GABA 2.0

Question 1

What is the major inhibitory NT in the brain?

Answer 1

GABA

Question 2

What kind of receptors can GABA activate?

Answer 2

Ionotropic and Metabotropic

Question 3

How is GABA synthesised?

Answer 3

Enzymatically via the krebs cycle

Question 4

What molecule is used to synthesise GABA in the krebs cycle?

Answer 4

glucose

Question 5

Where is GABA synthesised?

Answer 5

Nerve terminal

Question 6

What is the direct precursor to GABA?

Answer 6

Glutamate

Question 7

Which enzyme converts glutamate to GABA?

Answer 7

Glutamic acid decarboxylase

Question 8

Where are GABA transporters found?

Answer 8

Astrocytes and presynaptic nerve terminals

Question 9

If the GABA isn’t recycled, what is it converted to in the presynaptic terminal?

Answer 9

Succinic semialdehyde

Question 10

Which enzyme converts GABA to succinic semialdehye?

Answer 10

GABA transaminase

Question 11

What is succinic semialdehyde an intermediate of?

Answer 11

Krebs cycle

Question 12

What happens to GABA once it is reuptaken by astrocytes?

Answer 12

Converted to succinic semialdehyde

Question 13

In which brain areas is GABA found?

Answer 13

Cerebellum, basal ganglia, hippocampus, hypothalamus, cortex

Question 14

In which type of neurons is GABA is principally found?

Answer 14

local interneurones

Question 15

What could happen if the glutamate GABA balance gets out of control?

Answer 15

Seizures and epilepsy

Question 16

How does a neuron having multiple synapses on its dendrites affect the APs it may/may not fire down its axon?

Answer 16

It sums all the potentials from them (e.g. +ve from glutamate, -ve from GABA) and then fires the AP depending on the overall potential

Question 17

What kind of receptor is GABAa?

Answer 17

Ligand gated ion channel

Question 18

What kind of receptor is GABAb?

Answer 18

GPCR

Question 19

Where are GABAa receptors generally found?

Answer 19

postsynaptically

Question 20

Where are GABAb receptors generally found?

Answer 20

pre and postsynaptically

Question 21

What speed of inhibition does GABAa receptors mediate?

Answer 21

fast

Question 22

What speed of inhibition does GABAb receptors mediate?

Answer 22

slow

Question 23

To which ion is the GABAa ion channel permeable to?

Answer 23

Cl-

Question 24

Which ion channels can be regulated as a result of the GPCR receptor GABAb?

Answer 24

Ca2+ and K+

Question 25

Which GABA receptor can inhibit transmitter release?

Answer 25

GABAb

Question 26

Why do GABAb receptors exhibit a slow inhibition?

Answer 26

Second messenger systems take time

Question 27

What does the K+ Cl- transporter do?

Answer 27

Transports K+ and CL- out of the postsynaptic neuron

Question 28

What is the result of the K+ Cl- transporter?

Answer 28

A low conc of Cl- is maintained within the cell (maintains conc grad)

Question 29

How many subunits make up the GABAa receptor?

Answer 29

5

Question 30

How many transmembrane domains does each GABAa subunit have?

Answer 30

4

Question 31

What is the role of the transmembrane 2 domain on the GABAa?

Answer 31

Pore forming segment

Question 32

What is the subunit makeup of a GABAa receptor?

Answer 32

2 alpha, 2 beta, 1 gamma

Question 33

Where does GABA bind on GABAa?

Answer 33

Interface between alpha and beta subunit

Question 34

Why isnt there 3 GABAa binding sites?

Answer 34

The orientation of one of the alpha beta interfaces is incorrect so it cant be used as a binding site

Question 35

Which subunit do the δ, ε, π, θ and ρ take the place of?

Answer 35

gamma

Question 36

What is dependent on the subunit composition of GABAa receptors?

Answer 36

The inhibitory effect and the spatial distribution of the receptors

Question 37

GABA agonists?

Answer 37

Muscimol, GABA

Question 38

GABAa antagonists

Answer 38

bicuculline, gabazine

Question 39

What effect does the barbiturate/anesthetic binding site have on the GABAa receptor?

Answer 39

Prolong open time of channel

Question 40

What effect does the neurosteroid binding site have on the GABAa receptor?

Answer 40

Increase or decrease endogenous GABA inhibition

Question 41

Which molecules can bind to the GABAa channel blocking site?

Answer 41

Picrotoxin, pentylenetetrazole

Question 42

What effect does the channel blocking binding site have on the GABAa receptor?

Answer 42

block cl- permeability

Question 43

What effect does the benzodiazepine binding site have on the GABAa receptor?

Answer 43

increase frequency of channel opening

Question 44

What are GABAb receptors coupled to?

Answer 44

G alpha i/o

Question 45

What do GABAb receptors negatively regulate?

Answer 45

Adenyl cyclase and cyclic amp

Question 46

GABAb receptor agonists?

Answer 46

GABA, baclofen

Question 47

What do G beta gamma subunits regulate?

Answer 47

Ion channels

Question 48

What does the g beta gamma subunit do presynaptically?

Answer 48

Closes calcium ion channels

Question 49

What do GABAb receptors do postsynaptically?

Answer 49

Open K+ channels, allowing K+ to leave the cell thus hyperpolarising the postsynaptic neuron

Question 50

How many subunits are required to make a GABAb receptor?

Answer 50

2

Question 51

Where is GABAbR1?

Answer 51

In the ER

Question 52

Where is GABAbR2?

Answer 52

In the cell membrane

Question 53

What happens if there is a GABAbR2 that needs to be expressed in the cell surface?

Answer 53

GABAbR1 travels to the cell surface

Question 54

When GABAbR1 and 2 are expressed at the CSM, what type of interaction do their cytoplasmic domains form?

Answer 54

A coil-coil interaction

Question 55

Which subunit on GABAb does GABA bind to?

Answer 55

GABAbR1

Question 56

What is baclofen used to treat?

Answer 56

muscle spasticity