d-609 and Alzheimer-Disease

Sphingolipids (SLs), such as ceramide, glucosylceramide (GlcCer), and sphingomyelin, play important roles in the normal development/functions of the brain and peripheral tissues. Disruption of SL homeostasis in cells/organelles, specifically up-regulation of ceramide, is involved in multiple diseases including Alzheimer's disease (AD). One of the pathological features of AD is aggregates of amyloid beta (Aβ) peptides, and SLs regulate both the formation/aggregation of Aβ and Aβ-induced cellular responses. Up-regulation of ceramide levels via de novo and salvage synthesis pathways is reported in Aβ-treated cells and brains with AD; however, the effects of Aβ on ceramide decomposition pathways have not been elucidated. Thus, we investigated the effects of the 25-35-amino acid Aβ peptide (Aβ

Topics: Alzheimer Disease; Amyloid beta-Peptides; Cell Line; Glucosyltransferases; Humans; Norbornanes; Peptide Fragments; Thiocarbamates; Transferases (Other Substituted Phosphate Groups)

Considerable evidence supports the role of oxidative stress in the pathogenesis of Alzheimer's disease. One hallmark of Alzheimer's disease is the accumulation of amyloid beta-peptide, which invokes a cascade of oxidative damage to neurons that can eventually result in neuronal death. Amyloid beta-peptide is the main component of senile plaques and generates free radicals ultimately leading to neuronal damage of membrane lipids, proteins and nucleic acids. Therefore, interest in the protective role of different antioxidant compounds has been growing for treatment of Alzheimer's disease and other oxidative stress-related disorders. Among different antioxidant drugs, much interest has been devoted to "thiol-delivering" compounds. Tricyclodecan-9-yl-xanthogenate is an inhibitor of phosphatidylcholine specific phospholipase C, and recent studies reported its ability to act as a glutathione-mimetic compound. In the present study, we investigate the in vivo ability of tricyclodecan-9-yl-xanthogenate to protect synaptosomes against amyloid beta-peptide-induced oxidative stress. Gerbils were injected i.p. with tricyclodecan-9-yl-xanthogenate or with saline solution, and synaptosomes were isolated from the brain. Synaptosomal preparations isolated from tricyclodecan-9-yl-xanthogenate injected gerbils and treated ex vivo with amyloid beta-peptide (1-42) showed a significant decrease of oxidative stress parameters: reactive oxygen species levels, protein oxidation (protein carbonyl and 3-nitrotyrosine levels) and lipid peroxidation (4-hydroxy-2-nonenal levels). Our results are consistent with the hypothesis that modulation of free radicals generated by amyloid beta-peptide might represent an efficient therapeutic strategy for treatment of Alzheimer's disease and other oxidative-stress related disorders. Based on the above data, we suggest that tricyclodecan-9-yl-xanthogenate is a potent antioxidant and could be of importance for the treatment of Alzheimer's disease and other oxidative stress-related disorders.

Topics: Aldehydes; Alzheimer Disease; Amyloid beta-Peptides; Animals; Antioxidants; Brain; Bridged-Ring Compounds; Disease Models, Animal; Free Radicals; Gerbillinae; Lipid Peroxidation; Male; Nerve Degeneration; Neurons; Norbornanes; Oxidative Stress; Peptide Fragments; Reactive Oxygen Species; Synaptosomes; Thiocarbamates; Thiones; Type C Phospholipases; Tyrosine

Oxidative stress has been implicated in the pathophysiology of a number of diseases, including neurodegenerative disorders such as Alzheimer's disease (AD), a neurodegenerative disorder associated with cognitive decline and enhanced oxidative stress. Amyloid-beta peptide(1-42) (Abeta(1-42)), one of the main component of senile plaques, can induce in vitro and in vivo oxidative damage to neuronal cells through its ability to produce free radicals. The aim of this study was to investigate the protective effect of the xanthate D609 on Abeta(1-42)-induced protein oxidation by using a redox proteomics approach. D609 was recently found to be a free radical scavenger and antioxidant. In the present study, rat primary neuronal cells were pretreated with 50 microM of D609, followed by incubation with 10 microM Abeta(1-42) for 24 hr. In the cells treated with Abeta(1-42) alone, four proteins that were significantly oxidized were identified: glyceraldehyde-3-phosphate dehydrogenase, pyruvate kinase, malate dehydrogenase, and 14-3-3 zeta. Pretreatment of neuronal cultures with D609 prior to Abeta(1-42) protected all the identified oxidized proteins in the present study against Abeta(1-42)-mediated protein oxidation. Therefore, D609 may ameliorate the Abeta(1-42)-induced oxidative modification. We discuss the implications of these Abeta(1-42)-mediated oxidatively modified proteins for AD pathology and for potential therapeutic intervention in this dementing disorder.

