Analysis of Direct Effects of the CB1 Receptor Antagonist Rimonabant on Fatty Acid Oxidation and Glycogenolysis in Liver and Muscle Cells in vitro

Cannabis Is Not Doping

The World Anti-Doping Agency (WADA) classifies cannabis, all phytocannabinoids, and synthetics as doping, except for CBD. For agency, a method for doping substance must meet two criteria: performance enhancement (ergogenicity), health risk, or violation of the spirit of sports. Cannabis is neither ergogenic nor ergolytic (performance worsens), and the health risks for athletes are overestimated after 20 years of research. The significant problem remains in the complex (and difficult interpretation) definition of the spirit of sports, which transcends the objectives of sports excellence (performance and injury prevention) for moral policing. This perspective presents an evidence-based counterargument recommending the removal of cannabis and phytocannabinoids from the WADA Prohibited List.

Inhibition of the endocannabinoid system reverses obese phenotype in aged mice and partly restores skeletal muscle function

Sarcopenia, the age-related loss of skeletal muscle mass, is associated with lipid accumulation and anabolic resistance; phenomena also observed in obesity and worsen when obesity and aging are combined. The endocannabinoid system (ECS) is overactivated in obesity, but its role in aging obesity-related muscle dysfunction is unknown. The aims of this study were to evaluate the effect of inhibition of the ECS by rimonabant (RIM) on the metabolic alterations induced by a high-fat high-sucrose diet and on skeletal muscle mass/function in aged mice. Eighteen-month-old male mice were subjected to a control (CTL) or a high-fat high-sucrose (HFHS) diet for 24 weeks. Mice were administered with saline or RIM (10 mg/kg/day) for the last 4 weeks of the diet. Skeletal muscle function was evaluated by open-field, rotarod, and grip strength tests. Metabolic alterations in liver, adipose tissue, and skeletal muscle were investigated by quantitative RT-PCR. Body mass was higher in HFHS mice compared to CTL mice (48.0 ± 1.5 vs. 33.5 ± 0.7 g, P < 0.01), as a result of fat accumulation (34.8 ± 1.0 vs. 16.7 ± 0.8%, P < 0.01). RIM reduced body fat mass in both CTL (-16%, P < 0.05) and HFHS conditions (-40%, P < 0.01), without affecting hindlimb skeletal muscle mass. In HFHS mice, grip strength evolution was improved (-0.29 ± 0.06 vs. -0.49 ± 0.06 g/g lean mass, P < 0.05), and rotarod activity was increased by ≈60% in response to RIM (45.9 ± 6.3 vs. 28.5 ± 4.6 cm, P < 0.05). Lipolysis and β-oxidation genes were upregulated in the liver as well as genes involved in adipose tissue browning. These results demonstrate that inhibition of the ECS induces metabolic changes in liver and adipose tissue associated with a reversion of the obese phenotype and that RIM is able to improve motor coordination and muscle strength in aged mice, without affecting skeletal muscle mass.NEW & NOTEWORTHY In 24-month-old mice submitted to high-fat high-sucrose-induced obesity, inhibition of the endocannabinoid system by rimonabant reversed the obese phenotype by promoting adipose tissue browning and β-oxidation in the liver but not in skeletal muscle. These metabolism modifications are associated with improved skeletal muscle function.

Hepatic targeting of the centrally active cannabinoid 1 receptor (CB1R) blocker rimonabant via PLGA nanoparticles for treating fatty liver disease and diabetes

Over-activation of the endocannabinoid/CB1R system is a hallmark feature of obesity and its related comorbidities, most notably type 2 diabetes (T2D), and non-alcoholic fatty liver disease (NAFLD). Although the use of drugs that widely block the CB1R was found to be highly effective in treating all metabolic abnormalities associated with obesity, they are no longer considered a valid therapeutic option due to their adverse neuropsychiatric side effects. Here, we describe a novel nanotechnology-based drug delivery system for repurposing the abandoned first-in-class global CB1R antagonist, rimonabant, by encapsulating it in polymeric nanoparticles (NPs) for effective hepatic targeting of CB1Rs, enabling effective treatment of NAFLD and T2D. Rimonabant-encapsulated NPs (Rimo-NPs) were mainly distributed in the liver, spleen, and kidney, and only negligible marginal levels of rimonabant were found in the brain of mice treated by iv/ip administration. In contrast to freely administered rimonabant treatment, no CNS-mediated behavioral activities were detected in animals treated with Rimo-NPs. Chronic treatment of diet-induced obese mice with Rimo-NPs resulted in reduced hepatic steatosis and liver injury as well as enhanced insulin sensitivity, which were associated with enhanced cellular uptake of the formulation into hepatocytes. Collectively, we successfully developed a method of encapsulating the centrally acting CB1R blocker in NPs with desired physicochemical properties. This novel drug delivery system allows hepatic targeting of rimonabant to restore the metabolic advantages of blocking CB1R in peripheral tissues, especially in the liver, without the negative CB1R-mediated neuropsychiatric side effects.

Cannabinoid receptor type 1 antagonist inhibits progression of obesity-associated nonalcoholic steatohepatitis in a mouse model by remodulating immune system disturbances

SCOPE

This study investigated whether AM251, a cannabinoid receptor type 1 (CB1) antagonist, ameliorates hepatic levels of metabolic abnormalities and inflammatory responses in a murine nonalcoholic steatohepatitis (NASH) model via reversal of disturbances in the immune system.

METHODS AND RESULTS

Fifteen-week-old male obese db/db mice were randomly assigned to the following two groups: no treatment and treatment with AM251 at 5 mg/kg for 15 days. C57BL/6J-Lean mice were utilized as the control group. Plasma parameters, liver histopathology, and hepatic status were measured. For the in vitro study, macrophage-derived RAW264.7 cells were cultured with AM251 or CB1 small interfering RNA (siRNA) before challenge with arachidonyl-2'-chloroethylamide (ACEA) or a high concentration of fatty acids (HFFAs). The db/db mice exhibited an increase in CB1 levels, lipid droplet accumulation, mitogen-activated protein kinase-related inflammatory responses, and macrophage and neutrophil infiltration in the liver tissues. Flow cytometry analysis revealed an elevation in macrophages and T helper cells, plus a decrease in natural killer T cells and regulatory T cells in the liver tissues of the db/db mice; treatment with 5 mg/kg AM251 reversed these changes. Moreover, in vitro experiments revealed that administration of 3.3 μM AM251 or CB1 siRNA prevented 1 mM HFFA- and 1 μΜ ACEA-induced inflammatory cytokine protein expression in the RAW264.7 cells.

CONCLUSION

These findings suggested that a blockade caused by CB1 reduced obesity-associated NASH progression via correction of immune system dysregulations and elevated inflammatory responses in the liver tissues.