PE-22-28
A synthetic humanin-derived peptide investigated in rodent models for antidepressant-like effects via glial glutamate transporter (GLT-1/EAAT2) upregulation.
PE-22-28 is a synthetic seven-amino-acid peptide designed as a short analog of the mitochondrial-derived peptide Humanin, retaining cytoprotective signaling while simplifying the structure. Its proposed mechanism centers on upregulating glutamate transporter 1 (GLT-1/EAAT2) in astrocytes, connecting it to contemporary glutamatergic models of depression. As of 2026 it remains a preclinical research peptide with no published human clinical trials, and all human use is uncontrolled self-experimentation.
Class
Synthetic humanin-analog heptapeptide
Half-life
Not published in humans; as a small peptide, plasma half-life is expected to be short (minutes to a few hours) after subcutaneous administration.
Routes
Subcutaneous injection (community self-administration), Intranasal (research doses)
Category
Cognitive & Nootropic
Researched benefits
What it's studied for
Antidepressant-like activity (preclinical)
Preclinical rodent studies suggested antidepressant-like effects in depression-relevant behavioral paradigms, which is the primary basis for interest in the compound. Efficacy has not been demonstrated in humans.
Glutamate transporter (GLT-1/EAAT2) upregulation
The peptide is reported to increase expression or function of glial glutamate transporter 1, the principal astrocytic transporter that clears synaptic glutamate. GLT-1 dysfunction is implicated in depression, epilepsy, and neurodegeneration, giving a mechanistically coherent antidepressant rationale.
Neuroprotective / cytoprotective signaling
By virtue of its humanin-family origin, PE-22-28 is proposed to engage the humanin receptor complex and downstream STAT3 activation, which in humanin produces reduced neuronal apoptosis, improved mitochondrial function under stress, and anti-inflammatory effects. Direct PE-22-28-specific evidence for these effects is limited.
Support of astrocyte homeostatic function
Beyond glutamate transport, the mechanism implicates broader astrocyte support (potassium and water homeostasis, synaptic plasticity support), functions increasingly recognized as relevant to depression and neuropsychiatric disorders.
Anti-neuroinflammatory potential
Humanin and its analogs show anti-inflammatory activity in multiple preclinical models; chronic low-grade neuroinflammation is implicated in both depression and neurodegenerative disease. PE-22-28 is expected to share this activity, though it has not been directly demonstrated for this analog.
Mechanism
How it works
PE-22-28's proposed mechanism derives from its relationship to Humanin, a 24-amino-acid mitochondrial-derived peptide with cytoprotective activity mediated through a receptor complex involving CNTFR-alpha, WSX-1, and gp130, which activates STAT3 signaling and sequesters Bax away from the mitochondrial outer membrane. Short humanin analogs, including S14G-humanin and various truncations, have been characterized to identify the minimal active sequence. PE-22-28 represents one such analog, retaining central humanin residues thought to contribute to receptor binding and cytoprotective signaling.
The mechanism that most distinguishes PE-22-28 in published work is regulation of glutamate transporter 1 (GLT-1, encoded by SLC1A2; EAAT2 in humans), the principal glial transporter that clears synaptically released glutamate. GLT-1 dysfunction has been implicated in depression, epilepsy, neurodegeneration, and ischemic injury. Preclinical work reports that PE-22-28 increases GLT-1 expression or function, improving glutamate homeostasis in ways that could underlie the antidepressant-like effects observed in rodent assays.
The link between glutamate homeostasis and depression is well established: the rapid antidepressant effect of ketamine (an NMDA antagonist), postmortem alterations in glial glutamate transporters in depressed patients, antidepressant activity of riluzole (a glutamate modulator), and chronic-stress models showing reduced GLT-1 function all support a causal role for glutamatergic signaling. A compound that selectively increases GLT-1 function therefore has a coherent antidepressant rationale bridging classical monoamine and contemporary glutamatergic models. Additional humanin-derived effects on neuronal apoptosis, mitochondrial function, and neuroinflammation may contribute.
Important limitations apply. Binding affinities, target selectivity, and dose-response for PE-22-28 have not been characterized as thoroughly as for mature drug candidates. Translating a small peptide from peripheral administration to CNS effects requires blood-brain barrier penetration that is not well characterized. The behavioral data rest on a small number of studies that have not been extensively replicated, and assuming the analog fully recapitulates humanin biology is a mechanistic leap rather than an established fact. 'Proposed mechanism' remains a weaker claim than 'demonstrated mechanism.'
