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Pharm Block 2 > 12 - Serotonin > Flashcards

12 - Serotonin Flashcards

1
Q

How is serotonin synthesized?

A

Tryptophan -(Trp hydroxylase)-> 5-hydroxytryptophan -(L- aromatic aa decarboxylase)-> Serotonin (5HT).

Rate limiting step is tryptophan hydroxylase; trp concentrations limit synthesis in the brain.

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2
Q

Serotonin is converted to melatonin in the _______.

A

Pineal gland.

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3
Q

What metabolizes serotonin? How is neuronal action terminated?

A

Metabolized to 5-hydroxyindole acetic acid by monoamine oxidase.

Neuronal action terminated primarily by a high affinityt active uptake system (SERT) and then intraneuronal convertion to 5-hydroxyindoleacetic acid.

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4
Q

Where is most of the serotonin in the body found? Where is the rest of it?

A

90% is found in the GI system.

8% found in platelets where they’re store in vessels.

2% in the CNS whose cell bodies are in the midbrain raphe nuclei and project to the limbic system, brainstem, and spinal cord.

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5
Q

Which serotonin receptor is not a GPCR?

A

5-HT3

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6
Q

What are the serotonin receptor subtypes? How does each work?

A
  1. 5-HT1(A-E): inhibition of adenylate cyclase.
    - 1A also opens K+ chennal
  2. 5-HT2(A-C): PI hydrolysis
  3. 5-HT3: ligand-gated cation chennal (brain)
  4. 5-HT4-7 - activates adenylate cyclase
  5. Autoreceptors: decrease serotonin releasem like 1A
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7
Q

What role does serotonin play in the GI system? Which receptor here causes emesis?

A

Synthesized and stored in neuronal and non-neuronal cells: slow turn-over (1 day).

Contracts GI smooth muscle , increases tone, causes peristalsis and diarrhea.

5-HT3 receptors in the GI tract and brain cause emesis.

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8
Q

What is carcinoid syndrome? How is it treated?

A

Tumors of the enterochromaffin cells of the intestines or stomach.

Secrete serotonin and bradykinin and can cause severe diarrhea and asthma.

Treated with somatostatin anologs which block secretion of all mediators, or serotonin antagonists

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9
Q

What effect does serotonin have on the CV system?

A

Potent vasoconstrictor of large arteries and veins, and (5-HTiD) cranial blood vessels.

Vasodilation in coronary, skeletal muscle, and cutaneous blood vessels.

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10
Q

How does serotonin cause the bezold-jarisch reflex? What other negative affect can serotonin have (unrelated to the first question)?

A

Serotonin activates coronary chemoreceptors and causes bradycardia, hypotension, and hypoventilation.

Platelet aggregation can result from active uptake of serotonin from circulation.

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11
Q

Where are the cell bodies of the neurons of the CNS that respond to serotonin? What are they involved in?

A

Cell bodies in the midbrain raphe nuclei and project rostrally and caudally.

Involved in sensory perception (LSD), slow wae deep sleep, temp regulation, neuroendocrine regulation (ACTH, GH, etc.), and learning and short-term memory.

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12
Q

What are the negative effects of serotonin?

A

Pain perception - spinal and brain sites of action

Drug abuse

Emesis via the 5-HT3 receptor

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13
Q

What are some uses of serotonin therapeutically?

A

Mental illness:

  • Affective disorder: SSRIs and SNRIs
  • Schizophrenia: atypical antipsychotics
  • OCD: SSRIs
  • Anxiety: 5-HT1A receptors (stimulated to decrease anxiety).
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14
Q

What are three serotonin agonists?

A
  1. Lysergic acid diethylamide
  2. Buspirone
  3. Sumatriptan
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15
Q

What is lysergic acid diethylamide? What does it act on?

A

LSD

Relatively non-specific, acts on 5-HT2 receptors.

Very potent hallucinogen (1mg/kg)

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16
Q

What receptor does Buspirone act on? What is it used for?

A

5-HT1A receptor partial agonist.

Anti-anxiety

17
Q

What receptor does Sumatriptan work on? What is its mechanism of action? What is it used to treat?

A

5-HT 1D and 1B receptors on cerebral blood vessels.

Inhibits release of vasoactive peptides- calcitonin gene related peptide (CGRP) to promote vasoconstriction.

Used to treat migraines and stop existing ones.

18
Q

What are side effects of Sumatriptan?

A

Nausea, vommitting, angina, dizziness, and flushing.

19
Q

What drug is a selective 5-HT 2C receptor agonist approved for the treatment of obesity in adults with a BMI equal or greater than 30? Who else is it approved for?

A

Lorcaserin

Also approvied for adults with a BMI or 27 or more with at least one weight-related health condiciton such as high BP, T2DB, or high cholesterol.

DEA schedule IV drug (low abuse potential)

20
Q

How does the drug Lorcaserin work?

A

It’s activates the 5-HT 2C receptors in the hypothalamus to activate proopiomelanocortin (POMC) production and consequently promote weight loss through satiety.

21
Q

What is an example of a SSRI that blocks active reuptake of serotonin and increases the amount of transmitter in the synapse? What is this used to treat? What are side effects?

A

Fluoxetine

MDD, OCD, and panic attacks.

Side effects: sexual dysfunction, nausea.

22
Q

What’s an example of a monoamine oxidase inhibitor that blocks the metabolism of serotonin, NE, and DA to increase synaptic serotonin? What is it used to treat? What are side effects?

A

Phenelzine

Treats MDD and narcolepsy (NE).

Side effects: food-induced hypertensive crisis.

23
Q

What SNRI has its effects by blocks reuptake of both serotonin and norepinephrine into neurons? What is it used to treat?

A

Duloxetine

MDD and pain.

24
Q

What drug is a 5-HT2 antagonist? What is it’s therapeutic use?

A

Cyproheptadine

Also an histamine H1 antagonist.

Used to treat allergies, pruritis, and urticaria, and carcinoid (tumor).

25
Q

What drug is a 5-HT3 antagonist? What is it’s therapeutic use?

A

Ondansetron

Treatment of chemotherapy induced nausea and vomiting, post-op and x-ray therapy induced nausea and vomiting.

Has CNS and GI action.

26
Q

What drug is a 5-HT3 antagonist used to treat diarrhea predominant in IBS women? What are some adverse effects?

A

Alosetron.

Can produce severe GI adverse effects. Restricted prescribing program must be followed.

27
Q

What is melatonin make from? What are the associated receptors? What is it’s function?

A

Serotonin in the pineal gland.

M1 and M2 - G1 associated.

Entrains circadian clock.

28
Q

What drug is a target for insomnia treatment?

A

Ramelteon

Melatonin analog

Pharm Block 2 (12 decks)

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