Glutamate and GABA

Question 1

Explain the feature of glutamate and the number of receptors

Answer 1

most common excitatory neurotransmitters in the brain

all excitatory neurones fire glutamate

is glutamic acid but since it cannot break through the bbb, therefore has to be synthesised in the brain from glutamine

generated from glutamic acid and synthesised from glutamine

4 receptors that can bind to (3 ion receptors and 1 GPCR)

Question 2

Explain NMDA receptors

Answer 2

more than 6 binding sites
the receptor that activates when glutamate binds to it
however, couple of criteria before activation

1. glutamate and glycine bind at different sites
2. magnesium does not block the NMDA receptor

other binding sites modulate the function of the receptor

Question 3

Name the antagonists of NMDA receptors

Answer 3

alcohol
antagonist of NMDA receptors
leads to the inhibition of the NMDA receptors = less pain and thoughts and only strong signals go through the receptors
therefore leads to sedative effects and memory effect of alcohol
however it is the agonist of GABA

Ketamine and Phencyclidine
antagonists for NMDA receptors
cause dissociative hallucinations (unsure why)
also causes suicidal thoughts and psychosis
Ketamine itself is safe

Question 4

Explain the relationship between glutamate and psychosis

Answer 4

psychosis is a cluster of symptoms, not a disease
some study hypothesises a correlation between glutamate and psychosis. However, the results are controversial
patients with psychosis do not show any difference in brain structural scans, which has to suggest an issue with chemical communication instead

Psychosis symptoms of 75% of patients with NMDA-R encephalitis will be dismissed

Question 5

Full name of GABA and the features and synthesis of GABA

Answer 5

GABA = gamma-amino butyric acid
primary inhibitory transmitter
found in gabaergic neurons (inhibitory neurones)
form like a net (short neurones)
GABA helps the detection of incoming signals and the fire of glutamate by silencing nearby noise
GABA is generated from glutamic acid (which is the acid that creates glutamate)
synthesis of GABA
glutamine > glutamate > GABA > reuptake of the released GABA > glutamate > glutamine
however, although glutamine can be found in all neurones, glutamate neurones only fire glutamate, and GABA-ergic neurones only fire GABA

Question 6

How many GABA receptors are there and what are the antagonists and agonists of them

Answer 6

2 GABA receptors (GABA-A ion channels and GABA-B GPCR)
Agonist
Benzodiazepines (sedative actions)
Muscimol
Barbiturates
Alcohol

Antagonists
Picrotoxin

Question 7

Facts of seizures and the connection between GABA and seizures

Answer 7

Seizures = general and partial
can be caused by the abnormality of the gene that controls the ion channels
can also caused by the abnormalities of GABA and GABA receptors