What is Selank?

Selank is the common name for a synthetic heptapeptide whose formal designation is Thr-Lys-Pro-Arg-Pro-Gly-Pro (also written as TKPRPGP). It is classified as a synthetic analogue of the endogenous immunomodulatory tetrapeptide tuftsin (Thr-Lys-Pro-Arg), extended at the C-terminus by a Pro-Gly-Pro tripeptide sequence. The compound is also referred to in the literature as TP-7 and by the developmental code Selank. Its molecular formula is C33H57N11O9 and its molecular weight is approximately 751.9 g/mol. The N-terminal tetrapeptide portion corresponds to tuftsin, while the C-terminal Pro-Gly-Pro extension is a structural motif intended to confer resistance to enzymatic degradation and to prolong the peptide's half-life relative to tuftsin itself.

The research literature on Selank centres principally on the GABAergic system, with additional work examining its influence on enkephalin metabolism and on the balance of monoaminergic signalling. The compound is not a receptor agonist in the classical sense; rather, the work describes it as a peptide modulator whose effects are studied through behavioural, electrophysiological and biochemical endpoints in animal and in vitro preparations.

Research Studies

Selank and GABAA receptor expression in rodent brain

Preclinical work has examined whether repeated administration of Selank alters the expression of genes encoding subunits of the GABAA receptor complex in rodent brain regions. The rationale for this line of inquiry is that the anxiolytic-like effects reported for the peptide in animal models may be mediated through modulation of inhibitory neurotransmission rather than through direct receptor occupancy. Studies of this type typically measure mRNA levels for individual receptor subunits in the cortex, hippocampus and other limbic structures after a defined dosing period, and compare those levels against vehicle-treated controls. The findings are animal-only and do not establish whether comparable changes occur in humans.

Selank and enkephalin degradation in vitro

A separate body of in vitro work has investigated the effect of Selank on the enzymes responsible for degrading endogenous enkephalins, particularly enkephalinase. The proposed mechanism is that by inhibiting the breakdown of these endogenous opioid peptides, Selank may indirectly prolong their activity at opioid receptors without itself binding to those receptors. Such experiments are conducted in tissue homogenates or purified enzyme preparations, and they measure the rate of substrate cleavage in the presence and absence of the peptide. These are in vitro findings and their relevance to intact organisms has not been established.

Selank and anxiety-like behaviour in animal models

Several animal studies have assessed Selank in standard tests of anxiety-like behaviour, including the elevated plus maze, the open field test and the light-dark box. In these paradigms, rodents are placed in a novel environment and the amount of time spent in protected versus exposed areas is recorded as an index of anxiety-like behaviour. Some reports describe changes in these measures following Selank administration compared with vehicle, but the results vary with dose, route of administration and species. All such findings are animal-only and cannot be extrapolated to human anxiety disorders.

Selank and memory in rodent models

Research has also examined Selank in rodent models of learning and memory, including passive avoidance and spatial navigation tasks. In passive avoidance, an animal learns to avoid a location associated with an aversive stimulus, and the latency to enter that location is used as a retention measure. In spatial tasks such as the Morris water maze, the time taken to locate a hidden platform is recorded across training trials. Some studies report that Selank-treated animals show altered retention or acquisition performance relative to controls, but the effects are not uniform across all reports. These are animal-only findings.

Selank and monoamine levels in animal tissue

Biochemical studies have measured the concentrations of monoamine neurotransmitters and their metabolites in brain tissue and in dialysate from freely moving animals after Selank administration. The analytes typically include serotonin, dopamine, noradrenaline and their respective metabolites. The purpose of such work is to determine whether the behavioural effects observed in other paradigms are accompanied by measurable changes in monoaminergic tone. The results are derived from animal tissue and in vivo microdialysis in animals, and they do not demonstrate corresponding effects in humans.

Selank and immune function in animal and in vitro models

Because Selank is structurally derived from tuftsin, an immunomodulatory peptide, some research has explored its effects on immune parameters. These studies have examined cytokine production by cultured immune cells, phagocytic activity and antibody responses in animal models. The in vitro work uses isolated cell populations stimulated with mitogens or antigens, and measures the output of cytokines such as interleukin-2 or interferon-gamma. The animal work measures immune cell populations or antibody titres after peptide administration. These findings are preclinical and do not establish clinical immunomodulatory effects.

Selank and EEG in animal studies

Electrophysiological studies have recorded cortical EEG in animals following Selank administration, with attention to changes in spectral power across frequency bands. The aim of such work is to characterise the peptide's effect on cortical arousal and on the balance between excitatory and inhibitory activity. The findings are animal-only and are not a substitute for human EEG data.

Selank and stress-related endpoints in animal models

Some studies have examined Selank in animal models of acute or chronic stress, measuring endpoints such as corticosterone levels, adrenal weight and behavioural changes in response to stressors. The purpose is to determine whether the peptide modifies the neuroendocrine response to stress. These are animal-only findings and do not demonstrate effects on human stress physiology.

Selank and pharmacokinetics in animal models

Pharmacokinetic studies in animals have measured the plasma concentration of Selank over time after various routes of administration, and have examined its distribution to brain tissue. The Pro-Gly-Pro extension is understood to increase resistance to proteolysis relative to tuftsin, and this is reflected in a longer detectable half-life in animal plasma. These are animal pharmacokinetic data and do not define human pharmacokinetics.

Comparison of Selank and Tuftsin in Preclinical Models

The table summarises differences reported in the preclinical literature. Neither column represents human data.

If you are reading this for personal health reasons

This material is sold for laboratory research only. We do not provide dosing or medical guidance, and nothing here is intended to suggest that Selank is safe or effective for any human use. Anyone considering a compound for themselves should speak to a licensed clinician.

Sources

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• [7] Effects of Transcranial Magnetic Stimulation on Object Recognition. ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT01747200
• [8] Trial of Telephone-based Psychotherapy for Depression With and Without Adjunctive Supportive Mail. ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT01770990
• [9] Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions. europe_pmc. https://europepmc.org/article/PMC/PMC12753158