Most of what you can read about Selank online describes a single, tidy effect: calm without sedation. The preclinical literature is less tidy than that. Across a run of Russian studies using two different inbred mouse strains, Selank produced measurable behavioural and receptor changes in the strain that was anxious to begin with — and close to nothing in the strain that wasn't. If you're researching what Selank is and what the evidence actually supports, that split is one of the more informative things in the file, and it rarely makes it into the summaries.

This post looks at the strain-and-route data specifically. It is animal work. None of it tells you what happens in a person.

What is Selank, and why mouse strain matters

Selank is a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) built by extending the natural immunopeptide tuftsin with a Pro-Gly-Pro tail to slow enzymatic breakdown. It's studied as an anxiolytic that works indirectly — GABAergic and monoaminergic effects, inhibition of enkephalin-degrading enzymes — rather than as a direct receptor agonist. Background and sequence details sit on our Selank profile page.

The strain question comes from a design choice the Russian groups kept repeating. They ran Selank in BALB/c mice and C57BL/6 mice side by side. BALB/c are the classic high-anxiety, low-exploration strain; C57BL/6 are more exploratory and stress-resilient. Testing both is a way of asking whether a drug corrects a deficit or shifts everyone in the same direction.

The 2018 route comparison: effects in one strain only

A 2018 study in Eksperimental'naya i Klinicheskaya Farmakologiya gave mice Selank at 300 µg/kg/day for five days, by two routes — intraperitoneal injection and intranasal — then ran elevated plus-maze behaviour and measured radioligand binding at brain GABA and NMDA receptors.

The reported result: anxiolytic and nootropic effects were seen only in BALB/c mice, the strain with initially reduced exploratory activity and higher baseline anxiety. In those mice, intraperitoneal Selank increased GABA-receptor binding sites in the frontal cortex by 38%, without changing hippocampal NMDA binding.

A 2020 follow-up in the Neurochemical Journal extended the same comparison to Selank, Semax and Noopept together. In BALB/c mice all three improved exploratory activity and reduced anxiety by both routes — but the anxiolytic effect was stronger after injection, and the nootropic (exploration/learning) effect was stronger intranasally. In C57BL/6 mice, none of the three peptides shifted exploratory behaviour or anxiety by either route.

Two things follow from that, and they pull in different directions for anyone reading marketing copy. First, route appears to change which effect predominates, not just how much of it you get. Second, the baseline state of the animal appears to gate whether there's an effect at all.

The neurochemistry lines up with the behaviour

An earlier 2008 comparative study found the same pattern one layer down. Selank at 0.3 mg/kg raised noradrenaline in the hypothalamus of both strains, but lowered serotonin and its metabolite 5-HIAA in the hippocampus of BALB/c mice while leaving C57BL/6 mice unchanged. The authors read this as selectivity in Selank's anxiolytic action.

A 2023 Neurochemical Journal paper on the NMDA receptor glycine site adds a wrinkle: intranasal Selank did change binding in both strains in the cortex (a decrease, larger in C57Bl/6), but in the hippocampus it increased binding sites in BALB/c only, with no effect in C57Bl/6. So it isn't that Selank does nothing in resilient animals — it's that the region-specific changes that track with behavioural anxiolysis appear to be the strain-dependent ones.

What this does and doesn't license you to conclude

Honest framing: these are small rodent studies from a closely related group of Russian laboratories, using radioligand binding as a proxy for function, and the route comparison in particular has not been independently replicated elsewhere. Mouse strain is not a model of human personality. Elevated plus-maze behaviour is not clinical anxiety.

What it does do is undercut a specific claim you'll see online — that Selank reliably produces calm-without-sedation in anyone who uses it. The animal data most often cited for Selank are, on their own terms, data about correcting an elevated baseline. The human record doesn't resolve this either way: it consists of three small Russian trials, the most recent from 2015, conducted in people with diagnosed anxiety-spectrum conditions. There is no reasonable-sized trial in healthy volunteers to point at. More on how the human record sits against the mechanism work is in our peptides library.

Selank Australia: is Selank legal in Australia?

The Australian position hasn't changed, and it's worth stating plainly because the search results on this are poor.

  • Selank is unscheduled in the Poisons Standard — it isn't listed in any Schedule. That is not the same as being approved.
  • It is an unapproved therapeutic good in Australia. It has no ARTG registration, so it cannot lawfully be supplied or advertised as a therapeutic product here. Access to unapproved goods runs through prescriber pathways such as the Special Access Scheme and Authorised Prescriber scheme, at a clinician's discretion.
  • It is registered as a medicine in Russia for mild anxiety, as an intranasal formulation. A Russian registration carries no weight with the TGA.
  • Selank is not named on the WADA 2026 Prohibited List. Athletes should still note that WADA's S0 "non-approved substances" clause captures compounds with no current approval for human therapeutic use in any jurisdiction, and that exclusion from the list by name is not clearance.

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FAQ

What is Selank used for?

In Russia, where it is a registered medicine, Selank is used intranasally for mild anxiety and neurasthenia. Everywhere else it is an investigational peptide, and the wider claims made for it — sleep, focus, immune effects — rest mainly on animal and cell studies.

Is Selank legal in Australia?

Selank is unscheduled in the Australian Poisons Standard but is an unapproved therapeutic good with no ARTG registration, so it can't be lawfully supplied or advertised as a therapeutic product. Prescriber-mediated pathways for unapproved goods exist at a clinician's discretion.

Does Selank work in people who aren't anxious?

Nobody knows. The mouse studies that report the clearest effects found them in the high-anxiety BALB/c strain and largely not in the resilient C57BL/6 strain, and the three small Russian human trials enrolled people with diagnosed anxiety-spectrum conditions.

Is Selank banned by WADA?

Selank is not named on the WADA 2026 Prohibited List. Because it lacks approval for human therapeutic use in most jurisdictions, athletes should treat the S0 non-approved substances category as the relevant risk rather than assuming clearance.

Sources

This article is information only, not medical advice. Selank is not approved by the TGA and has no ARTG registration in Australia; it is registered as a medicine only in Russia. retatrutide.net.au is independent and does not sell or source peptides.