Notes

Oligodendrocytes Oligodendrocytes are involved in the myelination of axons, which favors propagation speed and distance.

Myelin

• White matter tracts.
• Schwann cells in the PNS
• Oligodendrocytes in the CNS.

Oligodendrocyte Maturation and Myelin Formation

1. Infiltration of oligodendrocyte precursor cells (OPCs).
2. Formation of immature oligos.
3. Immature oligos send out processes to axons.
4. Signals induce wrapping of membrane.

Oligodendrocytes Can Respond to Neurotransmitters

• OPCs express neurotransmitter receptors.
  • Glutamate, GABA, Acetylcholine, Dopamine, ...
  • May influence migration and proliferation.
• Mature oligos express glutamate receptors.

Immature Oligos Choose Axons Based on Size and Attractive Signals They need to know what axons to wrap and that is probably done by attractive and repulsive signaling, which is probably performed by the neurons to attract or repel this oligos process.

Steps of Myelin Formation

Why Are Oligodendrocytes Important?

• Myelin formation is critical for increasing action potential mconduction.
• But Oligodendrocytes also:
  • Provide metabolic support to axons through myelin.
  • Affect signal processing and long distance communication by modulating the degree of axonal myelination.

Oligos Provide Metabolite to Axons

• Oligos and astrocytes are connected by gap junctions (Cx): allows the flow of metabolites.
• Oligos express MCT1 (lactate transporter): knockout of this transporter induces axonal degeneration.

Myelin "Plasticity"

• Oligo coverage changes throughout adult life based on experience and neuronal activity.
• Neuronal activity appears to induce OPC proliferation and maturation (i.e., MORE oligos).
• This process is necessary for learning new motor tasks.

Summary Oligodendrocytes

• Myelin Formation: OPCs infiltrate tissue and immature oligos wrap membrane around axons.
• Mature Myelin
  • Oligos provide metabolic support for axons.
  • The degree of myelination may regulate information processing.
• Myelin Plasticity
  • Changes throughout life.
  • Necessary for learning new motor tasks.