Eight weeks of treadmill exercise reversed memory impairment caused by brain inflammation in rats, partly by modulating cannabinoid receptors and inflammatory enzymes in the hippocampus.
Exercise scientists, neuroinflammation researchers, and those interested in endocannabinoid system modulation.
Exercise reversed memory impairment via CB1/CB2 and COX-2 modulation
What the researchers found
Rats with LPS-induced neuroinflammation showed cognitive impairment in the water maze. Eight weeks of treadmill exercise reversed these deficits. Exercise increased CB1 receptor expression in healthy rats and reduced CB2 receptor, COX-2, and mPGES-1 expression in inflamed rats, suggesting the endocannabinoid system mediates some of exercise cognitive benefits.
Why it matters
The "runner high" has long been linked to the endocannabinoid system. This study provides a specific mechanism: exercise modulates cannabinoid receptors to counteract neuroinflammation-induced cognitive decline.
The numbers in context
8 weeks treadmill exercise; 5 days/week; exercise increased CB1 in healthy rats; reduced CB2, COX-2, and mPGES-1 in inflamed rats; reversed water maze impairment.
How the study worked
Animal study with rats receiving LPS injections to induce neuroinflammation, followed by 8 weeks of treadmill exercise (5 days/week). Water maze testing for cognition, Real-Time PCR for hippocampal gene expression of cannabinoid receptors and cyclooxygenases.
What this study cannot tell us
Animal study with chemically-induced inflammation (not natural neurodegeneration); forced treadmill exercise differs from voluntary exercise; only male rats; specific LPS doses may not reflect human neuroinflammatory conditions.
How to read the evidence
Preliminary: animal study with chemically-induced inflammation model.
When this study was published
Published 2020.
The bigger picture
This adds to growing evidence that the endocannabinoid system is a key mediator of exercise benefits on the brain. It suggests that some cognitive benefits of exercise may work through the same system that cannabis activates, but in a more physiologically regulated way.
Questions still open
- Could combining exercise with cannabinoid-based therapies enhance cognitive protection? Does cannabis use interfere with exercise-induced endocannabinoid benefits?
Common questions
How does exercise affect the endocannabinoid system?
Does this explain the "runner high"?
Read the original research
Treadmill exercise improves LPS-induced memory impairments via endocannabinoid receptors and cyclooxygenase enzymes.
Behavioural brain research, 380, 112440
Citation
Moosavi Sohroforouzani, Azam; Shakerian, Saeed; Ghanbarzadeh, Mohsen; Alaei, Hojjatallah. (2020). Treadmill exercise improves LPS-induced memory impairments via endocannabinoid receptors and cyclooxygenase enzymes.. Behavioural brain research, 380, 112440. https://doi.org/10.1016/j.bbr.2019.112440
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