BDNF and NT-3 widen the scope of neurotrophin activity: pharmacological implications.

The neurotrophin gene family comprises four structurally related basic proteins, NGF, BDNF, NT-3 and NT-4/5. Despite high structural homology, these neurotrophins operate via different high-affinity membrane receptors, differ in target specificity, patterns of spatial and temporal distribution and responses to injury of the neuronal tissue. Based on the recent data, some aspects of BDNF and NT-3 neurotrophin activity and their possible role in normal and damaged nervous system are presented. Different effectiveness of exogenously applied neurotrophins in the injured brain as a consequence of responsiveness of particular neuronal populations to these factors, dose requirements, route of delivery, parenchymal penetration and target availability is discussed.