GABA and Glutamate Flashcards
1
Q
glutamate
A
- glutamate is the main excitatory NT in the brain
- estimated that over half the synapses release glutamate
- 80% of cerebral cortex consists of pyramidal cells (glutamatergic)
- glutamate= Glutamic acid
- glutamate is an amino acid that acts as a NT in its og form, but this amino acid does not pass the blood brain barrier, so needs to be synthesized in the brain
2
Q
neurotransmitters: excitory
A
- found in most of the long projection neurons throughout the cortex
- excitatory connections are ‘point-point’ many region-specific functions.
3
Q
Glutamate receptors
A
- 4 major types
- 3 are ion channels
- NMDA receptor
- AMPA receptor
- Kainate receptor
- ## 1 is G-protein couples - the metabotropic glutamate receptor
4
Q
NDMA receptors: alcohol
A
- alcohol is an NDMA antagonist
- reduction in glutamate is believed to contribute to the general sedative effects and memory effects of alchol
- alcohol is also GABA agonist which further leads to brain inhibition
5
Q
NDMA Receptors: PCP and ketamine
A
- PCP and ketamine are both NDMA antagonists, both cause dissociative hallucinations (people feel disconnected rather than perceiving visions)
- risk of psychosis
6
Q
Ketamine and depression
A
- Ketamine is being trialed for the past decade which looks at kets affect on depression,
Looks at treatment resistant depression, they found that during trials comparing different depression meds, there is a dramatic shift of mood. Ketamine has been shown to be very effective.
7
Q
Glutamate and psychosis
A
- Psychosis= symptom cluster not a diagnosis.
- Schizophrenia = 1 % of population, psychosis = 3% of the population
- Delusions, hallucination, depression, anxiety, suicidal thoughts, difficulty functioning, disorganized thought, apathy, anhedonia.
- Some have suggested a link between glutamate and psychosis but this is controversial and is likely to involve other neurotransmitters such as DA
- Regardless of exact neurotransmitters involvement, the symptoms suggest widespread disruption and lack of coherent integration of sensory information
- It makes sense because glutamate is in control of our sensory perceptions, which is what psychosis affects
No MAJOR structural differences in psychosis, so illustrates the importance of chemical balance in health perception and cognition.
8
Q
NDMA receptors and learning and memory
A
- NDMA receptors are critical for learning and memory, perception and synaptic plasticity in general
- large genetic studies identify NDMA receptor genes as likely being rel in schizo, but also relevant for IQ
9
Q
GABA
A
- GABA is the primary inhibitory NT- decreasing the liklehood of the post synaptic neuron firing
- without the inhibitory synapses, the brain would be unstable with neurons firing uncontrollable, each excitatory neuron exciting the next neuron- causing seizure
10
Q
GABA overview in the brain
A
- most local neurons are inhibitory so they form a dense web around and between the excitatory neurons (20% of cerebral cortex interneurons.)
11
Q
role of gaba
A
- in a healthy brain GABA helps the delicate coordination of neurons to signal very specific information
- neurons are selective but not perfect- inhibitory networks reduce the likelihood neurons fire for the non-preferred stimulus
12
Q
GABA: synthesis
A
- GABA is produced from glutamic acid- glutamate is converted into GABA and GABA can be converted back to glutamate
13
Q
2 types of GABA receptors
A
- GABA receptors- ION channels
- GABA receptors- G protein-coupled
14
Q
GABA and seizure disorders
A
- are common with 400,000 in AUS
- seizure= sudden excessive activity of neurons
- epilepsy is a neurological disorder characterized by seizures
- epilepsy is believed to be caused by abnormality of the GABA neurons and in the gaba receptors
15
Q
generalized seizures
A
- widespread and involve most of the brain
