P21
Synthetic mimetic of a critical region of ciliary neurotrophic factor (CNTF); engages CNTF receptor complex and drives neurogenesis in hippocampal models without the systemic adverse effects of the full CNTF protein.
P21 is a synthetic peptide mimetic of a region of ciliary neurotrophic factor (CNTF), a cytokine of the IL-6 family. CNTF itself was investigated as a potential therapeutic for amyotrophic lateral sclerosis but its development was complicated by severe peripheral adverse effects, including a cachexia-like syndrome attributed to off-target signaling.
P21 was designed to retain CNTF’s neurotrophic activity at the CNTF receptor complex (CNTFRα/LIFRβ/gp130) while minimizing the peripheral effects that derailed the parent protein. In preclinical models, P21 administration has been reported to drive hippocampal neurogenesis, increase BDNF expression, and improve performance in Morris water maze and other learning paradigms. Mechanistically the effects are attributed to JAK/STAT3 signaling downstream of CNTFR engagement.
P21 remains an early-stage research peptide; no clinical trials have been completed and pharmacokinetic data in humans is unavailable. The compound is included in the PharmaKinetics catalog as a representative entry in the synthetic-neurotrophic class.