PE-22-28 Benefits: What the Research Has Looked At, and Its Limits

The honest summary: an interesting, well-characterised mechanism from one research group, replicated in pieces by others, and no test in a single human.

PE-22-28 is a seven-amino-acid peptide, a fragment of the sortilin propeptide. Sortilin is a receptor found throughout the nervous system, and when the body makes it, a 44-amino-acid propeptide is clipped off and released. Researchers in Nice, France, around Catherine Heurteaux, Marc Borsotto and Jean Mazella, found that residues 12 to 28 of that propeptide, which they named spadin, block a potassium channel in nerve cells called TREK-1. PE-22-28 is residues 22 to 28 only. "PE" stands for propeptide. It is not an antidepressant in the regulatory sense, not a stimulant, not a sedative, and not a replacement for treatment for a diagnosed mood disorder.

What research has looked at. The starting point was a 2006 Nature Neuroscience paper: mice bred without the TREK-1 gene behaved across standard tests as though given an antidepressant, and drugs such as fluoxetine reduce TREK-1 activity as one of their downstream effects. The 2010 PLoS Biology paper then reported antidepressant-like effects of spadin in mice across the forced-swim, tail-suspension, novelty-suppressed feeding and learned-helplessness tests. The 2017 Frontiers in Pharmacology paper reported PE-22-28 reproducing those effects. A 2018 ACS Chemical Neuroscience paper compared TREK-1 blockers with fluoxetine in a chronic unpredictable mild stress model in rats.

The limits. These are the standard rodent screens used across antidepressant development. They are an entry point, not proof of clinical efficacy, and passing them does not show that a compound works in people. PE-22-28 has never been tested for mood in a human.

What research has looked at. The 2010 paper reported spadin's behavioural effects appearing after four days, and the 2017 paper reported PE-22-28 reproducing them after a four-day course. The authors contrasted that window with the several weeks conventional antidepressants take for comparable changes in animals.

The limits. Four days is a mouse result. There is no human timeline for PE-22-28, and nothing here predicts when, or whether, a person would notice anything. See how long does PE-22-28 take to work.

What research has looked at. The 2010 PLoS Biology paper reported increased hippocampal neurogenesis in spadin-treated mice after four days. The 2017 paper reported PE-22-28 retaining the neurogenesis effect. The hippocampus is a region consistently implicated in depression research.

The limits. New neurons counted in a mouse brain are a laboratory endpoint. Nobody has measured neurogenesis in a person taking PE-22-28, and it would not be measurable in routine care.

What research has looked at. A 2015 paper in the British Journal of Pharmacology described spadin regulating synaptogenesis, the formation of connections between neurons, in cultured neurons and in mice.

The limits. This is spadin, the longer parent fragment, in cells and mice. It describes a mechanism, not an outcome in people.

What research has looked at. The 2017 paper reported PE-22-28 inhibiting TREK-1 in cultured cells at sub-nanomolar concentrations, against tens of nanomolar for spadin, and a half-life in the mouse of roughly a day rather than several hours. That is the practical reason a seven-residue fragment was pursued over the original seventeen.

The limits. Potency in a dish and half-life in a mouse are pharmacology, not benefits a person experiences. No human pharmacokinetic study exists.

What research has looked at. TREK-1 also helps with pain signalling, seizure protection and protecting neurons during reduced blood flow. A 2012 Neuropharmacology paper tested spadin in mice against those endpoints and reported no pro-pain, pro-seizure or ischaemia-worsening signal at doses that produced the behavioural effect.

The limits. Absence of a signal in mice is not human safety data. The side-effect picture in people is unknown; see PE-22-28 side effects.

What research has looked at. A 2019 paper in Neuropharmacology from the Nice group reported sortilin-derived peptides, including the shortened analog, associated with improved functional recovery and reduced depression-like behaviour in a mouse stroke model.

The limits. One study, in mice, framed by its authors as a first indication. PE-22-28 is not a stroke treatment.

What research has looked at. TREK-1 is expressed on serotonergic neurons in the dorsal raphe. Blocking it in the rodent studies was associated with increased firing of those neurons. A 2016 Brain Structure and Function paper described spadin interacting with prefrontal 5-HT4 and mGluR2 receptors in rats, and a 2015 European Neuropsychopharmacology paper from a separate group reported TREK-1 blockade producing an antidepressant-like response in rodents that synergised with 5-HT1A signalling.

The limits. This explains the interest and also the main caution: because the proposed mechanism overlaps with serotonin signalling, combining PE-22-28 with antidepressants or other serotonergic drugs is unstudied in people.

A 2017 paper in the Journal of Affective Disorders reported serum levels of the natural sortilin propeptide being lower in patients with major depressive disorder than in controls, and a 2018 Neuropsychiatric Disease and Treatment paper reported them rising after electroconvulsive therapy in treatment-resistant patients. Those concern the body's own propeptide as a possible marker. They are not studies of giving PE-22-28 to anyone.

• That PE-22-28 has any effect on mood, cognition, focus or anything else in humans.
• A human dose. The directions in use are a prescriber's translation from animal work.
• An effect size or a timeline in people.
• Safety in humans, or anything about long-term use.
• That it can replace or be combined with any antidepressant. Those interactions are unstudied.
• Efficacy for any condition as an approved treatment. It is not approved for anything.

In humans, unknown. Clinically, the commonest reports are injection-site redness, mild soreness or bruising, and occasionally a headache in the first days. Anyone on serotonin-affecting medication, anyone with diabetes, because cell work described the parent peptide increasing insulin secretion (Journal of Diabetes Research, 2016), and anyone with a seizure history should discuss it specifically. It is not used in pregnancy or breastfeeding. Any mood change that worries you goes to your physician promptly; thoughts of harming yourself are an emergency: call or text 988, or call 911.

PE-22-28 does not appear in Category 1, 2 or 3 of the FDA's 503A nominated-substances document updated 14 May 2026, is not on the significant-safety-risk page, is not on the 503A bulks list at 21 CFR 216.23, and was not on the July 2026 Pharmacy Compounding Advisory Committee agenda. It has not been through the process at all. Compounded medications are not FDA approved.

Selank and Semax have small Russian human studies behind them, which PE-22-28 does not; they are the more established conversation for stress and focus. Your physician sets your directions after reviewing your intake, and they are printed on the vial. The arithmetic is in PE-22-28 dosage.

Every price is all-in, covering medication, physician review, refill management and shipping, with no membership fee. Pepti is cash-pay and does not bill insurance. Vials ship refrigerated with ice packs, ready to use, with sterile syringes and alcohol prep pads. Refills run every 28 days, one vial per fill.

1. Complete a free online intake covering your history, every medication you take, and any mood diagnosis.
2. A physician licensed in your state reviews it, usually within 24 hours.
3. If it is appropriate, a PCAB-accredited, FDA-registered US 503A compounding pharmacy prepares it to that prescription. Lot test results are published at /quality/lab-results.
4. It ships refrigerated with your directions printed on the vial.
5. Your care team stays reachable for questions and side effects.

Step by step: how to get PE-22-28 prescribed online. Bloodwork is not required for any Pepti treatment. If your physician wants labs for your care, they'll ask through your account.