Opuntia ficus-indica Flour Modulates Fecal Microbiota, Reduces Cerebral Oxidative Stress and Improves Cognitive Function in Elderly Rats.

Abstract

This study aimed to investigate the effects of Opuntia ficus-indica flour (OFIF) consumption on fecal microbiota composition, cognitive function, and brain oxidative stress in RI elderly male rats. Animals were randomized into five groups: Adult Control (ACG) and Elderly Control (ECG), fed the AIN-93 M diet without OFIF; and three treated groups (OF5, OF10, OF15) receiving diets supplemented with 5%, 10%, or 15% OFIF, respectively. Memory performance was assessed using non-associative learning and novel object recognition tests, with recognition (DI) and discrimination (RI) indices. Brain fatty acid profile, protein carbonyls, and glutathione levels were measured, and fecal microbiota was analyzed by 16 S rRNA amplicon sequencing. The experimental groups showed reduced locomotion and number of crossings during the second exposure to the open field test. OF15 rats spent more time in the inner zone and achieved higher DI and RI scores in both short- and long-term evaluations. Regarding oxidative stress, OF15 exhibited elevated glutathione levels, while OF5 showed reduced protein carbonyls. Treated groups displayed increased brain concentrations of oleic, eicosenoic, arachidonic, and docosahexaenoic acids. Moreover, OF15 restored intestinal microbial diversity, evidenced by higher richness indices (Chao1 and Fisher) and enrichment of short-chain fatty acid-producing genera, including Faecalibaculum, Dorea, Prevotella, and Lachnospiraceae NK4A136. In conclusion, OFIF supplementation, particularly at 15%, modulated gut microbiota, improved memory performance, and enhanced antioxidant defenses in aged rats. These results highlight OFIF as a promising dietary strategy to modulate the gut-brain axis, supporting memory preservation, oxidative balance, and intestinal health during aging.