What Is PE-22-28? Definition and What Research Reports
PE-22-28 is the name given to a short synthetic peptide described in the literature as a shortened analogue of spadin, a sortilin-propeptide fragment investigated as a blocker of the TREK-1 two-pore-domain potassium channel. It is a research chemical, not an approved medicine, and most published evidence concerns the TREK-1 target rather than this specific sequence. Studies of TREK-1 blockade have reported antidepressant-like effects in rodent models and roles for the channel in pain, pressure sensing, cartilage and fat cells.
Plain definition
PE-22-28 is the laboratory name of a short synthetic peptide that scientists have studied because of the way it interacts with a potassium channel called TREK-1. Potassium channels are pores in the outer membrane of cells that let potassium ions leave, which makes a nerve cell harder to excite. TREK-1 is one of these pores, and it is unusually abundant in brain regions linked to mood. The idea behind peptides in this family is simple to state: if TREK-1 is closed, neurons in those regions become somewhat easier to activate, and that has been proposed as a route to antidepressant-like activity. PE-22-28 is discussed in the research literature as a shortened version of an earlier peptide, spadin, and it is not an approved drug anywhere. This page is for educational purposes only and is not medical advice; consult a licensed physician about any health question.
PE-22-28 in biochemical terms
The lineage of the term matters more than the string of letters. Spadin is a peptide fragment derived from the propeptide released when sortilin (also called neurotensin receptor 3, NTSR3) is matured inside the cell. Researchers identified this fragment as an endogenous-derived blocker of TREK-1 and then produced shorter, more stable analogues of it; PE-22-28 is the name used in the literature for one of those shortened analogues. A comprehensive review of TREK-1 blockers with a focus on spadin summarised this line of work and framed TREK-1 antagonism as a strategy under investigation for depression (PMID 30291907).
Where TREK-1 sits in cell biology
TREK-1 belongs to the two-pore-domain potassium (K2P) channel family. These channels are described as "leak" channels because they can pass current across a wide voltage range, and TREK-1 in particular responds to mechanical stretch, temperature, lipids and intracellular signalling. Researchers reported that PKC- and PKA-dependent phosphorylation modulated TREK-1 function in naïve and neuropathic rats, which illustrates that the channel is regulated, not simply open or shut (PMID 33006141). The channel also does not always act alone: one study reported that TREK-1 and TREK-2 subunits formed functional heterodimers with properties distinct from either homodimer (PMID 27129242), and another described blockers developed against TWIK-1/TREK-1 heterodimers as potential antidepressants (PMID 37454597). Any claim about "blocking TREK-1" is therefore a claim about a family of channel assemblies rather than a single uniform target.
Regulatory status of the term
PE-22-28 has no marketing approval as a medicine in the United States, the European Union or elsewhere, and it is not an ingredient recognised for use in dietary supplements. Material sold under this name is typically labelled research-use-only (RUO), a designation that describes laboratory materials not intended for diagnostic or therapeutic application in humans or animals. Because the name is not attached to an approved product, there is no official monograph, no standardised purity specification and no regulator-reviewed safety file associated with it. PeptideU does not sell peptides and offers no sourcing information; the point here is purely definitional.
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Try it freeHow the term is used in peptide research
In scientific writing, the term appears mainly in three ways:
- As a named chemical tool. Investigators use TREK-1 blocking peptides to test whether a biological effect depends on TREK-1 activity, in the same way that other channel blockers are used as pharmacological probes.
- As a member of the spadin series. Papers discuss spadin and its shortened analogues together when reviewing structure–activity work on TREK-1 antagonism (PMID 30291907).
- As a comparator. Newer TREK-1 or heterodimer-directed blockers are often introduced against the background of the spadin series (PMID 37454597).
Where the term is misused
Several patterns of misuse recur online and are worth naming plainly, because they distort what the literature actually contains:
- Calling it an antidepressant. Antidepressant-like activity in rodent behavioural assays is a preclinical signal, not a demonstration of clinical efficacy in people. The review of TREK-1 blockers framed this work as a research programme with a past and a future, not a settled therapy (PMID 30291907).
