Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) is a synthetic mild, highly effective antianxiety peptide drug that can be used to treat anxiety and depression. Compared with traditional anxiety therapies such as benzodiazepines, Selank has advantages in that it has no sedative or negative cognitive side effects, and no associated addiction or withdrawal issues.

Selank also has nootropic, anti-asthenia and psychostimulant effects. Clinical biological studies have shown that patients with generalized anxiety disorder and neurasthenia have reduced levels of tau (1/2) leupeptin, which is associated with the course of the disease, the severity of anxiety- and asthenia-related symptoms, and autonomic dysfunction. An increase in this parameter and a stronger positive correlation with anxiety levels were observed during selank treatment, mainly in patients with generalized anxiety disorder.

Mechanism of action

Selank affects [3H]GABA binding as a positive allosteric modulator. The combined action of Selank and some benzodiazepines also modulates [3H]GABA binding activity in a specific manner that is not cumulative and is different from that of either substance acting alone. Selank is able to block the modulatory activity of diazepam and olanzapine, whose peptide binding sites appear to be located differently but may partially overlap.

Side Effects

Common side effects of Selank include anxiety, headache, nausea, dizziness, and fatigue. Compared with the active control group, a single intraperitoneal injection of an anxiolytic dose of 0.3 mg/kg of Selank reduced the total index of morphine withdrawal syndrome by 39.6% in morphine-dependent rats, significantly (р<0.0001) reduced convulsive reactions, ptosis, and postural disorders, and increased the tactile sensitivity threshold of morphine-dependent rats by 9 times; at the same time, the pharmacological activity of Selank was slightly lower than that of a 2 mg/kg dose of diazepam (49.3% reduction in the total index of morphine withdrawal syndrome and 13-fold increase in the sensitivity threshold). Thus, Selank, like diazepam, attenuates morphine withdrawal aversion symptoms in opioid-dependent rats.

References：

[1] TATIANA V VYUNOVA. Peptide-based Anxiolytics: The Molecular Aspects of Heptapeptide Selank Biological Activity.[J]. Protein and Peptide Letters, 2018, 25 10: 914-923. DOI:10.2174/0929866525666180925144642.

[2] I I KOZLOVSKII; N D D. The optimizing action of the synthetic peptide Selank on a conditioned active avoidance reflex in rats.[J]. Neuroscience and Behavioral Physiology, 2003, 33 7: 639-643. DOI:10.1023/a:1024444321191.

[3] ANASTASIYA KASIAN. Peptide Selank Enhances the Effect of Diazepam in Reducing Anxiety in Unpredictable Chronic Mild Stress Conditions in Rats.[J]. Behavioural Neurology, 2017, 2017: 5091027. DOI:10.1155/2017/5091027.

[4] M A KONSTANTINOPOLSKY; L G K; I V Chernyakova. Selank, a Peptide Analog of Tuftsin, Attenuates Aversive Signs of Morphine Withdrawal in Rats.[J]. Bulletin of Experimental Biology and Medicine, 2022, 173 6: 730-733. DOI:10.1007/s10517-022-05624-x.