Noradrenaline

Question 1

Which system does noradrenaline exert its effect on?

Answer 1

Sympathetic nervous system

Question 2

How are noradrenaline/catecholamines synthesised? (derivative)

Answer 2

Synthesised from dietary tyrosine sources

Question 3

Synthesis of catecholamine; Noradrenaline (Steps)

Answer 3

Tyrosine 
| (Tyrosine hydroxylase)
DOPA
| (DOPA decarboxylase) 
Dopamine 
| (Dopamine B-hydroxylase)
Noradrenaline

Question 4

How are monoamines transported after synthesis?

Answer 4

By VMAT2 into vesicles

Question 5

What is the function of vesicles?

Answer 5

They protect neurotransmitters from degradation

Question 6

Give examples of noradrenaline degradation

main enzymes

Answer 6

Monoamine oxidase

Catechol-O-methyl transferase (COMT)

Question 7

List 3 potential sites of drug action

Answer 7

Storage of neurotransmitters
Influx of Ca (inhibition)
Inactivation of neurotransmitter = (increases levels of neurotransmitters)

Question 8

What is the location of noradrenergic neurons in the brain?

Answer 8

Locus coerulus

Question 9

The pathway for noradrenaline?

Answer 9

Locus coerulus projections via 5 tracts

Question 10

What type of receptors does noradrenaline bind to?

Answer 10

GPCRs (Metabotropic)

Question 11

List different uptake processes that noradrenaline can undergo.

Answer 11

Neuronal uptake 1 (NET)
Extraneuronal uptake 2 (EMT)
EMT

Question 12

Why are noradrenaline uptake pathways therapeutically important?

Answer 12

NET and EMT 1 are important for psychiatry.

Inhibiting the degradation of dopamine

Question 13

Name the 2 enzymes important for noradrenaline degradation

Answer 13

Monoamine oxidase (MAO)
Catecho-O-methyl transferase (COMT)

Question 14

Name any 2 of the steps in monoamine neurotransmission that are potential sites of antidepressant action

Answer 14

Inhibiting the influx of calcium ions

Inhibition of vesicle exocytosis

Question 15

Location of noradrenergic pathways in the brain

Answer 15

Neurons project from the locus coerulus (A6) pathway

Question 16

What is the role/relationship of noradrenaline and arousal

Answer 16

Firing of the locus coerulus is greater when awake than sleep.
Projections areas are medial septal and preoptic area

Question 17

List some of the functions served by noradrenaline in the central nervous system

Answer 17

Consolidating emotional behaviours (E.g. passive avoidance)

Role in arousal

Question 18

Activation of which receptor type is likely to have an inhibitory effect on the target cells?

Answer 18

Alpha 2 A receptor. It is linked to secondary messenger system Gi protein

Question 19

What is the rate determining step in the synthesis of catcecholamines?

Answer 19

Tyrsosine hydroxylase

Question 20

What can the drug recerpine result in?

Answer 20

Extreme behavioural sedation

Question 21

What receptors does noradrenaline have an effect on?

Answer 21

Adrenoreceptors

Question 22

Where is the enzyme MAO predominately found?

Answer 22

In the brain

Question 23

How does methylphenidate produce cognitive enhancing effects?

Answer 23

Blocks the reuptake of catecholamines & increases prefrontal cortex (PFC) levels of adrenaline