Antidepressant effects of Gardeniae Fructus on chronic unpredictable mild stress model mice: involvement of DNMT3B-mediated epigenetic regulation of GR in the prefrontal cortex.

This study aimed to investigate the antidepressant effects of Gardeniae Fructus (ZZ) and its potential mechanisms related to DNA methylation regulation via network pharmacology, in vivo experiments, and targeted molecular assessments; a depressive mouse model was established with chronic unpredictable mild stress (CUMS), ZZ at low/medium/high doses and fluoxetine as positive control were administered for 4 weeks, depressive-like phenotypes were assessed via behavioral tests, and Western blot, qPCR, immunofluorescence and targeted bisulfite sequencing (TBS) were used to detect key molecules, mRNA expression and gene methylation in the prefrontal cortex (PFC) and hippocampus. The results showed that ZZ significantly ameliorated CUMS-induced depressive-like behaviors with 2 g/kg (equivalent to 10 g in adult humans) as the optimal dose, downregulated DNMT3B and 5-mC levels, upregulated GR and reduced FKBP5 expression in the PFC with no hippocampal alterations, and TBS confirmed GR as a hypermethylated PFC target in CUMS mice while low-dose ZZ reversed hypermethylation at four key GR CpG loci. In conclusion, ZZ exerts antidepressant effects by downregulating PFC DNMT3B, reversing GR hypermethylation and restoring GR/FKBP5 balance to regulate the HPA axis, thus providing a novel epigenetic target for depression therapy.