OnePin Peptide Library · Cognitive & Mood
P-21
P21 · P-21 Peptide
P-21 is a synthetic 21-amino acid peptide derived from the active region of ciliary neurotrophic factor (CNTF) that promotes hippocampal neurogenesis. Unlike full-length CNTF, P-21 crosses the blood-brain barrier and does not produce the appetite suppression and weight loss associated with CNTF, making it suitable for targeted cognitive enhancement without metabolic side effects. P-21 stimulates the differentiation of neural progenitor cells into mature neurons in the hippocampus, the brain region critical for memory consolidation and spatial navigation. It is used in short intensive cycles (4-6 weeks) 2-3 times per year rather than continuously.
Can be taken any time. No fasting required. 4-8 week cycles.
Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.
How it works
P-21 promotes differentiation of hippocampal neural progenitor cells into mature, functional neurons through CNTF receptor-independent mechanisms. It increases expression of BDNF and other neurotrophic factors in the hippocampus, enhances synaptic plasticity and long-term potentiation (LTP), and supports the survival and integration of newly generated neurons into existing neural circuits. Unlike full-length CNTF, P-21 does not activate the CNTF receptor complex (CNTFRalpha/LIFRbeta/gp130), which is responsible for the appetite suppression and cachexia associated with systemic CNTF. This selectivity makes P-21 a targeted neurogenesis agent without metabolic side effects.
P-21 promotes differentiation of hippocampal neural progenitor cells into mature, functional neurons through CNTF receptor-independent mechanisms. It increases expression of BDNF and other neurotrophic factors in the hippocampus, enhances synaptic plasticity and long-term potentiation (LTP), and supports the survival and integration of newly generated neurons into existing neural circuits. Unlike full-length CNTF, P-21 does not activate the CNTF receptor complex (CNTFRalpha/LIFRbeta/gp130), which is responsible for the appetite suppression and cachexia associated with systemic CNTF. This selectivity makes P-21 a targeted neurogenesis agent without metabolic side effects.
What to expect
Days 1-14: Minimal perceptible changes. Neurogenesis is a slow process.
Weeks 2-4: Subtle cognitive improvements may emerge. Memory consolidation improves.
Weeks 4-6+: New neurons integrate into hippocampal circuits. Benefits may persist for months after cycle ends.
Evidence
The honest take
Hippocampal neurogenesis
Animal data supports increased neurogenesis. Mechanism is distinct from BDNF upregulation (Semax) and is additive when combined. Limited human validation.
P-21 was specifically designed to retain CNTF's neurogenic properties without the metabolic cachexia. Animal data confirms this selectivity.
Interactions & stacking
What's safe to combine, and what belongs in a separate pin.
Safe & synergistic
Keep separate
Side effects & safety
Commonly reported
- Generally well tolerated
- Mild injection site irritation
Less common & notes
- Limited safety data.
- P-21 is designed to avoid CNTF's appetite suppression and weight loss.
- No significant adverse events reported in community use.
- Long-term data not available.
Pharmacokinetics
Storage. Limited published stability data. Conservative 28-day estimate after reconstitution. BAC water 2-8C. Protect from light.
Regulatory status
Not FDA-approved. Available as research peptide. WADA status not specifically listed.
Put it to work
Calculate, log & track
Open P-21 straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.
Open P-21 in the app →Go deeper
The guide & community
The complete P-21 walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.
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