E3 Amino Acid Neurotransmitters

Question 1

T/F: amino acid neurotransmitters are the most prevalent neurotransmitter in the CNS

Answer 1

true

Question 2

what are the two major classes of amino acid neurotransmitters?

Answer 2

excitatory amino acid and inhibitory amino acids

Question 3

what are the two excitatory amino acids?

Answer 3

glutamate and aspartate

Question 4

what are the two inhibitory amino acids?

Answer 4

GABA and glycine

Question 5

Is glutamate ionotropic or metabotropic?

Answer 5

mostly ionotropic but have some degree of metabotropic binding?

Question 6

What does ionotropic mean?

Answer 6

membrane-bound receptor proteins that respond to ligand binding by opening an ion channel and allowing ions to flow into the cell

Question 7

what does metabotropic mean?

Answer 7

indirectly linked with ion channels on the plasma membrane of the cell through signal transduction mechanisms (g-protein)

Question 8

what are the two receptors associated with glutamate?

Answer 8

AMPA and NMDA

Question 9

what is NMDA associated with?

Answer 9

excitotoxicity (overproduction can cause neuronal damage)

Question 10

what does the cooperation of AMPA and NMDA receptors lead to?

Answer 10

long-term potentiation (long-term synaptic plasticity)

Question 11

what is long-term synaptic plasticity associated with?

Answer 11

long-term learning

Question 12

what does frequent activity across a synapse cause?

Answer 12

lasting changes in strength of signaling (enhancement of neuroplasticity)

Question 13

What is neuroplasticity?

Answer 13

the ability of the nervous system to change in response to experience or the environment

Question 14

In the activation of glutamate receptors, what does AMPA require to open its ion channel?

Answer 14

the binding of glutamate

Question 15

what does the activation of AMPA lead to?

Answer 15

membrane depolarization and excitatory transmission

Question 16

In the activation of glutamate receptors, what needs to bind to NMDA?

Answer 16

both glutamate and glycine (they bind to diff. sites)

Question 17

what is the ion channel of NMDA blocked by?

Answer 17

Magnesium

Question 18

what displaces the magnesium cork from NMDA?

Answer 18

depolarization by the activation of AMPA receptor displaces the magnesium cork

Question 19

what occurs when the magnesium cork is displaced from NMDA

Answer 19

-opening of NMDA ion channel
-Ca2+ influx (contributes to long-term potentiation)

Question 20

can glutamate pas through the BBB?

Answer 20

no - must be synthesized in the brain

Question 21

what is glutamate synthesized from

Answer 21

alpha ketogluterate

Question 22

what does glutamates interaction with the excitatory receptors cause?

Answer 22

a greater chance that an action potential will be fired

Question 23

how does glutamate increase the change of an action potential being fired?

Answer 23

when glutamate binds to the receptors and the ion channels open the influx of Na+ causes depolarization

Question 24

what are the metabotropic effects of glutamate?

Answer 24

glutamate is removed from the synaptic cleft by exciatory amino acid transporters (EAATS)

Question 25

What do EAATs do?

Answer 25

carry glutamate into glial cells

Question 26

what occurs to glutamate in the glial cells?

Answer 26

-converted to glutamine by glutamine synthetase

Question 27

what occurs to glutamate after it has been converted to glutamine?

Answer 27

transporter back into neurons where it is converted back into glutamine

Question 28

what is the process of converting glutamate into glutamine back into glutamate called?

Answer 28

glutamate/glutamine cycle

Question 29

what are the steps of glutamate receptor activation?

Answer 29

1. action potential into presynaptic cell 2. glutamate release (Ca2+ mediated exocytosis) 3. glutamate binds to both channels 4. Na+ influx (depolarization) 5. depolarization drives Mg2+ ion out of pore 6. Ca2+ activates 2nd messenger system 7. long-lasting increase in glutamate receptors and sensitivity

Question 30

what are the two inhibitory amino acids?

Answer 30

GABA and glycine

Question 31

what is GABA modified from?

Answer 31

glutamate (decarboxlyzed from glutamate to GABA)

Question 32

where is GABA located?

Answer 32

interneurons that dampen circuits (synapses in CNS)

Question 33

What forms of GABA are ionotropic?

Answer 33

GABA(A) and GABA(C)

Question 34

what is the direct ionotropic effect of GABA

Answer 34

GABA binds to the receptors on a neuron and causes the opening of Cl- channels (hyperpolarization)

Question 35

what is the indirect ionotropic effect of GABA?

Answer 35

opening of K+ channels or blocking of Ca2+

Question 36

what form of GABA is metabotropic?

Answer 36

GABA(B) - g-protein linked (open close channels via intermediates)

Question 37

what are the metabotropic effects of GABA

Answer 37

-indirect g-protein linked opening of K+ channels or blocking of Ca2+ channels

Question 38

what occurs when GABA interacts with receptors of a neuron?

Answer 38

makes the neuron less likely to fire and action potential or release neurotransmitters

Question 39

how is GABA terminated

Answer 39

GABA transporters transport GABA from synaptic cleft into neurons or glial cells where it is degraded by mitochondrial enzymes

Question 40

what does increased GABA activity cause?

Answer 40

sedative effects

Question 41

what increases the activity of the GABA receptor?

Answer 41

alcohol and benzodiazepines

Question 42

Where is glycine located?

Answer 42

spinal cord and brain stem (not in cerebral hemispheres)

Question 43

is glycine ionotropic or metobotropic?

Answer 43

ionotropic (chloride influx)

Question 44

what is glycine synthesized from?

Answer 44

serine

Question 45

how is glycine synthesized?

Answer 45

serine-hydroymethyltransferase converts serine to glycine

Question 46

what is the vesicular GABA transporter used for in glycine inhibition?

Answer 46

glycine is transported into vesicles where it is stored

Question 47

what are the steps of the glycine inhibitory pathway?

Answer 47

1. Ca2+ enters the presynaptic cell 2. Ca 2+ mediated exocytosis of glycine 3. glycine binds to ligand-gated Cl- receptor 4. influx of Cl- causes hyperpolarization 5. glycine is removed from synapse through the glycine reuptake channel and recycled