K4 Elite
A synthetic seven-amino-acid analog of the endogenous peptide spadin that inhibits the TREK-1 potassium channel, studied in rodent models for antidepressant-like effects and hippocampal neurogenesis.
PE-22-28 is a synthetic heptapeptide (seven amino acids) engineered as a shortened analog of spadin, a naturally occurring peptide cleaved from the propeptide of sortilin (neurotensin receptor-3) during its processing in the Golgi apparatus. Spadin was identified in the early 2010s as an endogenous molecule with antidepressant-like activity that acts by blocking the TREK-1 potassium channel.
Spadin's short duration of action and relatively modest receptor affinity limited its usefulness as a research tool. PE-22-28 was designed by Djillani, Mazella, Borsotto and colleagues to improve TREK-1 binding, extend in vivo stability, and prolong duration of action while retaining the core pharmacology.
No single PubChem compound CID is available for PE-22-28 in this reference, so the identifier field is left blank. All information is drawn from published preclinical research and is provided for research and reference use only.
PE-22-28 inhibits TREK-1, a two-pore-domain (K2P) potassium channel. TREK-1 normally allows potassium to leak out of neurons, contributing to a hyperpolarized, less excitable state. By blocking this leak in serotonin-associated brain regions, PE-22-28 is proposed to make relevant neurons easier to depolarize, which the authors frame as its antidepressant-like mechanism.
Downstream, short treatment courses in rodents were reported to increase hippocampal neurogenesis and markers of synaptic plasticity, which the authors suggested could relate to a faster onset of mood-related effects than conventional serotonergic agents in those models.
Djillani et al., Frontiers in Pharmacology (2017): The core study screened shortened spadin analogs and identified PE-22-28 as the standout, reporting substantially stronger TREK-1 inhibition, improved in vivo stability, and antidepressant-like behavior in mice using the forced swim and novelty-suppressed feeding tests. Reported for reference only.
Neurogenesis reports (same research line): Follow-up work from the Mazella/Borsotto group reported that short treatment courses increased hippocampal neurogenesis in rodents, framed as a possible basis for a faster behavioral response than conventional SSRIs. These are animal-model observations.
Spadin foundational studies: Earlier work characterizing spadin as an endogenous TREK-1 inhibitor with antidepressant-like activity provided the rationale for the PE-22-28 analog series. Any doses in these studies are experimental parameters, not recommendations.
Combinations examined in the research literature. Descriptive only — not a recommendation to combine compounds.
References are being compiled for this entry.