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Glutamate decreases mitochondrial size and movement in primary forebrain neurons
Gordon L Rintoul1, Anthony J Filiano, Jacques B Brocard
1Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Abstract:
Mitochondria are essential to maintain neuronal viability. In addition to the generation of ATP and maintenance of calcium homeostasis, the effective delivery of mitochondria to the appropriate location within neurons is also likely to influence their function. In this study we examined mitochondrial movement and morphology in primary cultures of rat forebrain using a mitochondrially targeted enhanced yellow fluorescent protein (mt-eYFP). Mt-eYFP-labeled mitochondria display a characteristic elongated phenotype and also move extensively. Application of glutamate to cultures results in a rapid diminution of movement and also an alteration from elongated to rounded morphology. This effect required the entry of calcium and was mediated by activation of the NMDA subtype of glutamate receptor. Treatment of cultures with an uncoupler or blocking ATP synthesis with oligomycin also stopped movement but did not alter morphology. Interestingly, application of glutamate together with the uncoupler did not prevent the changes in movement or shape but facilitated recovery after washout of the stimuli. This suggests that the critical target for calcium in this paradigm is cytosolic. These studies demonstrate that in addition to altering the bioenergetic properties of mitochondria, neurotoxins can also alter mitochondrial movement and morphology. We speculate that neurotoxin-mediated impairment of mitochondrial delivery may contribute to the injurious effects of neurotoxins.
Insights
Mitochondrial movement and shape in neurons are altered by glutamate, impacting neuronal viability. This study reveals how neurotoxins affect mitochondrial transport and morphology, potentially contributing to neuronal injury.
Area of Science:
- Neuroscience
- Cell Biology
- Mitochondrial Dynamics
Background:
- Mitochondria are crucial for neuronal survival, providing ATP and regulating calcium.
- Effective mitochondrial transport within neurons is vital for their function.
- Neurotoxins can impair neuronal health through various mechanisms.
Purpose of the Study:
- To investigate the effects of glutamate on mitochondrial movement and morphology in primary rat neurons.
- To elucidate the role of calcium and NMDA receptors in glutamate-induced mitochondrial changes.
- To explore the relationship between mitochondrial bioenergetics, movement, and morphology.
Main Methods:
- Utilized primary cultures of rat forebrain neurons.
- Employed mitochondrially targeted enhanced yellow fluorescent protein (mt-eYFP) for live imaging.
- Applied glutamate, NMDA receptor antagonists, calcium chelators, ATP synthesis inhibitors, and uncouplers.
Main Results:
- Glutamate rapidly reduced mitochondrial movement and altered morphology from elongated to rounded.
- These effects were dependent on calcium influx and NMDA receptor activation.
- ATP depletion or uncoupling inhibited movement but not morphology changes.
- Cytosolic calcium appears critical for glutamate-induced mitochondrial alterations.
Conclusions:
- Neurotoxins, like glutamate, can disrupt mitochondrial transport and morphology, not just bioenergetics.
- Impaired mitochondrial delivery due to neurotoxin action may contribute to neuronal damage.
- Understanding these dynamics offers insights into neuroprotection strategies.