Semaglutide administration protects cardiomyocytes in db/db mice via energetic improvement and mitochondrial quality control.

Diabetic cardiomyopathy causes end-stage heart failure, resulting in high morbidity and mortality in type 2 diabetes mellitus (T2DM) patients. Long-term treatment targeting metabolism is an emerging field in the treatment of diabetic cardiomyopathy. Semaglutide, an agonist of the glucagon-like peptide 1 receptor, is clinically approved for the treatment of T2DM and provides cardiac benefits in patients. However, the cardioprotective mechanism of semaglutide, especially its direct effects on cardiomyocytes (CMs), is not fully understood. Here, we used 8-week diabetic and obese db/db mice treated with semaglutide (200 μg·kg·d^-1, i.p.) to study its direct effect on CMs and the underlying mechanisms. Our results revealed that the consecutive application of semaglutide improved cardiac function. Increased AMPK and ULK1 phosphorylation levels were detected, accompanied by elevated [Ca²⁺]_mito. Seahorse analysis revealed that semaglutide increases ATP production via elevated basal and maximum respiration rates as well as spare respiration capacity in CMs. Transmission electron microscopy revealed improved mitochondrial morphology in the cardiomyocytes of db/db mice. On the other hand, Western blot analysis revealed increased Parkin and LC3 protein expression, indicating mitophagy in CMs. Collectively, our findings demonstrate that semaglutide directly protects CMs from high-glucose damage by promoting AMPK-dependent ATP production as well as ULK1-mediated mitophagy in db/db mice.