Metformin attenuates cuprizone-induced mitochondrial dysfunction and senescence-associated changes in primary neuronal cells.

Mitochondrial dysfunction and cellular senescence are key features of brain aging and neurodegenerative diseases. Cuprizone (CPZ), a mitochondrial toxin, induces oxidative stress, abnormal lipid metabolism, and iron accumulation in neurons and oligodendrocytes. Here, we investigated whether metformin (MFN), an AMPK activator with a known safety profile, can protect against CPZ-induced mitochondrial and senescence-like changes. Using confocal and transmission electron microscopy, we observed mitochondrial enlargement, increased reactive oxygen species (ROS) production, iron accumulation, and lipofuscin formation in CPZ-treated primary neuronal cultures. Next, we assessed the impact of MFN on mitochondrial changes and increase in lipid-radicals in cells exposed to CPZ. The treatment of MFN resulted in decreased abnormal mega-mitochondrial morphology, decreased levels of mitochondrial reactive oxygen species (mitoROS), and decreased iron accumulation within mitochondria. Moreover, MFN treatment prevented the typically observed increases in lipofuscin and lipid radicals in CPZ-affected cells. Analysis of gene expression in primary neuronal cells treated with CPZ showed differences in mitochondria-related genes linked to lipid peroxidation, oxidative stress, and cellular senescence. These findings suggest that MFN mitigates mitochondrial dysfunction and senescence-associated alterations, highlighting its therapeutic potential in aging-related neurodegeneration.Key words: mitochondria, CPZ, MFN, oxidative stress, lipofuscin.