Mechanism

How it works

PE-22-28 acts as a selective inhibitor of the TREK-1 (TWIK-related K+ channel 1) two-pore domain potassium channel, which plays a major role in regulating neuronal excitability and serotonergic tone. By blocking TREK-1, PE-22-28 increases serotonin availability at synapses in limbic and prefrontal regions, mimicking the antidepressant effects observed in TREK-1 knockout mice. This mechanism is distinct from SSRIs and monoamine oxidase inhibitors, as it targets upstream potassium channel regulation rather than serotonin reuptake transporters directly.

Reported in research

Benefits

Rapid antidepressant-like effects observed within days in preclinical models
Potential for addressing treatment-resistant depression through a novel TREK-1 mechanism
Possible anxiolytic (anti-anxiety) properties complementing mood stabilization
May enhance cognitive function and neuroplasticity via serotonergic modulation

Context, not a prescription

Dosing

Typical range: 1–3 mg/kg in animal studies; human dosing protocols not established — research use only (Subcutaneous, Intramuscular)
Cycle length: 4–8 weeks (research context only)
Half-life: ~2–4 hours (estimated, limited data)

Safety

Side effects & contraindications

Possible side effects

Potential sedation or drowsiness at higher doses
Possible mild gastrointestinal discomfort
Risk of serotonin dysregulation if combined with serotonergic drugs
Unknown long-term side effects in humans

Contraindications

Concurrent use with SSRIs, SNRIs, or MAOIs due to risk of serotonin syndrome
Pregnancy or breastfeeding (no safety data available)
History of bipolar disorder or mania (serotonergic agents can trigger manic episodes)
Individuals on anticoagulants or CNS-active medications without medical supervision

Research information, not medical advice. Always consult a licensed clinician before considering any peptide.

In depth

Full profile

What it does

In research models, subjects showed reduced depression-like behavior, improved stress resilience, and better responses to rewarding stimuli. Human equivalents have not yet been established.

How it works

Imagine your brain's mood center is like a city water supply. TREK-1 channels are valves that, when open, drain away water (serotonin). PE-22-28 is like closing those drains so the water level — and your mood — stays higher.

After injection, PE-22-28 crosses into the brain and binds to TREK-1 channels in mood-regulating areas. This boosts serotonin activity without directly flooding the system the way many antidepressants do, which may mean a gentler profile and faster onset.

What to expect

Animal studies suggest effects within 24–72 hours of initial dosing, which is notably faster than the 2–6 week onset typical of SSRIs.

Days 1–3: Peptide begins interacting with TREK-1 channels; some animal models show early mood-related changes within this window.
Weeks 1–2: Preclinical data suggests more consistent antidepressant-like effects; serotonin tone in key brain regions may be elevated.
Weeks 4–8: Continued research dosing in animal models shows sustained behavioral improvements; long-term neuroplasticity changes are hypothesized but not confirmed in humans.

Good to know

Never combine with other serotonergic substances without professional guidance
Start at the lowest possible research dose and monitor for any adverse reactions

Staying safe

Possible tiredness or sedation, especially at higher doses
Mild stomach discomfort around the injection site or systemically

Avoid if you have:

Anyone currently taking antidepressants (SSRIs, SNRIs, MAOIs)
Pregnant or breastfeeding individuals
Those with a history of bipolar disorder or manic episodes

Overview

Documented preclinical changes include: reduced immobility in forced swim and tail suspension tests, increased sucrose preference (anhedonia reversal), normalized corticosterone levels under chronic mild stress, increased hippocampal BDNF mRNA, and dendritic spine remodeling in CA1 and prefrontal cortex. Cognitive improvements in spatial memory tasks have also been reported in aged rodent models.

How it works

TREK-1 functions like a dimmer switch on serotonergic neurons in the raphe; its constitutive activity keeps neuronal firing subdued. PE-22-28 acts as a wedge holding the dimmer at a higher setting, allowing downstream limbic and cortical circuits to receive more tonic serotonergic input — analogous to removing an inhibitory brake rather than simply stepping on the serotonin accelerator.

Following systemic administration, PE-22-28 must cross the blood-brain barrier — its shorter peptide sequence relative to full-length spadin improves CNS penetration. It binds TREK-1 channels in their extracellular domain, stabilizing the closed-channel conformation. This leads to increased dorsal raphe nucleus firing rates, elevation of hippocampal extracellular 5-HT, and downstream increases in BDNF via TrkB/CREB signaling. TREK-1 inhibition also has reported effects on HPA axis regulation, potentially reducing corticosterone hypersecretion under stress.

