Effects of Psychobiotic and Prebiotic Administration on Gut Microbiota and Depression-Like Behaviors in Mice

Gülçin Yılmaz, Ayhan Dağ — 2026-05-12

Depression is a multifactorial mental disorder in which the gut–brain axis and gut microbiota have been suggested to play important roles. This study aimed to investigate the effects of psychobiotic (Bifidobacterium breve CCFM1025) and prebiotic (inulin) interventions on gut microbiota composition and depression-like behaviors in a chronic unpredictable mild stress (CUMS) mouse model. A total of 24 male C57BL/6 mice were randomly divided into four groups (n = 6): control, CUMS, CUMS + psychobiotic, and CUMS + prebiotic. Depression-like behaviors were induced using a 5-week CUMS protocol. The psychobiotic group received Bifidobacterium breve CCFM1025 (10⁹ CFU/day), while the prebiotic group received inulin (66 mg/kg) via oral gavage. Behavioral assessments were performed using the forced swim test (FST), tail suspension test (TST), and sucrose preference test (SPT). Gut microbiota composition was analyzed using 16S rRNA gene sequencing. Statistical analyses were conducted using Kruskal–Wallis and Mann–Whitney U tests. The results showed that both psychobiotic and prebiotic interventions significantly improved depression-like behaviors compared to the CUMS group, as indicated by reduced immobility time in FST and increased sucrose preference (p < 0.05). However, no statistically significant differences were observed in overall gut microbiota diversity or composition among the groups (p > 0.05). In conclusion, psychobiotic and prebiotic interventions improved behavioral outcomes in a CUMS-induced depression model; however, these effects were not accompanied by significant changes in gut microbiota composition. Therefore, the observed behavioral improvements may not be directly mediated by alterations in microbial diversity and may instead involve alternative mechanisms. These findings should be interpreted with caution due to the limited sample size and lack of functional analyses. These findings highlight the need for future studies incorporating detailed mechanistic investigations to better understand the underlying pathways.

Journal of Food and Nutrition Research

Effects of Psychobiotic and Prebiotic Administration on Gut Microbiota and Depression-Like Behaviors in Mice