Neurodeg: Pathophysiology of CNS astrocytes part 1

Question 1

Astrocytes make up how much of brain mass?

Answer 1

one third

Question 2

what are the two types of astrocyes?

Answer 2

1. protoplasmic (grey matter): wrap synapses & neuronal cell bodies
2. Fibrous (white matter) wrap oligodendroglial cells & nodes of Ranvier

Question 3

main role of oligodendrocyes?

Answer 3

myelination

Question 4

different types of macroglia?

Answer 4

• astrocytes
• oligodendrocytes
• polydendrocytes (NG2 glia)

Question 5

CNS glia represent how much of cells present in human brain?

Answer 5

~ 50%

Question 6

what are the two types of glia?

Answer 6

macroglia
microglia

Question 7

What experiment demonstrated the impact of human astrocytes on cognitive abilities and synaptic connections in mice?

Answer 7

• Study by Han et al.
• Transplanted human glial progenitor cells into immunosuppressed mice
• Progenitors survived, migrated, and formed astrocytes resembling human ones
• Mice with human astrocytes showed:
• Improved performance in learning tasks
• Enhanced long-term potentiation (LTP)
• Implication: Astrocytes potentially influence behavior and cognitive abilities

Question 8

What differences were observed in the evolution of astrocytes between mice and humans?

Answer 8

Size: Human astrocytes nearly three times larger
Complexity: Human astrocytes possess around ten times more GFAP-positive processes
Symmetry: Human astrocytes exhibit greater symmetry

Question 9

How did the evolution of neurons differ between mice and humans in the study’s findings?

Answer 9

Humans vs Mouse:
- Less significant changes compared to astrocytes
- Relatively stable in size and complexity across species

Implication:
- Astrocytes show disproportionate growth in complexity & size, possibly indicating their ↑ significance in higher brain functions compared to neurons

Question 10

What is the concept of the ‘tripartite synapse’ involving astrocytes?