P21
Cognitive & neuro Research only Animal studies only
Also called P021, Peptide 021
A small compound derived from ciliary neurotrophic factor, a protein that keeps nerve cells alive. It is built around a four-residue core with an adamantane cage attached to help it survive in the body and cross into the brain. It is studied for growing new neurons in the hippocampus, the brain's memory structure.
Evidence at a glance
- Evidence
- Animal studies — Not yet studied in people
- Status
- Research compound only
- Dosing
- No human study has set a dose
Every result is in mice and rats. There is no published human study of P21 at any dose, so nothing is known about whether it does any of this in people.
What studies report
- More new neurons in the dentate gyrus and better memory task performance in adult mice
- Increased BDNF, a nerve growth factor, and more synaptic markers in aged rats
- Less tau phosphorylation in 3xTg-AD mice, a transgenic Alzheimer's model
- Lower tau levels in rat cerebrospinal fluid
How it works
Mimics the active region of ciliary neurotrophic factor and raises BDNF signalling, which drives the birth of new neurons in the hippocampus. The adamantane group makes it stable enough to be given outside the brain and still act inside it.
Where it acts
BrainThe library groups this compound under Cognitive & neuro. The diagram shows that target, not every tissue it reaches.
Illustrated
AI-generated subject illustration; not a depiction of the compound or evidence of its effects.
Why people take it
Reasons people seek it out — not a list of proven effects.
In practice Unapproved use
- Taken by a small group interested in neurogenesis, usually alongside Semax or Dihexa
- Sold as a lyophilised powder and reconstituted like the injectable peptides
Science hasn't caught up: Practice here runs a long way ahead of the science. The entire case rests on rodent work from a single research group.
Reported real-world use, not evidence and not a recommendation.
Status: Preclinical research compound. Not approved anywhere.
- Route
- Subcutaneous injection in reported use; given by injection in the animal studies
- Sequence
- Asp-Gly-Gly-Leu, with a C-terminal adamantane unit
- Available as
- 5 mg, 10 mg
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Educational information only. Nothing here is medical advice, a dosing protocol, or a recommendation to use any compound. Most entries describe substances not approved for human use. Talk to a licensed clinician before acting on anything you read here. How to read these entries.