Regeneration Flashcards
What is the effect of a distal axon injury in adults?
No MN death
What is the effect of a proximal axon injury in adults?
MN death
What is the effect of a distal axon injury in neonates?
MN death
What is the effect of a proximal axon injury in neonates?
MN death
Describe the process of Wallerian degeneration
Macrophages arrive from blood
Schwann cells dedifferentiate and proliferate
Myelin and debris removed - mianly be macrophages - assisted by Schwann cells
Loss of blood/nerve barrier - endoneurial blood vessels become leaky
What is the band of Bungner?
Schwann cells dedifferentiate - send out processes - over lap - regenerating peripheral axons growth through
New axons lead back to original target if nerve fibre myelinated and Band of Bungner undamaged
Which cell adhesion molecule between neurons and Schwann cells is important for supporting neurite outgrowth?
L1
Where are repuslive molecules found, what is their purpose, and name an example
In basal lamina and endoneurial spaces
Keep regenerating axons in basal lamina
NG2
What are the effects of axotomy on the cell body?
NT genes downregulated
Growth cone protein and microtubule genes upregulated
Neurofilament genes downregulated
What cell type surrounds sensory neuron cell bodies?
Satellite cells
Which cells adhere to sensory neuron cell bodies in inflammation?
Macrophages
Which cells adhere to MN cell bodies in inflammation?
Microglia
Why don’t CNS neurons regenerate in mammals?
No macrophage/microglia accumulation around axotomised CNS neurons
What cells type surrounds the lesion site in the CNS?
Astrocytes
In general which CNS neuron type can grow into a peripheral nerve graft, and which cannot?
Spinal cord neurons can
Brain neurons cannot
Name 3 types of neurons that are good regenerators into a peripheral nerve graft
Deep cerebellar nuclei
Retinal ganglion cells
Thalamic reticular nucleus
Name 3 types of neurons that are poor regenerators into a peripheral nerve graft
Cerebral cortical projection neurons
Thalamic projection neurons
Purkinje cells
What is the effect of CNS myelin on axonal regeneration?
Inhibits/repels neurite growth
Name 3 types of myelin proteins that inhibit/repel neurite growth
Nogo
MAG
Ephrin B3
Is CNS myelin found at the injury site?
No
Describe the ways in which lesion sites block axonal regeneration in the CNS
Meningeal fibroblasts invade lesion site - express inhibitory molecules
Astrocytes around lesion site enlarge - form astrocyte scar
Name 4 types of inhibitory molecules found at a CNS lesion site
Chondroitin sulphate proteoglycans
Semaphorins
Ephrins
Slits
What are some techniques attempting to repair spinal cord injuries?
Olfactory ensheathing glia
Neurotrophins
Chondroitinase - removes GAG side cha
in from chondroitinase sulphate proteoglycans
Anti-Nogo antibodies / peptides blocking Nogo receptors
PTEN inhibition - activates mTOR - increases intrinsic regenerative ability of axon
