Serotonin Flashcards

1
Q

Where can serotonin be found in nature? (3 items)

A
  1. Plants
  2. Invertebrate venoms
  3. Vertebrate physiology
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2
Q

What essential amino acid is serotonin derived from?

A

Tryptophan

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3
Q

What is the rate limiting step of Serotonin synthesis?

A

Tryptophan hydroxylase

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4
Q

What limits the synthesis of Serotonin in the brain?

A

Tryptophan concentration

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5
Q

What similar enzyme to Tryptophan hydroxylase is used for catecholamine synthesis?

A

L-aromatic amino acid decarboxylase

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6
Q

Where is Serotonin converted to melatonin?

A

Pineal gland

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7
Q

What is Serotonin metabolized to?

By what enzyme?

A

5-hydroxyindole by

Monoamine oxidase

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8
Q

How is serotonin related neuronal action terminated?

A

SERT - high affinity active uptake system

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9
Q

Once serotonin is taken back up into the neuron to terminate neuronal action, what is it converted to?

A

5-hydroxyindoleacetic acid

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10
Q

Where is Serotonin located in the body and in what percentages? (3 items)

A
  1. GI System - 90%
  2. Platelets - 8%
  3. CNS - 2%
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11
Q

What is different about presence of Serotonin in platelets vs. GI or CNS?

A

Platelets cannot synthesize Serotonin

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12
Q

Where are the cell bodies of neurons that produce Serotonin in the CNS?

A

Midbrain - raphe nuclei

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13
Q

Is turnover of Serotonin in the brain fast or slow?

A

Fast - < 4 hours

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14
Q

Most serotonin receptors are _____ receptors.

A

G-protein coupled

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15
Q

5-HT1 A-E receptors have what type of molecular activity?

A

Inhibition of adenylate cyclase

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16
Q

5-HT1 A has what secondary activity besides inhibiting adenylate cyclase?

A

It opens K+ channels

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17
Q

5-HT2 A-C receptors have what type of molecular activity?

A

Phosphatydil Inositol hydrolysis (DAG/IP3/Ca+ system)

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18
Q

5-HT3 receptors have what kind of molecular activity?

A

Open ligand-gated Cation channel

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19
Q

5-HT4-7 receptors have what kind of activity?

A

Activation of adenylate cyclase

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20
Q

Serotonin auto-receptors do what?

A

Decrease serotonin release

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21
Q

Is turnover of GI system synthesis and storage fast or slow?

A

Slow ~1day

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22
Q

What action does serotonin release have on GI smooth muscle?

What symptomatic effect does this create?

A

Contraction of GI smooth muscle in esophagus, stomach, and intestine
This increases tone, peristalsis and diarrhea

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23
Q

Which receptor stimulates emesis and where is it located?

A

5-HT3 in GI tract and brain

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24
Q

What is the relationship of Carcinoid syndrome (enterochromaffin cell tumors) and serotonin?

A

They secrete serotonin and bradykinin causing diarrhea and asthma

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25
Q

What effect does Serotonin have on large arteries and veins?

A

Potent vasoconstriction

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26
Q

What effect does Serotonin have on cranial blood vessels and by what receptor?

A

Vasoconstriction by the 5-HT1D receptor

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27
Q

What effect does Serotonin have on Coronary, skeletal muscle, and cutaneous blood vessels?

A

Vasodilation

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28
Q

The Bezold-Jarisch reflex via the coronary chemoreceptors results in what symptoms? (3 items)

A
  1. Bradycardia
  2. Hypotension
  3. Hypoventilation
29
Q

What effect does excess Serotonin in the blood have on platelets?

A

Increased platelet aggregation by active uptake of Serotonin from the circulation.

30
Q

Projections from the cell bodies of serotonin related neurons in the raphe nuclei project in which direction?

A

Both rostrally and caudally

31
Q

What areas of CNS function might serotonin be involved in? (9 items)

A
  1. Sensory perception
  2. Sleep (slow wave deep sleep)
  3. Temperature regulation
  4. Neuroendocrine regulation (release of ACTH, GH, prolactin, TSH, FSH, and LH)
  5. Learning and memory (particularly short term)
  6. Pain perception
  7. Drug abuse
  8. Emesis
  9. Mental Illness
32
Q

What type of serotonin related drugs are used for Affective disorders?

A

SSRIs and SNRIs

33
Q

What type of serotonin related drugs are used for schizophrenia?

