The mPFC and hippocampus have an important role in the pathogenesis of MDD [35, 36]. To assess whether BDNF is involved in PPD in female mice, we first measured total Bdnf mRNA levels in CUS-treated postpartum female mice. The results indicated that total Bdnf mRNA (exon IX) levels were significantly decreased in the mPFC (Fig. 2a, P < 0.001) but not in the hippocampus (Fig. 2b, P = 0.215). Meanwhile, BDNF protein levels in the mPFC were also significantly reduced in CUS-treated postpartum mice compared to non-stressed mice (Fig. 2c, P < 0.001). Furthermore, the correlation between depression-related behavior and BDNF expression levels was analyzed and we found that sucrose preference (SPT) (p = 0.017), latency (NSFT) (p = 0.012), and immobility (FST) (p = 0.003) were significantly correlated with total Bdnf mRNA in the mPFC (Fig. 2d). At the same time, significant correlations were also observed between sucrose preference (p = 0.004), latency (p = 0.027), and immobility (p = 0.016) and BDNF protein levels in the mPFC (Fig. 2e). However, there were no significant correlations between sucrose preference
