Abstract
Rats received an injection of Freund's complete adjuvant into the right hindpaw and developed localized inflammation. Four to six days after inoculation, the antinociceptive effect of both the mu-agonist, morphine, and the kappa-agonist U-50,488H, administered subcutaneously, was markedly enhanced in the inflamed paws. This effect was dose dependently antagonized by low dose of intraplantar, but not subcutaneous or intravenous, (-)-naloxone. (+)-Naloxone was inactive. These data indicate that the enhanced antinociceptive effects of both agonists in inflammation are mediated by a peripheral, opioid receptor-specific mechanism.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
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Analgesics*
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Animals
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Freund's Adjuvant
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Inflammation / drug therapy
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Inflammation / etiology
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Inflammation / physiopathology
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Male
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Morphine / pharmacology
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Naloxone / pharmacology
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Pyrrolidines / pharmacology
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Rats
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Rats, Inbred Strains
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Receptors, Opioid / drug effects*
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Receptors, Opioid / physiology
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Receptors, Opioid, kappa
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Receptors, Opioid, mu
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Stereoisomerism
Substances
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Analgesics
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Pyrrolidines
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Receptors, Opioid
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Receptors, Opioid, kappa
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Receptors, Opioid, mu
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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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Freund's Adjuvant