| Type: | Family | Name: | Brain-derived neurotrophic factor |
| Description: | During the development of the vertebrate nervous system, many neurons become redundant (because they have died, failed to connect to target cells, etc.) and are eliminated. At the same time, developing neurons send out axon outgrowths that contact their target cells []. Such cells control their degree of innervation (the number of axon connections) by the secretion of various specific neurotrophic factors that are essential for neuron survival. One of these is nerve growth factor (NGF), which is involved in the survival of some classes of embryonic neuron (e.g., peripheral sympathetic neurons) []. NGF is mostly found outside the central nervous system (CNS), but slight traces have been detected in adult CNS tissues, although a physiological role for this is unknown []; it has also been found in several snake venoms [, ]. Proteins similar to NGF include brain-derived neurotrophic factor (BDNF) and neurotrophins 3 to 7, all of which demonstrate neuron survival and outgrowth activities. Originally purified from pig brain [], the neurotrophin BDNF is expressed in a range of tissues and cell types in the CNS and periphery. It exerts its effects by binding to neurotrophic tyrosine kinase receptor type 2 (NTRK2; also called TrkB) and the low affinity nerve growth factor receptor, p75NTR. While the former receptor mediates the neurotrophin's prosurvival functions, activation of p75NTR by BDNF has been shown to promote apoptosis and to inhibit axonal growth []. BDNF is a key regulator of synaptic plasticity, and plays an important role in learning and memory []. Several lines of evidence suggest that it is also involved in the control of food intake and body weight []. A number of clinical studies have demonstrated an association between aberrant BDNF levels and disorders and disease states, such as depression, epilepsy, bipolar disorder, Parkinson's disease and Alzheimer's disease []. | Short Name: | Brain-der_neurotrophic_factor |
