serotonin
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Questions and Answers

What is the primary mechanism by which CGRP is released in migraineurs?

  • Binding of lysergic acid diethylamide to 5-HT receptors
  • Increased estrogen levels
  • Activation of the trigeminovascular system (correct)
  • Decreased levels of serotonin

    • What is the primary effect of decreased serotonin levels in the trigeminovascular system?

  • Decreased nociceptive information to central neurons
  • Increased levels of CGRP (correct)
  • Constriction of arteriovenous anastomoses
  • Increased carotid blood flow

    • What is the role of 5-HT receptors in the trigeminovascular system?

  • To increase carotid blood flow
  • To constrict arteriovenous anastomoses
  • To increase levels of CGRP
  • To decrease levels of CGRP (correct)

    • What is the effect of a drop in estrogen levels on serotonin metabolism?

    <p>Decreases serotonin metabolism</p> Signup and view all the answers

    What type of molecules are used in migraine management?

    <p>Molecules that act as agonist/antagonist of 5-HT receptors</p> Signup and view all the answers

    What is the current status of olcegepant and telcagepant in migraine therapy?

    <p>They are under consideration as antimigraine therapy</p> Signup and view all the answers

    What is the mechanism of action of methysergide in migraine prophylaxis?

    <p>Constriction of arteriovenous anastomoses</p> Signup and view all the answers

    What is the primary difference between triptans and ergot derivatives?

    <p>Triptans have fewer side effects than ergot derivatives</p> Signup and view all the answers

    What is the primary advantage of olcegepant and telcagepant over triptans?

    <p>They selectively block CGRP receptor without the vasoconstrictive effect of triptans</p> Signup and view all the answers

    What is the primary mechanism of action of sumatriptan, zolmitriptan, rizatriptan, and frovatriptan?

    <p>They are selective agonists on 5-HT1B/1D receptor</p> Signup and view all the answers

    Study Notes

    5-HT Synthesis and Regulation

    • 5-HT synthesis involves the rate-limiting enzyme tryptophan hydroxylase and is mainly degraded by monoamine oxidases.
    • 95% of 5-HT is synthesized, stored, and released by enterochromaffin cells in the intestinal mucosa.

    5-HT and the Immune System

    • 5-HT signaling modulates the peripheral immune system.
    • Different immune cells, including T cells, macrophages, mast cells, dendritic cells, and platelets, can generate, store, respond to, and/or transport serotonin.
    • Serotonin modulates cytokine secretion in monocytes/macrophages and can suppress the release of TNF-α and IL-1β by activating serotonin receptors (5-HT2A).
    • Neutrophil recruitment and T-cell activation can be mediated by serotonin.

    5-HT and Food Intake

    • Serotonin can affect food intake via activation of the anorexigenic melanocortin system involving 5-HT2c receptors.
    • It also inhibits the orexigenic NPYergic system.
    • Reducing brain serotonin by reducing the availability of its precursor tryptophan has been shown to be beneficial in treating anorexia during cancer.

    5-HT Receptors and Functions

    • 5-HT receptors occur on other neurons in the ENS, where they can be stimulatory (5-HT3 and 5-HT4).
    • The availability of serotonergic prokinetic drugs has been restricted due to serious adverse cardiac events.
    • Prucalopride is a specific 5-HT4R agonist that facilitates cholinergic neurotransmission.

    Migraine and 5-HT Receptors

    • Recurrent unilateral headache which may be accompanied by GI and visual disorders, more prevalent in females than males (3:1).
    • 5-HT receptors, particularly 5-HT1, 5-HT2, and 5-HT3, are responsible for migraine.
    • Serotonin principally acts on serotonin receptors in the trigeminovascular system to lower levels of key molecules such as CGRP.

    Migraine Management

    • Molecules that act as agonist/antagonist of 5-HT receptors in the trigeminovascular system are used in migraine management.
    • CGRP receptor antagonists, such as olcegepant and telcagepant, are under consideration as antimigraine therapy.

    Ergot Derivatives and Triptans

    • Lysergic acid diethylamide (LSD), methysergide, and triptans (e.g., sumatriptan, zolmitriptan, rizatriptan, frovatriptan) are used in migraine treatment.
    • Triptans are potent cranial vasoconstrictors with neural antimigraine activity, selectively agonist on 5-HT1B/1D receptors.
    • Olcegepant and telcagepant selectively block CGRP receptors without the vasoconstrictive effect of triptans.

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