Lecture 20 - Glutamate and GABA

Question 1

What does GABA do?

Answer 1

GAGA is the main inhibitory neurotransmitter.

Question 2

What does Glutamate do?

Answer 2

Glutamate is the main excitatory neurotransmitter.

Question 3

What are GABA and Glutamate?

Answer 3

Glutamate and GABA are neurotransmitters.

Question 4

What neurotransmitter do ALL excitatory neurones release?

Answer 4

Glutamate.

Question 5

Neurons are either excitatory or inhibitory neurons.
True or false?

Answer 5

True.

Question 6

Are glutamate and glutamic acid the same thing?

Answer 6

Yes. Glutamate and glutamic acid are the same thing. Glutamate is an amino acid. Glutamate cannot cross the blood brain barrier and needs to be synthesised in the brain. Glutamine is released from cells surrounding excitatory neurons, which uptake this glutamine and from it synthesise glutamate.

Question 7

What are thought to be two of the first neurotransmitters to evolve?

Answer 7

Glutamate and GABA

Question 8

Glutamate is the main …. neurotransmitters?

Answer 8

The main excitatory neurotransmitters.

Question 9

Glutamate is consumed in food. It is an amino acid and the structure of glutamate in food and glutamate in the brain is the same.
Why is it then that glutamate needs to be synthesised in the brain?

Answer 9

Glutamate cannot pass through the blood brain barrier.
Post consumption glutamate is broken down into glutamine and transported to glial cells (astrocytes) which then synthesise glutamate from glutamine or release glutamine and it is absorbed by glutamtergic neurons which synthesise glutamate from it.

Question 10

How many glutamate receptors are there?

Answer 10

There are 4 types of glutamate receptors - 3 ion-gated channels and oen G-protein coupled receptor

Question 11

What type of receptor is NMDA receptor?

Answer 11

It is an ion-gated channel and is responsive to glutamate.

Question 12

Why is NMDA a particularly complex neurotransmitter receptor?

Answer 12

NMDA is a receptor for glutamate and is an ion-gated channel for Calcium.
In order for the channel to open glutamate needs to bind, as well as glycine, AND the magnesium that blocks the intracellular portion of the receptor needs to release. There are other extracellular sites that can be bound by other ligands, such as Zinc, that also modulate the function of the receptor.

Question 13

What three things need to bind in order for NMDA to open/function?

Answer 13

Glutamate and glycine need to bind on the extracellular portion of the NMDA receptor and Magnesium needs to release from the intracellular portion of the NMDA receptor.

Question 14

Alcohol affects both glutamate and GABA pathways in the brain.
In regards to behaving as an agonist or antagonist, how does alcohol affect these two pathways?

Answer 14

Alcohol as an glutamate antagonist and a GABA agonist.
This leads to the sedative effect of alcohol and the associated loss of memory that come along with excessive drinking.

Question 15

How do PCP (phenilcyclidine)/angel dust and ketamine affect the Glutamate pathway of neural excitation?
What is another substance that alters glutamate function?

Answer 15

Both PCP and ketamine act as NMDA antagonists.
Alcohol is also another NMDA antagonist.

Question 16

Is “psychosis” a diagnosis?

Answer 16

No. It is a cluster of symptoms. Schizophrenia can have an experience of psychosis.

Question 17

Glutamate has been linked to psychosis.
However, this link is controversial and is likely to involve other neurotransmitters/neuromodulators.
True?

Answer 17

True.

Question 18

Psychosis is not typically involved with brain structure differences compared to neurotypical brains.
What does this suggest about the aetiology of psychosis?

Answer 18

This suggests that cause of psychosis is much more likely due to neurotransmitter/modulator abnormal functioning.

Question 19

What does GABA refer to?

Answer 19

Gamma-amino butyric acid

Question 20

GABA is the main…? neurotransmitter?

Answer 20

Inhibitory neurotransmitter.

Question 21

What is a SEIZURE?

Answer 21

Uncontrolled neuronal firing.

Question 22

How does GABA/inhibitory neurons contribute to neuronal selectivity to specific stimuli?

Answer 22

Whilst neurons are selective to specific stimuli, they are not perfect and GABA can aid in selectivity.

Question 23

Is GABA synthesised from glutamate?

Answer 23

Yes.

Question 24

Glutamate can be synthesised into GABA and GABA can be synthesised into glutamate.
True?

Answer 24

True.

Question 25

In our lecture series, we were told what about GABA and glutamate specialised neurons?

Answer 25

We were told, but my research suggested otherwise, that neurons either synthesise and release glutamate or GABA, but not both, despite the fact that glutamate can be synthesised into GABA and in fact, GABA is synthesised from glutamine before being synthesised into GABA in GABA specialised neurons.

Question 26

There are two types of GABA receptors. What are they?

Answer 26

Gaba-a receptors are ion-gated channels.
Gaba-b receptors are g-protein coupled receptors.

Question 27

Benzodiazepines and alcohol work as agonists on which receptor?

Answer 27

The work as agonists on the GABA-a ion-gated channels/receptors.

Question 28

Epilepsy is characterized by seizures and believed to be caused by which neurotransmitters and their receptors?

Answer 28

GABA and GABA receptors.

Question 29

What has been one of the key findings around the link between febrile seizures/epilepsy in children and vaccinations?

Answer 29

It was found that vaccination may lead to fever and the onset of a child’s first seizure/start of epilepsy. However, in unvaccinated children this first seizure happened a few months later. So the vaccines may have caused the first seizure to occur earlier than it may have, but it would likely have developed shortly thereafter nontheless.

Question 30

Are seizures genetics based?

Answer 30

It appears that seizures are more linked to brain tissue abnormalities than to genes per se.