Related Experiment Videos
Endocannabinoid and Opioid System Interactions in Exercise-Induced Hypoalgesia
Kevin M Crombie1, Angelique G Brellenthin1, Cecilia J Hillard2
1Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin.
Pain Medicine (Malden, Mass.)
|April 8, 2017
Summary
Exercise-induced hypoalgesia (EIH) pain reduction may not primarily involve the opioid system. Endocannabinoids like 2-AG and 2-OG could contribute to non-opioid pain relief following exercise.
Area of Science:
- Neuroscience
- Pain Management
- Exercise Physiology
Background:
- Exercise-induced hypoalgesia (EIH) is a well-documented phenomenon involving reduced pain sensitivity after physical activity.
- The endogenous opioid and endocannabinoid (eCB) systems are known modulators of pain, but their interaction in EIH is not fully understood.
Purpose of the Study:
- To investigate the interplay between the endogenous opioid and endocannabinoid systems in exercise-induced hypoalgesia (EIH).
Main Methods:
- A randomized, double-blind, placebo-controlled trial was conducted with 58 healthy participants.
- Participants received either an opioid antagonist (naltrexone) or a placebo before undergoing pain testing and isometric exercise.
Main Results:
- Levels of 2-arachidonoylglycerol (2-AG) and 2-oleoylglycerol (2-OG) significantly increased post-exercise in both placebo and naltrexone conditions.
- N-arachidonylethanolamine (AEA) and oleoylethanolamine (OEA) increased post-exercise with placebo but not with naltrexone.
- No significant differences in palmitolethanolamine (PEA) were observed between conditions.
Conclusions:
- EIH-related pain reduction appears to be independent of the opioid system, with 2-AG and 2-OG potentially mediating non-opioid hypoalgesia.
- The opioid system may influence the exercise-induced increase of AEA and OEA, as these were attenuated by naltrexone pretreatment.