Boosting anandamide levels reduced morphine withdrawal symptoms in rats
The FAAH inhibitor URB597 reduced most morphine withdrawal symptoms in rats at multiple dose levels, supporting endocannabinoid modulation of opioid dependence.
Quick Facts
What This Study Found
Rats made dependent on morphine through 7 days of daily injections received URB597, a FAAH inhibitor that boosts anandamide levels, before naloxone-precipitated withdrawal. URB597 at doses of 0.1 to 1 mg/kg reduced most withdrawal symptoms including jumping, teeth chattering, paw tremor, wet dog shakes, face grooming, and weight loss.
Only the lowest dose tested (0.03 mg/kg) failed to produce significant effects. The broad dose-response range suggested robust endocannabinoid involvement in opioid withdrawal modulation.
The results demonstrated that endocannabinoids interact with the opioid system during withdrawal, and that boosting endocannabinoid tone through enzyme inhibition could be a therapeutic strategy for managing morphine addiction.
Key Numbers
URB597 effective at 0.1, 0.3, 0.5, and 1 mg/kg. Ineffective at 0.03 mg/kg. 10 withdrawal symptoms measured over 30-minute observation period. 7-day morphine dependence protocol.
How They Did This
Morphine dependence was induced by 7 consecutive days of morphine injections in rats. URB597 (0.03, 0.1, 0.3, 0.5, 1 mg/kg) was administered before naloxone-precipitated withdrawal. Ten different withdrawal symptoms were recorded during 30 minutes after naloxone injection.
Why This Research Matters
Opioid withdrawal is a primary driver of continued opioid use. Finding that boosting natural endocannabinoids reduces withdrawal opens a potential treatment path that avoids the psychoactive effects of directly using cannabinoid drugs.
The Bigger Picture
This study complemented RTHC-00512 (which tested both FAAH and MAGL inhibitors) and strengthened the case that endocannabinoid enzyme inhibitors could become tools for managing opioid withdrawal. The consistent findings across labs increased confidence in the approach.
What This Study Doesn't Tell Us
Rat model of opioid dependence. Naloxone-precipitated withdrawal is more abrupt than natural withdrawal. Only acute URB597 administration was tested. Long-term safety of FAAH inhibition was not assessed.
Questions This Raises
- ?Would URB597 or similar FAAH inhibitors work in human opioid withdrawal?
- ?Could FAAH inhibitors be combined with standard withdrawal medications for better outcomes?
- ?What is the long-term safety profile?
Trust & Context
- Key Stat:
- Effective at 4 out of 5 dose levels tested
- Evidence Grade:
- Animal study with dose-response data. Consistent with findings from other labs but no human data available.
- Study Age:
- Published in 2011. FAAH inhibitor development has continued, though clinical trials have faced setbacks including a serious safety incident with a different FAAH inhibitor (BIA 10-2474) in 2016.
- Original Title:
- Behavioral effects of fatty acid amide hydrolase inhibition on morphine withdrawal symptoms.
- Published In:
- Brain research bulletin, 86(1-2), 118-22 (2011)
- Authors:
- Shahidi, Siamak, Hasanein, Parisa
- Database ID:
- RTHC-00524
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
What is FAAH and why does blocking it help?
FAAH (fatty acid amide hydrolase) is an enzyme that breaks down anandamide, one of the body's natural endocannabinoids. Blocking FAAH allows anandamide levels to rise, which appears to reduce opioid withdrawal severity by modulating pain, anxiety, and autonomic responses.
Is this the same as using cannabis for opioid withdrawal?
No. This approach specifically boosts the body's own endocannabinoid anandamide rather than introducing external cannabinoids. It is more targeted and may avoid the psychoactive effects of cannabis.
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Cite This Study
https://rethinkthc.com/research/RTHC-00524APA
Shahidi, Siamak; Hasanein, Parisa. (2011). Behavioral effects of fatty acid amide hydrolase inhibition on morphine withdrawal symptoms.. Brain research bulletin, 86(1-2), 118-22. https://doi.org/10.1016/j.brainresbull.2011.06.019
MLA
Shahidi, Siamak, et al. "Behavioral effects of fatty acid amide hydrolase inhibition on morphine withdrawal symptoms.." Brain research bulletin, 2011. https://doi.org/10.1016/j.brainresbull.2011.06.019
RethinkTHC
RethinkTHC Research Database. "Behavioral effects of fatty acid amide hydrolase inhibition ..." RTHC-00524. Retrieved from https://rethinkthc.com/research/shahidi-2011-behavioral-effects-of-fatty
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 RethinkTHC 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.