Abstract: AIM: To investigate the relationship between sex difference of CUMS-induced depressive behaviors of rats and the expressions of monoamine oxidase B (MAO-B), 5-hydroxytryptamine transporter (5-HTT) and norepinephrine transporter (NET).METHODS: 60 SD rats (30 for each male and female) were randomly divided into following groups:male control group (MCG),male model group (MMG),female control group (FCG) and female model group (FMG). Chronically unpredicted mild stress (CUMS) with solitary condition was taken to establish rat depression model. The open-field test and forced swimming test were used to evaluate the behavioral changes of experimental rats. The expressions of MAO-B and 5-HTT in hippocampus and NET in pons were determined by Western blot (WB) and Real-time fluorescent quantitative PCR, respectively.RESULTS: Significantly decreasing locomotor activity in open-field test and increasing immobility time in forced swimming test in MMG and FMG with remarkable difference between MMG and FMG were observed, compared with corresponding control groups. Expressions of obviously decreased 5-HTT and elevated MAO-B and NET also were found in both model groups with significant sex differences.CONCLUSION: Depression model is much easier to be induced in male rats than female by CUMS, which may be at least partly related to the different expressions of MAO-B, 5-HTT and NET.

Key words: Depression, Sex difference, NET, 5-HTT, MAO-B