Delta Opioid Receptors in the Smell Center Stimulate Cell Signaling Instead of Inhibiting It
Delta opioid receptors in the rat olfactory bulb stimulate (rather than inhibit) adenylate cyclase, with deltorphin I being the most potent agonist at EC50 of 6.7 nM.
Quick Facts
What This Study Found
Delta opioid receptors primarily mediate adenylate cyclase stimulation in olfactory bulb. Deltorphin I EC50 = 6.7 nM. Mu receptors contribute. Kappa receptors inactive.
Key Numbers
How They Did This
Rat olfactory bulb homogenates treated with selective opioid agonists and antagonists. Adenylate cyclase activity measured. Concentration-response curves and antagonist profiles determined.
Why This Research Matters
Identifying the specific receptor (delta) responsible for unusual stimulatory opioid signaling helps explain how the same receptor family can produce opposite effects in different brain regions.
The Bigger Picture
This shows opioid receptors aren't one-trick ponies. The same receptor type can produce opposite effects depending on where in the brain it's located. This flexibility makes the opioid system far more versatile — and drug design more challenging.
What This Study Doesn't Tell Us
In vitro tissue homogenate study. Cannot identify the specific cell types responsible. The G-protein coupling mechanism for stimulation was not fully characterized.
Questions This Raises
- ?Why do delta receptors stimulate rather than inhibit signaling in the olfactory bulb?
- ?Do opioids affect the sense of smell through this mechanism?
Trust & Context
- Key Stat:
- EC50 = 6.7 nM Deltorphin I was an extremely potent stimulator of adenylate cyclase through delta opioid receptors in the olfactory bulb
- Evidence Grade:
- Preliminary — in vitro tissue homogenate study providing clear pharmacological characterization but not identifying specific cell types or in vivo relevance.
- Study Age:
- Published in 1992 (34 years ago). Stimulatory opioid signaling is now recognized as a real phenomenon in specific brain regions.
- Original Title:
- Characterization of opioid receptors mediating stimulation of adenylate cyclase activity in rat olfactory bulb.
- Published In:
- Molecular pharmacology, 42(1), 109-15 (1992)
- Authors:
- Olianas, M C(2), Onali, P(2)
- Database ID:
- RPEP-00242
Evidence Hierarchy
Frequently Asked Questions
How can the same receptor do opposite things?
Opioid receptors can couple to different intracellular signaling proteins (G-proteins) depending on the cell type and brain region. In most places they inhibit signaling, but in the olfactory bulb they connect to stimulatory pathways instead.
Does this affect how we smell?
Potentially. If delta opioid receptors actively regulate signaling in the smell center, opioid drugs or natural endorphins could modify olfactory processing — though this hasn't been directly tested in behavioral studies.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-00242APA
Olianas, M C; Onali, P. (1992). Characterization of opioid receptors mediating stimulation of adenylate cyclase activity in rat olfactory bulb.. Molecular pharmacology, 42(1), 109-15.
MLA
Olianas, M C, et al. "Characterization of opioid receptors mediating stimulation of adenylate cyclase activity in rat olfactory bulb.." Molecular pharmacology, 1992.
RethinkPeptides
RethinkPeptides Research Database. "Characterization of opioid receptors mediating stimulation o..." RPEP-00242. Retrieved from https://rethinkpeptides.com/research/olianas-1992-characterization-of-opioid-receptors
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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.