Changes in the rodent gut microbiome following chronic restraint stress and low-intensity rTMS

Gut microbiome composition is associated with mood-relating behaviours, including those reflecting depression-like phenotypes. Repetitive transcranial magnetic stimulation (rTMS), a non-invasive neummodulation technique, is an effective treatment for depression, but its effects on the gut microbiome remain largely unknown. This study assessed microbial changes from rat faecal samples longitudinally following chronic restraint stress (CRS) and 10 Hz low-intensity rTMS treatment. CRS increased abundance within the Pmteobacteria (Deltaproteobacteria, Desulfovibrionales) and Firmicutes (Anaerostipes, Frinsingococcus), with decreases in Firmicutes family (Acidaminococcaceae) and genera (Roseburia, Phascolarctobacterium and Fusicatenibacter) persisting for up to 4 weeks post CRS. The decrease in Firmicutes was not observed in the handling control and LI-rTMS groups, suggesting that handling alone may have sustained changes in gut microbiome associated with CRS. Nonetheless, LI-rTMS was specifically associated with an increase in Roseburia genus that developed 2 weeks after treatment, and the abundance of both Roseburia and Fusicatenibacter genera was significantly correlated with rTMS behavioural and MRI outcomes. In addition, LI-rTMS treated rats had a reduction in apoptosis pathways and several indicators of reduced inflammatory processes. These findings provide evidence that the brain can influence the gut micmbiome in a top-down manner, presumably via stimulation of descending pathways, and/or indirectly via behavioural modification.

Automated summary

The composition of gut microbiome is closely related to mood-related behaviors, including depression. This study found that chronic restraint stress (CRS) led to changes in gut microbiome composition, while low-intensity repetitive transcranial magnetic stimulation (LI-rTMS) treatment was associated with the restoration of the gut microbiome and improvement in depressive symptoms and inflammatory processes.