19.4 Neuronal Repair and Regeneration

Question 1

What is the difference in the regeneration of neurons in the CNS and periphery?

Answer 1

Periphery: nerve fibres can regenerate and reinnervate tissues via growth factors produced by Schwann cells
CNS: Nerves are myelinated by oligodendrocytes so nerve recovery is poor to non existent

Question 2

Describe how peripheral nerves regenerate?

Answer 2

Schwann cells divide and form hollow tube enclosed by endoneurium
Proximal end of the nerve fibre sends out sprouts towards those tubes
Sprouts are attracted by growth factors produced by Schwann cells in the tubes Proceeds at 3-4 mm/day

Question 3

Which growth factors are produced by Schwann cells?

Answer 3

NGF1, NT-3 and NT4

Question 4

State a possible therapy for PD?

Answer 4

Cell therapy and neuronal transplantation to restore dopmainergic neurons with injections of neurotrophins

Question 5

What is plasticity in the CNS?

Answer 5

it refers to the ability of the nervous system to show lasting changes in its structure and/or function in response to internal or external constraints

Question 6

What are the two types of plasticity, and when are they relevant?

Answer 6

• Experience-expectant plasticity is relevant in the developing CNS (selective stabilisation, dependent on expecting experiences and results in the formation of many synapses, but only a few are retained/most are pruned)
  
  • These are related to universal experiences undergone by all people, such as plasticity in response to movement or visual input
• Experience-dependent plasticity is seen in localised regions of the CNS, and is involved in the processing of specific experiences
  
  • E.g. repeated experiences will cause changes within the CNS

Question 7

What is the role of growth factors in neuronal survival and plasticity?

[IMPORTANT]

Answer 7

• Growth factors promote survival and plasticity of axons after a CNS lesion.
• This means that administration of e.g. neutrophins can improve repair at CNS lesion sites

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Question 8

Give an example of a condition which can potentially be treated using cell therapies.

[IMPORTANT]

Answer 8

Parkinson’s disease

Question 9

Describe how cell therapies could be used to treat Parkinson’s disease.

[IMPORTANT]

Answer 9

• Stem cells can be sourced or induced
• These can be used to create new dopaminergic neurons
• These can then be transplanted into the patient, helping to alleviate symptoms
• However, there are difficulties with these approaches, especially because they do not stop the progressive loss of dopaminergic neurons