Side-by-side · Research reference

PE 22-28vsPEG-MGF

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AAnimal-StrongHUMAN-REVIEWED16/47 cited

BAnimal-MechanisticHUMAN-REVIEWED2/69 cited

PE 22-28

TREK-1 Antagonist · Pre-Clinical

0.12 nMTREK-1 IC50Djillani 2017

7 AAPeptide lengthDjillani 2017

AnimalEvidence stage

IP · SQ · Once Daily (animal models)Djillani 2017 Pietri 2019

PEG-MGF

IGF-1Ec Splice Variant · PEGylated

~2 hrHalf-life (PEG)

~7 minNative MGF t½

IGF-1EcSplice variant

SQ · Research Protocol

01Mechanism of Action

Parameter

PE 22-28

PEG-MGF

Primary target

TREK-1 two-pore-domain potassium channelDjillani 2017 Ma 2020

IGF-1 receptor on muscle satellite cells and myocytes

Pathway

TREK-1 channel blockade → Neuronal membrane depolarisation → Enhanced hippocampal excitability → Increased neuroplasticity

IGF-1R → PI3K/Akt → mTOR activation → Satellite cell proliferation & myoblast fusion

Downstream effect

Antidepressant-like activity in forced swim test and tail suspension test; reduced A1-like reactive astrocyte activation; neuroprotection via NF-κB pathway modulationDjillani 2017 Cong 2023 Wu 2021

Satellite cell activation, muscle fiber repair, localized hypertrophy signaling

Feedback intact?

N/A — direct ion channel blockade; not receptor-mediated endocrine axis

Partially bypassed — does not require hepatic IGF-1 synthesis

Origin

Synthetic truncation of spadin (PE 12-28), itself derived from the sortilin propeptide C-terminus. Residues 22-28: Val-Val-Arg-Gly-Trp-Leu-Arg.Djillani 2017 Mazella 2018

IGF-1Ec splice variant (exon 4–6) conjugated to polyethylene glycol for extended circulation

Antibody development

Not reported in animal studies

Unknown — no long-term human immunogenicity data

02Dosage Protocols

Parameter

PE 22-28

PEG-MGF

Animal dose (antidepressant)

0.3–3 µg/kg IP

Effective in forced swim test, tail suspension test, CUMS models.

—

Animal dose (neuroprotection)

0.03 µg/kg IPPietri 2019

Low-dose TREK-1 activation post-stroke for 7 days, then high-dose blockade.

—

Frequency

Once daily

Sustained antidepressant effect over 7+ days.

Post-training or daily

Timing to match endogenous MGF pulse post-exercise.

Onset (animal)

Within hours (acute); full effect 4–7 days

—

Duration (animal)

7–28 days testedQi 2018 Pietri 2019

—

Comparison to fluoxetine

PE 22-28 outperforms fluoxetine in CUMS-sensitive rats by day 7

Chronic administration shows superior long-term efficacy.

—

Human equivalent (extrapolated)

Not established — no clinical trials

Allometric scaling from rodent data unavailable.

—

Evidence basis

Multiple rodent RCTs; behavioral + electrophysiology endpointsDjillani 2017 Qi 2018 Wu 2021

Animal / mechanistic

Research dose range

—

100–200 mcg

Extrapolated from animal models; no validated human protocols.

Half-life

—

~2 hours (PEGylated)

Native MGF: ~7 min; PEGylation extends circulation.

Reconstitution

—

Sterile bacteriostatic water

Lyophilized form; store reconstituted at 2–8 °C.

PEG molecular weight

—

Typically 5–30 kDa

Higher MW = longer t½, greater steric hindrance.

Timing

—

Within 30–60 min post-training

Aligns with endogenous MGF window.

03Metabolic / Fat Loss Evidence

Parameter

PE 22-28

PEG-MGF

Primary target

—

Muscle tissue (satellite cells, myocytes) — not adipose-specific

Indirect metabolic effect

—

IGF-1 signaling may modulate insulin sensitivity and lipid metabolismRen 2015

Mechanism distinct from direct lipolytic peptides.

