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Extracellular dopamine induces the oxidative toxicity of SH-SY5Y cells
Yuhua Jiang1, Lin Pei, Shupeng Li
1Department of Neuroscience, Centre for Addiction and Mental Health, Clarke Division, University of Toronto, Toronto, Ontario, Canada.
Abstract:
Dopamine-induced neuronal cytotoxicity has been proposed as a leading pathological mechanism underlying many neuronal degenerative disorders including Parkinson disease. Various hypotheses have been proposed including oxidative stress and dopamine (DA)-induced intracellular signal disorder via DA D1 and D2 receptors. The exact mechanism involved in this process is far from clear. In this study, employing a neuronal blastoma cell line, SH-SY5Y, we tried to elucidate the roles of these different suggested mechanisms in this pathological process. The results showed that DA induced cell toxicity in a dose- and time-dependent way. Selective D1 and D2 DA receptor antagonist could not block the cytotoxic effects, whereas reductive reagent ascorbic acid but not GSH could effectively rescue the cell death, suggesting that DA-induced cell toxicity was caused by an extracellular oxidative stress. This was further supported by the enhancing effects of DA transporter blocker, GBR, which could increase the cell death when pretreated. Finally, ascorbic acid could also protect SY5Y cells from DA-induced cellular apoptotic signal changes including PARP and P53. Our studies suggested that DA exerted its cytotoxic effects via an extracellular metabolism, whereas intracellular transportation could reduce its oxidative stress. Cytotoxicity effects induced by extracellular DA could be protected by reductive agents as ascorbic acid. These results help to broaden our understanding of the mechanisms of DA-induced cell death and may provide potentially therapeutical alternative for the neurodegenerative disorders.
Insights
Dopamine causes nerve cell damage through extracellular oxidative stress, not receptor signaling. Ascorbic acid protects against this dopamine toxicity, offering potential therapeutic strategies for neurodegenerative diseases.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Dopamine (DA) neurotoxicity is implicated in neurodegenerative disorders like Parkinson disease.
- Proposed mechanisms include oxidative stress and DA receptor signaling (D1/D2).
- The precise pathways of DA-induced neuronal damage remain unclear.
Purpose of the Study:
- To elucidate the mechanisms of dopamine-induced neuronal cytotoxicity.
- To investigate the roles of oxidative stress and receptor signaling in DA toxicity.
- To identify potential protective agents against DA-induced cell death.
Main Methods:
- Utilized the SH-SY5Y neuroblastoma cell line.
- Administered dopamine (DA) and assessed dose- and time-dependent toxicity.
- Tested the effects of D1/D2 receptor antagonists, ascorbic acid, and glutathione (GSH).
- Investigated the impact of dopamine transporter (DAT) blocker GBR.
- Examined the modulation of apoptotic markers (PARP, P53).
Main Results:
- DA induced dose- and time-dependent cytotoxicity in SH-SY5Y cells.
- D1/D2 receptor antagonists did not prevent DA-induced cell death.
- Ascorbic acid, but not GSH, rescued cells from DA toxicity, indicating extracellular oxidative stress.
- DA transporter blocker GBR enhanced DA-induced cell death.
- Ascorbic acid protected against DA-induced apoptotic signaling (PARP, P53).
Conclusions:
- DA exerts cytotoxic effects primarily through extracellular metabolism and oxidative stress.
- Intracellular transport of DA may mitigate oxidative stress.
- Extracellular DA-induced cytotoxicity can be counteracted by antioxidants like ascorbic acid.
- Findings offer insights into neuroprotection strategies for neurodegenerative disorders.
