Dopamine Flashcards

1
Q

Source

A

Tyrosine==> l-dopa==> dopamine

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2
Q

Rate limiting step

A

tyrosine hydroxylase

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3
Q

Breakdown enzymes

A
  • monoamine oxidase (MAO) and Catechol-o-methyl transferase (COMT)
  • MAO-A selectively metabolises norepinephrine and serotonin
  • MAO-B more selectively metabolises dopamine
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4
Q

Breakdown product

A

-Homovanillic acid

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5
Q

Reuptake

A
  • Dopamine transported

- cocaine inhibits this transporter

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6
Q

Function

A

-motivation, novelty seeking, reward circuitry, arousal and motor movement in basal ganglia

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7
Q

Receptors

A
  • 5 types D1-5
  • all G protein coupled
  • D1-like= D1 and D5- increase adenylate cyclase (stimulatory)
  • D1 is post-synaptic and resistant to antagonism
  • D5 is more limbic in distribution and has 10x higher dopamine affinity
  • D2 like= D2,3&4- decrease adenylate cyclase (inhibitory)
  • D4 is in the frontal cortex and clozapine has a high affinity
  • D4 selective antagonists do not have antipsychotic efficacy
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8
Q

Disorders

A
  • low level in Parkinson’s
  • high is psychosis especially at mesolimbic area
  • may be low in anhedonia and negative symptoms in mesocortical area
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