Impact of co-housing on anxiety- and depression-like behaviors in rats exposed to chronic unpredictable mild stress

To investigate the ameliorating effects of co-housing combined with fluoxetine intervention on anxiety- and depression-like behaviors and gut microbiota dysbiosis induced by chronic unpredictable mild stress (CUMS) in rats. SD rats were randomly divided into control group, CUMS stress group, stress + normal co-housing group, stress + fluoxetine group, and stress + normal co-housing + fluoxetine group. The stress group received chronic unpredictable mild stress, the normal co-housing group was housed with normal rats, the fluoxetine group received fluoxetine during CUMS stimulation, and the combined intervention group received fluoxetine intervention during stimulation followed by co-housing intervention. Behavioral changes were assessed through sucrose preference test, forced swimming test, tail suspension test, and open field test. Gut microbiota composition was analyzed using 16S rRNA gene sequencing. Compared to the stress group, the normal co-housing group showed significantly increased sucrose preference rate, significantly reduced immobility time in forced swimming test, and significantly increased activity time in the center area of open field test. The behavioral improvement effects of combined intervention were significantly superior to individual interventions. Gut microbiota analysis showed that Monoglobus abundance was significantly elevated in the stress group and significantly reduced in the normal co-housing group. The combined intervention group not only reduced Monoglobus abundance but also simultaneously reduced the abnormal elevation of Alloprevotella and uncultured_Bacteroidales_bacterium, two other stress-related bacterial species.