Brain neurotrophic supply in ontogenesis and during development of neurodegenerative diseases

Neurotrophic factors play a key role in ontogenetic changes of the nervous system’s functioning. The nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) were most completely characterized over six decades of active studies of neurotrophin family protein structure and functions. A complex coordination of synthesis, transport, secretion, and interaction of proneurotrophins and mature neurotrophins, as well as their receptors (Trk tyrosine kinase and p75^NTR receptor family proteins), cause a wide spectrum of their biological activity. In embryogenesis, neurotrophic factors are involved in the nervous system formation regulating both division, differentiation, survival, migration, and growth of neurons and their neurites and apoptosis activation. In the mature brain, neurotrophins are involved in the maintenance of the functional state of neurons and glial cells and synaptic plasticity regulation. It is natural that the development of processes typical for aging and neurodegenerative diseases is closely associated with a change in the brain neurotrophic supply caused both by a damage in neurotrophin metabolism and modification of their availability due to a change in the neuron microenvironment. The restoration of neurotrophic factor balance in the brain is considered as a promising approach to the therapy of neurodegenerative disorders.