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Updated: Mar 21, 2026
07:23
Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
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Opiates Modulate Noxious Chemical Nociception through a Complex Monoaminergic/Peptidergic Cascade
Holly Mills1, Amanda Ortega1, Wenjing Law1
1Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606.
Summary
Opioid agonists like morphine suppress withdrawal from noxious stimuli in C. elegans via the NPR-17 receptor and neuropeptides. This complex signaling pathway, involving serotonin and specific peptides, offers a model for mammalian opiate research.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Noxious stimuli detection and response are vital for survival.
- Opioid agonists, such as morphine, are widely used for pain management.
- The nematode Caenorhabditis elegans provides a model system for studying conserved biological pathways.
Purpose of the Study:
- To investigate the molecular mechanisms underlying opioid modulation of nociception in C. elegans.
- To identify the specific receptors and neuropeptides involved in this process.
- To explore the potential of C. elegans as a model for mammalian opiate signaling.
Main Methods:
- Utilized genetic analysis of npr-17-null mutants in C. elegans.
- Investigated the role of neuropeptides encoded by nlp-3 and nlp-24.
- Examined the effects of expressing human kappa opioid receptors in C. elegans.
- Administered opioid receptor agonists and ligands to assess behavioral responses.
Main Results:
- Opioid receptor agonists suppress withdrawal from noxious stimuli in C. elegans through the NPR-17 receptor.
- Serotonergic modulation of nociception involves neuropeptides NLP-3 and NLP-24, with differential functions.
- ASI sensory neuron opioid signaling inhibits neuropeptide release.
- Expression of human kappa opioid receptors rescues the null phenotype, and human ligands mimic opiate effects.
Conclusions:
- Opiate modulation of nociception in C. elegans involves a complex monoaminergic/peptidergic cascade.
- Specific neuropeptides, like NLP-3.3, play key roles, with some acting antagonistically.
- The C. elegans model system is valuable for dissecting conserved opiate signaling pathways relevant to mammals.
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