- Attributing spadin data to PE-22-28 without distinction. Analogues differ in potency, stability and selectivity, and results obtained with one sequence do not automatically transfer to another.
- Describing it as a nootropic or "neurogenesis peptide". These marketing categories have no formal definition and are not how the channel literature describes the target.
- Confusing TREK-1 blockade with mechanosensitive channel blockade generally. A distinct spider-venom peptide, GsMTx4, was reported to inhibit the mechanosensitive channel Piezo1 (PMID 21696149); it is a different molecule acting on a different protein, even though both fields use the word "mechanosensitive".
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Get the appRelated terms
| Term | How the literature uses it |
|---|---|
| Spadin | Sortilin-propeptide-derived peptide studied as a TREK-1 blocker and the parent of shortened analogues (PMID 30291907) |
| TREK-1 (KCNK2) | Two-pore-domain potassium channel; the proposed molecular target |
| K2P channels | Channel family including TREK-1, TREK-2 and TWIK-1, which can form heterodimers (PMID 27129242) |
| Sortilin / NTSR3 | Receptor whose propeptide gives rise to the spadin sequence |
| GsMTx4 | Unrelated peptide reported to inhibit Piezo1, often confused with TREK-directed peptides (PMID 21696149) |
What the published literature reports
TREK-1 blockade and mood-related research
Work on TREK-1 as a depression target has been summarised in a dedicated review of TREK-1 blockers focused on spadin (PMID 30291907). Building on that framework, researchers described novel potent blockers of TWIK-1/TREK-1 heterodimers and characterised them as potential antidepressants (PMID 37454597). A separate study reported that TREK-1 inhibition promoted synaptic plasticity in the prelimbic cortex, a region implicated in mood and cognitive control (PMID 38103709). The target has also been connected to other antidepressant mechanisms: one report concluded that TREK-1 channel blockade mediated the antidepressant-like effects of hydroxynorketamine, a ketamine metabolite (PMID 41167417).
TREK-1 outside the brain
Because the channel is widely expressed, blocking it is not a brain-only proposition. Researchers reported that TREK-1 channels regulated pressure sensitivity and calcium signalling in trabecular meshwork cells of the eye (PMID 30446509), and that osmotically sensitive TREK channels were expressed and functionally active in rat articular chondrocytes (PMID 39063089). A 2025 study described a novel function for TREK-1 in regulating adipocyte differentiation and lipid accumulation (PMID 40057491). In the heart, circulating autoantibodies targeting TREK-1 were identified in patients with short-coupled ventricular fibrillation (PMID 39315453), a finding that links interference with this channel to a serious arrhythmia phenotype.
Other peptides that act on TREK-1
PE-22-28 is not the only peptide reported to engage this channel. A 2024 paper described a tick-derived peptide that blocked TREK-1, showing that distinct natural scaffolds can converge on the same pore (PMID 39125945). Comparisons across such tools are how selectivity claims are tested.
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Start learning freeSafety and Adverse Events: What Studies Report
No controlled human safety data for PE-22-28 appear in the verified literature summarised here, and no human adverse-event profile can be stated for it. What the published record does provide is target-level context: because TREK-1 is expressed in the eye, cartilage, adipose tissue and cardiac tissue, effects of channel blockade would not be expected to remain confined to mood circuits (PMID 30446509, PMID 40057491). The identification of anti-TREK-1 autoantibodies in patients with short-coupled ventricular fibrillation is the clearest published example of a clinical phenotype associated with interference with this channel (PMID 39315453). These are observations about the target, not measured adverse events for the peptide, and they should be read as such.
