Noradrenaline Flashcards
Which system does noradrenaline exert its effect on?
Sympathetic nervous system
How are noradrenaline/catecholamines synthesised? (derivative)
Synthesised from dietary tyrosine sources
Synthesis of catecholamine; Noradrenaline (Steps)
Tyrosine | (Tyrosine hydroxylase) DOPA | (DOPA decarboxylase) Dopamine | (Dopamine B-hydroxylase) Noradrenaline
How are monoamines transported after synthesis?
By VMAT2 into vesicles
What is the function of vesicles?
They protect neurotransmitters from degradation
Give examples of noradrenaline degradation
main enzymes
Monoamine oxidase
Catechol-O-methyl transferase (COMT)
List 3 potential sites of drug action
Storage of neurotransmitters
Influx of Ca (inhibition)
Inactivation of neurotransmitter = (increases levels of neurotransmitters)
What is the location of noradrenergic neurons in the brain?
Locus coerulus
The pathway for noradrenaline?
Locus coerulus projections via 5 tracts
What type of receptors does noradrenaline bind to?
GPCRs (Metabotropic)
List different uptake processes that noradrenaline can undergo.
Neuronal uptake 1 (NET)
Extraneuronal uptake 2 (EMT)
EMT
Why are noradrenaline uptake pathways therapeutically important?
NET and EMT 1 are important for psychiatry.
Inhibiting the degradation of dopamine
Name the 2 enzymes important for noradrenaline degradation
Monoamine oxidase (MAO) Catecho-O-methyl transferase (COMT)
Name any 2 of the steps in monoamine neurotransmission that are potential sites of antidepressant action
Inhibiting the influx of calcium ions
Inhibition of vesicle exocytosis
Location of noradrenergic pathways in the brain
Neurons project from the locus coerulus (A6) pathway
What is the role/relationship of noradrenaline and arousal
Firing of the locus coerulus is greater when awake than sleep.
Projections areas are medial septal and preoptic area
List some of the functions served by noradrenaline in the central nervous system
Consolidating emotional behaviours (E.g. passive avoidance)
Role in arousal
Activation of which receptor type is likely to have an inhibitory effect on the target cells?
Alpha 2 A receptor. It is linked to secondary messenger system Gi protein
What is the rate determining step in the synthesis of catcecholamines?
Tyrsosine hydroxylase
What can the drug recerpine result in?
Extreme behavioural sedation
What receptors does noradrenaline have an effect on?
Adrenoreceptors
Where is the enzyme MAO predominately found?
In the brain
How does methylphenidate produce cognitive enhancing effects?
Blocks the reuptake of catecholamines & increases prefrontal cortex (PFC) levels of adrenaline
