Abstract
[D-Pen2, D-Pen5]enkephalin (DPDPE; 3-30 micrograms) and morphine (10 micrograms) both caused Straub tails, increased locomotion, and circling after ICV administration to ICR mice. DPDPE-induced tail stiffening was reduced when mice were pretreated with naloxone (0.5 mg/kg SC) or beta-funaltrexamine (10 micrograms ICV), but not with ICI 174864 (2 mg/kg SC), the selective antagonist at delta opioid receptors. These results point to (a) mu receptors mediating the tail stiffening and (b) the loss of delta receptor selectivity after 10 and 30 micrograms DPDPE.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Analgesics / pharmacology*
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Animals
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Behavior, Animal / drug effects*
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Dose-Response Relationship, Drug
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Enkephalin, D-Penicillamine (2,5)-
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Enkephalins / administration & dosage
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Enkephalins / pharmacology*
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Injections, Intraventricular
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Male
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Mice
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Mice, Inbred ICR
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Morphine / pharmacology*
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Motor Activity / drug effects
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Muscle Tonus / drug effects
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Naloxone / pharmacology
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Naltrexone / analogs & derivatives
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Naltrexone / pharmacology
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Narcotic Antagonists / pharmacology
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Stereotyped Behavior / drug effects
Substances
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Analgesics
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Enkephalins
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Narcotic Antagonists
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Naloxone
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Naltrexone
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beta-funaltrexamine
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Morphine
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Enkephalin, D-Penicillamine (2,5)-