Related Experiment Video
Updated: May 28, 2026
Gene-environment Interaction Models to Unmask Susceptibility Mechanisms in Parkinson's Disease
Published on: January 7, 2014
The role of the MYD88-dependent pathway in MPTP-induced brain dopaminergic degeneration
Janelle Drouin-Ouellet1, Claire Gibrat, Mélanie Bousquet
1Axe Neurosciences, Centre de Recherche du CHUL (CHUQ), T2-50, 2705 Boulevard Laurier, Québec, G1V 4G2, Canada.
Background:
Mounting evidence supports a significant role of inflammation in Parkinson's disease (PD) pathophysiology, with several inflammatory pathways being suggested as playing a role in the dopaminergic degeneration seen in humans and animal models of the disease. These include tumor necrosis factor, prostaglandins and oxidative-related stress components. However, the role of innate immunity has not been established in PD.
Methods:
Based on the fact that the myeloid differentiation primary response gene (88) (MyD88) is the most common adaptor protein implicated in toll-like receptor (TLR) signaling, critical in the innate immune response, we undertook a study to investigate the potential contribution of this specific pathway to MPTP-induced brain dopaminergic degeneration using MyD88 knock out mice (MyD88-/-), following our observations that the MyD88-dependent pathway was critical for MPTP dopaminergic toxicity in the enteric nervous system. Post-mortem analyses assessing nigrostriatal dopaminergic degeneration and inflammation were performed using HPLC, western blots, autoradiography and immunofluorescence.
Results:
Our results demonstrate that MyD88-/- mice are as vulnerable to MPTP-induced dopamine and DOPAC striatal depletion as wild type mice. Furthermore, MyD88-/- mice show similar striatal dopamine transporter and tyrosine hydroxylase loss, as well as dopaminergic cell loss in the substantia nigra pars compacta in response to MPTP. To evaluate the extent of the inflammatory response created by the MPTP regimen utilized, we further performed bioluminescence imaging using TLR2-luc/gfp transgenic mice and microglial density analysis, which revealed a modest brain microglial response following MPTP. This was accompanied by a significant astrocytic reaction in the striatum, which was of similar magnitude both in wild type and MyD88-/- mice.
Conclusions:
Our results suggest that subacute MPTP-induced dopaminergic degeneration observed in the central nervous system is MyD88-independent, in contrast to our recent observations that this pathway, in the same cohort of animals, is critical in the loss of dopaminergic neurons in the enteric nervous system.
Insights
The innate immune pathway involving MyD88 (myeloid differentiation primary response gene 88) does not protect against MPTP-induced brain damage in Parkinson's disease models. This contrasts with its critical role in the gut's nervous system.
Area of Science:
- Neuroscience
- Immunology
- Neurodegeneration
Background:
- Inflammation plays a key role in Parkinson's disease (PD) pathophysiology.
- Specific inflammatory pathways like TNF, prostaglandins, and oxidative stress are implicated in dopaminergic degeneration.
- The contribution of innate immunity to PD remains unclear.
Purpose of the Study:
- To investigate the role of the MyD88 (myeloid differentiation primary response gene 88) pathway in MPTP-induced dopaminergic degeneration in the brain.
- To compare the effects of MyD88 deficiency in the central nervous system (CNS) versus the enteric nervous system (ENS).
Main Methods:
- Utilized MyD88 knockout (MyD88-/-) and wild-type mice.
- Administered MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) to induce dopaminergic neurodegeneration.
- Performed post-mortem analyses including HPLC, western blots, autoradiography, and immunofluorescence to assess nigrostriatal degeneration and inflammation.
- Used bioluminescence imaging and microglial density analysis to evaluate the inflammatory response.
Main Results:
- MyD88-/- mice exhibited similar vulnerability to MPTP-induced striatal dopamine depletion as wild-type mice.
- Loss of dopamine transporters, tyrosine hydroxylase, and dopaminergic cells in the substantia nigra pars compacta were comparable between MyD88-/- and wild-type mice.
- MPTP induced a modest brain microglial response and a significant astrocytic reaction in the striatum, with no difference observed between MyD88-/- and wild-type mice.
Conclusions:
- MPTP-induced dopaminergic degeneration in the CNS is independent of the MyD88 pathway.
- This finding contrasts with the critical role of MyD88 in MPTP-induced dopaminergic neurotoxicity within the enteric nervous system.
Related Concept Videos
01:24Parkinson Disease ll: Pathophysiology
01:15Parkinson's Disease: Overview