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Updated: Apr 17, 2026
Assessment of Dopaminergic Homeostasis in Mice by Use of High-performance Liquid Chromatography Analysis and Synaptosomal Dopamine Uptake
Published on: September 21, 2017
Contribution of dopamine to mitochondrial complex I inhibition and dopaminergic deficits caused by
L Barros-Miñones1, B Goñi-Allo1, V Suquia1
1Department of Pharmacology and Toxicology, School of Medicine, University of Navarra, Spain.
Abstract:
Methylenedioxymethamphetamine (MDMA) causes a persistent loss of dopaminergic cell bodies in the substantia nigra of mice. Current evidence indicates that MDMA-induced neurotoxicity is mediated by oxidative stress probably due to the inhibition of mitochondrial complex I activity. In this study we investigated the contribution of dopamine (DA) to such effects. For this, we modulated the dopaminergic system of mice at the synthesis, uptake or metabolism levels. Striatal mitochondrial complex I activity was decreased 1 h after MDMA; an effect not observed in the striatum of DA depleted mice or in the hippocampus, a dopamine spare region. The DA precursor, L-dopa, caused a significant reduction of mitochondrial complex I activity by itself and exacerbated the dopaminergic deficits when combined with systemic MDMA. By contrast, no damage was observed when L-dopa was combined with intrastriatal injections of MDMA. On the other hand, dopamine uptake blockade using GBR 12909, inhibited both, the acute inhibition of complex I activity and the long-term dopaminergic toxicity caused by MDMA. Moreover, the inhibition of DA metabolism with the monoamine oxidase (MAO) inhibitor, pargyline, afforded a significant protection against MDMA-induced complex I inhibition and neurotoxicity. Taken together, these findings point to the formation of hydrogen peroxide subsequent to DA metabolism by MAO, rather than a direct DA-mediated mitochondrial complex I inhibition, and the contribution of a peripheral metabolite of MDMA, as the key steps in the chain of biochemical events leading to DA neurotoxicity caused by MDMA in mice.
Insights
Methylenedioxymethamphetamine (MDMA) causes neurotoxicity by affecting dopamine. MDMA
Area of Science:
- Neuroscience
- Pharmacology
- Toxicology
Background:
- Methylenedioxymethamphetamine (MDMA) is known to cause persistent dopaminergic neurotoxicity.
- Oxidative stress, likely from mitochondrial complex I inhibition, is implicated in MDMA's neurotoxic effects.
Purpose of the Study:
- To investigate the specific role of dopamine (DA) in MDMA-induced neurotoxicity.
- To elucidate the biochemical pathways underlying MDMA's effects on dopaminergic neurons.
Main Methods:
- Modulation of the dopaminergic system in mice (synthesis, uptake, metabolism).
- Assessment of striatal mitochondrial complex I activity post-MDMA administration.
- Administration of L-dopa, GBR 12909 (dopamine uptake blocker), and pargyline (MAO inhibitor) in conjunction with MDMA.
Main Results:
- MDMA decreased striatal mitochondrial complex I activity, an effect absent in dopamine-depleted mice.
- L-dopa exacerbated MDMA's toxicity, while dopamine uptake blockade and MAO inhibition offered protection.
- Findings suggest hydrogen peroxide from dopamine metabolism, not direct dopamine action, is key to MDMA neurotoxicity.
Conclusions:
- Dopamine metabolism, specifically via monoamine oxidase (MAO), generates hydrogen peroxide contributing to MDMA neurotoxicity.
- MDMA's neurotoxic effects on dopaminergic neurons are mediated by oxidative stress linked to dopamine metabolism.
- Peripheral MDMA metabolites also play a role in the observed neurotoxicity.