Onset & timeline

In rodent models (forced swim test, novelty-suppressed feeding), antidepressant-like effects are detectable within 24–72 hours of first administration — significantly faster than the delayed response of SSRIs (requiring chronic treatment for full effect). This rapid onset is consistent with direct ion channel pharmacology rather than neuroadaptive remodeling.

Days 1–3: Acute TREK-1 blockade initiated; peak plasma concentrations reached within 1–2 hours post-injection. Rapid depolarization of raphe serotonergic neurons begins, with measurable increases in extracellular 5-HT in hippocampus and frontal cortex in rodent microdialysis studies.
Weeks 1–2: Sustained TREK-1 inhibition drives cumulative upregulation of BDNF/TrkB signaling; early synaptic remodeling in prefrontal-limbic circuits; behavioral normalization in animal stress models becomes robust and reproducible.
Weeks 2–8: Hypothesized neuroplastic consolidation phase — dendritic arborization and hippocampal neurogenesis changes analogous to those seen after chronic antidepressant treatment, but potentially accelerated. No long-term human data. Washout pharmacokinetics and receptor adaptation upon discontinuation are unstudied.

Getting the most from it

Avoid co-administration with SSRIs, SNRIs, TCAs, MAOIs, triptans, lithium, or any agent affecting serotonin metabolism
Implement cardiac monitoring (ECG baseline) in prolonged research protocols given TREK-1 cardiac expression
Use the minimum effective dose derived from body-weight scaling of published animal studies; avoid extrapolating mg/kg doses linearly to humans without allometric correction

Common side effects

Dose-dependent sedation secondary to altered K+ channel activity in non-serotonergic neurons
Potential serotonin syndrome risk with concurrent serotonergic agents (mechanistically predictable)

Mechanism of action

PE-22-28 is a truncated analog of spadin (a 17-amino acid peptide derived from the propeptide of sortilin/neurotensin), optimized for improved TREK-1 channel affinity and membrane permeability. TREK-1 (KCNK2) is a two-pore domain background K+ channel expressed highly in the raphe nuclei, hippocampus, and prefrontal cortex. Its activation hyperpolarizes serotonergic neurons, suppressing 5-HT firing. PE-22-28 blocks this channel, thereby depolarizing these neurons, increasing action potential frequency, and elevating synaptic serotonin. Additionally, TREK-1 inhibition appears to activate downstream MAPK/ERK and CREB signaling pathways, promoting BDNF expression and synaptic plasticity in hippocampal circuits — a mechanism convergent with, but pharmacologically distinct from, classic antidepressant mechanisms.

Following systemic administration, PE-22-28 must cross the blood-brain barrier — its shorter peptide sequence relative to full-length spadin improves CNS penetration. It binds TREK-1 channels in their extracellular domain, stabilizing the closed-channel conformation. This leads to increased dorsal raphe nucleus firing rates, elevation of hippocampal extracellular 5-HT, and downstream increases in BDNF via TrkB/CREB signaling. TREK-1 inhibition also has reported effects on HPA axis regulation, potentially reducing corticosterone hypersecretion under stress.

Pharmacodynamics

In rodent models (forced swim test, novelty-suppressed feeding), antidepressant-like effects are detectable within 24–72 hours of first administration — significantly faster than the delayed response of SSRIs (requiring chronic treatment for full effect). This rapid onset is consistent with direct ion channel pharmacology rather than neuroadaptive remodeling.

Documented preclinical changes include: reduced immobility in forced swim and tail suspension tests, increased sucrose preference (anhedonia reversal), normalized corticosterone levels under chronic mild stress, increased hippocampal BDNF mRNA, and dendritic spine remodeling in CA1 and prefrontal cortex. Cognitive improvements in spatial memory tasks have also been reported in aged rodent models.

Timeline

Days 1–3: Acute TREK-1 blockade initiated; peak plasma concentrations reached within 1–2 hours post-injection. Rapid depolarization of raphe serotonergic neurons begins, with measurable increases in extracellular 5-HT in hippocampus and frontal cortex in rodent microdialysis studies.
Weeks 1–2: Sustained TREK-1 inhibition drives cumulative upregulation of BDNF/TrkB signaling; early synaptic remodeling in prefrontal-limbic circuits; behavioral normalization in animal stress models becomes robust and reproducible.
Weeks 2–8: Hypothesized neuroplastic consolidation phase — dendritic arborization and hippocampal neurogenesis changes analogous to those seen after chronic antidepressant treatment, but potentially accelerated. No long-term human data. Washout pharmacokinetics and receptor adaptation upon discontinuation are unstudied.

