Neurotrophins and the synapse

Neurotrophins have become the subject of intensive research because they regulate neuronal differentiation and survival during development and may prove to be useful in the treatment of certain neurodegenerative diseases. Neurotrophins regulate neuronal survival through a signaling cascade that depends on gene expression and new protein synthesis. Recently, several laboratories have shown independently that neurotrophins produce rapid and lasting changes in synaptic efficacy in the adult nervous system. Application of certain neurotrophins rapidly potentiates the efficacy of synaptic transmission. Conversely, brain slices from animals deficient for the brain-derived neurotrophic factor gene show marked impairments in long-term potentiation. In vivo application of specific neurotrophins blocks ocular dominance column formation, and ocular dominance depends on activity-dependent synaptogenesis. The mechanisms of neurotrophin-mediated synaptic plasticity are unknown but may involve the same signaling molecules that mediate neurotrophin-induced gene expression. Neurotrophins may prove to be a new class of molecules that regulate synaptic plasticity in the developing and adult nervous system.