Body composition

—

Lean mass preservation / hypertrophy focus

Fat loss evidence

—

No direct human or animal RCT data for PEG-MGF-driven fat reduction

04Side Effects & Safety

Parameter

PE 22-28

PEG-MGF

Toxicity (animal)

No adverse effects reported at therapeutic doses

—

Cardiovascular (theoretical)

TREK-1 expressed in cardiac tissue; arrhythmia risk unclear

—

Weight change

Not reported in animal studies

—

Neurological

No seizures or behavioral abnormalities noted

—

Long-term safety

Unknown — longest animal study 28 days

—

Injection site reaction

—

Erythema, induration (common with SQ peptides)

Hypoglycemia risk

—

IGF-1 axis activation can lower blood glucose

IGF-1R overstimulation

—

Theoretical risk of aberrant cell proliferation with chronic supraphysiological exposure

Fluid retention

—

Possible with IGF-1 pathway activation (dose-dependent)

PEG accumulation

—

Chronic high-dose PEGylated proteins may accumulate in tissues; clearance slower in renal impairment

Antibody formation

—

PEGylated proteins can elicit anti-PEG antibodies (neutralizing potential unknown)

Cancer risk

—

IGF-1 axis stimulation contraindicated in active malignancy

Human safety data

—

Absent — no published human trials for PEG-MGF

Absolute Contraindications

PE 22-28

·Human use — no clinical safety data available

PEG-MGF

·Active malignancy or history of cancer (IGF-1R proliferative signaling)
·Known hypersensitivity to PEGylated compounds
·Pregnancy / lactation (no reproductive toxicity data)

Relative Contraindications

PE 22-28

·Cardiac arrhythmia or channelopathy (theoretical TREK-1 cardiac role)

PEG-MGF

·Diabetes (monitor glucose closely)
·Renal impairment (PEG clearance reduced)
·Retinopathy (IGF-1 axis effects on vascular proliferation)

05Administration Protocol

Parameter

PE 22-28

PEG-MGF

1. Animal protocol (IP)

Dissolved in sterile saline or vehicle. Intraperitoneal injection, 0.3–3 µg/kg body weight. Once daily administration in rodent behavioral studies.

Add 1–2 mL bacteriostatic water to lyophilized vial. Swirl gently — do not shake. Solution should be clear to slightly opalescent.

2. Stability

Shorter peptide length (7 AA) confers improved plasma stability vs 17-AA spadin. Exact storage conditions not detailed in published protocols.Djillani 2017

Subcutaneous — abdomen or thigh. Rotate sites to avoid lipodystrophy. Avoid areas with scar tissue or active inflammation.

3. BBB penetration

Enhanced CNS bioavailability vs full spadin, likely due to smaller size. Mechanism (passive diffusion vs active transport) not fully characterized.

Post-training preferred (within 30–60 min) to align with endogenous MGF expression window. Alternatively, daily morning dose on non-training days.

4. Human formulation

Not established — peptide synthesis methods for research use only. No pharmaceutical-grade formulation available.

Lyophilized: room temperature, light-protected, desiccated. Reconstituted: refrigerate 2–8 °C, use within 14–21 days.

5. Needle

—

29–31G insulin syringe, 8–12 mm length. Pinch skin fold, insert at 45° angle for subcutaneous delivery.

06Stack Synergy

PE 22-28

— no documented stacks

PEG-MGF

+ BPC-157

Moderate

View BPC-157 →

BPC-157 promotes angiogenesis and tendon/ligament repair via VEGF and growth factor modulation, while PEG-MGF targets satellite cell activation and myocyte proliferation. Complementary pathways for comprehensive tissue repair post-injury or intensive training. BPC-157's systemic stability and oral bioavailability contrast with PEG-MGF's localized IGF-1R signaling.

PEG-MGF: 100–200 mcg SQ post-training
BPC-157: 250–500 mcg SQ or oral, twice daily
Duration: 4–6 weeks (injury-dependent)
Primary benefit: Accelerated muscle and connective tissue repair, enhanced recovery

+ TB-500

Strong

View TB-500 →

TB-500 (Thymosin Beta-4 fragment) upregulates actin polymerization, cell migration, and anti-inflammatory pathways, while PEG-MGF drives satellite cell proliferation via IGF-1R/mTOR. Synergistic for muscle regeneration: TB-500 mobilizes progenitor cells, PEG-MGF stimulates their differentiation into myocytes. Both have overlapping but distinct repair cascades.

PEG-MGF: 100–200 mcg SQ post-training
TB-500: 2–5 mg SQ, 2× per week (loading), then weekly
Timing: Stagger injections by 6–12 hours
Primary benefit: Maximal satellite cell recruitment and myogenic differentiation, injury repair