Synbiotic supplementation enhances memory processes in adult and aged male rats.

Synbiotic formulations, which combine prebiotics and probiotics in their composition, have shown promise in improving brain function and cognitive performance. However, the mechanisms by which synbiotics exert their beneficial effects on memory processes, particularly in the context of aging, remain unclear. In the present study, we investigated the effects of synbiotics supplementation on memory updating (reversal learning) and extinction in adult and aged rats. We also assessed the impact of the synbiotic intervention on the gut microbiota composition, diversity, and metabolism. The results showed that synbiotic supplementation (fructooligosaccharide and L. acidophilus, L. bulgaricius, L. casei, L. rhamnosus, and B. bifidum) improved memory updating in adult rats but not in aged rats. In contrast, the synbiotic facilitated memory extinction in aged rats, but not in adults. Interestingly, these cognitive benefits were not accompanied by significant alterations in the gut microbiome. This suggests that the synbiotic's effects on memory processes were mediated through more direct mechanisms, such as anti-inflammatory, antioxidant, and neuromodulatory actions, rather than through broad changes to the gut microbial community. These findings highlight the potential of synbiotic interventions to ameliorate age-related cognitive impairment and provide insights into the underlying mechanisms of the gut-brain axis.