Glia 3 Flashcards
Main functions of astrocytes?
Pathway formation, support, growth & death, Ca2+ signalling, glutamate involvement, BBB, K+ and glucose transport, channels and receptors and extracellular functions
Role of astrocytes in pathway formation?
During development astrocytes provide the pathways used by neurons to migrate to their appropriate sites
Which cells can produce the adhesion molecules needed in neuronal pathfinding?
Astrocytes
Role of astrocytes in support?
Gives the synapse a physical form and structure
Effects of astrocytes on a synapse?
Keeps molecules in the synapse
Regulates molecules taken up by the synapse
Role of astrocytes in growth?
Releases factors including growth factors, cytokines
Important for survival and development of neurons
Role of astrocytes in damage repair?
Proliferate around the site to aid repair, or form a glial scar
What is a glial scar?
Astrocytes can do this and use it to inhibit axonal regeneration
How are astrocytes around neurons linked?
Gap junctions
What do gap junctions between astrocytes allow?
Movement of various ions (Ca2+) between astrocytes
WHat is a calcium wave?
A wave of Ca2+ passing through all the astrocytes around a neuron
Purpose of a calcium wave?
Synchronising neurons
Role of astrocytes involving glutamate?
Clear released glutamate
Why is glutamate clearance by astrocytes important?
Prevention of excitotoxic cell death
What happens to glutamate once it is taken up by astrocytes?
Converted to glutamine and returned to neurones
How are astrocytes involved in the BBB?
Ensheath capillaries so all cells entering the brain must go through astrocytes
What is immunological privellage?
No active immune system in the brain
Astrocyte role in K+ and glucose transport?
They have uptake systems for K+ and glucose
Why is glucose from astrocytes needed in neurons?
Needed for sodium potassium pump to maintain resting potential
Astrocyte role in NTs?
Astrocytes express neurotransmitter receptors and channels (e.g. 5HT)
Why do astrocytes express NT receptors and channels?
Unknown
May be used to coordinate neuronal activity
Astrocyte function in extracellular volume?
Astrocytes can expand and shrink depending on how much water they uptake from the environment–> impacts the extracellular space
How could an astrocyte increase NT effectiveness?
Swell so less space for synapse so higher conc of NT in synapse
Which neuronal cells produce cytokines?
Astrocytes, microglia and neurons
WHat can affect whether a cytokine has a pro or inflammatory response?
Point of release, cells they act upon, concentration, receptor they bind to
Cytokines examples?
Interferons (IFN), interleukins(IL), tumour necrosis factor (TNF), transforming growth factors (TGF)
Which cytokine receptor do microglia express?
IL6
JAK STAT pathway?
Result of cytokine, ends up with triggering specific gene transcription
