A Novel Mouse Model of Parkinson's Disease for Investigating Progressive Pathology and Neuroprotection

Developing animal models that successfully recapitulate the features of progressive Parkinsons disease (PD) is crucial for understanding disease progression mechanisms and creating effective therapeutic interventions. In this study, we created a mouse model of PD by overexpressing -synuclein through a combined injection of AAV6--synuclein and preformed fibrils (PFFs) into the medial and lateral substantia nigra (SN). We also demonstrated that chronic administration of the c-Abl inhibitor PD180970 provides neuroprotection in this model. Mice injected with the AAV6--synuclein and PFF combination showed a progressive loss of dopaminergic (DA) neurons in the SN and their projections in the striatum over 24 weeks. This neuronal loss coincided with a time-dependent accumulation of phosphorylated -synuclein (p-syn) in the SN. The p-syn aggregates spread to synaptically connected DARPP-32-positive neurons in the striatum and further extended to the cortex. We also observed a contralateral spread of p-syn aggregates. Additionally, -synuclein overexpression led to a significant increase in activated microglia and astrocytes at all timepoints, with the strongest activation occurring early and gradually diminishing over time. Daily administration of PD180970 significantly reduced the loss of DA neurons caused by -synuclein injection and decreased the accumulation of p-syn in the SN. PD180970 treatment also reduced the neuroinflammation significantly. Overall, the combined injection of AAV6--synuclein and preformed fibrils into the mouse brain establishes a robust PD model, enabling detailed mechanistic studies of the disease. We further demonstrate the models utility for chronic neuroprotection studies using the potential drug PD180970, highlighting its broad applicability. Significance StatementThis study establishes a robust mouse model of Parkinsons disease (PD) by combining AAV6-mediated -synuclein overexpression and preformed fibrils (PFFs) to replicate key features of PD, such as progressive dopaminergic neuron loss, phosphorylated -synuclein accumulation, and neuroinflammation. The model captures the spread of pathological aggregates to synaptically connected brain regions, closely mimicking the human disease. By testing the c-Abl inhibitor PD180970, we demonstrate its neuroprotective effects, including reduced neuronal loss, decreased -synuclein accumulation, and neuroinflammation highlighting its therapeutic potential. This model offers a valuable platform for investigating PD mechanisms and evaluating novel interventions, bridging the gap between preclinical and clinical applications.