Research Only Cognitive & Nootropic

P21

also known as: Cerebrolysin-derived peptide 21, Cognitive enhancer peptide-21

A CNTF-derived research peptide (Institute for Basic Research, New York) that crosses the blood-brain barrier and stimulates hippocampal neurogenesis in rodent models of Alzheimer disease, Down syndrome, and aging. Not FDA-approved; not commercially marketed; research-only with no human trials to date.

A peptidomimetic derived from a 21-amino-acid region of the human ciliary neurotrophic factor (CNTF) D1 domain. Developed by Iqbal and colleagues at the New York State Institute for Basic Research in Developmental Disabilities as a small neurotrophic peptide candidate for age-related cognitive decline, Alzheimer disease, and Down syndrome; shown in rodent studies to enhance adult hippocampal neurogenesis, reduce tau phosphorylation, and improve spatial learning. No human clinical data; peptide remains a research tool.

Mechanism of action

Reported to bind the leukemia inhibitory factor receptor beta (LIFRβ) / gp130 complex — the shared CNTF signaling receptor — activating downstream JAK/STAT3 and MAPK signaling associated with neuronal survival and adult hippocampal neurogenesis. In rodent models, P21 has been reported to reduce tau hyperphosphorylation, improve hippocampal-dependent memory performance, and reverse cognitive deficits in APP/PS1 and 3xTg-AD Alzheimer models. Mechanism remains incompletely characterized and receptor binding data are derived from a small number of preclinical reports from a single research group.

Primary uses

Cognitive enhancement research (preclinical only)
Alzheimer disease model studies (rodent)
Down syndrome cognitive deficit models (rodent)

Typical dosing

Not established for human use

⚠ No human dosing has been established. Rodent studies have used 25–500 μg/kg ranges. Any human use would be entirely off-label, unapproved, and unsupported by any clinical evidence.

Regulatory status

Not FDA-approved. No human clinical trials registered on ClinicalTrials.gov. Sold informally in the research-chemical / nootropic grey market, often mislabeled or with questionable provenance. Any human use would be unapproved and unregulated.

References

[pubmed] Bolognin S, et al. "An experimental rat model of sporadic Alzheimer's disease and rescue of cognitive impairment with a neurotrophic peptide." Acta Neuropathol, 2014;127:841-855.
[pubmed] Kazim SF, et al. "Disease modifying effect of chronic oral treatment with a neurotrophic peptidergic compound in a triple transgenic mouse model of Alzheimer's disease." Neurobiol Dis, 2014;71:110-130.
[pubmed] Blanchard J, et al. "A mimetic peptide of ADNP (ADNP-derived peptide) partially restores memory in the 3xTg-AD mouse model." Neurobiol Aging, 2013;34:2008-2016.

Related peptides

Cerebrolysin

A porcine-derived neurotrophic peptide preparation approved in 40+ countries (not US) for stroke, dementia, and traumatic brain injury — with the largest clinical evidence base of any nootropic peptide preparation.

Davunetide

NAPVSIPQ, the minimum active fragment of ADNP — an 8-amino-acid neuroprotective peptide studied in Phase 2 (cognition in mild cognitive impairment, schizophrenia) and Phase 3 (progressive supranuclear palsy). The Phase 3 PSP trial failed in 2012; development continues in schizophrenia (Coronis / ATL-104) and ADNP syndrome research.

Semax

A synthetic ACTH-derived heptapeptide approved in Russia for stroke rehabilitation and optic nerve disorders, with documented BDNF upregulation and broad nootropic activity.

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.