Opioid Receptors
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A group of g-coupled proteins with opioids as Ligands.
o They are found in the brain, spinal cord and in the digestive tract.
o Their responsibility is that of supra-spinal analgesia but they also have many other significant effects:
Receptor
Functions
Delta
Analgesia, antidepressant, convulsant, dependency,
respiratory depression
Kappa
Analgesia, anticonvulsant, depression and anxiety,
hallucinations, pupil constriction, sedation, stress
Mu
Analgesia, dependency, respiratory depression,
pupil constriction, euphoria, constipation by
reduced GI peristalsis, dependency, hypotension by
vasodilation
Following the administration of Morphine sulphate, histamine is released which contributes further to the
vasodilation (and hypotension) and can sometimes produce a rash and bronchoconstriction.