Abstract
We compared morphine analgesia ED(50) values of male and female mice prior to (Day 1) and after (Day 4) 3 days of intracerebroventricular morphine injections. Increases in ED(50) values from Day 1 to Day 4, indicating tolerance, were of similar magnitude in both sexes. The data suggest that spinal opioid analgesic mechanisms, acting alone or in synergy with supraspinal loci, may contribute to pharmacodynamic explanations of sex differences in systemic morphine tolerance.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Analgesics, Opioid / administration & dosage
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Analgesics, Opioid / pharmacology
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Analysis of Variance
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Animals
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Cerebral Ventricles / drug effects
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Cerebral Ventricles / physiology*
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Drug Administration Schedule
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Drug Tolerance*
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Female
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Injections, Intraventricular
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Male
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Mice
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Morphine / administration & dosage
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Morphine / pharmacology*
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Sex Characteristics
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Time Factors
Substances
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Analgesics, Opioid
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Morphine