GABA

Question 1

Is GABA inhibitory or excitatory?

Answer 1

Inhibitory

Question 2

GABA is inactivated by which reuptake molecules?

Answer 2

GAT

Question 3

GABA is synthesised from glucose from the:

Answer 3

Krebs cycle

Question 3

What enzyme synthesises GABA from glutamate?

Answer 3

GAD

Question 3

What are the vesicular transporters called?

Answer 3

VGAT

Question 4

Some GABA is transported by VAT into glial cells, what happens with the rest?

Answer 4

Taken back up by presynaptic terminal, metabolised into succinic aldehyde by GABA-T and recycled back into the krebs cycle

Question 4

What is the product of the krebs cycle which is converted into glutamate

Answer 4

alpha ketoglutarate

Question 5

GABA neurones are localised discretely, true or false?

Answer 5

False (found all throughout the brain in the cerebellum, hippocampus, hypothalamus, cortex., basal ganglia)

Question 6

When excitatory glutamate and inhibitory GABA fire at the same time, is the threshold for an action potential reached?

Answer 6

No - local depolarisation (GABA balances glutamate)

Question 7

What are the two types of GABA receptors?

Answer 7

GABAa (ionotropic) and GABAb (metabotropic)

Question 8

Is GABAa responsible for fast or slow inhibition?

Answer 8

Fast

Question 9

Where can GABAa receptors be found?

Answer 9

Postsynaptically

Question 10

Where can GABAb receptors be found?

Answer 10

Both post and pre

Question 11

What ions do GABAa receptors control?

Answer 11

Cl-

Question 12

What do GABAb receptors control?

Answer 12

K+, Ca2+ (can inhibit neurotransmitter release)

Question 13

How many subunits are in a GABA receptor?

Answer 13

5 (each made up of 4 transmembrane segments)

Question 14

Which transmembrane segment lines the ion channel pore?

Answer 14

2 (TM2)

Question 15

How many GABA binding sites are there on GABA receptors

Answer 15

2

Question 16

Other than GABA, what is its GABAa receptor agonist?

Answer 16

muscimol

Question 17

What are the GABAa receptor antagonists?

Answer 17

bicuculline, gabazine

Question 18

Other than GABA, what is a GABAb agonist?

Answer 18

baclofen

Question 19

What are the antagonists of GABAb?

Answer 19

2-hydroxy saclofen, CGP55845A

Question 20

Does GABAb (the alpha subunit) inhibit or activate adenylyl cyclase?

Answer 20

inhibit

Question 21

Presynaptic GABAb couple to which ion channels?

Answer 21

Ca2+

Question 22

Postsynaptic GABAb couple to which ion channels?

Answer 22

K+

Question 23

Postynaptic GABAb opens or closes K+ channels and this leads to…

Answer 23

Opens, slow hyperpolarisation (inhibitory effect)

Question 24

Presynaptic GABAb opens or closes Ca2+ channels and what does this cause?

Answer 24

Closes, inhibits neurotransmitter release

Question 25

How many GABAb units are required to make a functional GABAb receptor?

Answer 25

2 (GABAb R1 and GABAb R2)

Question 26

Which unit of the GABAb receptor does GABA bind to?

Answer 26

GABAb R1

Question 27

Which unit of the GABAb receptor is coupled to the G protein?

Answer 27

GABAb R2

Question 28

What is used for muscle spasms and how does it work?

Answer 28

GABAb agonist baclofen, activates postsynaptic GABAb receptors in motor neurones

Question 29

What is used for epilepsy and how does it work?

Answer 29

GABAb antagonists (e.g. 2-hydroxy saclofen, CGP 55845A) which increase GABA release and therefore synaptic inhibition

Question 30

What effects do GABAb receptor agonist and antagonists have as drugs?

Answer 30

They are sedatives, baclofen is anxiolytic