Paeonol mitigates chronic stress–induced amygdalar neuronal damage through glycogen synthase kinase-3β/calcineurin axis regulation of synaptic plasticity

Objective This study aimed to elucidate the neuroprotective mechanisms of paeonol in ameliorating chronic stress–induced amygdala neuronal injury via modulation of the glycogen synthase kinase-3β (GSK3β)/calcineurin signaling pathway. Paeonol, a polyphenolic compound from Moutan Cortex , exhibits therapeutic effects. Studies show it alleviates lipopolysaccharide-induced depression-like behaviors in mice, though its mechanisms remain unclear. Methods Forty-eight Sprague–Dawley rats were divided into four groups: control, chronic unpredictable mild stress (CUMS) model, low-dose paeonol (25 mg/kg), and high-dose paeonol (80 mg/kg). Paeonol was administered intragastrically 1-week post-CUMS induction for 4 weeks. Behavioral tests assessed depression-like behaviors. Neuronal morphology was evaluated via hematoxylin and eosin, Nissl, and Golgi staining, while western blot quantified cofilin1, p-cofilin1, GSK3β, and calcineurin expression. Results CUMS rats exhibited depressive-like behaviors, neuronal nuclear pyknosis, interstitial edema, hyperchromatic cytoplasm, and reduced Nissl body integrity. Golgi staining revealed increased dendritic complexity and spine density. CUMS upregulated p-cofilin1 and GSK3β while downregulating total cofilin1 and calcineurin. Paeonol treatment alleviated depressive behaviors, reduced neuronal damage, and normalized dendritic complexity and spine density. Molecularly, paeonol suppressed p-cofilin1 and GSK3β expression while restoring cofilin1 and calcineurin levels. Conclusion Chronic stress induces dendritic hypertrophy and spine hyperplasticity, contributing to depressive phenotypes. Paeonol counteracts these effects, likely by modulating the GSK3β/calcineurin pathway, highlighting its therapeutic potential for stress-related neuronal injury.