PE-22-28

PE-22-28 is a synthetic peptide analog of spadin, an endogenous peptide derived from the protein sortilin. It has been investigated in preclinical research as a candidate for rapid-onset antidepressant effects, a property that has drawn interest because conventional antidepressants often take weeks to act.

PE-22-28 is investigational and animal-stage. It is not an approved medicine in any jurisdiction, and the descriptions below reflect exploratory laboratory work rather than validated clinical outcomes.

The central hypothesis behind PE-22-28 concerns the TREK-1 (KCNK2) potassium channel, which has been linked in animal models to mood regulation. High-level mechanistic themes include:

• Blocking or inhibiting the TREK-1 background potassium channel

• Modulating neuronal excitability in brain regions associated with mood, in a way researchers hypothesize could support neuroplasticity

• Acting more quickly than pathways targeted by traditional monoamine drugs

Whether these preclinical mechanistic observations translate into meaningful, reproducible effects in humans is entirely unestablished and remains a research question.

PE-22-28 has no approved therapeutic indication. It appears in the scientific literature as a research tool and antidepressant candidate studied in rodent models, not as a treatment for depression or any other condition in people.

Because it is investigational, any appearance of PE-22-28 in a catalog or research setting should be understood as reference material tied to early-stage neuroscience, not as an available or validated therapy.

PE-22-28 is not a recognized performance-enhancing agent, and it is not individually named on WADA prohibited lists. However, WADA category S0 covers any pharmacological substance not addressed by other sections and with no current approval for human therapeutic use. An investigational, non-approved peptide such as PE-22-28 would therefore be treated as prohibited at all times under that catch-all provision.

There are no notable publicized doping cases associated with PE-22-28, which is consistent with its status as an early-stage laboratory compound.

Because the compound has not undergone formal human safety evaluation, its side effect profile in people is unknown. General considerations that apply to investigational peptides include uncertainty about off-target effects, unknown long-term consequences, and product quality risks outside regulated frameworks.

The absence of documented harms is not evidence of safety; it reflects the very limited scope of study. Rigorous safety characterization has not been performed.

PE-22-28 is a modified analog of spadin engineered in laboratory studies to improve properties such as stability relative to the parent peptide. Its pharmacology has been explored in animal models rather than in defined human pharmacokinetic studies.

This information summarizes how the compound is described in preclinical research and does not constitute medical advice or a usage recommendation.

The name is a coordinate, not a brand. Sortilin (also called NTSR3) is cleaved by the enzyme furin, releasing a 44-amino-acid propeptide abbreviated PE. Spadin is residues 12–28 of that propeptide — 17 amino acids, written PE 12-28. PE 22-28 is residues 22–28: a seven-amino-acid fragment that the originating laboratory derived by studying how spadin was broken down in blood, then resynthesized as a shorter, more stable molecule (Djillani et al., Front. Pharmacol., 2017). "PE-22-28" and "spadin" are therefore related but not interchangeable, and a listing that treats them as synonyms is describing two different peptides.

The same paper reports several deliberately modified versions — variants with altered N- or C-terminal ends, including one designated G/A-PE 22-28 that produced the most prominent neurogenesis effect. Some N- and C-terminal changes abolished the effect on TREK-1 while leaving binding affinity intact, meaning small differences in how the peptide is capped can separate binding from function. That is a synthesis-quality issue, not a dosing one, and it is not something a purity percentage on a certificate of analysis would reveal.

No study has examined PE-22-28 in combination with any antidepressant or other agent, in any species.

The evidence base for PE-22-28 consists mainly of preclinical neuroscience studies exploring TREK-1 inhibition and rapid antidepressant-like effects in animal models. This work has generated mechanistic interest but has not advanced to established human clinical trials.

Because the literature is early-stage and narrow, claims that PE-22-28 treats depression in humans go well beyond what the evidence supports. High-level summaries are not a substitute for critical appraisal of the primary research.

For deeper dives on this peptide, see:

• PE-22-28 areas of research interest
• PE-22-28 side effects and safety context
• PE-22-28 pharmacology concepts (educational)
• PE-22-28 research and evidence overview

What is spadin, and how is PE-22-28 related to it? Spadin is a 17-amino-acid peptide released when the protein sortilin is processed by furin, and it was the first natural peptide identified with antidepressant-like activity, acting by blocking the TREK-1 potassium channel (Mazella et al., PLoS Biology, 2010). PE-22-28 is a seven-amino-acid fragment of spadin, designed by the same French laboratory from spadin's blood-degradation products in an effort to get a shorter molecule that survived longer in vivo (Djillani et al., Front. Pharmacol., 2017).

Why is TREK-1 a target for depression? Because deleting the TREK-1 gene in mice produces a depression-resistant phenotype resembling the effect of antidepressant treatment, which suggested that blocking the channel pharmacologically might do the same. Spadin bound TREK-1 with roughly 10 nM affinity, blocked the channel in cultured and brain-slice neurons, increased serotonin neuron firing in the dorsal raphe nucleus, and after four days of intravenous treatment produced antidepressant-like behavior plus hippocampal CREB phosphorylation and neurogenesis (PLoS Biology, 2010). Every one of those observations is in mice.

Is PE-22-28 an improvement on spadin? On the laboratory measures its designers cared about, yes. Patch-clamp work in human TREK-1 expressing cells gave PE-22-28 an IC₅₀ of 0.12 nM against 40–60 nM for spadin, and its duration of action in vivo extended to about 23 hours instead of roughly 7. In mice it reduced immobility in the forced swim test, shortened latency to eat in the novelty-suppressed feeding test after four days, induced neurogenesis, and raised PSD-95 expression in cortical neurons (Front. Pharmacol., 2017). Those are rodent behavioral proxies, not measures of mood.

Has PE-22-28 been tested in people? No. No trial of PE-22-28 or spadin is registered on ClinicalTrials.gov (searched August 2026), and no human safety, pharmacokinetic, or efficacy data have been published. A 2019 review by the originating laboratory describes the work as a drug-design program — retro-inverso analogs, cyclization, sequence shortening — rather than a clinical one (Djillani et al., Pharmacol. Ther., 2019).

What safety work has actually been done? Only rodent screening, and it is worth reading for what it implies rather than what it rules out. When the group tested spadin analogs, they specifically checked for effects on pain, epileptic processes, and cardiac function and reported none (Veyssiere et al., Psychopharmacology, 2015). Those were the checks they ran because TREK-1 and its channel family are expressed well outside mood circuitry — in cardiac and pain physiology among others. A negative rodent screen on three chosen endpoints is not a human safety dataset; it is a list of the risks the designers thought worth looking for.

Why does the "fast-acting" framing matter so much here? Because it is the entire clinical rationale. Conventional antidepressants typically require three to four weeks before an effect emerges, while the spadin mechanism produced effects within four days in mice (Pharmacol. Ther., 2019). That is a genuinely important problem to solve — which is also why the field is littered with fast-acting candidates that did not survive human testing. Depression is a serious medical condition, and a compound with no registered trial has no place in the same sentence as a treatment decision.