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Cd(2+)-induced injury in CNS white matter
R Fern1, J A Black, B R Ransom
1Department of Neurology, Yale University School of Medicine, New Haven 06510, USA.
Journal of Neurophysiology
|November 1, 1996
Summary
Cadmium (Cd2+) exposure significantly impairs central nervous system white matter function by disrupting mitochondrial respiration. This damage, evidenced by reduced compound action potential, is irreversible and linked to mitochondrial and cytoskeletal damage.
Area of Science:
- Neuroscience
- Toxicology
- Cellular Biology
Background:
- Cadmium (Cd2+) is a toxic heavy metal with known detrimental effects on biological systems.
- Central nervous system (CNS) white matter is crucial for nerve signal transmission.
- Understanding the specific mechanisms of Cd2+ neurotoxicity is vital for public health.
Purpose of the Study:
- To investigate the effects of extracellular Cd2+ on CNS white matter function using an isolated rat optic nerve model.
- To elucidate the mechanisms underlying Cd2+ induced neurotoxicity in white matter.
Main Methods:
- Isolated rat optic nerve preparation exposed to varying concentrations of Cd2+.
- Measurement of compound action potential (CAP) to assess nerve function.
- Assessment of Cd2+ effects in the absence and presence of extracellular Ca2+ and other ions.
- Pharmacological inhibition of various cellular pathways and proteins.
- Electron microscopy to examine ultrastructural changes.
Main Results:
- Cd2+ exposure significantly reduced CAP area, indicating impaired white matter function.
- This effect was irreversible and not mitigated by Ca2+ or chelators once established.
- Cd2+ induced damage was mimicked by antimycin A, a mitochondrial respiration inhibitor.
- Ultrastructural analysis revealed mitochondrial swelling, cristae disruption, and microtubule dissolution in Cd2+-exposed nerves.
- Cd2+ influx occurred via voltage-gated Ca2+ channels, leading to mitochondrial dysfunction.
Conclusions:
- Cd2+-induced white matter injury in the CNS is primarily caused by the disruption of mitochondrial respiration.
- Mitochondrial dysfunction and cytoskeletal damage are key pathological features of Cd2+ neurotoxicity.
- Voltage-gated Ca2+ channels play a role in Cd2+ entry, initiating the cascade of cellular damage.