Neuronal Growth Factors and Neuronal Death

What determines the fate of a cell
1. Influence of neural growth inducers and inhibitors, which is dependent on cell location in the developing nervous system
2. Cell proliferation and migration
3. Migration
  1. Movement of neuron along radial glia
4. Sonic hedgehog is mainly involved in proliferation step
5. Neurotrophins mainly involved in survival
Neurotrophins
1. Types
  1. NGF
    1. Nerve growth factor
  2. BDNF
  3. NT-3
  4. NT-4
2. Effects
  1. Survival - prevent cell death
  2. Growth - stimulate axonal and dendrite growth
  3. Sprouting - stimulate multiple projections
    1. Boutons are small projections that increase cell density along the nerve
  4. Increase soma size
  5. Promote neuronal differentiation
  6. Stimulate increased production of neurotransmitter
  7. Electrical sensitivity - alter levels and activity of ion channels
Receptors for neurotrophins
1. Trk ((RTK) receptor tyrosine kinase) receptor family
2. P75 receptors (common receptor)
3. Activation of receptor can be activated in different ways
  1. e.g. dimerisation
4. There can be cross-talk between 2 receptors
  1. Allows for different responses
What happens to neurons that do not succeed in finding the neurotrophins?
1. Neural cells undergo cell death, usually via apoptosis
2. How do neurons die?
  1. Apoptosis
    1. Developmental stages
    2. Pathological conditions
  2. Excitotoxic cell death
    1. Hypoxia
    2. Over stimulation by neurotransmitters (e.g. glutamate)
The brain makes new neurons throughout life
Neuronal plsticity
Potential to repair itself after injury or disease

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Neuronal Growth Factors and Neuronal Death

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