Dosing protocols
Dosing & administration
Dosing reflects protocols reported in research and community literature for educational purposes. It is not medical advice or a recommendation. Most peptides here are not approved for human use.
Reconstitution
Supplied as a lyophilized white-to-off-white powder in a sealed glass vial, typically 2 mg or 5 mg. Bring the vial to room temperature (10-15 minutes on the counter; do not heat). Bacteriostatic water (0.9% benzyl alcohol, USP) is the preferred diluent as its preservative extends reconstituted shelf life. A common reconstitution for a 5 mg vial is 2 mL of bacteriostatic water, yielding 2.5 mg/mL (2500 mcg/mL) so a 500 mcg dose is 0.2 mL (20 units on a U-100 insulin syringe). A 2 mg vial in 2 mL yields 1 mg/mL (1000 mcg/mL), making 500 mcg a 0.5 mL dose (50 units). Inject the water slowly down the vial wall, swirl gently (do not shake), inspect for clarity and particulates, label with the date, and refrigerate. Reconstituted solution is typically stable 2-4 weeks refrigerated; discard if cloudy, discolored, or particulate.
Beginner
- Dose
- 250-500 mcg per injection (start at 250 mcg)
- Frequency
- Daily or every other day
- Timing
- Typically morning; some shift to afternoon/evening if they notice subjective sedation
- Duration
- 4-6 week cycles, followed by a 2-4 week break
- Route
- Subcutaneous (28-31 gauge insulin syringe, into abdomen, thigh, or upper arm)
Hold the starting dose for at least 2-3 weeks before any titration. Track mood/cognition with standardized scales (PHQ-9, GAD-7, cognitive assessments). Not an adequate approach to clinical depression, which warrants professional care.
Intermediate
- Dose
- 500-1000 mcg per injection
- Frequency
- Daily or every other day
- Timing
- Typically morning
- Duration
- 6-8 week cycles with 2-4 week off-periods
- Route
- Subcutaneous
For users who have completed one or two beginner cycles with documented tracking. Higher doses assume beginner doses may be subtherapeutic; this is empirically driven, not clinically validated. If stacking, add one compound at a time to preserve attribution.
Advanced
- Dose
- 1000-2000 mcg per injection
- Frequency
- Daily or every other day
- Timing
- Typically morning
- Duration
- 8-12 week cycles with 4-week off-periods
- Route
- Subcutaneous
For experienced self-experimenters integrating PE-22-28 into comprehensive neuropsychiatric stacks. No published evidence that higher doses produce proportionally better outcomes; advanced ranges mainly increase cumulative exposure and cost. Requires extensive monitoring and clinical infrastructure.
- The most commonly reported community dose is 500 mcg once daily or every other day subcutaneously. All dosing is extrapolated from rodent studies and self-report community patterns, not validated clinical data.
- At a glance, vendor-listed research doses are cited as 10-50 mcg intranasal; the self-experimentation community overwhelmingly uses far higher subcutaneous doses (250-2000 mcg). These reflect different routes and unvalidated conventions.
- Subcutaneous is the safest and most-used self-administration route. Oral administration would not work (GI degradation). PE-22-28 is not formulated for reliable sublingual or intranasal delivery.
- Human pharmacokinetics, tissue distribution, and blood-brain barrier penetration are not published, which is why dosing remains empirical rather than principle-based.
- Store lyophilized powder frozen in the sealed vial; use reconstituted peptide within 2-4 weeks refrigerated. Verify unit-to-mcg arithmetic before every injection to avoid dramatic dosing errors.
- Cycle off rather than dose continuously; use standardized tracking and a clear stop rule if the compound produces no detectable benefit or any adverse effect.
Combinations
Stacking & blends
Neuropsychiatric mood-and-cognition stack
Broader mood, anxiolytic, and cognitive/neuroprotective coverage
Intermediate and advanced users commonly pair PE-22-28 with Selank (anxiolytic) and Semax (cognitive/neuroprotective) to combine glutamatergic support with complementary neuropsychiatric peptides. Each added compound introduces attribution loss and risk stacking.
Nootropic synergy pairing
Cognitive enhancement and neuroprotection
Interaction data lists Semax and Noopept as synergistic and P-21 as compatible with PE-22-28, supporting their use together in nootropic protocols.
Advanced cytoprotective / longevity stack
Comprehensive neuroprotective, neurotrophic, and tissue-repair support
Advanced self-experimenters integrate PE-22-28 into broad stacks adding neurotrophic (Cerebrolysin, Dihexa), longevity (Epithalon), and repair (BPC-157, TB-500) agents. These combinations have essentially no clinical validation and make attribution of effects to any single compound impossible.
