W19/L3: Chemical transmission Flashcards
What are the functional requirements of a cell for neurotransmission?
Synthesis/storage
Release
Receptors
Inactivation
What initiates NA release?
Ca2+ influx
What is the pre-synaptic receptor for NA?
Alpha2 adrenoceptor
What enzyme metabolises NA?
MAO (monoamine oxidase)
What is the main process of NA inactivation?
Neuronal uptake (95%) Extraneuronal uptake (5%)
What is the benefit of using reuptake as the mechanism of NA inactivation?
It mean the molecule can be re-used. It’s “expensive” to have to manufacture new NA
CNS MoA of cocaine?
Blocks neuronal uptake of NA, dopamine and 5HT
(The dopaminergic effects are implicated in dependence
The 5HT effects are implicated in eurphoria)
How do indirectly-acting sympathomimetics act?
They displace the NA from the vesicle so it “leaks” out and acts on the adrenoceptors
What are some indirectly-acting sympathomimetics?
Amphetamine
Ephedrine
Are all NTs found all over the brain?
No some are widespread, but others are localised
Why is NO a unique NT?
It can’t be made in advance and stored in vesicles, so it has to be manufactured “on demand”
What are the steps of catecholamine synthesis?
Tyrosine enters the cell
Converted to L-DOPA by tyrosine hydroxylase
Converted to Dopamine by dopa decarboxylase
Enters the vesicle
Converted to NA by dopamine-beta-hydroxylase
Converted to adrenaline by PENMT
What’s an excitatory NT?
Glutamate
What’s an inhibitory NT?
GABA
What sort of receptor is the NicR?
Excitatory ligand-gated ion channel
causes Na+ influx