Comparisons

PE-22-28 — effectiveness Moderate, safety Moderate, cost $$, Medium to use
Selank — effectiveness Moderate, safety Good, cost $$, Medium to use
Semax — effectiveness High, safety Good, cost $$, Medium to use

Adverse effects

Common:

Dose-dependent sedation secondary to altered K+ channel activity in non-serotonergic neurons
Potential serotonin syndrome risk with concurrent serotonergic agents (mechanistically predictable)

Rare:

Possible dysregulation of cardiac rhythm at supratherapeutic doses — TREK-1 is also expressed in cardiomyocytes; incidence in animal studies not well characterized

Contraindications & risk mitigation

Contraindicated in:

Individuals with 5-HTTLPR polymorphisms or known serotonin transporter abnormalities — unpredictable serotonergic amplification possible
Patients with QT-prolongation risk or on cardiac medications — TREK-1 cardiac expression creates theoretical arrhythmia risk
Those with active manic or hypomanic states — serotonin elevation can destabilize mood cycling

Avoid co-administration with SSRIs, SNRIs, TCAs, MAOIs, triptans, lithium, or any agent affecting serotonin metabolism
Implement cardiac monitoring (ECG baseline) in prolonged research protocols given TREK-1 cardiac expression
Use the minimum effective dose derived from body-weight scaling of published animal studies; avoid extrapolating mg/kg doses linearly to humans without allometric correction

Qué hace

In research models, subjects showed reduced depression-like behavior, improved stress resilience, and better responses to rewarding stimuli. Human equivalents have not yet been established.

Cómo funciona

Imagine your brain's mood center is like a city water supply. TREK-1 channels are valves that, when open, drain away water (serotonin). PE-22-28 is like closing those drains so the water level — and your mood — stays higher.

After injection, PE-22-28 crosses into the brain and binds to TREK-1 channels in mood-regulating areas. This boosts serotonin activity without directly flooding the system the way many antidepressants do, which may mean a gentler profile and faster onset.

Qué esperar

Animal studies suggest effects within 24–72 hours of initial dosing, which is notably faster than the 2–6 week onset typical of SSRIs.

Days 1–3: Peptide begins interacting with TREK-1 channels; some animal models show early mood-related changes within this window.
Weeks 1–2: Preclinical data suggests more consistent antidepressant-like effects; serotonin tone in key brain regions may be elevated.
Weeks 4–8: Continued research dosing in animal models shows sustained behavioral improvements; long-term neuroplasticity changes are hypothesized but not confirmed in humans.

Bueno saber

Never combine with other serotonergic substances without professional guidance
Start at the lowest possible research dose and monitor for any adverse reactions

Manteniéndose seguro

Possible tiredness or sedation, especially at higher doses
Mild stomach discomfort around the injection site or systemically

Evitar si tienes:

Anyone currently taking antidepressants (SSRIs, SNRIs, MAOIs)
Pregnant or breastfeeding individuals
Those with a history of bipolar disorder or manic episodes

Descripción general

Documented preclinical changes include: reduced immobility in forced swim and tail suspension tests, increased sucrose preference (anhedonia reversal), normalized corticosterone levels under chronic mild stress, increased hippocampal BDNF mRNA, and dendritic spine remodeling in CA1 and prefrontal cortex. Cognitive improvements in spatial memory tasks have also been reported in aged rodent models.

Cómo funciona

TREK-1 functions like a dimmer switch on serotonergic neurons in the raphe; its constitutive activity keeps neuronal firing subdued. PE-22-28 acts as a wedge holding the dimmer at a higher setting, allowing downstream limbic and cortical circuits to receive more tonic serotonergic input — analogous to removing an inhibitory brake rather than simply stepping on the serotonin accelerator.

Following systemic administration, PE-22-28 must cross the blood-brain barrier — its shorter peptide sequence relative to full-length spadin improves CNS penetration. It binds TREK-1 channels in their extracellular domain, stabilizing the closed-channel conformation. This leads to increased dorsal raphe nucleus firing rates, elevation of hippocampal extracellular 5-HT, and downstream increases in BDNF via TrkB/CREB signaling. TREK-1 inhibition also has reported effects on HPA axis regulation, potentially reducing corticosterone hypersecretion under stress.

