Abstract
During CNS ischaemia, accumulating evidence suggests that raised intracellular Zn(2+) levels may play a significant role in inducing neuronal cell death. Several mechanisms mediating Zn(2+)-induced cell death have been suggested, however the precise molecular mechanisms remain uncertain. Employing the HT-22 murine hippocampal neuronal cell line, we have evaluated possible mechanisms of cytotoxic extracellular Zn(2+) insults. Increased extracellular Zn(2+) levels was found to induce concentration-dependent cytotoxicity. When tested at 200muM, Zn(2+) increased intracellular Zn(2+) levels (determined via FluoZin-3 fluorescence) and rapidly induced cell death. However, neither L-type (nimodipine) nor T-type (mibefradil) voltage-activated Ca(2+) channel inhibitors limited Zn(2+)-induced cytotoxicity. Furthermore, and in contrast with staurosporine, Zn(2+) cytotoxic insults failed to induce significant caspase-3 activation and were insensitive to the poly-caspase inhibitor, zVAD-fmk. Antioxidant co-application (Trolox and N,N'-diphenyl-1,4-phenylenediamine (DPPD)) was neuroprotective versus 6h Zn(2+) insults. Additionally, despite inducing significant mitochondrial membrane potential loss, Zn(2+) failed to induce detectable increased superoxide production. However, both pyruvate and oxaloacetate were found to afford significant neuroprotection versus Zn(2+) cytotoxic insults, without significantly influencing intracellular Zn(2+) accumulation. We conclude that cultured HT-22 neurones are vulnerable to Zn(2+) cytotoxic insults via a non-caspase-3 mediated mechanism, which involves glycolytic inhibition.
Original language | English |
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Pages (from-to) | 1043-1051 |
Number of pages | 0 |
Journal | NeuroToxicology |
Volume | 27 |
Issue number | 6 |
DOIs | |
Publication status | Published - Dec 2006 |
Keywords
- Analysis of Variance
- Animals
- Caspase 3
- Cell Death
- Cell Line
- Transformed
- Cytotoxins
- Diagnostic Imaging
- Dose-Response Relationship
- Drug
- Drug Interactions
- Flow Cytometry
- Insecticides
- Membrane Potential
- Mitochondrial
- Mice
- Neurons
- Oxaloacetic Acid
- Phenanthridines
- Pyruvic Acid
- Rotenone
- Zinc