Wilcox Flashcards
when do glia develop in relation to neurons?
neurons develop first, then astrocytes, then oligodendrocytes (synapses begin to form around the same time as glia)
Criteria for classification as
an astrocyte
*Absence of electrical excitability (i.e. astrocytes cannot
generate action potential).
*A very negative membrane potential (-80 to -90 mV)
because of a prevalence of K permeability
*Transporters for GABA and glutamate that permits the
astroglial role in neurotransmitter homeostasis.
*A large number of intermediate filament bundles, which
are the sites of the astrocyte specific protein GFAP.
*Glycogen granules.
*Processes from each cell contacting and surrounding
blood vessels.
*Elaborated perisynaptic processes –tripartite synapse
*Connected to other astrocytes (other glia?) by gap
junctions formed by connexin 43 and/or 30.
Functions of astrocytes
- Development of the CNS
- Structural support
- Barrier function
- Homeostatic function
- Metabolic support
- Synaptic transmission
*Regulation of blood flow
*Higher brain functions
*Brain defense
Astrocyte receptors
Astrocytes have both ionotropic and metabatropic receptors.
Activation of ____ induces calcium release
from internal stores
IP3R2
How do Ca2+ waves travel through astrocytes?
(can travel a long distance) – induced by ATP
Diffusion of InsP3 thru gap
junctions
Ca2+ - dependent release of
gliotransmitters
Ca2+ - dependent release of
gliotransmitters that diffuse a long
way
How are astrocytes coupled?
Gap Junctions!
Triggers of reactive astrogliosis
Reactive Astrocytes
are the receptors in an astrocyte constant throughout its life?
no, reactive astrocytes have changed receptors
Faster decay times and residual glutamate uptake currents
following a train of stimuli in slices from KA-SE mice are_____
mGluR5
dependent
What is an NG2 cell?
- Expresses chondroitin sulphate proteoglycan NG2(cspg4) and platelet-derived growth factor receptor a(PDGFRa), but not GFAP, myelin genes or markers for microglia.
- Stellate morphology, highly branched, slowly proliferating, and undergo asymmetric cell division and increase proliferation in response to CNS insults.
- They generate oligodendrocytes in the adult CNS in vivo.
–And sometimes astrocytes too it turns out - They receive synaptic input from neurons (Bergles et al., 2010).
- Involved in inflammation as well (Bell et al., 2020)
NG2-glia are _____ in adult CNS
an abundant population
role of NG2-glia
where are NG2 glia found in brain?
Distributed evenly throughout most gray and
white matter regions
NG2 glia can monitor their environment
via
numerous receptors and ion channels
tripartite synapse
quad-partite synapse
tetrapartite synapse
