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Is Parkinson's disease a mitochondrial disorder?
Y Nakagawa-Hattori1, H Yoshino, T Kondo
1Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan.
Abstract:
Parkinson's disease (PD) is a common degenerative disease, but its etiology is still unknown. However, since the discovery of MPTP, many investigators have been interested in the mitochondrial function in PD. We investigated mitochondrial functions in PD patients using the methods which have successfully been applied to mitochondrial myopathies (MM), i.e. assay of lactate and pyruvate, measurement of muscle mitochondrial respiratory enzyme activities and Southern blot analysis of muscle mitochondrial DNA. Parkinson's disease patients did not differ from controls in the mean blood and CSF (cerebrospinal fluid) lactate and pyruvate levels at the basal resting state or during an aerobic exercise. But mitochondrial complex I activity of the skeletal muscle was significantly decreased in PD. In the Southern blot analysis, we could not find major deletions or insertions of mitochondrial DNA in PD. Our studies disclosed a differential mitochondrial impairment between PD and MM. We discuss the implication of our observation.
Insights
Parkinson's disease (PD) patients show decreased mitochondrial complex I activity in skeletal muscle, unlike in mitochondrial myopathies (MM). This suggests a specific mitochondrial impairment in PD, distinct from MM, despite normal lactate levels.
Area of Science:
- Neuroscience
- Mitochondrial Biology
- Biochemistry
Background:
- Parkinson's disease (PD) etiology remains unknown, but MPTP research highlights potential mitochondrial dysfunction.
- Investigating mitochondrial function is crucial for understanding PD pathogenesis.
- Mitochondrial myopathies (MM) offer a comparative model for studying mitochondrial impairments.
Purpose of the Study:
- To investigate mitochondrial function in Parkinson's disease (PD) patients.
- To compare mitochondrial impairments in PD with those found in mitochondrial myopathies (MM).
- To identify specific mitochondrial deficits in PD.
Main Methods:
- Assay of lactate and pyruvate levels in blood and cerebrospinal fluid (CSF).
- Measurement of skeletal muscle mitochondrial respiratory enzyme activities.
- Southern blot analysis of muscle mitochondrial DNA.
Main Results:
- PD patients exhibited normal lactate and pyruvate levels, both at rest and during exercise, compared to controls.
- A significant decrease in skeletal muscle mitochondrial complex I activity was observed in PD patients.
- No major deletions or insertions in mitochondrial DNA were detected in PD patients via Southern blot analysis.
Conclusions:
- Mitochondrial impairment in PD is distinct from that observed in mitochondrial myopathies (MM).
- Reduced mitochondrial complex I activity in skeletal muscle is a potential biomarker for PD.
- These findings suggest a specific, differential mitochondrial deficit in Parkinson's disease.