Intrathecal opioids block a spinal action of substance P in mice: functional importance of both μ-and δ-receptors
JLK Hylden, GL Wilcox - European journal of pharmacology, 1982 - Elsevier
JLK Hylden, GL Wilcox
European journal of pharmacology, 1982•ElsevierInhibition of intrathecal substance P-elicited behavior by μ-, δ-and κ-opioids was compared.
In both the substance P behavioral test and the tail flick antinociceptive test, intrathecal [D-
Ala 2, Met 5] enkephalinamide and [D-Ala 2, D-Leu 5] enkephalin (DADL) were equipotent,
morphine and ethylketazocine were less potent, but nalorphine was inactive. A long-lasting,
highly selective, μ-receptor antagonist, β-funaltrexamine, blocked the inhibition of substance
P behaviors by both morphine and ethylketazocine, but did not block the effect of DADL …
In both the substance P behavioral test and the tail flick antinociceptive test, intrathecal [D-
Ala 2, Met 5] enkephalinamide and [D-Ala 2, D-Leu 5] enkephalin (DADL) were equipotent,
morphine and ethylketazocine were less potent, but nalorphine was inactive. A long-lasting,
highly selective, μ-receptor antagonist, β-funaltrexamine, blocked the inhibition of substance
P behaviors by both morphine and ethylketazocine, but did not block the effect of DADL …
Abstract
Inhibition of intrathecal substance P-elicited behavior by μ-, δ- and κ-opioids was compared. In both the substance P behavioral test and the tail flick antinociceptive test, intrathecal [D-Ala2,Met5]enkephalinamide and [D-Ala2, D-Leu5]enkephalin (DADL) were equipotent, morphine and ethylketazocine were less potent, but nalorphine was inactive. A long-lasting, highly selective, μ-receptor antagonist, β-funaltrexamine, blocked the inhibition of substance P behaviors by both morphine and ethylketazocine, but did not block the effect of DADL. These results suggest that spinal postsynaptic modulation of nociception is mediated by both δ-type and μ-type opioid agonists.
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