Abstract
In mice, activation of sigma1 receptors antagonizes opioid analgesia. Sigma antagonists potentiate opioid analgesia, implying that the anti-opioid sigma system is tonically active. Co-administration of haloperidol with the mu opioid morphine, the kappa 1 analgesic U50,488H or the kappa 3 agonist naloxone benzoylhydrazone enhances the analgesic activity of all agents. The effect results from sigma receptor blockade since (-)sulpiride, a selective D2 antagonist which does not block sigma receptors, is inactive.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
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Analgesics / pharmacology*
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Animals
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Drug Synergism
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Haloperidol / pharmacology
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Morphine / pharmacology
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Naloxone / pharmacology
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Narcotics / pharmacology*
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Pain Measurement / drug effects
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Pyrrolidines / pharmacology
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Rats
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Rats, Sprague-Dawley
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Receptors, sigma / antagonists & inhibitors*
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Sulpiride / pharmacology
Substances
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Analgesics
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Narcotics
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Pyrrolidines
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Receptors, sigma
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Naloxone
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3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
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Morphine
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Sulpiride
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Haloperidol