Delta-Opioid Peptide Triggered Hibernation in Active Ground Squirrels
A delta-opioid agonist (DADLE) induced hibernation in summer-active ground squirrels at rates comparable to the natural hibernation trigger — mu and kappa opioids had no effect.
Quick Facts
What This Study Found
DADLE (D-Ala2-D-Leu5 enkephalin), a delta-opioid receptor agonist, at 1.50 mg/kg/day induced summer hibernation comparable to that caused by natural Hibernation Induction Trigger (HIT).
Morphine (1.50 mg/kg/day), morphiceptin (0.82 mg/kg/day), and dynorphin A (0.82 mg/kg/day) did not induce hibernation.
Strikingly, morphine, morphiceptin, and dynorphin A actually antagonized HIT-induced hibernation. They blocked the natural hibernation signal.
This suggests delta-opioid receptors promote hibernation while mu and kappa opioid receptors promote the arousal (waking) state. Natural hibernation may involve a shift in the balance between these receptor systems.
Key Numbers
How They Did This
Summer-active thirteen-lined ground squirrels (Citellus tridecemlineatus) received continuous infusions of receptor-selective opioids. Hibernation Induction Trigger (HIT) from winter-hibernating animals was also tested alone and in combination with the opioids. Body temperature and behavioral state monitored.
Why This Research Matters
Hibernation involves dramatic metabolic slowdown that could have medical applications. If delta-opioid receptors control this switch, they could theoretically be used to induce therapeutic hypothermia in stroke, cardiac arrest, or organ preservation. This is one of the most fascinating areas of opioid peptide research.
The Bigger Picture
If delta-opioid pathways can induce a hibernation-like state, this could have revolutionary applications in emergency medicine, organ preservation, space travel, and therapeutic hypothermia.
What This Study Doesn't Tell Us
Tested in ground squirrels, a species with specialized hibernation biology. Results may not apply to non-hibernating mammals including humans. Only one delta agonist was tested. The mechanism by which delta receptors trigger hibernation was not identified.
Questions This Raises
- ?Could controlled hibernation be induced in humans for medical purposes?
- ?Is the hibernation trigger itself a delta-opioid peptide?
- ?Could this apply to organ preservation or space travel?
Trust & Context
- Key Stat:
- Delta-specific hibernation Only DADLE at 1.5 mg/kg/day induced summer hibernation — other opioid types failed
- Evidence Grade:
- Preliminary animal study in a specialized model — fascinating finding but limited to one species.
- Study Age:
- Published in 1988 — groundbreaking work connecting opioid receptors to metabolic suppression.
- Original Title:
- Further studies on opioids and hibernation: delta opioid receptor ligand selectively induced hibernation in summer-active ground squirrels.
- Published In:
- Life sciences, 43(19), 1565-74 (1988)
- Authors:
- Oeltgen, P R, Nilekani, S P, Nuchols, P A, Spurrier, W A, Su, T P
- Database ID:
- RPEP-00085
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
What is hibernation induction trigger?
A naturally occurring substance in hibernating animals that can trigger hibernation when injected into active animals. Its exact identity is still being researched.
Could humans ever hibernate?
Not naturally, but understanding the delta-opioid hibernation pathway could lead to controlled metabolic suppression for emergency medicine, surgery, or long-duration space travel.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-00085APA
Oeltgen, P R; Nilekani, S P; Nuchols, P A; Spurrier, W A; Su, T P. (1988). Further studies on opioids and hibernation: delta opioid receptor ligand selectively induced hibernation in summer-active ground squirrels.. Life sciences, 43(19), 1565-74.
MLA
Oeltgen, P R, et al. "Further studies on opioids and hibernation: delta opioid receptor ligand selectively induced hibernation in summer-active ground squirrels.." Life sciences, 1988.
RethinkPeptides
RethinkPeptides Research Database. "Further studies on opioids and hibernation: delta opioid rec..." RPEP-00085. Retrieved from https://rethinkpeptides.com/research/oeltgen-1988-further-studies-on-opioids
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.