Safety
Side effects & considerations
Commonly reported effects
Contraindications & cautions
- Pregnancy and breastfeeding (absolute); discontinue 2-4 weeks before attempting conception
- Children and adolescents (glutamatergic signaling is critical to brain maturation)
- Active severe psychiatric illness (major depression with suicidality, active psychosis, severe bipolar or anxiety disorders) without professional supervision
- Bipolar spectrum disorders (theoretical risk of inducing mania/mood cycling) without psychiatric supervision
- Seizure disorders / epilepsy without neurologist consultation (glutamate transporter modulation may affect seizure threshold)
- Active cancer, particularly brain tumors, without oncology consultation
- Recent head injury or stroke (avoid at least 3-6 months, per neurology)
- Concurrent ketamine therapy or NMDA antagonists (memantine, dextromethorphan at high doses)
- Concurrent mood stabilizers (lithium, valproate), SSRIs/SNRIs, and especially MAOIs without prescriber supervision
- Known hypersensitivity to peptide products or preparation components (including bacteriostatic water preservative)
Documented side effects are limited because no clinical trials have been conducted; all reports are anecdotal. The most important practical contraindication is the absence of clinical infrastructure for safe self-experimentation with a CNS-targeted compound for a psychiatric indication. Users should maintain ongoing mental-health care, must not substitute PE-22-28 for established treatments, and should have a plan to escalate care if symptoms worsen. Long-term safety is unknown; conservative use cycles on and off rather than dosing continuously.
FAQ
PE-22-28 — common questions
What is PE-22-28 and how is it related to humanin?
PE-22-28 is a synthetic 7-amino-acid peptide derived from the parent mitochondrial-derived peptide Humanin, representing residues 22-28 of an extended humanin-family sequence. It was developed as an analog retaining cytoprotective signaling while simplifying the structure, and has been investigated primarily for antidepressant-like effects in rodent models via glial glutamate transporter 1 (GLT-1/EAAT2) upregulation.
Has PE-22-28 been tested in humans?
No. As of 2026, no Phase 1 or later clinical trials have been published, no IND applications have been publicly disclosed, and no registered trials appear on ClinicalTrials.gov. All human use is self-experimentation with research-chemical vendor supply; the evidence base is entirely preclinical.
How does PE-22-28 work for depression?
The proposed mechanism is upregulation of glutamate transporter 1 (GLT-1) in astrocytes, which clears synaptically released glutamate. GLT-1 dysfunction is implicated in depression, so enhancing its function could improve glutamate homeostasis in mood-relevant brain regions. The mechanism is plausible and connects to contemporary glutamatergic models of depression, but clinical efficacy has not been demonstrated in humans.
What dose of PE-22-28 is typically used?
Community doses range from about 250-2000 mcg per subcutaneous injection, with 500 mcg once daily or every other day being a common starting point. Beginners typically use 250-500 mcg daily for 4-6 week cycles, intermediate users 500-1000 mcg for 6-8 weeks, and advanced users up to 1000-2000 mcg. These are empirical extrapolations from rodent studies with no clinical validation.
How long before PE-22-28 effects are noticeable?
Community reports describe onset over days to weeks of daily dosing, consistent with a proposed transcriptional GLT-1 upregulation mechanism rather than acute receptor signaling. Response timing is variable, some notice effects within a week, others need several weeks, and some report no effect at all, suggesting effects, if present, are gradual.
What are the main side effects?
Because no clinical trials exist, documented side effects are limited to anecdote: occasional headaches, mild fatigue or sedation, injection-site reactions, and rare emotional sensitivity or anxiety. Paradoxical mood worsening is possible with any mood-modulating compound, and pyrogen contamination in research-chemical supply can cause flu-like symptoms that may be misattributed to the peptide.
Can I combine PE-22-28 with my antidepressant medication?
Any combination with prescription antidepressants should be discussed with the prescribing physician first. Theoretical interactions exist with SSRIs, SNRIs, and other antidepressants. You should not substitute PE-22-28 for prescribed medication, should not discontinue prescribed medication to use it, and should maintain regular psychiatric follow-up.
Can PE-22-28 be used for anxiety, not just depression?
Preclinical studies focused on depression-relevant paradigms, but the proposed glutamatergic mechanism has theoretical relevance to anxiety given the role of glutamate in fear circuitry. Community use includes anxiety as a target with mixed reports, but no controlled data exist for anxiety specifically. People with significant anxiety disorders should pursue evidence-based treatment alongside any experimental peptide use.
