Neurotransmitter Systems II : GABA & Glycine Flashcards
What is the criteria for being a neurotransmitter?
β The molecule must be synthesized and stored in a presynaptic neuron
β The molecule must be released by the presynaptic axon terminal upon stimulation
β the molecule must produce a response in the post synaptic cell
What are the two main methods that inhibitory neurotransmitters use?
β Influx of negative ions via chloride channels
β Efflux of positive ions via potassium channels
Describe the conversion from Glutamate to GABA?
β Carboxylic acid group is removed from glutamate to make GABA
β vitamin B6 (pyridoxal phosphate) acts as a cofactor
How is GABA transported into vesicles?
β VIAAT
β vesicular inhibitory amino acid transporters
What is the difference in shape between glutamate, GABA and glycine vesicles?
β Glutamate vesicles are round
β GABA or glycine vesicles are more oval in shape
Where are GABA A receptors found?
β Postsynaptically
β They can sometimes be found presynaptically on glia
What are the two ways that GABA can be broken down?
β GABA transaminase
β can diffuse away from the synapse
Between what two receptors does GABA bind?
β Alpha and beta receptors
How many molecules of GABA are needed for the GABA A channels to open?
β 2 molecules
Where is the benzodiazepine binding site found?
β At the alpha and gamma interface of the GABA A receptor
What are channel modulators?
β They increase the conductance of chloride through the GABA A channels such as alcohol
What is an example of a GABA A channel blocker?
β Picrotoxin
What type of G protein is a GABA B receptor?
β Gi protein channel
What is one of the major effects of the GABA B receptors?
βit opens K+ channels so it hyperpolarizes
What is another effect of the GABA B receptor?
β It blocks Ca2+ channels
What are the 4 types of GABA A receptor enhancers?
β Barbiturates
β Benzodiazepines
β Progesterone
β Ganaloxone
What is an example of a GABA transaminase inhibitor?
β Vigabatrine
How do the majority of epileptics work?
β Increasing inhibition
β Enhance the currents through GABA A
What is the transporter that takes GABA to the presynaptic terminal?
β GAT
Describe the steps for glycine synthesis?
3-phosphoglycerate (glycolysis) β serine (serine hydroxy methyl transferase) β glycine