A new mouse model of depression induced by chronic restraint stress combined with lipopolysaccharide.

The aim of this study was to establish a multi-factor-induced depression model in mice within a relatively short period, specifically through the combination of intraperitoneal injection of lipopolysaccharide (LPS) and chronic restraint stress (CRS), and to evaluate the differences in depressive-like behaviors among three different strains of mice, seeking mouse strains more suitable for this combined model. The mice of each strain were randomly divided into the normal group and model group. The mice in the model group received a single intraperitoneal injection of LPS once daily (1 mg/kg/d for 7 days) and subsequent CRS for 6 h, to induce depression, while the mice in the normal group received no treatment. Behavioral tests: sucrose preference test (SPT), open field test (OFT), forced swim test (FST), and tail suspension test (TST) were conducted to assess depressive-like behaviors in the mice. Data analysis showed that there were significant intergroup differences in depressive-like behaviors in ICR and C57BL/6 J mice, while KM mice exhibited minor differences with relatively high deviation in individual behavioral score. This study indicated that the combined depression mouse model could successfully induce significant depressive-like behaviors in ICR and C57BL/6 J mice.