P21

Also known as: NAPVSIPQ, P021 peptide, Neurotrophic peptide P21

Cognitive & NootropicNeuroprotective

Overview

P21 (also called P021) is a synthetic tetrapeptide derived from the CNTF (ciliary neurotrophic factor) binding interface and designed to mimic neurotrophic signaling without the typical side effects of full CNTF. Research by Iqbal and colleagues at the New York State Institute for Basic Research has shown P21 stimulates BDNF expression, promotes neurogenesis, reduces amyloid-beta deposition, and decreases tau hyperphosphorylation in Alzheimer's disease models. It also supports dendritic architecture and synaptic protein expression.

Mechanism of Action

P21 acts as a compact neurotrophic mimetic by supporting BDNF-TrkB signaling, increasing BDNF mRNA in hippocampal tissue and BDNF protein in cortical samples. This drives phospho-CREB activation and downstream TrkB signaling cascades including PI3K/Akt and GSK3β inhibition. Inhibitory phosphorylation of GSK3β reduces both tau hyperphosphorylation (at AT8 and PHF1 epitopes) and amyloid precursor protein processing/Aβ production. P21 also increases MAP2 (dendritic stability), PSD95 (synaptic scaffolding), and synaptophysin (synaptic vesicle) expression.

Potential Benefits

  • BDNF upregulation promoting neuroplasticity
  • Reduction in amyloid-beta deposits in transgenic Alzheimer's models
  • Decrease in tau hyperphosphorylation at multiple epitopes
  • GSK3β inhibition protecting against neurofibrillary tangle formation
  • Hippocampal neurogenesis stimulation
  • Improved spatial learning and memory in aged animal models
  • Dendritic spine density and synaptic protein preservation

Research Dosage Notes

The following reflects doses used in published research studies. This is not medical advice.

Rodent models: oral gavage or subcutaneous injection 1-10 mg/kg. No established human doses.

Amino Acid Sequence

Ac-DGGLAG-NH2 (based on CNTF binding domain fragment; specific sequence varies by source)

Side Effects & Safety

  • Limited data; generally well-tolerated in preclinical models
  • No human safety data

Synergistic Compounds

The following compounds have been studied alongside P21 for potential complementary or synergistic effects:

CerebrolysinDihexaSemax

Learn More

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References & Further Reading

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BPC-157SelankSemaxDihexaCerebrolysinDavunetide