Objective To observe the differences in gut microbiota in chronic unpredictable mild stress(CUMS)-induced depression model rats of both sexes,and to provide experimental evidence for exploring sex differences in depression onset.Methods Thirty-two healthy SD rats were divided randomly into four groups based on sex:Male control group(Control-M),Female control group(Control-F),Male model group(Model-M),and Female model group(Model-F)(n=8 rats per group).Rats in the control groups were fed without stimulation,while rats in the model groups were stimulated using the 28 d CUMS-induced depression method.After successful modeling,fresh feces were collected from all rats for high-throughput 16S rRNA sequencing.Behavioral observations were also conducted before and after preparing the model.Results The result of sucrose-preference,open-field,and forced-swimming tests differed significantly between the control and model groups.The result of the sucrose-preference test also differed between the sexes,while there was no difference in the open-field or forced-swimming test between the sexes.The α and β diversity of the gut microbiota genera showed an upward trend in the CUMS group compared with the control group.The ratio of Firmicutes/Bacteroidetes and the richness of the Roseburia and Lachnospiraceae_NK4A136_group were decreased in male rats but showed an increasing trend in female rats.Conclusions The ratio of Firmicutes/Bacteroidetes in the gut microbiota may be a key factor affecting the difference in the onset of depression between males and females,while the Roseburia and Lachnospiraceae_NK4A136_group be potential factors in correcting the gut microbiota and improving the symptoms of depression.

Objective To observe the differences in gut microbiota in chronic unpredictable mild stress(CUMS)-induced depression model rats of both sexes,and to provide experimental evidence for exploring sex differences in depression onset.Methods Thirty-two healthy SD rats were divided randomly into four groups based on sex:Male control group(Control-M),Female control group(Control-F),Male model group(Model-M),and Female model group(Model-F)(n=8 rats per group).Rats in the control groups were fed without stimulation,while rats in the model groups were stimulated using the 28 d CUMS-induced depression method.After successful modeling,fresh feces were collected from all rats for high-throughput 16S rRNA sequencing.Behavioral observations were also conducted before and after preparing the model.Results The result of sucrose-preference,open-field,and forced-swimming tests differed significantly between the control and model groups.The result of the sucrose-preference test also differed between the sexes,while there was no difference in the open-field or forced-swimming test between the sexes.The α and β diversity of the gut microbiota genera showed an upward trend in the CUMS group compared with the control group.The ratio of Firmicutes/Bacteroidetes and the richness of the Roseburia and Lachnospiraceae_NK4A136_group were decreased in male rats but showed an increasing trend in female rats.Conclusions The ratio of Firmicutes/Bacteroidetes in the gut microbiota may be a key factor affecting the difference in the onset of depression between males and females,while the Roseburia and Lachnospiraceae_NK4A136_group be potential factors in correcting the gut microbiota and improving the symptoms of depression.