NEUROTRANSMITTER SYSTEMS Flashcards
(23 cards)
Outline the 5 criteria for defining a Neurotransmitter
1) synthesis in nerve terminal
2) storage in nerve terminal vesicles
3) Ca2+ regulated release
4) Post-synaptic effect
5) Inactivation by specific mechanism
Name the 4 chemical categories of Classical Neurotransmitters
Amino Acids
Derivative of AAs
Peptides
Esters
Give examples of Amino Acid Neurotransmitters
Glutamate, GABA and Glycine
Give examples of Derivative of AA Neurotransmitters
Dopamine, Norepinephrine, 5-HT and Histamine
What chemical class of Neurotransmitter does Ach belong?
Esters
Name the 3 classes of Atypical Neurotransmitters
1) Nucleotides/ Nucleosides
2) Lipid Derivatives
3) Gases
Give an example of a Lipid Derivative Neurotransmitter
Endocannabinoids; are derived from membrane phospholipids. They aren’t released in vesicles. They are retro-transmitters.
Describe the role of Glutamate in the CNS
Is very high conc. as its the major excitatory NT. In the synapse, glutamate is converted to glutamine by the enzyme glutamine synthase
Describe the synthesis of GABA
Glutamate is converted to GABA by the enzyme Glutamic Acid Dehydrogenase (GAD), the process is highly linked with the Krebs Cycle
describe the synthesis of ACh
Ach is the ester of choline and acetyl-CoA, the enzyme Choline acetytransferase (ChAT) transfers the Acetylt group from acetyl-CoA onto Choline
Describe the degradation of ACh
The enzyme Acetyl cholinesterase (AChe) breaks the eser bond and produces choline and acetyl. Ache is present in the synaptic cleft
What is the rate limiting step of Ach formation?
The availability of Choline, aka the rate of transport of choline into the neuron by the plasma membrane High affinity Choline Uptake System (HACU)
What are the 3 Catecholamines?
Dopamine, Norepinephrine and Epinephrine
What amino acid are the catecholamines derivatives of?
Tyrosine
What is L-Dopa and how is it made?
The precursor of Dopamine
Tyrosine + Tyrosine Hydroxylase –> L-DOPa
What enzyme is responsible for the formation of Dopamine?
AADC changes L-DOPA to Dopamine
How is Norepinephrine synthesised from Dopamine?
The enzyme DBH adds a hydroxyl group to Dopamine thus producing Norepinephrine. The DBH is held in vesicles so DA is transported into a vesicle where it is changed to NE
How is Epinephrine made?
The enzyme PNTM methylates NE, producing Epinephrine.
What is the name of the enzyme responsible for the breakdown of the Catecholamines?
Monoamine Oxidase.
What are the Indoleamines?
The NTs derived from tryptophan
Describe the synthesis of 5-HT
The enzyme Tryptophan Hydroxylase converts Tryptophan to 5-HT
What are the Imidazoles?
The NTs derived from Histidine.
How is Histamine produced?
A single decarboxylation reaction of histidine by the enzyme Histidine Decarboxylase produces Histamine
