Abstract
Opioid agonists selective for mu- or delta opioid receptors inhibit adenylyl cyclase in membranes from rat caudate-putamen and nucleus accumbens. The presence of subtypes of delta opioid receptors has been suggested. In both brain regions we have found that the inhibition of adenylyl cyclase by DPDPE was more readily antagonized by 7-benzylidenenaltrexone (BNTX), than by naltriben. In contrast, the inhibitory effects of deltorphin-II and DSLET were more readily antagonized by naltriben, than by BNTX. Neither naltriben nor BNTX significantly antagonized the effect of a mu selective agonist. These results suggest that inhibition of adenylyl cyclase in caudate-putamen and nucleus accumbens is regulated by two forms of delta-opioid receptor with ligand selectivities similar to those two forms proposed to mediate analgesic effect.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenylyl Cyclase Inhibitors
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Adenylyl Cyclases / physiology*
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Analgesics / pharmacology
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Animals
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Benzylidene Compounds / pharmacology
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Caudate Nucleus / drug effects
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Caudate Nucleus / metabolism*
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Enkephalin, D-Penicillamine (2,5)-
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Enkephalin, Leucine / analogs & derivatives
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Enkephalin, Leucine / pharmacology
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Enkephalins / pharmacology
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Male
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Naltrexone / analogs & derivatives
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Naltrexone / pharmacology
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Narcotic Antagonists / pharmacology
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Nucleus Accumbens / drug effects
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Nucleus Accumbens / metabolism*
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Oligopeptides / pharmacology
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Rats
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Rats, Sprague-Dawley
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Receptors, Opioid, delta / classification
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Receptors, Opioid, delta / drug effects
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Receptors, Opioid, delta / physiology*
Substances
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Adenylyl Cyclase Inhibitors
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Analgesics
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Benzylidene Compounds
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Enkephalins
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Narcotic Antagonists
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Oligopeptides
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Receptors, Opioid, delta
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deltorphin II, Ala(2)-
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7-benzylidenenaltrexone
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Enkephalin, Leucine
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Naltrexone
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enkephalin, Ser(2), Leu(5), Thr(6)-
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Enkephalin, D-Penicillamine (2,5)-
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Adenylyl Cyclases
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naltrindole