Side-by-side · Research reference
P21vsPE 22-28
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AAnimal-MechanisticHUMAN-REVIEWED8/36 cited
BAnimal-StrongHUMAN-REVIEWED16/47 cited
P21
CNTF-Derived Neuropeptide · Animal Model Evidence
Animal onlyEvidence level
SQ · Site unspecified · Frequency unknown
PE 22-28
TREK-1 Antagonist · Pre-Clinical
IP · SQ · Once Daily (animal models)Djillani 2017Pietri 2019
01Mechanism of Action
Parameter
P21
PE 22-28
Primary target
CNTF receptor alpha (CNTFRα) / LIF receptor (LIFR) / gp130 complex on neural stem cells
TREK-1 two-pore-domain potassium channelDjillani 2017Ma 2020
Pathway
CNTF mimetic → CNTFRα/LIFR/gp130 heterotrimer → JAK/STAT3 signaling → neurogenesis, stem cell proliferation, neuroprotection
TREK-1 channel blockade → Neuronal membrane depolarisation → Enhanced hippocampal excitability → Increased neuroplasticity
Downstream effect
Increased neural stem cell self-renewal, globose basal cell activation (Mash1+ cells), olfactory sensory neuron regeneration, hippocampal neurogenesis, neuroprotection in developmental disorders
Antidepressant-like activity in forced swim test and tail suspension test; reduced A1-like reactive astrocyte activation; neuroprotection via NF-κB pathway modulationDjillani 2017Cong 2023Wu 2021
Feedback intact?
—
N/A — direct ion channel blockade; not receptor-mediated endocrine axis
Origin
Small-molecule peptide mimetic derived from full-length ciliary neurotrophic factor (CNTF), designed to retain receptor activation with improved pharmacokineticsMottolese 2024
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 2017Mazella 2018
Antibody development
—
Not reported in animal studies
02Dosage Protocols
Parameter
P21
PE 22-28
Human dosing
No established protocol
No clinical trial data available.
—
Animal models (mice)
Dose and route not specified in abstractsMottolese 2024Jia 2020
In vitro and in vivo studies demonstrate efficacy; precise dosing protocols not disclosed.
—
Evidence basis
Animal models only
CDKL5 KO mice, methimazole-induced olfactory injury, CNTF-/- knockout models.Mottolese 2024Cox 2026Jia 2020
Multiple rodent RCTs; behavioral + electrophysiology endpointsDjillani 2017Qi 2018Wu 2021
Duration
Not specified
—
Route
Presumed subcutaneous or intraperitoneal (animal studies)
—
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.
Onset (animal)
—
Within hours (acute); full effect 4–7 days
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.
04Side Effects & Safety
Parameter
P21
PE 22-28
Human safety data
None available
No clinical trials in humans.
—
Animal tolerability
Well-tolerated in mouse models; no toxicity reported in available abstracts
—
Theoretical risks
Uncontrolled stem cell proliferation, immune response to peptide, unknown long-term CNS effects
—
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
Absolute Contraindications
P21
- ·Use in humans not validated
PE 22-28
- ·Human use — no clinical safety data available
Relative Contraindications
P21
- ·Active malignancy (theoretical — neurotrophic signaling may affect tumour growth)
- ·Pregnancy or lactation (no safety data)
PE 22-28
- ·Cardiac arrhythmia or channelopathy (theoretical TREK-1 cardiac role)
05Administration Protocol
Parameter
P21
PE 22-28
1. Human protocol
Not established. No FDA approval, no clinical trial data.
Dissolved in sterile saline or vehicle. Intraperitoneal injection, 0.3–3 µg/kg body weight. Once daily administration in rodent behavioral studies.
2. Animal research context
In vivo studies used systemic administration (route not specified in abstracts) in mouse models of neurodegeneration, olfactory injury, and CDKL5 deficiency disorder. In vitro studies used primary cell cultures.
Shorter peptide length (7 AA) confers improved plasma stability vs 17-AA spadin. Exact storage conditions not detailed in published protocols.Djillani 2017
3. BBB penetration
—
Enhanced CNS bioavailability vs full spadin, likely due to smaller size. Mechanism (passive diffusion vs active transport) not fully characterized.
4. Human formulation
—
Not established — peptide synthesis methods for research use only. No pharmaceutical-grade formulation available.