Selank

Overview

Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. The first four amino acids are tuftsin, a short peptide cut from an antibody fragment and known for signaling to immune cells. The Pro-Gly-Pro tail, shared with its sister peptide Semax, was added to slow breakdown in the body.

Selank has been studied mainly for anxiety. In a Russian clinical comparison with a benzodiazepine, the authors described stimulant-like and anti-fatigue effects alongside similar anxiety scale changes, rather than sedation. Laboratory work has looked at three possible routes: effects on the GABA system that benzodiazepines also act on, effects on enzymes that break down enkephalins (the body's own opioid-like peptides), and shifts in immune signaling molecules.

Selank is a registered medicine in Russia but has no approval in the United States or the European Union. Almost all published research comes from a small cluster of Moscow institutes, frequently with the same senior authors. The clinical trials that exist are small and mostly published in Russian, so the evidence is best described as early and narrow.

Research history

Selank came out of the same program at the Institute of Molecular Genetics of the Russian Academy of Sciences that produced Semax, under Nikolai Myasoedov, working with pharmacologists at the Zakusov Research Institute of Pharmacology in Moscow. The idea was to take tuftsin, a natural immune peptide, and stabilize it with a proline-rich tail so that it lasted long enough to be studied as a central nervous system agent.

Early rat studies in the 2000s reported effects on learning and on anxiety-like behavior. In 2008 two Russian clinical papers compared Selank with a benzodiazepine in people with generalized anxiety disorder and neurasthenia, and looked at immune markers in the same patient groups.

From about 2011 onward, a genetics team at the Institute of Molecular Genetics published a series of gene expression studies in mouse spleen, rat brain and human cell lines, trying to explain how a small peptide could have both immune and behavioral effects.

What published studies have examined

Cell and biochemical studies

• GABA receptor binding (2018). Vyunova and colleagues used radioligand assays on rat brain membranes and reported that Selank acted as a positive allosteric modulator of GABA binding, meaning it changed how the receptor responded to GABA rather than binding in its place.
• Neuroblastoma cells (2017). Filatova and colleagues found that Selank alone did not change expression of 84 GABA system genes in human IMR-32 cells, though it altered the response to GABA and to olanzapine when combined with them.

Animal studies

• Rat brain genes (2016). Volkova and colleagues measured 84 neurotransmission genes in rat frontal cortex. Expression of 45 genes changed one hour after Selank or GABA, and 22 after three hours, with the two compounds producing correlated patterns.
• Immune genes (2011). In mouse spleen, Kolomin and colleagues reported that Selank and two of its fragments changed expression of 34 of 84 inflammation-related genes.
• Behavior (2017). Kasian and colleagues tested Selank, diazepam and the combination in rats under chronic mild stress, scoring anxiety-like behavior in an elevated plus maze. Results differed by condition, with the combination performing best under stress.

Human studies

• Anxiety comparison (2008). Zozulia and colleagues compared Selank in 30 patients with medazepam, a benzodiazepine, in 32 patients with generalized anxiety disorder or neurasthenia. The authors reported similar anxiety scale changes in both groups. Blinding details are limited in the indexed abstract.
• Immune markers (2008). Uchakina and colleagues reported shifts in blood cytokine balance in similar patients who received Selank for 14 days.

Open questions

• Small, local evidence base. The human data consist of a few small trials from groups tied to Selank's development. No large, preregistered, placebo-controlled trial with published results was found in the indexed literature.
• Mechanism. GABA modulation, enkephalin effects and immune signaling have all been proposed, and the gene expression studies show broad but hard-to-interpret changes. Which, if any, explains the reported clinical effects is unresolved.
• Safety. Long-term safety, dependence potential and interactions with other drugs acting on GABA are not well characterized in the international literature. The rat work combining Selank with diazepam shows interactions are possible.
• Replication. Independent groups outside Russia have published very little on Selank.
• Material quality. Products sold outside Russia are unregulated research chemicals. See what makes a peptide research grade.