Two Mouse Strains Had Opposite Stress Pain Relief Despite Similar Opioid Systems
C57 mice showed strong stress-induced pain relief while DBA mice did not — the difference traced to how their opioid receptors respond to stress rather than peptide levels.
Quick Facts
What This Study Found
DBA mice had higher baseline pain thresholds than C57 mice. But C57 mice showed much greater stress-induced analgesia (pain relief from stress).
The opioid systems differed genetically: DBA mice had significantly more dynorphin in the hypothalamus and neurointermediate pituitary. C57 mice had lower KD values (better affinity) for spinal mu receptors but higher KD (lower affinity) for cerebral kappa receptors.
Under stress, the two strains activated different opioid systems. C57 mice: beta-endorphin decreased in hypothalamus and increased in neurointermediate pituitary lobe. DBA mice: dynorphin decreased in hypothalamus and beta-endorphin increased in the anterior pituitary.
Both strains showed spinal cord dynorphin decreases under stress.
Key Numbers
How They Did This
C57BL/6 and DBA/2 mice compared for baseline pain thresholds, opioid peptide concentrations (beta-endorphin and dynorphin in brain and pituitary), opioid receptor binding (mu and kappa), and stress-induced changes. Two stress procedures tested.
Why This Research Matters
This study demonstrated that genetic differences in the opioid system produce dramatically different pain and stress responses. It helps explain why people respond differently to pain and stress, and why opioid medications work better in some people than others.
The Bigger Picture
Genetic differences in opioid receptor sensitivity may explain why some people respond well to stress and pain while others do not — with implications for personalized pain medicine.
What This Study Doesn't Tell Us
Tested in two inbred mouse strains, which represent extreme genetic uniformity. Human opioid system variation is much more complex. Only two stress procedures tested. The causal relationship between opioid differences and behavioral differences was not established.
Questions This Raises
- ?Do similar receptor variants exist in humans?
- ?Could receptor profiling predict pain treatment response?
Trust & Context
- Key Stat:
- Receptor sensitivity, not peptide levels Determined which mouse strain got pain relief from stress
- Evidence Grade:
- Preliminary animal study comparing two inbred strains — good genetic control but limited to two genotypes.
- Study Age:
- Published in 1988 — early pharmacogenomics of opioid pain response.
- Original Title:
- The difference in stress-induced analgesia in C57BL/6 and DBA/2 mice: a search for biochemical correlates.
- Published In:
- Polish journal of pharmacology and pharmacy, 40(5), 497-506 (1988)
- Authors:
- Przewłocka, B(3), Vetulani, J, Lasoń, W(2), Dziedzicka, M, Silberring, J, Castellano, C, Przewłocki, R
- Database ID:
- RPEP-00089
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Why do some people handle pain better than others?
Genetic differences in opioid receptor sensitivity — not the amount of natural painkillers — appear to determine how effectively the body suppresses pain under stress.
What is stress-induced analgesia?
Natural pain relief that occurs during intense stress. The body releases opioid peptides that suppress pain — useful in emergencies but variable between individuals due to receptor genetics.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-00089APA
Przewłocka, B; Vetulani, J; Lasoń, W; Dziedzicka, M; Silberring, J; Castellano, C; Przewłocki, R. (1988). The difference in stress-induced analgesia in C57BL/6 and DBA/2 mice: a search for biochemical correlates.. Polish journal of pharmacology and pharmacy, 40(5), 497-506.
MLA
Przewłocka, B, et al. "The difference in stress-induced analgesia in C57BL/6 and DBA/2 mice: a search for biochemical correlates.." Polish journal of pharmacology and pharmacy, 1988.
RethinkPeptides
RethinkPeptides Research Database. "The difference in stress-induced analgesia in C57BL/6 and DB..." RPEP-00089. Retrieved from https://rethinkpeptides.com/research/przewlocka-1988-the-difference-in-stressinduced
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.