Describe the major neurotransmitters and their physiological role, with particular reference to GABA, excitatory and inhibitory amino acids, acetylcholine, noradrenaline, dopamine and serotonin and NMDA receptor


Gamma aminobutyric acid is the major inhibitory CNS neurotransmitter. GABA receptors have three subtypes:

    Ionotropic receptor important for the action of many drugs.
    • Pentameric structure
      • 2 α
        Bind GABA.
      • 2 β
      • 1 γ
    • Affected by many different drugs:
      • Benzodiazepines
        Positive allosteric modulation at at the α/γ interface.
      • General anaesthetic agents
        Including propofol, barbiturates, halogenated volatiles, and etomidate.
        • Act at the β subunit
          Cause a conformational change which increases Cl- opening time, hyperpolarising the cell.
    Metabotropic receptor.
    Ionotropic receptor located only in the retina.


N-methyl D-aspartate receptor is an ionotropic receptor that is:

  • Agonised by glutamate
    • Glycine is co-agonist
  • Voltage dependent
    • Central pore usually blocked by an Mg2+ ion
    • Becomes unblocked when partially depolarised
  • Important in the action of drugs which do not act at the GABAA receptor
    Agonised by:
    • Ketamine
    • Xenon
    • N2


  1. Petkov V. Essential Pharmacology For The ANZCA Primary Examination. Vesselin Petkov. 2012.
Last updated 2017-09-21

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