We all know that neurons are highly complex, capable of establishing numerous connections with other neurons as well as brain structures, and able to carry out and regulate important neurological processes. But, are neurons all-powerful or sufficient for these roles?
In order to support healthy neuronal function, neurotrophins act to increase neuron survival, regulate proper development and maintain proper function of the vertebrate nervous system. Neurotrophins belong to a class of secreted proteins or growth factors that bind to specific receptors (Trk family of receptor tyrosine kinases and p75NTR) in order to activate signaling pathways that help neurons survive, differentiate and grow.
Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are 2 well-studied neurotrophic factors.
- NGF was the first neurotrophic factor to be discovered and it’s predominant action is on sympathetic (a neuronal division of the peripheral nervous system) and sensory neurons. NGF’s receptor is Trk-A1.
- Another popular neurotrophin is BDNF, which supports motorneuron survival and prevents apoptosis, or naturally occuring cell death. It is postulated that BDNF also participates in motor neuron development but is not sufficient nor required. BDNF binds to the Trk-B1 receptor.
Some additional processes regulated by neurotrophins:
- Cell-fate decisions
- Axonal growth
- Dendritic pruning
- Synaptic function
Juang, Eric J., and Louis F. 2001. Reichhardt. Neurotrophins: Roles in neuronal development and function. Annual Neuroscience Reviews. 24: 677-736.