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Methylmalonate toxicity in primary neuronal cultures
B A McLaughlin1, D Nelson, I A Silver
1Institute of Neurological Sciences, University of Pennsylvania, Philadelphia 19104, USA.
Neuroscience
|August 6, 1998
Summary
Methylmalonate, a malonate-producing compound, causes dose-dependent neuronal death by inhibiting mitochondrial complex II. This leads to ATP depletion, ion gradient collapse, and increased calcium, triggering apoptosis and necrosis, particularly in striatal neurons.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Inhibitors of mitochondrial complex II induce neuronal death.
- Malonate's effects mimic Huntington's disease pathology in the striatum.
- Methylmalonate produces malonate intracellularly, serving as a model compound.
Purpose of the Study:
- To characterize the in vitro effects of malonate on neuronal death.
- To investigate the mechanisms underlying methylmalonate-induced neurotoxicity.
- To compare the vulnerability of striatal and cortical neurons to mitochondrial inhibition.
Main Methods:
- Primary neuronal cultures (striatal and cortical) from embryonic rats.
- Exposure to methylmalonate and assessment of cell viability.
- Measurement of ATP/ADP ratio, neurotransmitter levels, and ion concentrations.
- DNA laddering, videomicroscopy, and Hoechst staining for cell death analysis.
Main Results:
- Methylmalonate caused dose-dependent neuronal death (>90% mortality at 10 mM), with cortical cells being more vulnerable.
- Antioxidants attenuated cell death, indicating oxidative stress involvement.
- Apoptosis and necrosis were observed, with apoptosis being more prevalent.
- Methylmalonate decreased ATP/ADP ratio, altered neurotransmitter levels (GABA, aspartate), and disrupted ion gradients ([Na+]i, [K+]i, membrane potential, [Ca2+]i).
Conclusions:
- Malonate-induced neurotoxicity involves ATP depletion and ion gradient collapse, increasing cellular stress.
- Early elevation of intracellular calcium may trigger apoptotic and necrotic pathways.
- Maturational and/or extrinsic factors likely influence striatal neuron vulnerability to mitochondrial inhibition.