Ionotropic Glutamate Receptors Quiz
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Questions and Answers

Which of the following are regarded as agonists for kainate receptors?

  • NMDA
  • PCP
  • Domoic acid (correct)
  • BMAA
  • What is a characteristic feature of AMPA and Kainate receptor subunit mutations?

  • They always lead to epilepsy.
  • They enhance synaptic plasticity.
  • They only affect GluD subunits.
  • They are linked to conditions like mental retardation. (correct)
  • Which ions can kainate receptors primarily allow to pass through?

  • Na+ and K+ (correct)
  • Only Ca2+
  • Mg2+ and Na+
  • Ca2+ and Cl-
  • Which of the following substances acts as a channel blocker for NMDA receptors?

    <p>Ketamine</p> Signup and view all the answers

    What potential risks are associated with excessive activation of glutamate receptors?

    <p>Excitotoxicity due to Ca2+ influx</p> Signup and view all the answers

    Which of the following subunits are part of the NMDA receptor?

    <p>GluN1</p> Signup and view all the answers

    What is required for the activation of the NMDA receptor?

    <p>Binding of both glutamate and glycine</p> Signup and view all the answers

    What role does Mg2+ play in the function of the NMDA receptor?

    <p>It blocks the channel under resting conditions</p> Signup and view all the answers

    What effect does ketamine have on the NMDA receptor?

    <p>It serves as an open channel blocker</p> Signup and view all the answers

    Which of the following is NOT an agonist for AMPA receptors?

    <p>NMDA</p> Signup and view all the answers

    Which receptor subunit mutation is associated with focal epilepsy?

    <p>GluN2A</p> Signup and view all the answers

    What is the primary effect of amantadine at NMDA receptors?

    <p>It serves as a channel blocker</p> Signup and view all the answers

    Which property distinguishes AMPA receptors from NMDA receptors?

    <p>AMPA receptors have low permeability to Ca2+</p> Signup and view all the answers

    What is the primary functional role of L-Glutamate in the central nervous system?

    <p>It is the main excitatory neurotransmitter.</p> Signup and view all the answers

    Which receptor type is NOT classified as an ionotropic glutamate receptor?

    <p>GABAA receptor</p> Signup and view all the answers

    What is the structure of ionotropic glutamate receptors?

    <p>Tetramers composed of four protein subunits.</p> Signup and view all the answers

    Which subunit is NOT part of the NMDA receptor?

    <p>GluK3</p> Signup and view all the answers

    What can sodium valproate stimulate?

    <p>GABA decarboxylase.</p> Signup and view all the answers

    What ion permeability is associated with AMPA receptors?

    <p>Na+ and Ca2+.</p> Signup and view all the answers

    What is a key action of Ketamine at NMDA receptors?

    <p>It acts as an open channel blocker.</p> Signup and view all the answers

    What physiological process is mediated by ionotropic glutamate receptors?

    <p>Excitatory neurotransmission.</p> Signup and view all the answers

    Which of the following statements is correct regarding the types of ionotropic glutamate receptors?

    <p>NMDA receptors can form both homo- and hetero-oligomers.</p> Signup and view all the answers

    Which of the following ions does NOT penetrate the NMDA receptor?

    <p>Mg2+</p> Signup and view all the answers

    Study Notes

    Ionotropic Glutamate Receptors

    • Ionotropic glutamate receptors are a type of ligand-gated ion channel receptor.
    • They are responsible for mediating excitatory neurotransmission in the central nervous system.
    • There are three main types of ionotropic glutamate receptors: NMDA, AMPA, and kainate.
    • These receptors are tetramers, meaning they are composed of four protein subunits.
    • They can be either homo-oligomers (AMPA receptors) or hetero-oligomers (NMDA, kainate receptors).

    NMDA Receptors

    • Composed of GluN1, GluN2A, GluN2B, GluN2C, GluN2D, GluN3A and GluN3B subunits.
    • Agonists include glutamate and NMDA.
    • Permeable to Na+, K+ and highly permeable to Ca2+.
    • Require binding of both glutamate and the co-agonist glycine for activation.
    • The channel of the NMDA receptor is normally blocked by Mg2+.
    • Following membrane depolarisation the Mg2+ ions are removed and the channel is able to conduct.

    Drugs Targeting NMDA Receptors

    • Ketamine: Open channel blocker at the NMDA receptor. Used in the induction and maintenance of anaesthesia.
    • Amantadine: Antiviral used to treat influenza, but also acts as a channel blocker at NMDA receptors. Indicated for treatment of Parkinson’s disease.

    AMPA Receptors

    • Composed of GluA1, GluA2, GluA3 and GluA4 subunits.
    • Agonists: glutamate and AMPA.
    • Kainate and domoic acid have low potency at AMPA receptors.
    • Permeable to Na+ and K+ with little permeability to Ca2+.

    Kainate Receptors

    • Expressed as homo-oligomers of GluK1, GluK2 or GluK3 subunits.
    • GluK1-3 subunits can assemble into hetero-oligomers.
    • Agonists: glutamate, kainate and domoic acid.
    • Permeable to Na+ and K+ with little permeability to Ca2+.

    GluD1 and GluD2

    • "Orphan" receptor subunits.
    • Ligand not confirmed.
    • May be involved in synaptic plasticity.

    Drug Targets: AMPA, Kainate and NMDA Receptors

    • Excitotoxicity: rise in intracellular Ca2+ from glutamate receptor activation.
    • Neurotoxins: glutamate analogues domoic acid β-N-oxylaminoalanine (BOAA) and β-N-methylamino-L-alanine (BMAA).
    • Ischaemic neuronal death: mediated by NMDA and AMPA receptors.
    • PCP and ketamine are channel blockers for NMDA receptors.
    • Mutations of glutamate receptors are associated with epilepsy.

    Domoic Acid Poisoning

    • Domoic acid is a neurotoxin produced by the algae Pseudo-nitzschia.
    • It can accumulate in shellfish, specifically mussels.
    • Consumption of contaminated shellfish can lead to domoic acid poisoning.

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    Description

    This quiz delves into ionotropic glutamate receptors, focusing on their structure, function, and types, specifically NMDA receptors. Explore the complexity of excitatory neurotransmission and the pharmacological agents targeting these receptors.

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