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Flashcards in Neural Regeneration Deck (26)

what is the main environmental difference between CNS and PNS neuron regeneration?

the glial environment


can CNS neurons sprout and make new connections like PNS neurons?

Yes, but glial environment inhibits it


What is the structural difference between CNS and PNS neurons?

there is connective tissue around PNS neurons to help regrowth

PNS neurons have 1 to 1 relationship. CNS is one to many


2 weeks post-injury, what will happen to a PNS neuron

cell soma changes morphology, such that nucleus moves to periphery

loss of Nissl substance, and ribosomes stop working, forming chromolysis

axon breakdown

muscle fibre atrophy


What is Wallerian Degeneration

degeneration of myelin on axon distal to site of injury
debris is cleaned up by macrophages


what happens 3-weeks post PNS injury

Schwann cells proliferation forming a compact cord, guiding axon regrowth

nucleus moves central again


What happens if the regeneration is successful

electrical activity will restore and muscle fibre regenerate


What happens if the regeneration is unsuccessful

neuroma formation, and patient gets unwanted sensation and pain from the bundle of nerve sprouts


Does neuron regenerate faster in a crushed injury? Why?

Yes, faster than having it cut, because the route of connective tissue is still intact. Neurons regenerate better with better alignment


T/F Oligodendrocytes encourage neural growth

False, oligodendrocytes are very inhibitory to regrowth


What is the treatment to primary CNS neural injury

remove primary causative agent to minimise extent of damage


What is an agent used to minimise CNS damage

tissue plasminogen activator (tPA) used in stroke


What are some immediate secondary damage to CNS neurons

degenerative chemical insults in much larger area, including
Ca influx,
free radical production,
glutamate excitotoxicity (glutamate released but not cleared)
BBB breakdown allow other things to enter


What are some secondary damage that develop in hours to days

immune cell infiltration
microglial activation
inflammatory mediators


What are some secondary damage that develop in days to weeks

axonal degeneration in large area
slow phagocytosis encouraging apoptosis
glial scar formation
meningeal fibroblast migration (scar)


what are the four potential ways of repairing CNS

protect surviving cells
axonal regeneration with functional integration
modulate astrocytic gliosis
neuron stem cells


Why won't axons regrow in CNS

lack of trophic factor to guide growth
environment inhibits regrowth


What is trophic support treatment? Why has it stopped

provide growth factors like NGF and BDNF to encourage axonal growth, but it causes neuropathic pain


what is axonal plasticity? How can it be enhanced?

damaged axon retracts, and nearby axon sprouts an extra process to re-innervate

can be enhanced by exercise


What is the cytoskeletal protein of astrocyte that inhibits axonal regrowth? What is its normal role

glial fibrillary acidic protein (GFAP)
helps with neuronal stability


Why can't we just ablate the astrocytes to prevent glial formation

astrocytes are very important for wound repair. A lack of astrocyte will cause increased inflammation, increased tissue destruction, and BBB repair inhibition


what are the three myelin inhibitor? What do they bind to?

Myelin associated glycoprotein

all bind to Nogo receptor, resulting in Rho pathway and growth inhibition


What are the two ways of utilising stem cells

mobilise endogenous cells
transplant exogenous cells


where are the endogenous stem cells found

subventricular zone of the lateral ventricle
subgranular zone of the dentate gyrus in hippocampus


where do the cells of subventricular zone go to?

migrate to the olfactory bulb


How can we promote axonal regrowth

by blocking inhibitory molecules and promote axon guidance molecules like Eph