Serotonin Flashcards

1
Q

Synthesis of Serotonin from L-Tryptophan.

  • 2 steps.

Which one is the rate-limiting step?

A

L-Tryptophan——->(via Tryptophan hydroxlase)

—-> L-5-Hydroxytryptophan(5-HTP)——(_Aromatic L-amino acid decarboxylase( AADC)_)

—–>5-Hydrozytryptamine(5-HT;Serotonin).

  • Conversion of tryptophan—>5-HT, is the rate-limiting step.
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2
Q

Function of Para-chlorophenylamine(PCPA)?

A
  • Blocks 5-HT synthesis,

via irreversibly inhibiting tyrosine hydroxylase.

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3
Q

L-tryptophan : amino acid and the blood-brain barrier?

A
  • Ratio determines is serotonin is synthesised or not in the brain.
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4
Q

Consequences of a low protein diet,and a high carbohydrate meal?

A
  • increase levels of tryptophan relative to ratio.
  • allowing more tryptophan to pass BBB and more serotonin to be made.
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5
Q

How is serotonin transported into vesicles?

Function of reserpine?

A
  • Transported via VMAT2( vesicular monoamine transporters).
  • Reserpine:
    • blocking VMAT, depletes 5-HT.
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6
Q

The difference in function between terminal autoreceptors and somatodendritic autoreceptors?

A
  • Terminal Autoreceptors: inhibit 5-HT release directly.
  • Somaticautodendritic autoreceptors:
    • inhibit release indirectly by slowing the rate of neuronal firing.
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7
Q

Physiology of MDMA(3,4-methylenedioxymethamphetamine)?

A
  • Stimulates the release of 5-HT.
  • Results in:
    • low doses: leading to treatment of chronic PTSD.
    • High doses: leading to neuropsychiatric impairment.

*

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8
Q

Function of SSRIs and examples?

Function of 5-HT transporters and SERT?

How is 5-HT broken down?

Effects of cocaine and MDMA?

A

SSRIs: Fluoxetine(prozac)

  • block 5-HT transporters and SERT.
    • prevents serotonin reuptake.

Broken down via MAO.

  • Cocaine and MDMA block SERT but also DA transporters.
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9
Q

Function of 5-HT1A receptors?

Where are these receptors concentrated?

what type of receptors are they in the dorsal and median raphe nuclei?

What are the actions of these receptors?

A

Function:

  • inhibitory, reducing AP potential.

Locations:

  • hippocampus, septal area, amygdala, and Dorsal raphe nucleus.

Type of receptor:

  • Somatodendritic autoreceptors in the dorsal and median raphe nuclei.

Actions:

  • inhibits adenylyl cyclase, reducing cAMP synthesis.
  • Increase K+ channel opening leading to membrane hyperpolarisation.
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10
Q

What is the function of Buspirone, Ipsapirone and 8-OHDPAT?

A
  • Are 5-HT1A receptor agonists.
  • Antidepressant and anxiolytic.
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11
Q

5-HT2A receptors:

  • area of high abundance of these receptors?
  • Result of activation?
  • Difference in function between LSD and Clozapine and risperidone?
A
  • HIgh abundance within the Cortex.
  • Activation:
    • activates phosphoinositide second-messenger system.
    • increase levels of Ca2+ and activates PKC.

LSD:

  • Hallucinogenic, stimulates 5-HT2A receptors.

Clozapine and Risperidone:

  • block 5-HT2A.
  • Used to treat schizophrenia, as it also blocks DA receptors.
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12
Q
A
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