Dihydromyricetin ameliorates depressive-like behaviors in Parkinson's disease mice by promoting A2 astrocyte polarization and inhibiting neuronal ferroptosis via suppression of the LCN2/NLRP3 axis

Depressive-like behaviors is one of the most prevalent non-motor symptoms in Parkinson's disease (PD), severely compromising patients' quality of life. Dihydromyricetin (DHM), a natural flavonoid, exhibits neuroprotective effects, but its ability to ameliorate PD-related depressive-like behaviors and the underlying mechanisms remain unclear. This study aimed to investigate DHM's mechanism for improving depressive-like behaviors in PD and identify its key molecular targets.

Thirty-two 7 weeks old male C57 BL/6J mice (weighting 24.5±1.5 g) were randomly divided into 4 groups (n=8): Control, PD model, PD+Madopar (positive control), and PD+DHM. Except the control group, all groups received intraperitoneal 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to establish subacute PD models. Motor function was assessed via rotarod, pole and wire hang tests; depressive-like behaviors were evaluated using the open field, forced swimming, and tail suspension tests. Network pharmacology, dataset mining, and molecular docking predicted DHM's key targets for PD treatment. Western blotting and immunofluorescence detected DHM's effects on synaptic plasticity, astrocyte polarization, and ferroptosis. Conditioned medium experiments further validated the predicted mechanisms.

Compared with the PD group, PD+DHM mice showed significantly prolonged rotarod duration and suspension time (P<0.001), reduced pole descent time (P=0.0055), increased total distance (P<0.001) and velocity (P<0.001) in open field test, with higher central activity distance/time ratios (P<0.01), and shorter immobility times in forced swimming and suspension tests (P<0.01). Network pharmacology and molecular docking identified the Lipocalin-2 (LCN2)/NOD-like receptor thermal protein domain associcated protein 3 (NLRP3) axis as DHM's potential target. DHM intervention reversed neuronal loss and Nissl body reduction while upregulating synaptic plasticity markers BDNF, SYN1 and PSD95, compared with the PD group (P<0.01). DHM significantly downregulated LCN2, NLRP3, and A1-astrocyte marker complement component 3 (C3; P<0.001), but upregulated A2-marker S100 calcium binding protein A10(S100A10; P<0.01). Compared with the PD gruop, immunofluorescence revealed reduced GFAP/C3-positive cells and increased GFAP/S100A10 cells in the prefrontal cortex of PD+DHM group (P<0.05). Additionally, DHM decreased acyl-CoA synthetase long chain family member 4 (ACSL4) and Transferrin receptor (TFRC) expression (P<0.001), while increasing GPX4 and SLC7A11 levels (P<0.001) in the prefrontal cortex. Conditioned medium experiments confirmed that DHM and NLRP3 inhibitor MCC950 reversed abnormal ferroptosis-related changes in dopaminergic neurons (P<0.01).

DHM may ameliorate depressive-like behaviors in PD mice by inhibiting the LCN2/NLRP3 axis which promotes A2-astrocyte polarization, mitigates imbalance in astrocyte polarization and alleviates neuronal ferroptosis.