What Is PE-22-28?

1. How does PE-22-28 work?

TREK-1 helps regulate the voltage across a cell’s membrane by allowing potassium to flow through it. That contributes to how readily a neuron fires. Researchers investigated whether inhibiting this channel could produce antidepressant effects.

In Mazella and colleagues’ 2010 spadin study, the parent peptide inhibited TREK-1, increased the firing rate of serotonin neurons in a mouse brain region and produced antidepressant-like behavior in mice. Spadin contains 17 amino acids. The later PE-22-28 work shortened it to seven while retaining activity in the laboratory assay.

This makes PE-22-28 interesting as a possible route to altering mood-related circuitry. It does not mean that increasing neuronal excitability universally improves brain function. Effects depend on which cells are exposed, how much compound reaches them and how long the effect lasts.

The mechanism also depends on experimental conditions. Ma and Lewis’s 2020 study tested the parent spadin in frog egg cells expressing mouse channels. Spadin did not inhibit baseline currents in that system; pretreatment interfered specifically with subsequent TREK-1 activation by arachidonic acid. That study did not directly test PE-22-28, but it shows why “TREK-1 blocker” needs the assay conditions attached.

2. What do the PE-22-28 studies show?

Most of the direct claims trace to Djillani, Pietri, Moreno, Heurteaux, Mazella and Borsotto’s 2017 paper. The team examined standard PE-22-28 alongside chemically modified analogues. Those results need to stay attached to the molecule tested.

The 2017 experiments provide several measurable findings:

The forced-swim difference is about a 43% reduction in immobility, calculated from the reported group means. It cannot be described as “43% less depression.” Mice did not complete a depression questionnaire, and these tests cannot measure relief from hopelessness, restored motivation at work or enjoyment of daily life.

Several positive experiments within one paper also provide less independent confirmation than replications by separate groups. The direct evidence is concentrated in a small preclinical research program.

3. Is PE-22-28 500 times stronger than spadin?

The number comes from laboratory potency. An IC50 is the concentration needed to produce half of the measured inhibitory effect under specified assay conditions. A lower value means less compound was needed in that experiment.

The 2017 paper reports approximately 0.1–0.12 nanomolar for PE-22-28 and 40–60 nanomolar for spadin. Using the abstract’s 0.12 nM gives a ratio of about 333–500. The paper is internally inconsistent: its abstract and results prose assign 0.12 nM to PE-22-28, while Figure 3’s caption and the discussion assign it 0.10 nM and give 0.12 nM to the G/A analogue.

Both versions indicate much greater potency in that channel assay. Neither predicts a multiplier for human mood, memory or motivation. A compound can act at a very low concentration in a dish yet have poor absorption, rapid breakdown or inadequate brain exposure in a person.

These numbers also cannot establish that PE-22-28 is stronger than an SSRI. That would require a clinical comparison measuring the same outcomes in comparable patients.

4. Neurogenesis, BDNF and memory claims

The increase from 899 to 1,736 BrdU-positive cells was approximately 93%, calculated from the group means in the mouse experiment. BrdU labeling detects newly synthesized DNA and is used to study cell proliferation. The authors interpreted the result as evidence of hippocampal neurogenesis.

That measurement alone cannot show that all the labeled cells became mature neurons, survived long term or formed useful connections. It also cannot tell a healthy person how much faster they might learn a language.

In a separate culture experiment, the researchers measured PSD-95, a protein associated with synapses, in mouse cortical neurons. Its level increased over time after exposure to PE-22-28 and related analogues. A synaptic protein measurement supports investigating changes at neuronal connections; it does not directly count functional new connections or demonstrate better memory.

BDNF, a protein involved in neuronal survival and plasticity, appears in the paper’s discussion of earlier spadin work. That background should not become a claimed percentage increase in human BDNF from PE-22-28. The direct experiments summarized here measured channel activity, mouse behavior, BrdU labeling and PSD-95. They did not establish human cognitive enhancement. See the original measurements in Figures 3, 5 and 6.

5. PE-22-28 half-life and the 23-hour claim

A drug’s elimination half-life describes how quickly its concentration falls. The widely repeated 23-hour PE-22-28 figure came from measuring how a behavioral effect faded in mice.

More specifically, Figure 7 of the 2017 paper studied G/A-PE-22-28, which replaces glycine with alanine, and a biotinylated version of that analogue. Standard PE-22-28 was not one of the two molecules in this duration experiment.

These are reported animal-study conditions, not suggested human doses. Researchers tested 10 previously untested mice per time group and estimated when the forced-swim effect had fallen to half its initial value. They did not take serial blood samples to establish peptide clearance.

Entering 23 hours into a half-life calculator would therefore model an unsupported assumption about human PE-22-28 exposure. It cannot establish accumulation, a washout period or a safe redosing interval.