Inicio y cronología

In rodent models (forced swim test, novelty-suppressed feeding), antidepressant-like effects are detectable within 24–72 hours of first administration — significantly faster than the delayed response of SSRIs (requiring chronic treatment for full effect). This rapid onset is consistent with direct ion channel pharmacology rather than neuroadaptive remodeling.

Days 1–3: Acute TREK-1 blockade initiated; peak plasma concentrations reached within 1–2 hours post-injection. Rapid depolarization of raphe serotonergic neurons begins, with measurable increases in extracellular 5-HT in hippocampus and frontal cortex in rodent microdialysis studies.
Weeks 1–2: Sustained TREK-1 inhibition drives cumulative upregulation of BDNF/TrkB signaling; early synaptic remodeling in prefrontal-limbic circuits; behavioral normalization in animal stress models becomes robust and reproducible.
Weeks 2–8: Hypothesized neuroplastic consolidation phase — dendritic arborization and hippocampal neurogenesis changes analogous to those seen after chronic antidepressant treatment, but potentially accelerated. No long-term human data. Washout pharmacokinetics and receptor adaptation upon discontinuation are unstudied.

Cómo aprovecharlo al máximo

Avoid co-administration with SSRIs, SNRIs, TCAs, MAOIs, triptans, lithium, or any agent affecting serotonin metabolism
Implement cardiac monitoring (ECG baseline) in prolonged research protocols given TREK-1 cardiac expression
Use the minimum effective dose derived from body-weight scaling of published animal studies; avoid extrapolating mg/kg doses linearly to humans without allometric correction

Efectos secundarios comunes

Dose-dependent sedation secondary to altered K+ channel activity in non-serotonergic neurons
Potential serotonin syndrome risk with concurrent serotonergic agents (mechanistically predictable)

Mecanismo de acción

PE-22-28 is a truncated analog of spadin (a 17-amino acid peptide derived from the propeptide of sortilin/neurotensin), optimized for improved TREK-1 channel affinity and membrane permeability. TREK-1 (KCNK2) is a two-pore domain background K+ channel expressed highly in the raphe nuclei, hippocampus, and prefrontal cortex. Its activation hyperpolarizes serotonergic neurons, suppressing 5-HT firing. PE-22-28 blocks this channel, thereby depolarizing these neurons, increasing action potential frequency, and elevating synaptic serotonin. Additionally, TREK-1 inhibition appears to activate downstream MAPK/ERK and CREB signaling pathways, promoting BDNF expression and synaptic plasticity in hippocampal circuits — a mechanism convergent with, but pharmacologically distinct from, classic antidepressant mechanisms.

Following systemic administration, PE-22-28 must cross the blood-brain barrier — its shorter peptide sequence relative to full-length spadin improves CNS penetration. It binds TREK-1 channels in their extracellular domain, stabilizing the closed-channel conformation. This leads to increased dorsal raphe nucleus firing rates, elevation of hippocampal extracellular 5-HT, and downstream increases in BDNF via TrkB/CREB signaling. TREK-1 inhibition also has reported effects on HPA axis regulation, potentially reducing corticosterone hypersecretion under stress.

Farmacodinamia

In rodent models (forced swim test, novelty-suppressed feeding), antidepressant-like effects are detectable within 24–72 hours of first administration — significantly faster than the delayed response of SSRIs (requiring chronic treatment for full effect). This rapid onset is consistent with direct ion channel pharmacology rather than neuroadaptive remodeling.

Documented preclinical changes include: reduced immobility in forced swim and tail suspension tests, increased sucrose preference (anhedonia reversal), normalized corticosterone levels under chronic mild stress, increased hippocampal BDNF mRNA, and dendritic spine remodeling in CA1 and prefrontal cortex. Cognitive improvements in spatial memory tasks have also been reported in aged rodent models.

Cronología

Days 1–3: Acute TREK-1 blockade initiated; peak plasma concentrations reached within 1–2 hours post-injection. Rapid depolarization of raphe serotonergic neurons begins, with measurable increases in extracellular 5-HT in hippocampus and frontal cortex in rodent microdialysis studies.
Weeks 1–2: Sustained TREK-1 inhibition drives cumulative upregulation of BDNF/TrkB signaling; early synaptic remodeling in prefrontal-limbic circuits; behavioral normalization in animal stress models becomes robust and reproducible.
Weeks 2–8: Hypothesized neuroplastic consolidation phase — dendritic arborization and hippocampal neurogenesis changes analogous to those seen after chronic antidepressant treatment, but potentially accelerated. No long-term human data. Washout pharmacokinetics and receptor adaptation upon discontinuation are unstudied.

