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Synuclein Model Overview

Alpha-synuclein (α-synuclein; α-syn) is major pathogenic protein found in Lewy bodies in the substantia nigra pars compacta and other brain regions in Parkinson's disease (PD). For this Parkinson's disease model, we perform stereotaxic inoculation of recombinant preformed fibrils (PFFs) of human α-syn into the brains of M83 transgenic mice [B6;C3-Tg( Prnp SNCA A53T )83Vle/J] with α-syn overexpression or murine α-syn into the brains of non-transgenic, wild-type (B6-C3H) mice.

Our validated injection sites are Striatum +/- Overlying Cortex or Medial Forebrain Bundle (MFB).

A simplified illustration of a cross-sectional view of a rodent brain - Parkinson's Disease - Synuclein PFF injection striatum cortex
A simplified illustration of a cross-sectional view of a rodent brain - Parkinson's Disease - MFB model injection site

The rationale for targeting the Striatum +/- Overlying Cortex includes:

  • It is the injection site originally reported (Luk et al., J. Exp. Med., 209: 975-986, 2011; doi: 10.1084/jem.20112457; Luk et al., Science, 338: 949-953, 2012; doi: 10.1126/science.1227157)
  • The dopaminergic nerve terminals in the striatum originate from neurons in the substantia nigra
  • Injection into the overlying cerebral cortex increases the extent alpha-synuclein pathology in the brain

Our rationale for targeting the MFB includes:

  • It is a tract directly connected to the substantia nigra and ventral tegmental area, and is often targeted in toxin-based models of human Parkinson's disease (e.g. 6-hyroxydopamine [6-OHDA])
  • It serves as a "hub" for projections from many other brain regions, thereby serving as an excellent seeding location to facilitate spreading of alpha-synuclein pathology to distant brain regions
  • This model results in significant loss of dopaminergic neurons in the substantia nigra and associated motor deficits

A significant advantage of this animal model of Parkinson's disease is that it reproduces many aspects of the human disease, including:

  • Highly reproducible spreading of alpha-synuclein in a well-defined spatiotemporal pattern, resulting in extensive alpha-synuclein pathology in neuronal cell bodies and neurites
  • Strong neuroinflammation (microgliosis and astrogliosis)
  • Neurodegeneration with loss of tyrosine hydroxylase positive neurons in the substantia nigra & regional brain atrophy
  • Measurable motor function changes
  • Amenable to disease modification via therapeutic intervention

Synuclein Model Generation

A general schema for synuclein PFF animal model generation is:

Parkinson's Disease - PFF Model Generation process
 A stereotaxic surgery setup with a rodent, commonly used in neurological research to administer treatments with precision to specific brain regions, particularly for Parkinson's Disease (PD) studies.

We have in-licensed the M83 transgenic (tg) mice. As a Preclinical Neuroscience CRO, we maintain a well-established breeding colony of these transgenic alpha-synuclein mice in-house at Biospective, allowing us to conduct large-scale (>100 mice) studies.

For this specific rodent model, we breed and age M83+/- male mice to 8-12 weeks-of-age. Alternatively, we use wild-type (B6-C3H) mice at 8-12 weeks-of-age. We then perform stereotaxic injection of sonicated, recombinant human alpha-synuclein PFFs into the target region. We use digital stereotaxic devices with automated microinjectors for high accuracy & precision.

This animal model is highly reproducible with a nearly 100% success rate of synuclein PFF seeding.

Our Synuclein Mouse Model Validated Measures

Immunohistochemistry (IHC) staining of brain tissue sections to reveal alpha synuclein burden in anterior olfactory nucleus (AON), associated with Parkinson's Disease (PD)

Phosphorylated alpha-synuclein immunohistochemistry staining of the ipsilateral (left) and contralateral (right) striatum at 12 weeks post-injection following unilateral stereotaxic inoculation of alpha-synuclein preformed fibrils (PFFs) into the striatum and overlying cerebral cortex of an M83+/- mouse.

Learn more about our characterization of this model, our validated measures, and our Preclinical Neuroscience CRO services.

Discover more of our Parkinson's Disease Models


What is the difference between using the M83+/- transgenic compared to wild-type model?

Striatum Ctx NFL Plasma Graph

The M83+/- transgenic (tg) mice demonstrate a significantly higher level of pathology in a shorter period of time compared to wild-type mice. They also demonstrate a range of progressive changes that can be measured during the in-life phase of the study, including elevated neurofilament light levels in the plasma & CSF, brain atrophy by in vivo MRI, and alterations in motor function, which we do not observe in the milder, wild-type (wt) mouse model.

Does the α-synuclein fibril seeding model (motor system) show progressive motor dysfunction?

Yes. In particular, the MFB-injection Parkinson disease model demonstrates a number of motor deficits typically associated with loss of dopaminergic neurons in the substantia nigra. We have a wide range of motor function tests that are applicable to this mouse model.

Does Biospective perform unilateral or bilateral stereotaxic injections of PFFs?

We can do both. For analysis of spreading, the unilateral injection is ideal as it allows us to assess spread to the contralateral hemisphere. Bilateral injections can be advantageous when a higher level of pathology is desired or when we want equivalence between the brain hemispheres (for example, when one hemisphere will be used for IHC analysis and the other hemisphere for biochemistry analysis).

Can Biospective use human brain extracts/homogenates rather than recombinant PFFs?

Yes, we can do that. Our scientists would be happy to discuss the specifics of this type of animal model with you.

Is the α-synuclein fibril seeding model (motor system) readily available for studies?

Yes. We maintain a well-established breeding colony of M83 transgenic synuclein mice so that mice are readily available for studies. Mice are typically aged to 8-12 weeks prior to inoculation with alpha-synuclein preformed fibrils (PFFs).

What is a "preformed fibril" (PFF)?

Preformed fibrils (PFFs) are recombinant, monomeric proteins (e.g. alpha-synuclein or tau) are incubated under specific conditions to generate aggregated, misfolded fibrils. These fibrils are then sonicated to generate short fibrils that can be used for in vitro or in vivo studies.

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