Brain energy, and role of astrocytes Flashcards
Describe how astrocytes are involved in the glutamate-glutamine cycle.
Removes glutamate from the synapse via GLT1 and GLAST: glutamate + NH4+ –> glutamine –> glutamine is transported out if astrocyte and into neuron: glutamine -(PAG)-> glutamate + NH4+
Describe how the lactate cycle are involved in the glutamate-glutamine cycle.
In astrocytes:
Glucose –> pyruvate + NH4+ (delivered to glutamine production) –> lactate –> lactate transported out of astrocyte into neuron
In neuron:
Lactate –> pyruvate –>
Are astrocytes excitable cells?
No, as they do not depolarize to send APs
How are astrocytes involved in neuronal signaling?
Indirectly: involved in clearance of NTs, production of glutamate and GABA
What does astrocyte clearance and participation in neurotransmission depend on?
How much of the synapse the astrocyte cover
Which NTs released by astrocytes affect the presynaptic terminal and the postsynaptic terminal, respectively?
Pre: endocannabinoids and glutamate
Post: D-serine and lactate
What are the two types of astrocytes, and how do they differ?
Fibrous: white tissue, connect to oligodendrocyte
Protoplasmic: gray tissue, endfeet are part of BBB
True or false: the astrocyte shape does not differ in regions of the brain?
False, different subtypes are found within brain regions, and they differ in shape
What does the subtype of an astrocyte depend on?
Modulation of gene expression during development
How does astrocytes and other glial cells communicate/are connected?
Via gapjunction
Describe how gap junctions are involved in the spatial K+ buffering, and what it is.
During neuronal activity K+ is taken up and released at the blood vessel by astrocytes (either from the synapse or oligodendrocytes)
What type of pores are found in the end feet of astrocytes forming the BBB?
Aquaporins (AQ4)
How are astrocytes involved in pathologies?
Become reactive –> protection, inhibition and neurogenesis
How does an upregulation of GFAP affect astrocytes?
–> hypertrophic (swell) + death +/proliferation (form scar tissue)
Does electrophysiology show glial activity?
No, as it’s Ca2+ signaling
