Sex-Specific Cognitive and Metabolic Effects of Lifelong Caloric Restriction and Sodium Butyrate in Aging Rats

Aging is associated with progressive metabolic dysfunction and cognitive decline, often accompanied by hippocampal dysfunction and sex-specific vulnerabilities. Caloric restriction (CR) and sodium butyrate (NaBu), a short-chain fatty acid that acts as a histone deacetylase inhibitor, have independently demonstrated neuroprotective properties, yet their combined effects in aging remain underexplored. This study investigated the impact of lifelong CR and acute NaBu administration on spatial learning, memory, and cognitive flexibility in aged male and female Wistar rats, using the Morris water maze (MWM), a hippocampus‑dependent spatial memory task. Key metabolic parameters were assessed through plasma levels of triglycerides, insulin, and leptin. Aged rats exhibited significant impairments in all MWM tasks compared to younger controls, with female rats consistently outperforming males. Both CR and NaBu improved cognitive performance in aged rats, with the combined intervention yielding the most pronounced effects. Structural equation modelling revealed sex-specific pathways. In females, CR-mediated reductions in triglycerides enhanced memory and flexibility, while lower insulin levels were associated with improved learning. In males, NaBu had direct effects on spatial learning, whereas CR’s benefits on memory and flexibility were mediated by decreases in insulin and leptin, respectively. NaBu treatment increased hippocampal histone H3 acetylation in both sexes, whereas CR had no significant effect. All these findings highlight the distinct biological mechanisms through which CR and NaBu influence aging and underscore the necessity of considering sex as a critical variable, as it determines the efficacy of interventions and the underlying physiological pathways. Overall, this study supports the therapeutical potential of combining interventions that modulate metabolic and epigenetic pathways to mitigate cognitive decline and promote healthy brain aging.