PE-22-28: A Spadin-Derived TREK-1 Channel Blocker in Antidepressant Research

Research summary. PE-22-28 is a synthetic short peptide derivative of spadin, an endogenous peptide produced from cleavage of the sortilin (NTSR3) propeptide. Both spadin and PE-22-28 act as inhibitors of the TREK-1 (TWIK-related potassium channel-1) two-pore-domain potassium channel, which is highly expressed in CNS regions implicated in mood, learning, and memory regulation. PE-22-28 has been studied in rodent depression and stroke-recovery models as a candidate antidepressant-pathway research peptide with a mechanism distinct from monoaminergic SSRI/SNRI antidepressants.

Molecular profile

• Sequence (PE-22-28): Gly-Val-Ser-Trp-Gly-Leu-Arg (GVSWGLR) — the 7-residue active fragment derived from spadin
• Parent (spadin) sequence: A 17-residue peptide derived from cleavage of the sortilin propeptide
• Class: TREK-1 (KCNK2) two-pore-domain potassium channel inhibitor
• Approximate molecular weight (PE-22-28): ~772 g/mol
• Note on naming: The "PE-22-28" designation refers to the residue numbering of the active fragment within the spadin propeptide source. Some literature also reports related shortened analogues with similar TREK-1 inhibitory activity.

Origin and rationale

Spadin was identified by the Borsotto-Heurteaux laboratory in France as an endogenous peptide produced during sortilin propeptide processing. The interest in spadin derived from the prior identification of TREK-1 as a candidate antidepressant target — TREK-1 knockout mice display a depression-resistant phenotype, and TREK-1 inhibition was hypothesised to produce antidepressant-like effects without the receptor-binding profile of monoaminergic antidepressants. Spadin showed reliable TREK-1 inhibitory activity in cell-culture and rodent models, and shortened spadin analogues (including PE-22-28) were subsequently identified that displayed comparable or improved TREK-1 inhibitory activity with improved pharmacokinetic profiles.

Mechanism of action

PE-22-28 binds and inhibits TREK-1, a two-pore-domain potassium channel that contributes to setting neuronal resting membrane potential and modulating neuronal excitability. TREK-1 is expressed prominently in mood- and cognition-related brain regions (prefrontal cortex, amygdala, hippocampus, dorsal raphe). Inhibition of TREK-1 in these regions has been reported to:

• Increase excitability of serotonergic dorsal raphe neurons, with associated downstream effects on mood and behaviour.
• Promote adult hippocampal neurogenesis, an effect typically seen with chronic SSRI administration but reportedly faster-onset with TREK-1 inhibition.
• Modulate synaptogenesis, with associated changes in dendritic-spine density in hippocampal preparations.

The reported time-course of antidepressant-like effects in rodent models with PE-22-28 is faster than the multi-week onset typical of SSRIs, which has driven interest in TREK-1 inhibition as a candidate fast-acting antidepressant mechanism.

Preclinical research highlights

Rodent depression-paradigm endpoints. PE-22-28 administration in standard rodent depression-research paradigms (forced-swim test, tail-suspension test, chronic mild-stress models) has been reported to produce antidepressant-like effects, with effects emerging on a shorter time-course than SSRI reference compounds.

Adult hippocampal neurogenesis. Rodent studies have reported that PE-22-28 administration increases dentate-gyrus neurogenesis and synaptogenesis within approximately four days of administration onset, faster than the multi-week onset typical of standard antidepressants.

Post-stroke depression models. Rodent stroke-recovery research has reported elevated TREK-1 expression in post-stroke brain tissue and reductions in depression-like behaviour with TREK-1 inhibitors, motivating PE-22-28 interest in post-stroke depression research models.

Selectivity and side-effect-profile considerations. Reports include relatively limited engagement with non-mood-related TREK-1-mediated functions (e.g. some peripheral effects associated with TREK-1 channels in other tissues), although the full selectivity profile of PE-22-28 across the broader two-pore-domain potassium-channel family is incompletely characterised.

Limitations of the evidence base

Several caveats apply when reading the PE-22-28 literature:

• The supporting research is concentrated in a small number of laboratories; the broader replication base remains modest.
• Pharmacokinetic data for PE-22-28 in vivo (oral bioavailability, blood-brain-barrier penetration, plasma stability) is incompletely characterised.
• No registered late-stage clinical-trial programmes for PE-22-28 or for spadin appear in major Western trial registries at the time of writing.
• The "fast-acting antidepressant" framing should be considered cautiously in the broader context — multiple candidate fast-acting mechanisms (NMDA antagonism, psychedelic-related mechanisms, TREK-1 inhibition) have produced different translational signals at different stages of clinical development.

Current research status

PE-22-28 is an investigational research peptide. It is not approved by the FDA for any indication. Research interest is concentrated in TREK-1 channel pharmacology, fast-acting antidepressant-mechanism studies, post-stroke depression research models, and adult hippocampal neurogenesis biology.

For research-supplier contexts, PE-22-28 is supplied as a research-grade investigational peptide and is not intended for self-administration.

Key takeaways for researchers

• PE-22-28 is a 7-residue synthetic peptide derived from the active region of the endogenous TREK-1 inhibitor spadin (GVSWGLR).
• It blocks TREK-1, a two-pore-domain potassium channel highly expressed in mood- and cognition-related brain regions.
• TREK-1 inhibition produces antidepressant-like effects in rodent paradigms with a reportedly faster time-course than SSRI reference compounds.
• Reported preclinical effects include antidepressant-like behaviour, accelerated adult hippocampal neurogenesis and synaptogenesis, and applications in post-stroke depression research models.
• The supporting literature is concentrated in a small number of laboratories.
• PE-22-28 is not an FDA-approved drug.

References

1. Mazella J, Pétrault O, Lucas G, et al. Spadin, a sortilin-derived peptide, targeting rodent TREK-1 channels: a new concept in the antidepressant drug design. PLoS Biol. 2010;8(4):e1000355.
2. Djillani A, Pietri M, Mazella J, Heurteaux C, Borsotto M. Fighting against depression with TREK-1 blockers: past and future. A focus on spadin. Pharmacol Ther. 2019;194:185–198.

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This article is provided for educational and research purposes only. PE-22-28 is a research peptide. It is not an approved drug or therapeutic agent and is not intended for human consumption, diagnosis, treatment, cure, or prevention of any disease or condition. All work involving this peptide should be conducted by qualified personnel within an appropriate research setting and in compliance with applicable institutional and regulatory requirements.