Cannabinoid receptor 1 expression is higher in muscle of old vs. young males, and increases upon resistance exercise in older adults

Scientific Reports“Aged skeletal muscle undergoes metabolic and structural alterations eventually resulting in a loss of muscle strength and mass, i.e. age-related sarcopenia. Therefore, novel targets for muscle growth purposes in elderly are needed.

Here, we explored the role of the cannabinoid system in muscle plasticity through the expression of muscle cannabinoid receptors (CBs) in young and old humans.

The CB1 expression was higher (+ 25%; p = 0.04) in muscle of old (≥ 65 years) vs. young adults (20-27 years), whereas CB2 was not differently expressed. Furthermore, resistance exercise tended to increase the CB1 (+ 11%; p = 0.055) and CB2 (+ 37%; p = 0.066) expression in muscle of older adults. Interestingly, increases in the expression of CB2 following resistance exercise positively correlated with changes in key mechanisms of muscle homeostasis, such as catabolism (FOXO3a) and regenerative capacity (Pax7, MyoD).

This study for the first time shows that CB1 is differentially expressed with aging and that changes in CB2 expression upon resistance exercise training correlate with changes in mediators that play a central role in muscle plasticity.

These data confirm earlier work in cells and mice showing that the cannabinoid system might orchestrate muscle growth, which is an incentive to further explore CB-based strategies that might counteract sarcopenia.”

“In conclusion, cell culture and murine experiments suggested that CBs can be a promising target to treat cachexia and sarcopenia through modulation of the metabolism and muscle regenerative capacity. These data imply that CB modulation might be a promising tool to combat muscle degeneration. ”

Mechanism of action of cannabinoids: how it may lead to treatment of cachexia, emesis, and pain.

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“Many patients with life-threatening diseases such as cancer experience severe symptoms that compromise their health status and deny them quality of life. Patients with cancer often experience cachexia, pain, and depression,which translate into an unacceptable quality of life. The discovery of the endocannabinoid system has led to a renewed interest in the use of cannabinoids for the management of nausea, vomiting, and weight loss arising either from cancer or the agents used to treat cancer. The endocannabinoid system has been found to be a key modulator of systems involved in pain perception, emesis, and reward pathways. As such, it represents a target for development of new medications for controlling the symptoms associated with cancer. Although the cannabinoid receptor agonist tetrahydrocannabinol and one of its analogs are currently the only agents approved for clinical use, efforts are under way to devise other strategies for activating the endocannabinoid system for therapeutic uses.”