Icariin Combined with Probiotics Ameliorates MPTP-Induced Parkinson‘s Disease in Mice via Gut Microbiota Regulation and the Ras Signaling Pathway

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons and the aggregation of α-synuclein (α-syn), with limited effective treatment options available currently. This study investigated the therapeutic effect and mechanism of Icariin (ICA) combined with Enterococcus faecium R-026 and Bacillus subtilis R-179 on MPTP-induced PD in mice. The results showed that the motor function of PD mice was significantly improved after combined drug treatment. Biochemical analysis indicated that in the combined treatment group, the activities of Superoxide dismutase (SOD) and Catalase (CAT) were increased, the content of Dopamine (DA) in brain tissue was elevated, the level of Malondialdehyde (MDA) was reduced, and the content of Glutathione (GSH) was restored simultaneously. Immunofluorescence staining results revealed that the relative number of Tyrosine hydroxylase (TH)-positive neurons in the brain tissue of mice in the MPTP group was significantly lower than that in the control (Con) group; meanwhile, the number of α-syn-positive neurons in the brain regions of mice in the MPTP group was significantly increased. At the molecular level, the combined treatment downregulated the expression of α-syn, Nuclear factor kappa-B (NF-κB), Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), and BCL2-Associated X (BAX), while upregulating the expression of TH, B-cell lymphoma/leukemia-2 (Bcl-2), PTEN-induced kinase 1 (PINK1), and Inhibitor of nuclear factor kappa B alpha (IκBα). Gut microbiota analysis demonstrated that the combined treatment reversed dysbiosis and restored the abundances of Akkermansia and Lactobacillus. Transcriptomic analysis showed that the Ras signaling pathway was activated, and the expressions of the Epha2, Angpt2, Tgfa, and pla2g4a genes were upregulated. These findings suggest that Icariin combined with probiotics exerts a significant therapeutic effect on MPTP-induced PD in mice, and its action may be mediated by antioxidant activity, gut microbiota regulation, and Ras signaling pathway modulation. This provides experimental evidence for its potential application in the management of Parkinson's disease.