1: Glial Biology

Question 1

List the 7 types of glial cells and from which embryonic tissues they arise.

Answer 1

Macroglia: from neuroectoderm

• 1. Oligodendrocytes
• 2. Astrocytes
• 3. Ependymal cells
     
     4. Choroid plexus epithelial cells
     5. Radial glia
• 6. Microglia: from mesoderm, members of monocyte/macrophage system
     
     7. Schwann cells: from neural crest, in PNS

Question 2

Describe the concept of the tripartite synapse.

Answer 2

Tripartite synapse: between dendritic spine, axon terminal, and astrocyte process

Astrocyte removes/recycles NT, maintains nerve terminal with trophic influence, energy donation

Question 3

Discuss the role of glial cells in neuroinflammation: cells involved, associated diseases, pharmacological approaches

Answer 3

Cells involved: astrocytes, microglia, endothelial cells, perivascular cells, and circulating immune cells

Associated diseases: brain infections, MS, degenerative diseases

Pharmacological approaches: steroids, NSAIDs, antibiotics, cytokines/modulatory drugs, cannabinoids, vaccines

Question 4

Discuss the role of glial cells in neuroplasticity.

Answer 4

Glia, especially astrocytes, can regulate synapse breakdown or formation

Question 5

List the principal functions of astrocytes. (12!)

Answer 5

1. Structural support and scaffolding, esp. during development (-> migration)
2. Regulate extracellular K+ ion concentration
3. Regulate formation of BBB
4. Aid in vascular regulation
5. Form part of tripartite synapse
6. Release trophic factors, neuropeptides, NT, inflammatory mediators
7. Produce ECM proteins
8. Detoxification (metals)
9. Regulate synapse formation
10. Aid in repair of the brain
11. Recycle glutamate
12. Communicate via calcium waves (possible role in migraine aura)
13. Aid in energy metabolism of neurons (make lactate anaerobically and pass it on to neurons -> aerobic)

Question 6

Describe the anatomical features of astrocytes that permit them to perform their functions.

Answer 6

Have many processes that they send out to surround synapses, the outer surface of the brain, the ventricles, neurons, and blood vessels.

Question 7

What is a reactive astrocyte?

Answer 7

An astrocyte involved in repair of damaged brain tissue
Can proliferate and form a glial scar
May become a source of pathology

Question 8

What is a glioma? Why are they so dangerous?

Answer 8

Most common and serious brain tumor
Comprised of glial cells
Dangerous: cannot be completely removed; spread far beyond visible abnormalities because they are migratory

Question 9

List the principal function of oligodendrocytes and their anatomical features that permit them to perform their function.

Answer 9

Processes contact axons and form the myelin sheath of the CNS
Myelinate ~10-14 axons each

Question 10

List the principal function of ependymal cells and their anatomical features that permit them to perform their function.

Answer 10

Form a discontinuous single layer along the ventricle system and central canal of the spinal cord
Ciliated cells
Function not seemingly critical

Question 11

List the principal function of microglia and their anatomical features that permit them to perform their function.

Answer 11

Tiny glial cells that are extremely important for immune surveillance
Have lots of processes that weave in and out all areas of brain
When activated (under pathological conditions), grow huge and become phagocytic to clear infectious particles and other antigens