Comparaciones

PE-22-28 — efectividad Moderate, seguridad Moderate, costo $$, Medium de usar
Selank — efectividad Moderate, seguridad Good, costo $$, Medium de usar
Semax — efectividad High, seguridad Good, costo $$, Medium de usar

Efectos adversos

Comunes:

Dose-dependent sedation secondary to altered K+ channel activity in non-serotonergic neurons
Potential serotonin syndrome risk with concurrent serotonergic agents (mechanistically predictable)

Raros:

Possible dysregulation of cardiac rhythm at supratherapeutic doses — TREK-1 is also expressed in cardiomyocytes; incidence in animal studies not well characterized

Contraindicaciones y mitigación de riesgos

Contraindicado en:

Individuals with 5-HTTLPR polymorphisms or known serotonin transporter abnormalities — unpredictable serotonergic amplification possible
Patients with QT-prolongation risk or on cardiac medications — TREK-1 cardiac expression creates theoretical arrhythmia risk
Those with active manic or hypomanic states — serotonin elevation can destabilize mood cycling

Avoid co-administration with SSRIs, SNRIs, TCAs, MAOIs, triptans, lithium, or any agent affecting serotonin metabolism
Implement cardiac monitoring (ECG baseline) in prolonged research protocols given TREK-1 cardiac expression
Use the minimum effective dose derived from body-weight scaling of published animal studies; avoid extrapolating mg/kg doses linearly to humans without allometric correction

Reference data

Specifications

Molecular formula: C38H56N10O10S
Molecular weight: 849.0 g/mol (approximate)
Half-life: ~2–4 hours (estimated, limited data)
Route: Subcutaneous, Intramuscular
Cycle length: 4–8 weeks (research context only)
Storage: Lyophilized powder: store at -20°C, protected from light and moisture. Once reconstituted, refrigerate at 2–8°C and use within 7–14 days. Avoid repeated freeze-thaw cycles.
Legal status: Unscheduled research chemical in most jurisdictions; not approved by FDA, EMA, or equivalent regulatory bodies for human use. Legal to purchase for research purposes in the US, UK, EU, and Australia as of 2024.

FAQ

Common questions

How does PE-22-28 differ mechanistically from spadin?

Spadin is a 17-amino acid peptide derived from the propeptide of sortilin. PE-22-28 is a truncated fragment (residues 22–28 of the spadin sequence) that retains TREK-1 binding affinity but with improved metabolic stability and potentially enhanced BBB permeability due to its reduced size. Studies by Mazella et al. and colleagues demonstrated that this fragment preserves antidepressant-like activity in rodent models.

Is there a risk of tolerance or receptor downregulation with chronic use?

TREK-1 channel expression and gating kinetics under chronic pharmacological blockade have not been fully characterized. Unlike GPCRs, ion channels may exhibit different adaptive mechanisms; however, compensatory upregulation of TREK-1 or downstream serotonin receptor desensitization cannot be excluded with extended administration.

What is the human equivalent dose extrapolated from animal studies?

Using standard FDA allometric scaling (animal dose × Km factor), a rodent dose of 1–3 mg/kg in mice does not translate directly to human equivalents without PK/PD validation. Human studies have not been conducted, and any human dosing remains entirely speculative and outside the bounds of established research protocols.

What is the evidence level?

This compound is classified as Animal data. Most data comes from preclinical animal studies. Human clinical trial evidence is limited or absent.

Research

Research & sources

Animal data

Current evidence for PE-22-28 is rated as Animal data. Research is based primarily on animal models.

1. Spadin, a sortilin-derived peptide, targeting rodent TREK-1 channels: a new concept in the antidepressant drug design (2010) — PLoS Biology, Mazella J et al., doi:10.1371/journal.pbio.1000355
2. Antidepressant properties of the spadin peptide and its shorter analog PE-22-28 (2016) — Frontiers in Pharmacology, Djillani A et al.
3. TREK-1 is a heat-activated background K+ channel (2000) — EMBO Journal, Maingret F et al.
4. Deletion of the background potassium channel TREK-1 results in a depression-resistant phenotype (2006) — Nature Neuroscience, Heurteaux C et al.

Explore

Often discussed alongside

Selank · cognition Semax · cognition BPC-157 · healing Dihexa · cognition Cerebrolysin · cognition