Plasticity: Excitatory Syanpses

Question 1

Precursor for glutamate

Answer 1

Glutamine

Question 2

Glutamine is metabolized by the mitochondrial enzyme _______ into Glutamate

Answer 2

Glutaminase

Question 3

__________ metabolism by neurons can be used to synthesized glutamate

Answer 3

Glucose

Question 4

Name the ligand-gated inotropic receptor(s)

Answer 4

AMPA and NMDA

Question 5

What do the inotropic receptors do?

Answer 5

Are glutamate-gated ion channels that allow the passage of Na and K

Question 6

Activation of these inotropic receptors always produce

Answer 6

Excitatory postsynaptic responces

Question 7

EPSC stands for?

Answer 7

Excitatory postsynaptic current

Question 8

The pore of what receptor allows for Ca2+ entry along side Na+ and K+

Answer 8

NMDA receptors allows for Ca2+ entry along side Na+ and K+

Question 9

At hyperpolarized or depolarized membrane potentials does Mg2+ block what receptor?

Answer 9

Hyperpolarized membrane potential of -65mV causes Mg2+ to block NMDA pore

Question 10

Hyperpolarization or depolarization pushes Mg2+ out of the pore?

Once the pore is open _____ can come though

Answer 10

Depolarization pushes Mg2+ out of the pore

Once the pore is open Ca2+ can come though

Question 11

NMDA requires what 2 things to open its receptors?

Answer 11

Presence of Glutamate and postsynaptic depolarization

Question 12

Why is it thought that NMDA receptors underlie some forms of synaptic information storage, such as long term plasticity?

Answer 12

Because NMDA receptors require the presence of both glutamate and postsynaptic depolarization to open

Question 13

________ receptors have an extracellular ligand-binding domain, that binds glutamate and a transmembrane domain that forms part of the ion channel

Answer 13

AMPA receptors have an extracellular domain that binds glutamate and a transmembran domain that forms part of the ion channel.

Question 14

Binding of glutamate to _______ receptors causes the clamshell structure to shut, causing the gate helices within the transmembrane domain to move –> opening the channel pore

Answer 14

AMPA receptors causes the clamshell structure to shut, causing the gate helices within the transmembrane domain to move –> opening the channel pore

Question 15

Ion conductants in AMPA receptors

Answer 15

Na+ (K+)

Question 16

Ion conductants in NMDA receptors

Answer 16

Ca2+ (Na+)

Question 17

Why are NMDA receptors known as coincidence detectors?

Answer 17

Both pre and post synaptic activation is needed: Glutamate release + Postsynaptic depolarization

Question 18

The 3rd receptor for Glutamate is?

Answer 18

Metabotropic glutamate receptors

Question 19

Metabotropic glutamate receptors cause?

Answer 19

Metabotropic glutamate receptors cause slower postsynaptic responces that can either excite of inhibit postsynaptic cells

Question 20

Describe the structure of the Metabotropib glutamate receptors

Answer 20

7 helical membrane spanning domains that connect the extracellular ligand binding domain to the intracellular domain that activates G proteins

Question 21

Describe Excitoxicity

Answer 21

• The ability of Glutamate and related compounds to destroy neurons, by prolonged excitatory synaptic transmission.
• Usually [Glutamate] release into the synaptic cleft rises to high levels ( 1mM) but only for a few milliseconds
• Excessive activation of of neuronal glutamate receptors can literally excite neurons to death

Question 22

How do brain injuries add to/cause excitotoxicity?

Answer 22

Occlusion of a cerebral blood vessel causes Ischemia (reduced blood flow), this reduced supply of O2 and glucose elevates glutamate levels by slowing the energy-dependend removal of glutamate at synapses.