Intra-striatal infusion of the small molecule alpha-synuclein
aggregator, FN075, fails to enhance Parkinsonism in a subclinical
AAV-alpha-synuclein rat model.
Abstract
Numerous challenges hinder the development of neuroprotective treatments
for Parkinson’s disease, with a regularly identified issue being the
lack of clinically relevant animal models. Viral vector overexpression
of α-synuclein is widely considered the most relevant model, however
this has been limited by high variability and inconsistency. One
potential method of optimisation is pairing it with a secondary insult
such as FN075, a synthetic molecule demonstrated to accelerate
α-synucleinopathy. Thus, the aim of this study was to investigate if
sequential infusion of AAV-α-synuclein and FN075 into the rat brain can
replicate α-synucleinopathy, nigrostriatal pathology and motor
dysfunction associated with Parkinson’s disease. Rats received a
unilateral injection of AAV-α-synuclein (or AAV-GFP) into two sites in
the substantia nigra, followed 4 weeks later by unilateral injection of
FN075 (or vehicle) into the striatum. Animals underwent behavioural
testing every 4 weeks until sacrifice at 20 weeks, followed by
immunohistochemistry assessment post-mortem. As anticipated,
AAV-α-synuclein led to extensive overexpression of human α-synuclein
throughout the nigrostriatal pathway, as well as elevated levels of
pathological and aggregated forms of the protein. However, the
sequential administration of FN075 into the striatum did not exacerbate
any of the α-synuclein pathology. Furthermore, despite the extensive
α-synuclein pathology, neither administration of AAV-α-synuclein nor
FN075, alone or in combination, was sufficient to induce dopaminergic
degeneration or motor deficits. In conclusion, this approach did not
replicate the key characteristics of Parkinson’s disease, and further
studies are required to create more representational models for testing
of novel compounds and treatments for Parkinson’s disease.