Imeglimin Attenuates Skeletal Muscle Atrophy in Mouse Models of Obesity and Ageing

Sarcopenia is a major contributor to frailty and mortality in ageing and obesity and is tightly linked to metabolic dysfunction. Imeglimin is a first-in-class oral hypoglycaemic agent targeting mitochondrial function; however, despite the central role of mitochondria in skeletal muscle homeostasis, its effects on skeletal muscle under sarcopenia-relevant conditions remain unclear.

Imeglimin was administered to male C57BL/6 mice with high-fat diet (HFD)-induced obesity for 6 weeks and to naturally aged (18 months old) male mice for 12 weeks. Skeletal muscle fibre morphology and transcriptomic profiles were analysed in fast- and slow-twitch muscles. In parallel, C2C12 myotubes were exposed to palmitate with or without imeglimin, and inflammatory gene expression and reactive oxygen species (ROS) generation were assessed.

Imeglimin significantly increased the cross-sectional area (CSA) of Type II fibres in the extensor digitorum longus (EDL) muscle of HFD-fed mice (+66%, p < 0.01 vs. controls). Transcriptomic analyses revealed suppression of conserved molecular signatures of muscle atrophy, including activation of immediate-early genes and inflammatory pathways (-62% to -79%, p < 0.05 vs. HFD-fed mice). In palmitate-treated C2C12 myotubes, imeglimin attenuated lipotoxicity-induced inflammatory gene expression (-28% to -72%, p < 0.05 vs. controls) with reduced ROS generation, consistent with its cell-autonomous effect on myocytes. Notably, in naturally aged mice, 12-week imeglimin treatment preserved EDL muscle fibre size (+14%, p < 0.05 vs. controls) without altering systemic glucose tolerance, accompanied by transcriptomic changes overlapping with those observed in the HFD model (-27% to -82%, p < 0.05 vs. aged controls).

Imeglimin attenuates skeletal muscle atrophy in obesity and ageing, accompanied by coordinated suppression of stress- and inflammation-associated transcriptional programmes. These findings indicate that pharmacological regulation of mitochondrial stress responses influences skeletal muscle vulnerability under chronic metabolic stress and identify skeletal muscle as a previously underappreciated target of imeglimin action.