20.3 Path: Neural regeneration Flashcards
What is the major difference between regeneration after injury in the PNS vs. CNS? Why?
PNS: motor neurons can regenerate
CNS: no regeneration (glial scar inhibits regrowth)
When a peripheral axon is damaged, what direction does it regenerate in?
Does the cell body have to be in a peripheral ganglion?
Proximal axon regenerates distally
Cell body can be in peripheral ganglion or in CNS
What happens to a PNS neuron:
2 weeks post injury:
Nucleus moves to periphery, loss of Nissl substance
Wallerian degeneration
What happens to a PNS neuron:
3 weeks post injury:
Schwann cells proliferate
What happens to a PNS neuron:
3 months post injury:
Successful regeneration, electrical activity restored–>muscle fibre regen
OR
unsuccessful regen, a neuroma forms
Is repair faster with nerve crushing or cutting?
Crushing
Are oligodendrocytes excitatory or inhibitory to regrowth?
Inhibitory
What prevents axonal regeneration in the CNS?
Lack of trophic support
Injury environment inhibits
What is the difference between axonal plasticity and regeneration?
Plasticity: e.g. an improvement after SCI, uninjured axon-terminal end sprouts (no increase in no. of axons)
Regeneration: injured axon acutally regrows
What is a major inhibitor of neural degeneration? Why does this form?
Astrocytic gliosis– a glial scar forms a barrier between undamaged tissue and injury site
What is Nogo important for? What happens if we block it?
Nogo R results in Rho signalling pathway, inhibits axon growth (myelin inhibitors)
What can axon guidance molecules do? What is an example of one?
Promote, repel or guide growing axons
EphA4
Where are the two main neurogenic regions in the adult mammalian brain?
SVZ: subventricular zone (lateral ventricle)
SGZ: subgranular zone (dentate gyrus in hippocampus)
