A combined stimulus of acute fasting and exercise modulates hippocampal mitochondrial quality control in healthy mice

Exercise and fasting are recognized for their ability to improve brain health and mitigate neurodegeneration. However, little is known about how these interventions acutely impact mitochondrial quality control mechanisms including mitophagy.

We examined the effects of a single bout of fasting and exercise (FEx) on hippocampal mitochondrial function and proteomic remodeling in male and female mice. To assess in vivo autophagy dynamics, we combined proteomics with chloroquine (CQ) inhibition of autophagic flux. Mice were assigned to sedentary (Sed), fasting (F), exercise (Ex), or combined FEx groups and received unilateral intrahippocampal injections of CQ or PBS following treatments. Four hours later, hippocampi were collected for analysis.

LC3-II levels significantly increased in the FEx group only following CQ treatment, indicating enhanced autophagic flux. Proteomic profiling showed sedentary males failed to mount a robust response to FEx however females exhibited upregulation of proteins involved in the TCA cycle, glutathione metabolism, and oxidative phosphorylation, suggesting greater mitochondrial adaptability. Functional assays supported these findings, females showed increased complex IV activity post-FEx. The mitochondrial DNA / nuclear DNA ratio increased after FEx regardless of sex, and upstream regulator analysis predicted activation of mitochondrial biogenesis.

Together, these data reveal sex-specific mitochondrial remodeling in response to acute fasting and exercise. Defining these normative responses is critical for understanding how mitochondrial adaptability shapes resilience or vulnerability to neurological challenges.