Abstract
The ability of naltrexone but not methyl naltrexone to cross the blood-brain barrier (BBB) was used to provide a different approach for the demonstration that opiates can enter the brain. Cortical electroencephalographic (EEG) measurements were made in rats receiving peripheral (IP) injections of naltrexone or methyl naltrexone and morphine or an enkephalin analog [Tyr-D-Ala-Gly-MePhe-Met(O)-ol]. Naltrexone significantly blocked the EEG effects of morphine and the enkephalin analog, but methyl naltrexone failed to do so. The results provide biological evidence that an opiate peptide can cross the BBB to affect the activity of the brain.
Publication types
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Comparative Study
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Blood-Brain Barrier* / drug effects
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D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / chemistry
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D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / pharmacokinetics*
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Electroencephalography
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MSH Release-Inhibiting Hormone / pharmacology
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Male
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Molecular Sequence Data
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Morphine / pharmacokinetics*
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Naltrexone / analogs & derivatives
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Naltrexone / pharmacology
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Quaternary Ammonium Compounds
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Rats
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Rats, Inbred Strains
Substances
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Quaternary Ammonium Compounds
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methylnaltrexone
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Naltrexone
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D-Ala(2),MePhe(4),Met(0)-ol-enkephalin
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Morphine
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MSH Release-Inhibiting Hormone