A

atypical anti-psychotics

34
Q

What type of serotonin related drugs are used for OCD?

A

SSRIs

35
Q

What type of receptors are associated with Anxiety?

A

5-HT1 A receptors

36
Q

What relatively non-specific 5-HT2 receptor agonist is a potent hallucinogen?

A

Lysergic acid diethylamide

37
Q

What receptor is LSD an agonist for?

A

5-HT2

38
Q

What 5-HT1 A receptor partial agonist is used for anti-anxiety?

A

Busprione

39
Q

What receptor is Buspirone a partial agonist for?

A

5-HT1 A

40
Q

What 5-HT1 D receptor agonist is used for migraine headaches?

A

Sumatriptan

41
Q

What is the mechanism of action for Sumatriptan?

A

It inhibits the release of vasoactive peptides - Calcitonin gene related peptide - CGRP

42
Q

Is sumatriptan a prophylactic or abortive medication for headaches?

A

abortive - it stops existing headaches

43
Q

What are the side effects of sumatriptan? (5 items)

A

Nausea, vomiting, angina, dizziness, flushing

44
Q

What 5-HT4 partial agonist is used for irritable bowel syndrom with constipation in women?

A

Tegaserod (Zelnorm)

45
Q

What does Tegaserod do?

A

It normalizes impaired intestinal motility and stimulates intestinal secretion

46
Q

Lorcaserin (Belviq) is used for what?

A

It is used in treatment of obesity for adults with a BMI equal to or greater than 30 or adults with a BMI of 27 or greater who “have at least one weight-relate health condition”

47
Q

What type of action does Lorcaserin (Belviq) have?

A

It is a selective 5-HT2 C receptor agonist

48
Q

What is the mechanism of action for Lorcaserin (Belviq)

A

Activation of 5-HT2 C receptors in the hypothalamus activates POMC production and consequently promotes weight loss through satiety.

49
Q

What two classes of drugs are indirect serotonin agonists?

A

Serotonin Specific Re-uptake Inhibitors (SSRIs)

Monoamine Oxidase Inhibitors (MAOIs)

50
Q

What is the prototype SSRI for this course?

A

Fluoxetine

51
Q

What is the effect of Fluoxetine?

A

It blocks active re-uptake of serotonin. This increases the amount of transmitter in the synapse.

52
Q

What are the therapeutic uses for SSRIs like Fluoxetine?

A

Affective disorders, OCD, Panic attacks

53
Q

What are some of the adverse effects/side effects of SSRIs like Fluoxetine? (2 items)

A

Sexual dysfunction, Nausea

54
Q

What are some other SSRIs? (4 drugs)

A

Sertraline, Paroxetine, Fluvoxamine, Citalopram

55
Q

What is the prototype MAOI for this course?

A

Phenelzine

56
Q

What is the mechanism of action of MAOIs like Phenelzine?

A

They block the metabolism of Serotonin, NE and DA which increases synaptic Serotonin.

57
Q

What are two therapeutic uses for MAOIs?

A

Affective disorders and Narcolepsy (due to NE effect)

58
Q

What are three serotonin antagonists?

A
  1. Cyproheptadine
  2. Ondansetron
  3. Alosetron
59
Q

What receptor is Cyproheptadine an antagonist of?

A

5-HT2

60
Q

What receptor does Cyproheptadine secondarily antagonize?

A

Histamine H1

61
Q

What are the therapeutic uses of of Cyproheptadine? (4 items)

A
  1. Allergies
  2. Pruritis
  3. Urticaria
  4. Carcinoid Syndrome
62
Q

What 5-HT3 receptor antagonist is used for the treatment of chemo, post-op, and xray induced N/V?

A

Ondansetron

63
Q

What is the location of action of Ondansetron?

A

CNS and GI

64
Q

What two receptors do atypical antipsychotics like Clozapine and Olanzapine block?

A

5HT2 and Dopamine

65
Q

What 5HT3 receptor antagonist is used to treat diarrhea predominant IBS in women?

A

Alosetron

66
Q

Why must a restricted prescribing program be followed?

A

It can produce severe GI adverse effects

67
Q

What receptors does Melatonin use?

A

It has it’s own receptors M1 and M2

68
Q

What type of receptors are Melatonin’s M1 and M2 receptors?

A

Gi associated receptors

69
Q

What is the primary purpose of Melatonin?

A

It entrains the circadian clock