Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacology > Principles of GABA-ergic Transmission > Flashcards

Principles of GABA-ergic Transmission Flashcards

1
Q

What are the two main inhibitory amino acid neurotransmitters?

A

GABA

Glycine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the main excitatory amino acid neurotransmitters?

A

Glutamate
Aspartate
(L-homocysteine – sulphur containing)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of amino acids are the inhibitory neurotransmitters?

A

Neutral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of amino acids are the excitatory neurotransmitters?

A

Acidic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why is GABA called GABA?

A

Gamma amino butyric acid

This is because the amino group is on the gamma carbon of GABA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the distribution of GABA neurones.

A 
Cerebral cortex 
Cerebellum 
Hippocampus  
Corpus striatum  
Hypothalamus  
Dorsal horn of spinal cord  
Relatively little in the PNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the morphology of GABA neurones.

A

They are generally short inhibitory interneurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where do you find longer GABA tracts?

A

Striato-nigral

Cerebellar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the main action of GABA neurones?

A

Widespread inhibitory action in the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the main functions of GABA neurones in terms of CNS activity?

A

Emotional control
Motor control
Extrapyramidal activity
Endocrine function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the precursor for GABA and what enzyme converts it to GABA?

A

Glutamic acid

Glutamic acid decarboxylase (GAD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where is this enzyme found?

A

This enzyme is exclusive to GABA nerve terminals – it is a marker for GABA neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What product of the Krebs’ cycle gives rise to glutamate?

A

Alpha-oxoglutarate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is GABA broken down?

A

Initially by GABA-T (GABA transaminase) to succinic semialdehyde
Succinic semialdehyde is broken down by succinic semialdehyde dehydrogenase (SSDH) to succinate
Succinate then enters the Krebs’ cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the release of GABA from GABAergic nerve terminals.

A

Calcium-mediated exocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the two main GABA receptors and why type of receptorsare they?

A 
GABA-A = type 1 – ionotropic  
GABA-B = type 2 – metabotropic
17
Q

How is GABA inactivated?

A

By reuptake

18
Q

What are the uptake mechanisms dependent on?

A

Sodium dependent

Energy dependent

19
Q

Where are the transport proteins for GABA found?

A

Presynaptic neurones

Glial cells

20
Q

What type of enzymes are the enzymes that break down GABA?

A

Mitochondrial enzymes

21
Q

What type of enzyme is GAD?

A

Cytoplasmic enzyme

22
Q

Name two drugs that are used as anti-convulsants that decrease the metabolism of GABA.

A 
Sodium valproate (acts on GABA-T and SSDH (but more so on SSDH)) 
Vigabatrin (selective GABA-T inhibitor)
23
Q

Where are GABA-A receptors found?

A

Postsynaptic

24
Q

Describe the structure of GABA-A receptors.

A 
They are ionotropic receptors (type 1) 
They have a pentameric structure consisting of the following subunits:
 2 x alpha 
 2 x beta 
 1 x gamma
25
Q

What is the mechanism of action of GABA-A receptors?

A

GABA binding causes opening of the chloride channel leading to chloride influx
This causes hyperpolarisation of the postsynaptic neurone (inhibitory post-synaptic potential)
This causes inhibition of firing

26
Q

Name two agonists of GABA-A.

A

GABA

Muscimol

27
Q

Name two antagonist of GABA-A

A

Bicuculline (competitive antagonist)

Picrotoxin (non-competitive antagonist)

28
Q

What effect do the antagonists have?

A

They are convulsants

They are used experimentally but not therapeutically

29
Q

Where are GABA-B receptors located?

A

Presynaptic

30
Q

What is the effect of GABA-B?

A

It is the negative feedback receptor for GABA release (similar to the effect of alpha-2 receptors on noradrenaline release)

31
Q

What are the two different terms used to describe GABA-B receptors that regulate GABA release and other neurotransmitter release (e.g. dopamine)?

A

Autoreceptors – when they regulate GABA release

Heteroreceptors – when they regulate the release of other neurotransmitters

32
Q

Describe the mechanism of action of GABA-B receptors.

A

G protein linked receptor
Causes a decrease in calcium conductance
Reduction in neurotransmitter release
Stimulation of GABA-B also causes a reduction in cAMP

33
Q

Name two agonists of GABA-B receptors.

A

Baclofen

GABA

34
Q

Name an antagonist of GABA-B receptors.

A

Saclofen (competitive antagonist)

35
Q

What can GABA-B receptor agonists be used for?

A

Muscle relaxant and spasmolytic
Mechanism – reduced GABA release in the spinal cord and reduced activation of alpha motor neurone output causes relaxation of skeletal muscles
This reduces spasticity

36
Q

Describe how G-protein coupling works.

A

GABA binds to the GABA receptor and changes its conformation so that it can bind the alpha subunit of the G protein
The alpha subunit normally has GDP bound to it, when it binds to the receptor it exchanges GDP for GTP
The alpha-GTP subunit is active at the target
The alpha subunit breaks down GTP to GDP, which then inactivates it

Pharmacology (32 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions