Neurotransmitter systems II:GABA and glycine Flashcards
What do inhibitory neurotransmitters do and how does this happen?
Inhibitory neurotransmitters hyperpolarize membranes:
- This happens by the ligand binding Cl- to enter the cell
- Also it can happen by opening K+ channels causing K+ to leave the cell
What is GABA synthesised by alongside what cofactor and enzymes?
Synthesised by glutamate converted to GABA by glutamate decarboxylase with cofactor vitamin B6
Where is GABA synthesised?
Synthesised in the nerve terminals
What is GABA transported into vesicles by?
Transported into vesicles by VIAAT
What shape are vesicles which contain glutamate?
Vesicles which contain glutamate are round
What shape are vesicles which contain GABA or glycine?
Vesicles which contain GABA or glycine are more oval shaped
What is the GABAA receptor?
Is a ligand gated cl- channel
What structure does a GABAA receptor have?
Has a pentameric structure
What subunits are possible in a GABAA receptor?
- 6 alpha subunits
- 3 beta subunits
- 3 gamma subunits
What is the most common configuration of a GABAA receptor?
-2 alpha,2 beta, 1 gamma is the most common configuration
Where are GABAA receptors most commonly found?
Most commonly found postsynaptically
What 3 things is GABA activity terminated upon?
- Terminated upon the reuptake of GABA by GAT
- By the breakdown of GABA by GABA transaminase
- By the diffusion of GABA away from the synapse
What binding sites does a GABAA receptor have?
Has multiple sites
-Agonist/Antagonist binding site
-2 GABA need to bind between alpha and beta interface
for channels to open
-Benzodiazepine binding site
-Channel modulators
-These tend to increase conductance of Cl- through
channels
-Allosteric modulators
-Channel blockersWhat is a GABAB receptors?
Is a G protein coupled receptor
What can GABAB receptors form?
Can form dimers
What is GABAB receptors coupled to?
Is Gi/o coupled
What 2 major effects does the GABAB receptor have?
- Opens K+ channels making inside of the cell more negative
2. Blocks Ca2+ gated ion channel
What is epilepsy?
Too much excitation in the brain
What can treat epilepsy?
Increasing inhibition by increasing hyperpolarisation can reduce excitation:
- GABAA receptor enhancers
- GAT blockers
- GABA transaminase inhibitor
- GAD modulators
- Prodrug
What is glycine synthesised by?
Synthesised by the conversion of 3-phosphoglycerate to serine to glycine
Where is glycine synthesised?
Synthesised in nerve terminals
What is glycine transported into vesicles by?
Transported into vesicles by VIAAT
What is a glycine receptor?
Is a ligand gated Cl- channel
What structure does a glycine receptor have?
Has a pentameric structure
What subunits do glycine receptors have a possibility of?
- 4 alpha subunits
- 1 beta subunit
What is the most common configurations of the glycine receptor?
- 3 alpha, 2 beta
- 4 alpha, 1 beta
Where are glycine receptors most commonly found?
Found most commonly pre or post synaptically
What 3 ways is glycine activity terminated upon?
- Reuptake of glycine by GlyT
- By glycine decarboxylase breaking down glycine
- By neurotransmitters diffusing away from the synaptic cleft
In whom can glycine receptor deficiency occur?
Can occur in goats
How do goats compensate to glycine receptor deficiency?
-As the goats mature, GABAA receptors are regulated to compensate
