Note: This is a guest post from Smarter Nootropics and does not necessarily represent the opinions of Peak Nootropics.

Selank is an anxiolytic peptide which was developed by the Institute of Molecular Genetics of the Russian academy of sciences (IMG RAS). IMG RAS were responsible for the development of Semax, a potent cognitive enhancer.
As with Semax, Selank is taken either intranasally via a nose-dropper, or is administered via sub-cutaneous injection.

What exactly is Selank?

Selank is a classed as a heptapeptide, which is a series of amino acids joined together, in selank’s case this is 7 amino acids. Specifically; threonine-lysine-proline-arginine-proline-glycine-proline
 
Selank is based off an endogenous immunomodulatory peptide we naturally make, called tuftsin. Tutsin is classed as a tetrapeptide, made of; threonine-lysine-proline-arginine.
Here’s a side by side comparison of the molecules.

Note that the difference between the molecules is the addition of a proline,glycine,profile tail, called a PGP tail in the literature.

Selank’s Mechanism Of Action

Selank appears to exert its effects through dopamine, serotonin and norepinephrine modulation while also having potent effects on the immune system.

A rodent study showed a 0.3mg/kg injection of Selank was able to increase norepinephrine and serotonin in various regions of the brain, including the hippocampus and frontal cortex>
Study Link

A similar study noted an increase of serotonin metabolism in the hypothalamus 30-120 minutes after 0.3mg/kg injection into rodents. Study Link

A third study demonstrated selank was able to prevent hypoxia induced decreases in serotonin and norepinephrine, which preserved normal behavior Study Link

Interestingly, when compared directly to tuftsin, the endogenous peptide that selank is based upon, selank would appear superior. A rodent study which sought to block the synthesis of serotonin with p-chlorophenylalanine saw enhanced serotonin levels with selank administration but no result with tuftsin. Clearly the PGP “tail” addition to the molecule somehow enhances its effects. Study Link

Benefits

Reducing depression / ahedonia
In rodents, selank was able to restore pleasure seeking activity in mice who were otherwise depressed and suffered with ahedonia. Study Link.The same study also noticed a decrease in immobility time during the forced swim test, a common objective measure of motivation levels.

Selank Fights Anxiety
To date, two human studies involving selank and anxiety have been indexed. Both of which look promising.
One trial of 62 patients diagnosed with generalized anxiety disorder showed selank was comparable to benzodiazepine treatment. Remarkably, selank didn’t induce fatigue typically associated with anxiety treatments.
Study Link

A second human trial was administered to patients with generalized anxiety disorder and showed selank was able to reduce interlukien-6 levels in depressed patients while leaving control subjects unaffected.
Study Link

Roundup

Research on Selank looks promising, as do anecdotal reports for this nootropic. Far from simply enhancing the synthesis of serotonin as an SSRI drug would, selank appears to impact immune function whose downstream effects may be altering serotonin, dopamine and norepinephrine turnover.