GABA

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 14

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

Answer 14

Seizures and epilepsy

Question 15

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

Answer 15

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 16

What kind of receptor is GABAa?

Answer 16

Ligand gated ion channel

Question 17

What kind of receptor is GABAb?

Answer 17

GPCR

Question 18

Where are GABAa receptors generally found?

Answer 18

postsynaptically

Question 19

Where are GABAb receptors generally found?

Answer 19

pre and postsynaptically

Question 20

What speed of inhibition does GABAa receptors mediate?

Answer 20

fast

Question 21

What speed of inhibition does GABAb receptors mediate?

Answer 21

slow

Question 22

To which ion is the GABAa ion channel permeable to?

Answer 22

Cl-

Question 23

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

Answer 23

Ca2+ and K+

Question 24

Which GABA receptor can inhibit transmitter release?

Answer 24

GABAb

Question 25

Why do GABAb receptors exhibit a slow inhibition?

Answer 25

Second messenger systems take time

Question 26

What does the K+ Cl- transporter do?

Answer 26

Transports K+ and CL- out of the postsynaptic neuron

Question 27

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

Answer 27

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

Question 28

How many subunits make up the GABAa receptor?

Answer 28

5

Question 29

How many transmembrane domains does each GABAa subunit have?

Answer 29

4

Question 30

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

Answer 30

Pore forming segment

Question 31

What is the subunit makeup of a GABAa receptor?

Answer 31

2 alpha, 2 beta, 1 gamma

Question 32

Where does GABA bind on GABAa?

Answer 32

Interface between alpha and beta subunit

Question 33

Why isnt there 3 GABAa binding sites?

Answer 33

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

Question 34

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

Answer 34

gamma

Question 35

What is dependent on the subunit composition of GABAa receptors?

Answer 35

The inhibitory effect and the spatial distribution of the receptors

Question 36

GABA agonists?

Answer 36

Muscimol, GABA

Question 37

GABA antagonists

Answer 37

bicuculline, gabazine

Question 38

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

Answer 38

Prolong open time of channel

Question 39

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

Answer 39

Increase or decrease endogenous GABA inhibition

Question 40

Which molecules can bind to the GABAa channel blocking site?

Answer 40

Picrotoxin, pentylenetetrazole

Question 41

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

Answer 41

block cl- permeability

Question 42

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

Answer 42

increase frequency of channel opening

Question 43

What are GABAb receptors coupled to?

Answer 43

G alpha i/o

Question 44

What do GABAb receptors negatively regulate?

Answer 44

Adenyl cyclase and cyclic amp

Question 45

GABAb receptor agonists?

Answer 45

GABA, baclofen

Question 46

What do G beta gamma subunits regulate?

Answer 46

Ion channels

Question 47

What does the g beta gamma subunit do presynaptically?

Answer 47

Closes calcium ion channels

Question 48

What do GABAb receptors do postsynaptically?

Answer 48

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

Question 49

How many subunits are required to make a GABAb receptor?

Answer 49

2

Question 50

Where is GABAbR1?

Answer 50

In the ER

Question 51

Where is GABAbR2?

Answer 51

In the cell membrane

Question 52

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

Answer 52

GABAbR1 travels to the cell surface

Question 53

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

Answer 53

A coil-coil interaction

Question 54

Which subunit on GABAb does GABA bind to?

Answer 54

GABAbR1

Question 55

What is baclofen used to treat?

Answer 55

muscle spasticity