Combining a MAGL inhibitor (which boosts the endocannabinoid 2-AG) with morphine produced synergistic pain relief in a neuropathic pain model without the constipation, tolerance, or cannabis-like side effects of either drug alone.
Read this if you have chronic pain and are interested in alternatives to high-dose opioid treatment.
Endocannabinoid boost + morphine: synergistic pain relief with no constipation, no tolerance, no cannabis-like side effects.
What the researchers found
Researchers combined morphine with MJN110, a selective MAGL inhibitor that boosts 2-AG levels, in a mouse model of neuropathic pain (chronic constriction injury).
When used alone, both drugs reduced pain in a dose-dependent manner. When combined at low doses, the effect was synergistic (better than additive), meaning significantly lower doses of each drug produced full pain relief.
The combination produced pain relief through mu-opioid, CB1, and CB2 receptors simultaneously. Critically, the combination avoided three major side effects: it did not reduce gastric motility (no constipation), did not produce cannabis-like subjective effects (drug discrimination test), and when given repeatedly for 6 days, showed no evidence of tolerance development.
This is significant because opioid tolerance, constipation, and addiction are the primary clinical limitations of opioid pain treatment.
Why it matters
The opioid epidemic has highlighted the urgent need for alternative or opioid-sparing pain treatments. This study shows that boosting the body's natural endocannabinoid system can dramatically reduce the amount of morphine needed for pain relief while avoiding the most dangerous opioid side effects, including tolerance that drives dose escalation.
The numbers in context
Morphine ED50: 2.4 mg/kg. MJN110 ED50: 0.43 mg/kg. Combination: synergistic (isobolographic analysis). 6 days of twice-daily combination dosing: no tolerance. No reduction in gastric motility. No cannabimimetic effects in drug discrimination. Required mu-opioid, CB1, and CB2 receptors.
How the study worked
Mouse chronic constriction injury model of neuropathic pain. Dose-response curves generated for morphine and MJN110 separately. Isobolographic analysis determined synergistic, additive, or antagonistic interactions. Receptor involvement confirmed with selective antagonists for mu-opioid, CB1, and CB2 receptors. Side effect testing included gastric motility, drug discrimination (cannabimimetic effects), and 6-day repeated dosing for tolerance assessment.
What this study cannot tell us
Mouse study that needs human translation. The 6-day tolerance assessment is short. The neuropathic pain model (CCI) may not represent all chronic pain conditions. MJN110 is a research tool, not an approved drug. The drug discrimination test for cannabimimetic effects may not capture all subjective experiences relevant to humans.
How to read the evidence
Moderate evidence from a comprehensive animal study with multiple validated outcome measures and control conditions.
When this study was published
Published in 2016. Opioid-sparing cannabinoid combinations remain an active area of preclinical and early clinical investigation.
The bigger picture
The endocannabinoid system and opioid system interact extensively. This study provides a practical demonstration of how this interaction can be exploited therapeutically: by boosting endocannabinoids alongside low-dose opioids, the therapeutic benefit is maintained while the addiction, tolerance, and side effect risks are dramatically reduced.
Questions still open
- Would this opioid-sparing approach work in humans with chronic pain? Could MAGL inhibitors reduce opioid prescribing needs? Would the lack of tolerance persist beyond 6 days? Could this approach help people currently on high-dose opioids reduce their doses?
Common questions
Can cannabinoids reduce the need for opioid painkillers?
How does this work?
Read the original research
The Selective Monoacylglycerol Lipase Inhibitor MJN110 Produces Opioid-Sparing Effects in a Mouse Neuropathic Pain Model.
The Journal of pharmacology and experimental therapeutics, 357(1), 145-56
Citation
Wilkerson, Jenny L; Niphakis, Micah J; Grim, Travis W; Mustafa, Mohammed A; Abdullah, Rehab A; Poklis, Justin L; Dewey, William L; Akbarali, Hamid; Banks, Matthew L; Wise, Laura E; Cravatt, Benjamin F; Lichtman, Aron H. (2016). The Selective Monoacylglycerol Lipase Inhibitor MJN110 Produces Opioid-Sparing Effects in a Mouse Neuropathic Pain Model.. The Journal of pharmacology and experimental therapeutics, 357(1), 145-56. https://doi.org/10.1124/jpet.115.229971
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