*3.3. Molecular Mechanism of the Cerebral Protection E*ff*ect of PAPZ*

To investigate the underlying molecular mechanism of PAPZ in CORT-induced depressive-like mice, we examined the effect of PAPZ on the expression of *bdnf* on hippocampal tissue in mice (Figure 3). The real-time qPCR result demonstrated that the mRNA level of *bdnf* significantly decreased by almost 50% when compared with the non-treated control group. Treatment with PAPZ showed that the *bdnf* values were significantly increased when compared with the CORT group, which indicated that the PAPZ could promote the expression of *bdnf* at the level of transcription (Figure 3a). We next detected the expression of BDNF protein. The immunoblot result was consistent with the qPCR result (Figure 3b) and revealed that the expression of BDNF protein in the model group significantly decreased after treatment with CORT, and PAPZ could enhance the expression of BDNF protein, which indicates that PAPZ could ameliorate the damage of CORT to hippocampus tissues.

**Figure 3.** PAPZ enhanced the expression of brain-derived neurotrophic factor BDNF in hippocampal tissue. (**a**) Real-time quantitative polymerase chain reaction (qPCR) analysis of *bdnf* gene in the hippocampal tissues in mice. (**b**) Representative Western blots show the difference of BDNF protein expression in hippocampal tissue. Data from the CORT group and PAPZ+CORT group were normalized to the control group and data are expressed as mean ± SEM. \* *p* < 0.05 represents a significant difference.
