a substantial body of preclinical and clinical research conducted primarily in Russia. Research has focused on anxiolytic, cognitive, and mood-related applications.

Research AreaKey FindingsStudy Type
Anxiolytic ActivityRussian clinical studies have investigated Selank in generalized anxiety disorder, with observed reductions in anxiety scores without the sedation or cognitive impairment associated with benzodiazepinesHuman clinical
Cognitive FunctionPreclinical research has reported improvements in learning, memory, and attention in rodent models, with some supportive clinical dataIn vivo (rodent) / clinical
Mood and DepressionStudies have examined Selank's effects on depressive-like behavior in rodent models, with investigations of co-administration alongside standard antidepressantsIn vivo (rodent)
Stress and AdaptationResearch has examined Selank's influence on stress response markers and adaptive behavior in animal stress modelsIn vivo (rodent)
Immune ModulationConsistent with its tuftsin lineage, Selank has been investigated for effects on immune parameters including cytokine balanceIn vivo / in vitro
NeuroprotectionPreclinical models of ischemic and excitotoxic neuronal injury have examined Selank's potential protective activityIn vivo (rodent)
Research Context

Most of Selank's published research has been conducted in Russia, where the peptide has approved clinical applications. Research availability in English-language literature is more limited than for many comparably studied peptides, which has contributed to relatively lower international awareness despite the compound's long research history.

Common Areas of Research Interest

The scientific focus on Selank centers on its central nervous system activity and its unique profile as a non-sedating, non-addictive anxiolytic candidate in preclinical models.

Pharmacokinetics

Selank's pharmacokinetic profile is notable for its ability to cross the blood-brain barrier despite its peptide nature, a property attributed to its structural modifications.

~Minutes
Plasma Half-Life
Yes
Crosses BBB
752
Molecular Weight (Da)
7
Amino Acid Residues

Selank has a short plasma half-life measured in minutes, but its central nervous system effects have been reported to persist for substantially longer periods in preclinical and clinical studies. This disconnect between peripheral pharmacokinetics and central pharmacodynamics is a common observation across small-peptide anxiolytics and is a reason intranasal administration has been explored as a research route.

Comparison to Similar Peptides

Selank is often considered alongside other small peptides investigated for cognitive, anxiolytic, or neuroprotective effects.

FeatureSelankSemaxTuftsin
OriginSynthetic tuftsin analogSynthetic ACTH(4-7) analogEndogenous IgG-derived tetrapeptide
Primary Research FocusAnxiolytic, cognitiveCognitive, neuroprotectiveImmunomodulatory
Amino Acids774
BBB PenetrationYesYesLimited

Frequently Asked Questions

No. Selank is a peptide and is structurally and mechanistically distinct from benzodiazepines. Research has suggested its anxiolytic activity is mediated through indirect modulation of the GABAergic system, rather than direct binding at the GABA-A receptor where benzodiazepines act.
Selank contains the four-amino-acid tuftsin core sequence with an additional three-residue proline-glycine-proline extension. The tuftsin fragment is responsible for immunomodulatory activity inherited by Selank, while the added residues confer metabolic stability and central nervous system activity.
Selank was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences in the late 20th century. It has been the subject of extensive Russian preclinical and clinical research, and it is approved in the Russian Federation for certain anxiety-related applications. Research outside Russia remains more limited.
Research to date has characterized Selank as producing anxiolytic activity without the sedation, cognitive impairment, or motor coordination effects associated with benzodiazepine anxiolytics. Some preclinical and clinical data have in fact reported cognitive-enhancing effects, an unusual combination for an anxiolytic candidate.
Available preclinical data has not documented the tolerance, dependence, or withdrawal phenomena seen with benzodiazepines or other GABA-A-targeting anxiolytics. Long-term human data is more limited, and this remains an active area of research.
In published research, Selank has been administered via intranasal and parenteral (subcutaneous, intramuscular) routes. Intranasal delivery is particularly prevalent given Selank's central nervous system activity and short peripheral half-life.

Sources & References

  1. Medvedev VE, et al. "Peptide anxiolytic Selank: Clinical data on effectiveness and safety in the treatment of generalized anxiety disorder." Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova. 2015;115(6):26-32.
  2. Kost NV, et al. "The anxiolytic activity of tuftsin analogue Selank and its metabolites." Bulletin of Experimental Biology and Medicine. 2001;132(3):876-878. PubMed
  3. Semenova TP, et al. "Comparative analysis of the effects of selank and tuftsin on the behavior and monoamine levels in the brain of rats in open field conditions." Eksperimental'naia i Klinicheskaia Farmakologiia. 2007;70(4):6-9. PubMed
  4. Sollertinskaya TN, et al. "Compensatory and restorative effects of Selank in primates." Zhurnal Vysshei Nervnoi Deiatelnosti Imeni I P Pavlova. 2008;58(1):56-65.
  5. Kolik LG, et al. "Effect of the peptide anxiolytic selank on alcohol motivation: experimental research." Bulletin of Experimental Biology and Medicine. 2014;157(1):26-30. PubMed
  6. Zozulya AA, et al. "The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity." Bulletin of Experimental Biology and Medicine. 2001;131(4):315-317.

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