Glutamate Flashcards
Glutamate Synthesis
- Glutamine from foods
- ATP needed
- Glutaminase converts Glutamine into Glutamate
What are nootropics?
cognitive enhancing compounds that act on cholinergic system
Function of VGLUT
packages glutamate into vesicles
Function of EAAT
extends signal of synapse to postsynaptic or astrocyte
Steps of Glutamate at Synapse
- VGLUT packages glutamate into vesicles
- EAAT extends signal to postsynaptic and astrocyte
- glutamate is recovered by astrocyte and converted into glutamine
- glutamine is transporter back into neuron
What is cotransmission
When Glu and another NT are released from the same terminal
What is corelease?
When Glu and another NT are released from the same vesicle
Glutamate ionotropic receptors and how many subunits
NMDA, AMPA: 4 subunits
Kainate: 5 subunits
Describe how the coincidence detectors / AND gate works in NMDA receptors
2 events must occur at the same time to open the channel.
1. Glutamate and a co-agonist must bind (glycine, D-serine)
2. membrane depolarization (removal of Mg2+ from channel)
–> flow of Na+ and Ca2+ ions
what flows in AMPA and Kainate channels
Na+ only
what blocks AMPA and Kainate receptors?
NBQX
What are the differences in the 3 glutamate metabotropic receptors
- lead to different 2nd messenger systems
- have different affinities for glutamate and agonist
Describe Group 1 for glutamate metabotropic receptors
mGluR1 + 5
1. activate IP3 / DAG pathways
2. increase Ca2+
3. postsynaptic
Describe Group 2 and 3 of glutamate metabotropic receptors
Group 2: mGluR2 + 3
Group 3: mGluR 6, 7, 8
- inhibits cAMP - PKA activity
- presynaptic
- function as autoreceptors
Glutamate Functions
- Learning and memory, Cognition
- seizure activity, excitotoxicity
What is long-term potentiation?
increase strength of synapse after repeated activation
What is long-term depression?
decrease strength of synapse after repeated activation
why do we want LTP?
basis for memory?
Process of having LTP
to induce: requires NMDA receptor activity
to express: requires increase of AMPA receptors
what does abnormal glutamate signaling cause
abnormal cognitive function
what are ampakines?
AMPA allosteric modulators
How do ampakines enhance AMPA receptor activity?
- increase NA+ current into AMPA receptors
- decrease rate of deactivation or desensitization
Glutamate differs from other neurotransmitters such as acetylcholine (ACh), dopamine (DA), and serotonin (5HT) in that
Question 1Answer
a.
glutamate also plays a role in protein synthesis and cell metabolism
b.
glutamate can only be synthesized by a single chemical reaction
c.
glutamate is the only neurotransmitter that causes EPSPs
d.
only specialized neurons in the brain synthesize and release glutamate
a.
glutamate also plays a role in protein synthesis and cell metabolism
Which of the following is considered to be a glutamate co-agonist at the NMDA receptor site?
Question 2Answer
a.
Ketamine
b.
D-serine
c.
Aspartate
d.
Magnesium
b.
D-serine
