Glossary
BDNF
BDNF acts via TrkB and p75NTR, and proBDNF and mature BDNF pull in opposite directions. Definition, the Val66Met variant and why assays measure it so often.
BDNF, or brain-derived neurotrophic factor, belongs to the neurotrophin family and is released as a non-covalent homodimer made of ~13.5 kDa subunits. The mature protein binds the receptor tyrosine kinase TrkB tightly, setting off Ras-MAPK, PI3K-Akt and PLC-gamma signalling and, further downstream, CREB-driven transcription and the trafficking of AMPA receptors.
BDNF as an experimental readout
Its precursor is biologically active as well. ProBDNF engages p75NTR together with sortilin and promotes apoptosis and long-term depression — effects opposite to those of mature BDNF — so an assay unable to tell them apart may point in entirely the wrong direction. Every ELISA used for BDNF should declare whether it detects the pro or mature form, and serum measurements are additionally distorted by platelets releasing BDNF as blood clots.
The molecule turns up again and again in the nootropic peptide literature, since raised BDNF expression is the mechanism usually proposed for Semax, P-21, PE-22-28 and Cerebrolysin — mostly on the basis of rodent and cell experiments, not human outcome trials. In humans, the frequent Val66Met polymorphism changes activity-dependent secretion and is routinely included as a covariate in cognition research.
Related terms and material
nootropic · in vivo · recombinant. Reference material: BDNF research family, Semax, PE-22-28. Further reading: Dihexa vs P-21.