α-Synuclein-Based Animal Models of Parkinson’s Disease

Establishment and Efficacy Evaluation of α-Synuclein-Based Animal Models of Parkinson’s Disease

OncoWuXi Express will continue to keep you informed about updates to our online pharmacology model database (OncoWuXi Database), as well as our recent progress in preclinical research. In this issue, we are pleased to introduce our α-synuclein-based animal models for Parkinson’s disease.

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Parkinson’s disease (PD) is the second most common neurodegenerative disease globally, affecting over 10 million people worldwide ^[1]. As population aging continues to accelerate, its incidence rate remains on the rise. However, current therapeutic strategies are largely limited to symptomatic relief and fail to halt disease progression. The core pathological hallmarks of PD are the progressive loss of dopaminergic neurons in the substantia nigra pars compacta of the midbrain, along with the emergence of Lewy bodies and Lewy neurites—primarily composed of α-synuclein—within the cytoplasm of surviving neurons ^[2]. Extensive genetic and pathological evidence indicates that the abnormal aggregation, fibrillation, and spreading of α-synuclein within the brain play a pivotal role in the onset and progression of PD ^[3]. Therefore, developing α-synuclein-targeted animal models that more closely recapitulate human pathological features is invaluable for elucidating the pathogenesis and screening disease-modifying drugs, emerging as a critical breakthrough point in current PD research.

α-Synuclein: From Physiological Function to “Pathological Seed”

Under physiological conditions, α-synuclein is involved in synaptic vesicle trafficking and neurotransmitter release. However, under pathological conditions, α-synuclein undergoes misfolding to form pathogenic conformations with “seeding” activity (Figure 1)^[4-5]. These pathological aggregates can act as templates, inducing conformational transitions in endogenous normal α-synuclein and spreading throughout the brain along neuroanatomical pathways—a “prion-like” hypothesis that has garnered widespread support. Targeting this mechanism, WuXi Biology has developed a variety of α-synuclein-based preclinical animal models, providing powerful tools for the mechanistic research and drug R&D of PD.

Figure 1. Pathological mechanism of abnormal α-synuclein aggregation ^[6]

α-Synuclein-Based PD Animal Models

AAV-α-Syn + PFFs induced rodent models

Among numerous PD animal models,α-synuclein-based models have garnered significant attention due to their ability to highly recapitulate human pathological features. Among these, the model induced by the combination of AAV-α-Syn and preformed fibrils (PFFs) is currently one of the most widely applied tools^[7]. This model combines two complementary strategies: first, AAV-mediated overexpression of human α-synuclein in the brains of the animal models, followed by the injection of PFFs. Acting as “exogenous seeds,” PFFs can rapidly initiate the pathological aggregation of endogenous proteins, significantly accelerating the formation of α-synuclein inclusions.

Key pathological features of this model include:

Classic pathology: Intracellular formation of abnormal aggregates of phosphorylated α-synuclein (p-α-syn) within neurons.
Loss of dopaminergic neurons: PFFs induce a significant reduction of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra pars compacta (SNpc), accompanied by the degeneration of striatal nerve terminals (Figure 2).
Neurotransmitter abnormalities: A decrease in dopamine content, accompanied by the dysregulation of monoamine neurotransmitter metabolism (Figure 3).
Neuroinflammatory response: Significant activation of microglia (Iba1 positive) and astrocytes (GFAP positive) can be observed in the substantia nigra region.
Motor dysfunction: Phenotypes such as impaired motor coordination and gait abnormalities can be evaluated through various behavioral assays, including CatWalk gait analysis, the rotarod test, and the open field test.
Neurofilament light chain (NfL) analysis: The levels of NfL, a biomarker reflecting axonal damage, can be detected in the cerebrospinal fluid (CSF) or peripheral blood.

Figure 2. PFFs induce the loss of dopaminergic neurons in the substantia nigra

Figure 3. PFFs induce a decrease in dopamine content in the striatum.

AAV-α-Syn A53T-Induced Animal Models

A53T is a familial mutation of α-synuclein that is closely associated with early-onset PD. Delivery of human A53T mutant α-synuclein via AAV can induce typical PD pathological phenotypes in rodents, including widespread abnormal aggregation of α-synuclein and the loss of TH-positive dopaminergic neurons (Figure 4).

Figure 4. Pathological α-synuclein deposition and loss of TH-positive neurons.

Multidimensional Efficacy Evaluation Platform

To comprehensively evaluate the intervention effects of candidate drugs on α-synuclein pathology, WuXi Biology has established a well-developed behavioral testing and histopathological evaluation platform. This platform covers multidimensional functional and mechanistic analyses, enabling the systematic assessment of disease phenotypes and pathological mechanisms. The platform includes:

Motor function testing: Includes CatWalk gait analysis, the rotarod test, the open field test, the cylinder test, the apomorphine-induced rotation test, the pole test, and grip strength testing, among others.
Pathological testing: Evaluation of dopaminergic neuron damage via TH immunohistochemistry, detection of abnormal pathological p-α-syn aggregation via α-syn immunohistochemistry, and analysis of neuroinflammatory responses using Iba1 and GFAP labeling.
Biochemical and biomarker analysis: Includes the detection of dopamine and its metabolites, as well as the determination of NfL levels.

Conclusion

Precise animal models serve as a crucial bridge connecting basic research with clinical translation. Parkinson’s disease models constructed around α-synuclein pathology can effectively recapitulate the core pathological features of PD, thereby providing vital tools for studying the dynamic processes of disease onset and progression.

Targeting the core mechanism of abnormal α-syn aggregation, these models enable systematic and direct efficacy evaluation of various therapeutic modalities. This includes innovative small-molecule drugs, α-synuclein-targeted immunomodulatory strategies, and gene therapies (such as inhibiting α-syn expression using antisense oligonucleotides or small interfering RNAs ). Capable of comprehensively reflecting the impact of various interventions on disease progression in an in vivo environment, these models provide solid translational support for the potential development of breakthrough anti Parkinson’s therapies.

References：

[1] Castonguay AM, Gravel C, Lévesque M. Treating Parkinson’s Disease with Antibodies: Previous Studies and Future Directions. J Parkinsons Dis. 2021;11(1):71-92.

[2] Li B, Xiao X, Bi M, et al. Modulating α-synuclein propagation and decomposition: Implications in Parkinson’s disease therapy. Ageing Res Rev. 2024;98:102319.

[3] Yaribash S, Mohammadi K, Sani MA. Alpha-Synuclein Pathophysiology in Neurodegenerative Disorders: A Review Focusing on Molecular Mechanisms and Treatment Advances in Parkinson’s Disease. Cell Mol Neurobiol. 2025;45(1):30. Published 2025 Mar 26.

[4] Hallacli E, Kayatekin C, Nazeen S, et al. The Parkinson’s disease protein alpha-synuclein is a modulator of processing bodies and mRNA stability. Cell. 2022 Jun 9;185(12):2035–2056.e33.

[5] Björklund A, Mattsson B. The AAV-α-Synuclein Model of Parkinson’s Disease: An Update. J Parkinsons Dis. 2024;14(6):1077-1094.

[6] Ye H, Robak LA, Yu M, Cykowski M, Shulman JM. Genetics and Pathogenesis of Parkinson’s Syndrome. Annu Rev Pathol. 2023;18:95-121.

[7] Bellini G, D’Antongiovanni V, Palermo G, et al. α-Synuclein in Parkinson’s Disease: From Bench to Bedside. Med Res Rev. 2025;45(3):909-946.