Comparison of the chronic unpredictable mild stress and the maternal separation in mice postpartum depression modeling

Postpartum depression (PPD) is a serious mental health concern of new mothers worldwide. In view of the particularity of puerpera, the research on pathogenesis and drug development of PPD are highly dependent on animal models. Although both maternal separation (MS) and chronic unpredictable mild stress (CUMS) modeling approaches have been used in PPD studies, the characteristics of the two rodent models have not been compared to explain which is more advantageous in PPD research. In this study, we applied 21-day MS and CUMS paradigms to induce mouse model of PPD and compared their differences in behavior, physiology and gut microbiota. As a result, the two models exhibited significant increases of immobility time in forced swim test (FST) and tail suspension test (TST), whereas sucrose preference index and pup weight were significantly decreased. Both displayed depression-like behaviors, and CUMS was more obvious, which demonstrated by the lower levels of 5-hydroxytryptamine (5-HT) and higher hypothalamic-pituitary-adrenal (HPA) axis related mRNA expression (corticotropin releasing hormone, corticotropin releasing hormone receptor 1) in CMUS group than that in MS group. The gut microbiota in MS and CUMS groups were significantly different in terms of the relative abundances of Bacteroidetes, Firmicutes, Proteobacteria. In conclusion, MS model and CUMS model have different performance in behavior and physiology. The CUMS model showed more obvious parameter changes, which may be more suitable for PPD induced by various social environmental factors.