Pharmacology lecture 14

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What are the symptoms of Parkinsons disease?
Resting tremor, muscle rigidity, suppression of voluntary movements
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What is Parkinsons disease?
It is the degeneration of DAergic neurones of the nigrostriatal tract. Loss of DA neurotransmission (D2 receptors) in the striatum.
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What is Parkinsonism?
ANY condition with loss of striatal DA transmission
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Name the 4 dopamine pathways.
1) Nigrostriatal 2) Mesolimbic 3) Mesocortical 4) Tuberoinfundibular
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What does the nigrostriatal pathway consist of?
Substantia nigra to striatum - Parkinsons
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What does the mesolimbic pathway consist of?
Ventral segmental area to nucleus accumbens
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What does the mesocortical pathway consist of?
Ventral segmental area to frontal cortex
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What does the tuberoinfundibular pathway consist of?
Arcuate nucleus to pituitary gland
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What are the two isoforms of monoamine oxidase?
MAOa, MAOb
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DA is mainly metabolised by.....
MAOb
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There are 2 dopamine receptors, what are they?
D2 and D1
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What does the D2 receptor do?
Inhibitory. Inhibit adenylate cyclase or open K+ channel - hyperpolarizing
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What does the D1 receptor do?
Excitatory. Stimulate adenylate cyclase
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What transports dopamine into the vesicles?
VMAT
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What happens if you give someone with Parkinsons L-DOPA?
Bypasses rate limiting step
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What is L-DOPA given with and why?
Carbidopa. It stops L-DOPA being metabolised by aromatic AA decarboxylase
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Why do we not give DA itself?
Its polar - can't cross membranes. Metabolised by MAO in the gut
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Name an MAOb inhibitor and what does it do?
Selegiline. Blocks intraneural metabolism of DA.
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Name some drugs that interact with D2 receptors and the side effects of these drugs
Bromcriptine, apomorphine, lisuride. Side effects: Psychosis, cognitive dysfunction
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What is Iatrogenic Parkinsonism?
Where antipsychotic drugs block D2 receptors in ALL 4 pathways. Increased D2 mediated neurotransmission in mesocortical and mesolimbic systems (Schizophrenia and psychotic illness)
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Card 2

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What is Parkinsons disease?

Back

It is the degeneration of DAergic neurones of the nigrostriatal tract. Loss of DA neurotransmission (D2 receptors) in the striatum.

Card 3

Front

What is Parkinsonism?

Back

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Card 4

Front

Name the 4 dopamine pathways.

Back

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Card 5

Front

What does the nigrostriatal pathway consist of?

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