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Manganese and 1-methyl-4-(2'-ethylpheny1)-1,2,3,6-tetrahydropyridine induce apoptosis in PC12 cells
M S Desole1, L Sciola, M R Delogu
1Institute of Pharmacology, University of Sassari, Italy. desole@ssmain.uniss.it
Abstract:
Oxidative stress is thought to play a key role both in the neurotoxin MPTP- and manganese (Mn)-induced neurotoxicity and in apoptotic cell death. In the present study, we report that Mn and the MPTP analogue 1-methyl-4-(2'-ethylphenyl)-1,2,3,6-tetrahydropyridine (2'Et-MPTP), which is metabolized by MAO-A to 1-methyl-4-(2'-ethylphenyl)-pyridinium ion (at concentrations of 0.5 and 1.0 mM), induced apoptosis in PC12 cells. Apoptosis was tested by terminal deoxynucleotidyl transferase-mediated 2'-deoxy-uridine-5'-triphosphate nick end labelling (TUNEL) technique, flow cytometry and fluorescence microscopy. Both Mn and 2'Et-MPTP induced also a time-dependent decrease in cell viability, as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Only Mn-induced apoptosis and decrease in cell viability were inhibited by the antioxidant ascorbic acid. We conclude that apoptosis may be an important mechanism of cell death in MPTP- and Mn-induced parkinsonism. However, an oxidative stress mechanism may be recognized only in the Mn-induced apoptosis.
Insights
Manganese (Mn) and 2'Et-MPTP induced apoptosis in PC12 cells. Only Mn-induced cell death was mitigated by ascorbic acid, suggesting oxidative stress is specific to Mn neurotoxicity.
Area of Science:
- Neuroscience
- Toxicology
- Cell Biology
Background:
- Oxidative stress is implicated in neurotoxicity from MPTP and manganese (Mn).
- Apoptotic cell death is a key cellular process investigated in neurodegenerative diseases.
Purpose of the Study:
- To investigate the role of manganese (Mn) and 1-methyl-4-(2'-ethylphenyl)-1,2,3,6-tetrahydropyridine (2'Et-MPTP) in inducing apoptosis in PC12 cells.
- To determine if oxidative stress mediates Mn- and 2'Et-MPTP-induced neurotoxicity.
Main Methods:
- PC12 cells were treated with Mn or 2'Et-MPTP.
- Apoptosis was assessed using TUNEL assay, flow cytometry, and fluorescence microscopy.
- Cell viability was measured using the MTT assay.
- The effect of ascorbic acid on Mn- and 2'Et-MPTP-induced toxicity was evaluated.
Main Results:
- Both Mn and 2'Et-MPTP induced apoptosis and decreased cell viability in PC12 cells.
- Ascorbic acid inhibited Mn-induced apoptosis and cell viability reduction, but not that induced by 2'Et-MPTP.
- These findings suggest Mn-induced apoptosis involves oxidative stress, while 2'Et-MPTP-induced apoptosis may not.
Conclusions:
- Apoptosis is a significant mechanism in MPTP- and Mn-induced parkinsonism.
- Oxidative stress appears to be a specific mechanism contributing to Mn-induced neurotoxicity and apoptosis.