metallothionein and linsidomine

We have examined potent peroxynitrite ion (ONOO-) generator 3-morpholinosydnonimine (SIN-1)-induced neurotoxicity in control wild-type (control(wt)) mice, metallothionein double knockout (MT(dko)) mice, metallothionein-transgenic (MT(trans)) mice, and in cultured human dopaminergic (SK-N-SH) neurons to determine the neuroprotective potential of metallothionein against ONOO(-)-induced neurodegeneration in Parkinson disease (PD). SIN-1-induced lipid peroxidation, reactive oxygen species synthesis, caspase-3 activation, and apoptosis were attenuated by metallothionein gene overexpression and augmented by metallothionein gene down-regulation. A progressive nigrostriatal dopaminergic neurodegeneration in weaver mutant (wv/wv) mice was associated with enhanced nitrite ion synthesis, metallothionein down-regulation, and significantly reduced dopamine synthesis and 18F-DOPA uptake as determined by high-resolution micropositron emission tomography neuroimaging. The striatal (18)F-DOPA uptake was significantly higher in MT(trans) mice than in MT(dko) and alpha-synuclein knockout (alpha-Syn(ko)) mice. These observations provide further evidence that nitric oxide synthase activation and ONOO- synthesis may be involved in the etiopathogenesis of PD, and that metallothionein gene induction may provide neuroprotection.

Topics: Animals; Apoptosis; Caspase 3; Caspases; Coenzymes; Dopamine; Enzyme Activation; Lipid Peroxidation; Metallothionein; Mice; Mice, Inbred C57BL; Mice, Transgenic; Molsidomine; Oxidative Stress; Parkinson Disease; Reactive Oxygen Species; Ubiquinone

Parkinson's disease is characterized by a progressive loss of dopaminergic neurons in the substantia nigra zona compacta, and in other subcortical nuclei associated with a widespread occurrence of Lewy bodies. The causes of cell death in Parkinson's disease are still poorly understood, but a defect in mitochondrial oxidative phosphorylation and enhanced oxidative stress have been proposed. We have examined 3-morpholinosydnonimine (SIN-1)-induced apoptosis in control and metallothionein-overexpressing dopaminergic neurons, with a primary objective to determine the neuroprotective potential of metallothionein against peroxynitrite-induced neurodegeneration in Parkinson's disease. SIN-1 induced lipid peroxidation and triggered plasma membrane blebbing. In addition, it caused DNA fragmentation, alpha-synuclein induction, and intramitochondrial accumulation of metal ions (copper, iron, zinc, and calcium), and enhanced the synthesis of 8-hydroxy-2-deoxyguanosine. Furthermore, it down-regulated the expression of Bcl-2 and poly(ADP-ribose) polymerase, but up-regulated the expression of caspase-3 and Bax in dopaminergic (SK-N-SH) neurons. SIN-1 induced apoptosis in aging mitochondrial genome knockout cells, alpha-synuclein-transfected cells, metallothionein double-knockout cells, and caspase-3-overexpressed dopaminergic neurons. SIN-1-induced changes were attenuated with selegiline or in metallothionein-transgenic striatal fetal stem cells. SIN-1-induced oxidation of dopamine to dihydroxyphenylacetaldehyde was attenuated in metallothionein-transgenic fetal stem cells and in cells transfected with a mitochondrial genome, and enhanced in aging mitochondrial genome knockout cells, in metallothionein double-knockout cells and caspase-3 gene-overexpressing dopaminergic neurons. Selegiline, melatonin, ubiquinone, and metallothionein suppressed SIN-1-induced down-regulation of a mitochondrial genome and up-regulation of caspase-3 as determined by reverse transcription-polymerase chain reaction. The synthesis of mitochondrial 8-hydroxy-2-deoxyguanosine and apoptosis-inducing factors were increased following exposure to 1-methyl-4-phenylpyridinium ion or rotenone. Pretreatment with selegiline or metallothionein suppressed 1-methyl-4-phenylpyridinium ion-, 6-hydroxydopamine-, and rotenone-induced increases in mitochondrial 8-hydroxy-2-deoxyguanosine accumulation. Transfection of aging mitochondrial genome knockout neurons with mitochondrial genome encoding complex-1 or mela

Topics: alpha-Synuclein; Animals; Apoptosis; Caspase 3; Caspases; Cell Line, Tumor; Corpus Striatum; Deoxyadenosines; Dopamine; Gene Expression Regulation; Humans; Lipid Peroxidation; Metallothionein; Metals; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitochondria; Molsidomine; Nerve Tissue Proteins; Neurons; Neuroprotective Agents; Oxidative Stress; Selegiline; Stem Cells; Synucleins; Transcriptional Activation

Previous studies have demonstrated that metallothionein functions as an antioxidant that protects against oxidative DNA, protein, and lipid damage induced by superoxide anion, hydrogen peroxide, hydroxyl radical, and nitric oxide. The present study was undertaken to test the hypothesis that metallothionein also protects from DNA and lipoprotein damage induced by peroxynitrite, an important reactive nitrogen species that causes a diversity of pathological processes. A cell-free system was used. DNA damage was detected by the mobility of plasmid DNA in electrophoresis. Oxidation of low density lipoprotein was measured by a thiobarbituric acid-reactive substance, which was confirmed by lipid hydroperoxide assay. Plasmid DNA damage and low density lipoprotein oxidation were induced by 3-morpholinosydnomine, which produces peroxynitrite through the reaction between nitric oxide and superoxide anion or by synthesized peroxynitrite directly. DNA damage by 3-morpholinosydnomine was prevented by both metallothionein and superoxide dismutase, whereas the damage caused by peroxynitrite was prevented by metallothionein only. The oxidation of low density lipoprotein by 3-morpholinosydnomine and peroxynitrite was also significantly inhibited by metallothionein. This study thus demonstrates that metallothionein may react directly with peroxynitrite to prevent DNA and lipoprotein damage induced by this pathological reactive nitrogen species.

Topics: Antioxidants; Cell-Free System; DNA Damage; Dose-Response Relationship, Drug; Lipid Peroxides; Lipoproteins; Lipoproteins, LDL; Metallothionein; Molsidomine; Nitrates; Nitrogen; Oxygen; Plasmids; Temperature; Thiobarbituric Acid Reactive Substances; Time Factors