Glutamate

Question 1

Glutamate

Answer 1

• Found everywhere in brain
• Not localized (synthesized everywhere)
• Excitatory amino acid neurotransmitter
• Binds to receptor, opens NA channels, causes depolarization

Question 2

Glutamate Synthesis Cycle:

Answer 2

• Astrocyte removes glutamate from synapse and breaks it down
• Glutamine is converted to glutamate via glutaminase
• Glutaate packaged into vesicles containing VGLUT
o Vesicular Glutamate Transporter
• VGLUT load vesicles with neurotransmitter
• Too much glutamate kills neurons (occurs in stroke)
• EAAT (Excitatory amino acid transporter) removes any excitatory amino acid (not just glutamate)

Question 3

Glutamate Receptors:

Answer 3

NMDA
AMPA
Metabotropic glutamate receptor
Kainate receptor

Question 4

NMDA Receptor

Answer 4

o Important for formation of memories
o Transports Ca when activated (Ca can act as second messenger)
o Acts as both ionotropic and metabotropic receptors
o Conducts both Na and Ca
o Made of 4 subunits with various binding sites
o Opens when pre and post synaptic neurons are firing together (coincidence detector- helps wire cells together)

Question 5

AMPA Receptor

Answer 5

Inotropic

Question 6

Metabotropic Glutamate Receptor

Answer 6

o Sends second messengers, can cause negative feedback

Question 7

Kainite Receptor

Answer 7

o Ionotropic

Question 8

NMDA Binding Sites

Answer 8

Glutamate
Glycine
PCP
Magnesium

Question 9

PCP Binding Site

Answer 9

o Binding site is within channel
o Inhibitory effects
o Blocks channel, but doesn’t compete with glutamate

Question 10

Magnesium Binding Site

Answer 10

o Blocks channel, when bound, Ca and Na can’t go through

o Mg binds at -70 mV removed at -65 mV

Question 11

NMDA Receptor Subtypes:

Answer 11

• NR1, NR2A, NR2B
• All NMDA have 2 NR1 subtypes, but can vary by whether they have NR2A or NR2B subtypes
• NR2B receptors are more sensitive, causes more Ca to enter cell

Question 12

Long Term Potentiation

Answer 12

• Can be produced by experiences that result in learning

* NMDA dependent

Question 13

CA1 Knockout

Answer 13

• Disrupted circuit to disrupt hippocampus dependent memory storage
• Determined that NR1 subunit in CA1 is needed to produce LTP (electrode stimulation) and for Place Learning (water maze test)

Question 14

NR2B Overexpression:

Answer 14

• Enhanced LTP, spatial learning

* Acquired memory more quickly, are better learners