6_Oligodendrocytes

Oligodendrocytes

Myelin

Function

Saltatory conduction of AP

Increase conduction velocity

Function

Saves a lot of space (axon length)

Saves a lot of energy (Na/K pump used less)

Function

Regulate ion channel distribution

Keeps ion channels in nodes of Ranvier

Fucntion

Neuroprotective:

Protects against inflammatory environment

Function

Help maintain axon diameter

Help axons survive

MCT1 lactate transporter

Used by OLs to transport lactate from myelin to axon for energy

Damaging OLs

Excitotoxicity

Excess Glu--> excess Ca2+ --> mitochondria mess up --> activate caspase --> apoptosis of OL

Normal conditions

Astrocytes, Microglia keep Glu in check via Glu transporters

Causes

Dying neurons release Glu

Inflamed neurons release Glu

Glu release from activated microglia/macrophage

Decrease uptake by astrocytes

Via pro-inflammatory cytokines

TNF-a , Il-1B, etc.

Effect

OL differentiation/maturation impaired

Benefits of Inflammation

SCI

NG2 progenitors contact macrophages to begin recovery

Toll-Like Receptor

Stimulate NG2 cell proliferation

TLR effect

TLR activate macrophages

Role of Iron/Ferritin

Macrophages uptake ferritin (an iron carrying molecule)

Deposit ferritin with NG2 cells, which is necessary for proliferation of NG2 --> OL

This is through the TLR4 pathway