BDNF and depressive symptom measurement: 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).