Involvement of the Endocannabinoid System in the Control of Pain and Obesity by Exercise in Rodents: A Systematic Review

Studies in recent years have shown that the endocannabinoid (eCB) system is activated by exercise and modulates several physiological processes. Thus, the present review aimed to summarize the literature about the involvement of the eCB system in the control of pain, obesity, and metabolism by exercise. MEDLINE, EMBASE, and Web of Science were searched for experimental studies that investigated the presence of the eCB system in animal models of pain and obesity, in which the animals were subjected to different exercise modalities. The primary outcomes were pain, obesity, and metabolism. The databases were searched for articles from their inception up until March 2020. Two independent reviewers extracted the data and assessed the methodological quality of the included studies. Thirteen studies were considered eligible for this review. The results indicated that there was increased expression and levels of cannabinoid receptors and eCBs, respectively, after aerobic and resistance exercise, and that this effect was associated with antinociception. The eCB system was modulated by exercise in obese rats, confirming that it may also be involved in the control of obesity and metabolism when these are modulated by aerobic training. Exercise can be effective in controlling pain, partly through the involvement of the eCB system. In addition, exercise can modulate the imbalance of the eCB system in obesity and metabolic disorders, thus also controlling these pathologies through this signaling system.