Vanillin Mitigates the MPTP-Induced α-Synucleinopathy in a Mouse Model of Parkinson's Disease: Insights into the Involvement of Wnt/β-Catenin Signaling

Background: The abnormal aggregation of alpha-synuclein (alpha-syn) in the substantia nigra pars compacta (SNpc) region of the brain is characteristic of Parkinson's disease (PD), leading to the selective demise of neurons. Modifications in the post-translational processing of alpha-syn, phosphorylation at Ser(129) in particular, are implicated in alpha-syn aggregation and are considered key hallmarks of PD. Furthermore, dysregulated Wnt/beta-catenin signaling, influenced by glycogen synthase kinase-3 beta (GSK-3 beta), is implicated in PD pathogenesis. Inhibition of GSK-3 beta holds promise in promoting neuroprotection by enhancing the Wnt/beta-catenin pathway. Methods: In our previous study utilizing 1-methyl-4-phenylpyridinium (MPP+)-administered differentiated SH-SY5Y cells and a PD mouse model, we explored Vanillin's neuroprotective properties and related mechanisms against neuronal loss induced by MPP+/1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration. In the current study, we elucidated the mitigating effects of Vanillin on motor impairments, P-Ser(129)-alpha-syn expression, Wnt/beta-catenin signaling, and autophagic neuron death induced by MPTP in a mouse model of PD by performing motor function tests, western blot analysis and immunostaining. Results: Our results show that Vanillin effectively modulated the motor dysfunctions, GSK-3 beta expression, and activity, activated the Wnt/beta-catenin signaling, and reduced autophagic neuronal demise in the MPTP-lesioned mice, highlighting its neuroprotective effects. Conclusions: These findings underscore the complex interplay between alpha-syn pathology, GSK-3 beta, Wnt/beta-catenin signaling, and autophagic-cell death in PD pathogenesis. Targeting these pathways, particularly with Vanillin, can be a promising therapeutic strategy for restoring dopaminergic (DA-ergic) neuronal homeostasis and slowing the progression of PD. Further research is crucial to resolving existing disputes and translating these discoveries into effective therapeutic interventions for PD patients.