References
- Fighting against depression with TREK-1 blockers: Past and future. A focus on spadin (Pharmacology & Therapeutics, 2019)
- Novel potent blockers for TWIK-1/TREK-1 heterodimers as potential antidepressants (Biomedicine & Pharmacotherapy, 2023)
- TREK-1 inhibition promotes synaptic plasticity in the prelimbic cortex (Experimental Neurology, 2024)
- TREK-1 channel blockade mediates the antidepressant-like effects of hydroxynorketamine (Neuropharmacology, 2026)
- PKC- and PKA-dependent phosphorylation modulates TREK-1 function in naïve and neuropathic rats (Journal of Neurochemistry, 2021)
- Formation of Functional Heterodimers by TREK-1 and TREK-2 Two-pore Domain Potassium Channel Subunits (Journal of Biological Chemistry, 2016)
- TREK-1 channels regulate pressure sensitivity and calcium signaling in trabecular meshwork cells (Journal of General Physiology, 2018)
- Osmotically Sensitive TREK Channels in Rat Articular Chondrocytes: Expression and Functional Role (International Journal of Molecular Sciences, 2024)
- Novel function of TREK-1 in regulating adipocyte differentiation and lipid accumulation (Cell Death & Disease, 2025)
- Circulating Autoantibodies Targeting TREK-1 in Patients With Short-Coupled Ventricular Fibrillation (Circulation, 2024)
- Tick-Derived Peptide Blocks Potassium Channel TREK-1 (International Journal of Molecular Sciences, 2024)
- The mechanosensitive ion channel Piezo1 is inhibited by the peptide GsMTx4 (Biochemistry, 2011)
Frequently asked questions
What does PE-22-28 mean in one sentence?▾
PE-22-28 is the research name for a short synthetic peptide described in the literature as a shortened analogue of spadin, a sortilin-propeptide fragment investigated as a blocker of the TREK-1 potassium channel. A review of TREK-1 blockers focused on spadin summarised this line of research and framed TREK-1 antagonism as an investigational strategy for depression (PMID 30291907).
What is TREK-1 and why does it matter here?▾
TREK-1 is a two-pore-domain potassium channel that helps set how easily neurons fire. Researchers reported that TREK-1 inhibition promoted synaptic plasticity in the prelimbic cortex (PMID 38103709) and that TREK-1 blockade mediated the antidepressant-like effects of hydroxynorketamine (PMID 41167417). The channel can also assemble with TREK-2 into functional heterodimers (PMID 27129242).
Is PE-22-28 an approved medicine?▾
No. PE-22-28 has no marketing approval as a drug and is not a recognised supplement ingredient; material bearing the name is typically labelled research-use-only. The published work in this area concerns the TREK-1 target and related blockers, including compounds directed at TWIK-1/TREK-1 heterodimers described as potential antidepressants (PMID 37454597), rather than an approved product.
How is the term commonly misused?▾
It is misused when preclinical, rodent-level antidepressant-like signals are described as clinical efficacy, when spadin data are attributed to analogues without distinction, and when TREK-1 blockade is conflated with mechanosensitive channel blockade in general. GsMTx4, for example, was reported to inhibit Piezo1, a different channel entirely (PMID 21696149).
Does TREK-1 act only in the brain?▾
No. Researchers reported that TREK-1 regulated pressure sensitivity and calcium signalling in trabecular meshwork cells of the eye (PMID 30446509), that osmotically sensitive TREK channels were functional in rat articular chondrocytes (PMID 39063089), and that TREK-1 influenced adipocyte differentiation and lipid accumulation (PMID 40057491). The target is therefore broadly distributed.
What do studies report about safety related to this target?▾
No controlled human safety data for PE-22-28 appear in the verified literature. At the target level, one study identified circulating autoantibodies against TREK-1 in patients with short-coupled ventricular fibrillation (PMID 39315453), and other work showed TREK-1 function is modulated by PKC- and PKA-dependent phosphorylation in naïve and neuropathic rats (PMID 33006141). These are target observations, not peptide adverse-event data.
Are other peptides known to block TREK-1?▾
Yes. A 2024 study described a tick-derived peptide that blocked the TREK-1 channel, showing that unrelated natural scaffolds can converge on the same pore (PMID 39125945). Separately, researchers characterised synthetic blockers of TWIK-1/TREK-1 heterodimers as potential antidepressants (PMID 37454597). Comparing such tools is how selectivity claims are tested in the literature.
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References
This page summarises published research for education — it is not medical advice, and nothing here is a recommendation to use, purchase, or dose any substance. Study parameters described are what researchers reported, not instructions. Consult a qualified clinician before any health decision.