BDNF

BDNF (Brain-Derived Neurotrophic Factor) is a member of the neurotrophin family that supports neuronal survival, synaptic plasticity, and the differentiation of new neurons. It is the most-studied neurotrophin in the context of learning, memory, and mood.

BDNF expression is upregulated by exercise, sleep, caloric restriction, and a number of pharmacological interventions. Several research peptides — Semax, Selank, Cerebrolysin, and N-Acetyl variants of Semax / Selank — are studied for their effects on BDNF and related neurotrophic signaling.

BDNF is not directly drug-able as an exogenous compound (it is too large to cross the blood-brain barrier efficiently), so most therapeutic strategies aim to upregulate endogenous expression rather than supplement BDNF directly.