ObjectiveTo investigate the antidepressant effects and mechanisms of total flavonoids from Cuscutae Semen （TFCC） in the mouse model of chronic unpredictable mild stress （CUMS）.MethodsFifty male 4-week-old ICR mice were randomized into five groups （n=10 per group）： blank control， model， Cuscutae Semen decoction （10.2 g·kg^-1·d^-1）， paroxetine （2.6 mg·kg^-1·d^-1）， and TFCC （173.2 mg·kg^-1·d^-1）. The other groups except the blank control group underwent chronic unpredictable mild stress （CUMS） for 4 weeks. Behavioral assessments were conducted post-modeling. Then， the model group received distilled water （10 mL·kg^-1·d^-1）， while treatment groups were administrated with respective agents via oral gavage （10 mL·kg^-1） for 4 weeks. Depression-like behaviors were evaluated by the sucrose preference test （SPT）， forced swimming test （FST）， and tail suspension test （TST）. Hippocampal neuronal morphology was observed via hematoxylin-eosin staining， and apoptosis in the brain tissue was assessed via terminal- deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling （TUNEL）. enzyme-linked immunosorbent assay （ELISA） was employed to measure the hippocampal levels of inflammatory cytokines ［interleukin （IL）-1β， IL-6， and TNF-α）］ and neurotransmitters ［5-hydroxytryptamine （5-HT）， dopamine （DA）， and brain-derived neurotrophic factor （BDNF）］， while the reactive oxygen species （ROS） levels were quantified via the DCFH-DA probe. Real-time PCR was performed to measure the mRNA levels of NOD-like receptor protein 3 （NLRP3）， apoptosis-associated Speck-like protein containing a CARD （ASC）， cysteinyl aspartate-specific proteinase-1 （Caspase-1）， IL-1β， and inducible nitric oxide synthase （iNOS）. Western blot was employed to evaluate the protein levels of NLRP3， ASC， Caspase-1， uncoupling protein 2 （UCP2）， and thioredoxin-interacting protein （TXNIP）.ResultsCompared with the blank control group， the model group exhibited weight loss （P<0.01）， reduced sucrose preference （P<0.01）， prolonged immobility time in FST and TST （P<0.01）， neuron disarrangement with nuclear pyknosis in hippocampal CA3 region， increased apoptosis in the brain tissue， elevated levels of IL-1β， IL-6， and TNF-α （P<0.01）， declined levels of 5-HT， DA， and BDNF （P<0.01）， increased ROS accumulation （P<0.01）， upregulated mRNA levels of NLRP3， ASC， Caspase-1， IL-1β， and iNOS （P<0.01）， down-regulated protein level of UCP2 （P<0.01）， and up-regulated protein levels of NLRP3， ASC， Caspase-1， and TXNIP （P<0.01）. Compared with the model group， the interventions restored sucrose preference （P<0.01）， shortened immobility time （P<0.01）， repaired hippocampal neuronal structure， reduced apoptosis， lowered the levels of inflammatory cytokines （P<0.01）， restored the levels of neurotransmitters （P<0.01）， alleviated ROS accumulation （P<0.01）， downregulated the mRNA levels of NLRP3， ASC， Caspase-1， IL-1β， and iNOS （P<0.01）， upregulated the protein level of UCP2 （P<0.01）， and reduced the protein levels of NLRP3， ASC， Caspase-1， and TXNIP （P<0.01）. Moreover， TFCC outperformed Cuscutae Semen decoction in ameliorating depressive behaviors. TFCC excelled in neuronal repair， neurotransmitter regulation， anti-inflammatory effects， and modulation of the UCP2/TXNIP/NLRP3 pathway （P<0.05）.ConclusionTFCC modulates the hippocampal UCP2/TXNIP/NLRP3 pathway to inhibit inflammasome activation， reduce oxidative stress， restore neurotransmitters， thus suppressing neuronal apoptosis and promoting the rearrangement and morphology recovery of hippocampal cells. It outperforms Cuscutae Semen decoction in the antidepressant efficacy.

Cuscutae Semen;total flavonoids;depression;uncoupling protein 2/thioredoxin-interacting protein/NOD-like receptor protein 3 （UCP2/TXNIP/NLRP3） signaling pathway;oxidative stress-inflammation axis