Selank Research Peptide

Selank is the synthetic heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro (TKPRPGP), with the formula C33H57N11O9, a molecular weight of 751.89 and CAS number 129954-34-3. Its first four residues reproduce the immune peptide tuftsin and the last three add a glyproline tail. It is also listed as Selank peptide or Selank acetate, and Crown Peptides supplies 5mg and 10mg vials.

Radioligand work suggests not. In rat brain membranes, Selank changed how tritiated GABA bound, acting as a positive allosteric modulator: a substance that tunes the receptor's response to GABA from a separate site. That places it closer in mechanism to benzodiazepines than to GABA, although its site does not appear identical to theirs.

The two interact in ways that are not simply additive. In membrane binding assays, Selank blocked diazepam's modulating effect on GABA binding. In unstressed rats, a course of either compound nudged elevated plus maze measures in an unfavourable direction, but the shift was smaller with Selank, one of several hints that the two act through related yet distinct mechanisms.

The two strains differ in baseline anxiety-like behaviour and in brain monoamine levels, which makes them a natural test of selectivity. Selank's behavioural and neurochemical effects repeatedly appeared in the passive, high-anxiety BALB/c strain and were weak or absent in C57BL/6 mice, a pattern the researchers interpret as an effect that depends on the animal's initial state.

The answer depended on the animal. In BALB/c mice, hippocampal serotonin and 5-HIAA fell after Selank, while C57BL/6 mice showed no change. In Wistar rats, a single injection during training activated serotonin metabolism in the hypothalamus and caudal brainstem for up to two hours, a finding the authors tied to the peptide's effect on memory retention in that task.

Actinomycin D halts RNA synthesis and, with it, the new protein production that long-term memory consolidation requires in animals. Researchers used it to disrupt learning in rats trained to find the safe exit in a 16-door maze, and Selank prevented or offset that disruption while shortening the time the rats needed to learn the task.

The spleen is packed with lymphocytes and macrophages, so it gives a direct readout of immune gene activity after a single treatment. Because Selank descends from tuftsin, which was first characterised through its action on immune cells, the Moscow group used spleen panels of chemokine, cytokine and receptor genes to check whether that immune heritage survived in the longer peptide.

Gly-Pro is the dipeptide at the very end of Selank. Antiviral screening identified it as the smallest fragment that kept antiviral activity, so the group calls it the Selank pharmacophore. In mouse spleen, Gly-Pro reproduced many of the gene-expression changes seen with the full peptide, including a similar fall in C3 mRNA, which makes it a handy comparison for separating the roles of the two halves.

The data are mixed but interesting. In cultured blood cells from patients with depression, Selank at 10^-7 M completely suppressed IL-6 gene expression, an effect not seen in cells from healthy donors, yet IL-6 protein measured in the patients' cultures rose.

It has, using thromboelastography, which records how a clot forms and strengthens over time. Selank, the related glyproline His-Phe-Arg-Trp-Pro-Gly-Pro and the tripeptide Pro-Gly-Pro all shifted clotting parameters towards slower, weaker coagulation compared with controls, and Selank showed the strongest anticoagulant effect of the three.

By labelling every residue of the peptide with tritium through high-temperature catalytic isotope exchange, then extracting tissue and separating intact Selank from its breakdown products by chromatography. Because the label sits on all seven residues, nearly every possible fragment can be measured at once, and the method was used both for degradation pathways in blood plasma and for brain concentrations after intranasal delivery in animals.

At neutral pH Selank carries three positive charges, from its amino terminus, lysine and arginine, and it has no acidic side chains to offset them. In electrospray mass spectrometry it therefore appears readily as doubly and triply charged ions, near m/z 376.7 and 251.5, as well as the singly charged ion at about 752.4 (monoisotopic mass 751.43). The same positive charge can make it cling to glass and some plastics in very dilute solutions.

A single 5mg vial is a sensible way to set up and validate an assay. Once a protocol is fixed, the 10mg strength and the five- or ten-vial boxes reduce the cost per milligram and keep one batch running through a whole series of binding, behaviour or gene-expression experiments, which helps when results from different weeks need to be compared.

It is. Crown Peptides also sells a Semax + Selank blend containing 5mg of each peptide per vial, for projects that want both in a single preparation. The single Selank vial remains the better choice when its own effects need to be isolated.