ArticleJournal of neuroscience research2025
Sex and Strain Differences in Analgesic and Hyperlocomotor Effects of Morphine and μ-Opioid Receptor Expression in Mice.
Article in Journal of neuroscience research, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
1 citing paper in PubMed.
- Fentanyl decreases arterial blood oxygen saturation more than furanylfentanyl in mice due to increased apnea.Psychopharmacology · 2026Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
4 authors.
Funding
Abstract
Sex and gender differences in the analgesic efficacy and side effects of opioids have been widely reported, but their underlying neurobiological mechanisms remain poorly understood. Preclinical animal models are essential tools for investigating these differences and providing insights into the neurobiology of opioid effects. Although studies in rats have revealed sex-specific effects of opioids, the sex-dependent behavioral profiles of opioids in mice, particularly across strains, remain largely unexplored. In this study, we characterized sex and strain differences in the antinociceptive and hyperlocomotor effects of morphine in the two most widely used mouse strains-CD1 and C57BL/6-and quantified regional expression of the μ-opioid receptor (MOR) in key brain and spinal cord regions. Both strains exhibited clear, dose-dependent antinociceptive and hyperlocomotor responses to morphine. While no significant sex or strain differences were observed in antinociceptive effects, C57BL/6 mice displayed significantly greater hyperlocomotor activity than CD1 mice. Western blot analyses revealed strain-specific MOR expression, with CD1 mice showing higher spinal cord and periaqueductal gray MOR levels, particularly in females, while C57BL/6 mice exhibited elevated MOR expression in the caudoputamen. Morphine treatment increased spinal MOR expression in CD1 mice but not C57BL/6, suggesting strain-dependent regulation of MOR. These findings highlight strain-specific behavioral and molecular responses to morphine, emphasizing the importance of strain and sex considerations in preclinical opioid research.
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Registered trials
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