Maslinic Acid Alleviates Obesity-Associated Skeletal Muscle Atrophy and Adipose Tissue Dysfunction in Obese Mice

Maslinic acid, a triterpenoid isolated from Olea europaea L., has been reported to exert anti-tumor and anti-inflammatory effects. Previous studies have shown that maslinic acid promotes skeletal muscle hypertrophy via mTORC1 and TGR5 signaling. Here, we examined the effects of maslinic acid on obesity-associated skeletal muscle atrophic changes and adipose tissue dysfunction. Male C57BL/6 mice were fed a high-fat diet (HFD) to induce obesity and subsequently received maslinic acid via intraperitoneal injection. In parallel, differentiated C2C12 myotubes were exposed to palmitic acid to induce lipotoxic stress-associated atrophic changes and were treated with maslinic acid to examine related cellular responses. Maslinic acid increased gastrocnemius muscle weight and attenuated obesity-associated myofiber atrophic changes in HFD-fed mice. In skeletal muscle, maslinic acid treatment was associated with increased myosin IIa expression and AKT phosphorylation, reduced expression of the atrophy-related proteins MuRF1 and Atrogin-1, and changes in mitochondrial morphology and mitochondrial dynamics-related protein expression, including increased mitofusin-2 expression and decreased phosphorylation of dynamin-related protein 1 (DRP1). Consistently, in palmitic acid-treated C2C12 myotubes, maslinic acid treatment was associated with increased myosin IIa and mitofusin-2 levels and reduced MuRF1, Atrogin-1, and DRP1 phosphorylation. In addition, maslinic acid reduced epididymal fat mass in obese mice and altered macrophage-associated marker expression in epididymal adipose tissue. Collectively, these findings suggest that maslinic acid may ameliorate obesity-associated skeletal muscle atrophic changes and adipose tissue dysfunction, accompanied by reduced adiposity and treatment-associated changes in atrophy-related, mitochondrial dynamics-related, and macrophage-associated marker expression.