Regeneration

Question 1

What is the effect of a distal axon injury in adults?

Answer 1

No MN death

Question 2

What is the effect of a proximal axon injury in adults?

Answer 2

MN death

Question 3

What is the effect of a distal axon injury in neonates?

Answer 3

MN death

Question 4

What is the effect of a proximal axon injury in neonates?

Answer 4

MN death

Question 5

Describe the process of Wallerian degeneration

Answer 5

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

Question 6

What is the band of Bungner?

Answer 6

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

Question 7

Which cell adhesion molecule between neurons and Schwann cells is important for supporting neurite outgrowth?

Answer 7

L1

Question 8

Where are repuslive molecules found, what is their purpose, and name an example

Answer 8

In basal lamina and endoneurial spaces
Keep regenerating axons in basal lamina
NG2

Question 9

What are the effects of axotomy on the cell body?

Answer 9

NT genes downregulated
Growth cone protein and microtubule genes upregulated
Neurofilament genes downregulated

Question 10

What cell type surrounds sensory neuron cell bodies?

Answer 10

Satellite cells

Question 11

Which cells adhere to sensory neuron cell bodies in inflammation?

Answer 11

Macrophages

Question 12

Which cells adhere to MN cell bodies in inflammation?

Answer 12

Microglia

Question 13

Why don’t CNS neurons regenerate in mammals?

Answer 13

No macrophage/microglia accumulation around axotomised CNS neurons

Question 14

What cells type surrounds the lesion site in the CNS?

Answer 14

Astrocytes

Question 15

In general which CNS neuron type can grow into a peripheral nerve graft, and which cannot?

Answer 15

Spinal cord neurons can

Brain neurons cannot

Question 16

Name 3 types of neurons that are good regenerators into a peripheral nerve graft

Answer 16

Deep cerebellar nuclei
Retinal ganglion cells
Thalamic reticular nucleus

Question 17

Name 3 types of neurons that are poor regenerators into a peripheral nerve graft

Answer 17

Cerebral cortical projection neurons
Thalamic projection neurons
Purkinje cells

Question 18

What is the effect of CNS myelin on axonal regeneration?

Answer 18

Inhibits/repels neurite growth

Question 19

Name 3 types of myelin proteins that inhibit/repel neurite growth

Answer 19

Nogo
MAG
Ephrin B3

Question 20

Is CNS myelin found at the injury site?

Answer 20

No

Question 21

Describe the ways in which lesion sites block axonal regeneration in the CNS

Answer 21

Meningeal fibroblasts invade lesion site - express inhibitory molecules
Astrocytes around lesion site enlarge - form astrocyte scar

Question 22

Name 4 types of inhibitory molecules found at a CNS lesion site

Answer 22

Chondroitin sulphate proteoglycans
Semaphorins
Ephrins
Slits

Question 23

What are some techniques attempting to repair spinal cord injuries?

Answer 23

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