6. Human trials, dosage and delivery routes

A ClinicalTrials.gov search for PE-22-28, PE 22-28 or spadin returned no registered studies on September 22, 2026. The literature search for this guide did not identify a published human treatment trial. These searches cannot exclude unregistered exposure or research indexed under another name.

There is consequently no validated human dose, cycle or maintenance schedule in the evidence reviewed here. Converting mouse micrograms per kilogram into a human amount leaves absorption, brain exposure and toxicity unanswered. The IC50 from a channel assay supplies none of those missing measurements.

The 2017 paper used intraperitoneal injections, into the abdominal cavity, and included oral gavage experiments in mice. Gavage delivers material through a tube into the stomach. Neither method validates a commercial nasal spray, capsule or subcutaneous injection for humans. Bioavailability needs to be measured for the exact formulation and route.

Claims that nasal delivery “bypasses the blood-brain barrier” also need direct exposure data. A route’s theoretical appeal does not establish how much intact PE-22-28 reaches a person’s brain.

7. PE-22-28 side effects and safety gaps

The 2017 researchers screened several other potassium channels and reported no inhibition under the tested conditions, including no effect on hERG, a channel relevant to cardiac electrical function. That is useful early screening. It cannot establish human heart safety or exclude effects at other concentrations, on other targets or during repeated exposure.

Without clinical safety data, there is no dependable rate for insomnia, headache, anxiety or other symptoms that users may describe online. Long-term effects, tolerance, withdrawal and interactions with antidepressants remain unresolved. The absence of a documented adverse effect in a small animal study cannot supply a human safety estimate.

Product identity adds another uncertainty. Standard PE-22-28, G/A-PE-22-28 and biotinylated analogues have different structures. A purity certificate cannot make their research interchangeable, establish sterility or show that a preparation is safe for a particular route.

For someone seeking relief from persistent depression, this evidence does not support replacing prescribed care or adding PE-22-28 to an antidepressant without clinical guidance.

8. PE-22-28 vs Semax, Selank and Dihexa

These compounds often come up together in discussions of brain health, but the research asks different questions.

There is no human head-to-head evidence here that ranks PE-22-28 against these compounds for focus or mood. Nor does a combination of different proposed mechanisms demonstrate that a stack works better or is safer.

If the goal is better concentration, the relevant outcome is performance on attention tasks. For memory, it is learning and delayed recall. For depression, it is symptom improvement and daily functioning assessed against a control group. PE-22-28 still needs human studies that measure those outcomes and follow adverse events over time.

9. PE-22-28 FAQ

• What is PE-22-28 used for?

  PE-22-28 is an experimental peptide investigated for TREK-1 inhibition and antidepressant-like effects in mice. It attracts interest for mood and cognitive enhancement, but the research reviewed here does not establish those benefits in humans.

• Is PE-22-28 the same as spadin?

  PE-22-28 is a shorter fragment. Spadin contains 17 amino acids and corresponds to positions 12–28 of the sortilin propeptide; PE-22-28 contains the seven amino acids at positions 22–28. Modified PE-22-28 analogues are also separate molecules.

• Does PE-22-28 grow new brain cells?

  A 2017 study found more BrdU-labeled cells in mouse hippocampus after four days of treatment. BrdU marks newly synthesized DNA. This supports further research into cell proliferation but does not establish lasting new neurons or improved cognition in humans.

• Is PE-22-28 500 times stronger than spadin?

  That figure comes from comparing concentrations in a TREK-1 channel assay. The paper reports roughly 0.1–0.12 nM for PE-22-28 versus 40–60 nM for spadin, with an internal mismatch in the exact values. These laboratory results cannot quantify a human mood benefit or determine a dose.

• What is the half-life of PE-22-28?

  A dependable human elimination half-life has not been established. The frequently repeated 23-hour value describes the fading of a behavioral effect in mice given biotinylated G/A-PE-22-28, a modified analogue. It did not measure standard PE-22-28 disappearing from human blood.

• What is the recommended PE-22-28 dosage?

  No validated human dose, cycle or maintenance schedule was identified. Mouse experiments cannot establish a safe human regimen, and the channel-inhibition concentration is not an injectable dose.

• Does PE-22-28 work orally or as a nasal spray?

  The main paper includes oral gavage experiments in mice. It does not establish human oral bioavailability or validate commercial capsules, nasal sprays or injections. No human comparison identifies a preferred route.

• What are PE-22-28's side effects?

  Human studies have not established reliable side-effect frequencies, long-term safety, tolerance or withdrawal risk. Limited channel screening and mouse experiments cannot establish that PE-22-28 is free of adverse effects.

• Can PE-22-28 be stacked with Semax or Selank?

  No controlled human evidence identified in this review establishes the safety or added benefit of these combinations. Separate proposed mechanisms do not establish synergy, and a blend makes it harder to attribute benefits or adverse reactions to one ingredient.

10. Sources