A high fat, sugar, and salt Western diet induces motor-muscular and sensory dysfunctions and neurodegeneration in mice during aging: Ameliorative action of metformin.

Aims: To explore the novel linkage between a Western diet combining high saturated fat, sugar, and salt (HFSS) and neurological dysfunctions during aging as well as Metformin intervention, we assessed cerebral cortex abnormalities associated with sensory and motor dysfunctions and cellular and molecular insights in brains using HFSS-fed mice during aging. We also explored the effect of Metformin treatment on these mice.

Methods: C57BL/6 mice were fed with HFSS and treated with metformin from 20 to 22 months of age, resembling human aging from 56 to 68 years of age (an entry phase of the aged portion of lifespan).

Results: The motor and sensory cortexes in mice during aging after HFSS diet showed: (A) decreased motor-muscular and sensory functions; (B) reduced inflammation-resolving Arg-1 microglia; (C) increased inflammatory iNOs microglia and TNFα levels; (D) enhanced abundance of amyloid-β peptide and of phosphorylated Tau. Metformin attenuated these changes.

Conclusion: A HFSS-combined diet caused motor-muscular and sensory dysfunctions, neuroinflammation, and neurodegeneration, whereas metformin counteracted these effects. Our findings show neuroinflammatory consequences of a HFSS diet in aging. Metformin curbs the HFSS-related neuroinflammation eliciting neuroprotection.