Topics: 14-3-3 Proteins; Alzheimer Disease; Amyloid beta-Peptides; Animals; Bridged-Ring Compounds; Cells, Cultured; Glyceraldehyde-3-Phosphate Dehydrogenases; Image Processing, Computer-Assisted; Malate Dehydrogenase; Mass Spectrometry; Neurons; Neuroprotective Agents; Norbornanes; Oxidation-Reduction; Protein Carbonylation; Proteomics; Pyruvate Kinase; Rats; Rats, Sprague-Dawley; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Thiocarbamates; Thiones

Tricyclodecan-9-yl-xanthogenate (D609) has in vivo and in vitro antioxidant properties. D609 mimics glutathione (GSH) and has a free thiol group, which upon oxidation forms a disulfide. The resulting dixanthate is a substrate for glutathione reductase, regenerating D609. Recent studies have also shown that D609 protects brain in vivo and neuronal cultures in vitro against the potential Alzheimer's disease (AD) causative factor, Abeta(1-42)-induced oxidative stress and cytotoxicity. Mitochondria are important organelles with both pro- and antiapoptotic factor proteins. The present study was undertaken to test the hypothesis that intraperitoneal injection of D609 would provide neuroprotection against free radical-induced, mitochondria-mediated apoptosis in vitro. Brain mitochondria were isolated from gerbils 1 h post injection intraperitoneally (ip) with D609 and subsequently treated in vitro with the oxidants Fe(2+)/H(2)O(2) (hydroxyl free radicals), 2,2-azobis-(2-amidinopropane) dihydrochloride (AAPH, alkoxyl and peroxyl free radicals), and AD-relevant amyloid beta-peptide 1-42 [Abeta(1-42)]. Brain mitochondria isolated from the gerbils previously injected ip with D609 and subjected to these oxidative stress inducers, in vitro, showed significant reduction in levels of protein carbonyls, protein-bound hydroxynonenal [a lipid peroxidation product], 3-nitrotyrosine, and cytochrome c release compared to oxidant-treated brain mitochondria isolated from saline-injected gerbils. D609 treatment significantly maintains the GSH/GSSG ratio in oxidant-treated mitochondria. Increased activity of glutathione S-transferase, glutathione peroxidase, and glutathione reductase in brain isolated from D609-injected gerbils is consistent with the notion that D609 acts like GSH. These antiapoptotic findings are discussed with reference to the potential use of this brain-accessible glutathione mimetic in the treatment of oxidative stress-related neurodegenerative disorders, including AD.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Antioxidants; Apoptosis; Brain; Bridged-Ring Compounds; Cytochromes c; Gerbillinae; Glutathione; Glutathione Peroxidase; Glutathione Reductase; Glutathione Transferase; Injections, Intraperitoneal; Lipid Peroxidation; Male; Mitochondria; Neurodegenerative Diseases; Neuroprotective Agents; Norbornanes; Oxidation-Reduction; Oxidative Stress; Thiocarbamates; Thiones; Type C Phospholipases; Tyrosine

Amyloid-beta (1-42) [Abeta (1-42)] deposition in the brain is a hallmark of Alzheimer's disease (AD) and has been shown to induce apoptosis and disrupt cellular ion homeostasis. Abeta (1-42) induces membrane lipid peroxidation, and 4-hydroxynonenal (HNE) and 2-propenal (acrolein) are the two reactive products of lipid peroxidation, which structurally modify proteins by covalent interaction and inhibit enzyme function. Phosphatidylserine (PS), an aminophospholipid, is sequestered in the inner leaflet of the plasma membrane in nonstimulated cells. An early signal of synaptosomal apoptosis is the loss of phospholipid asymmetry and the appearance of phosphatidylserine in the outer leaflet of the membrane. The ATP-requiring enzyme, flippase, maintains phospholipid asymmetry of PS. Here, we have investigated the inactivation of the transmembrane enzyme aminophospholipid-translocase (or flippase) by Abeta (1-42). Flippase activity depends on a critical cysteine residue, a putative site of covalent modification by the Abeta (1-42)-induced lipid peroxidation products, HNE or acrolein. The present study is aimed to investigate the protective effects of tricyclodecan-9-xanthogenate (D609) and ferulic acid ethyl ester (FAEE) on Abeta (1-42) induced modulation in phospholipid asymmetry in the synaptosomal membranes. Pretreatment of synaptosomes with D609 and FAEE significantly protected Abeta (1-42)-induced loss of phospholipid asymmetry in synaptosomal membranes. Our results suggest that D609 and FAEE exert protective effects against Abeta (1-42) induced apoptosis. The increase in intracellular Ca(2+) might not be the sole cause for the loss of flippase activity. Rather, other mechanisms that could modulate the function of flippase might be important in the modulation of phospholipid asymmetry. The results of this study are discussed with relevance to neuronal loss in the AD brain.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Apoptosis; Bridged-Ring Compounds; Cell Membrane; Cerebral Cortex; Coumaric Acids; Enzyme Inhibitors; Gerbillinae; Lipid Peroxidation; Membrane Proteins; Norbornanes; Oxidative Stress; Peptide Fragments; Phosphodiesterase Inhibitors; Phospholipid Transfer Proteins; Phospholipids; Protective Agents; Synaptosomes; Thiocarbamates; Thiones

Tricyclodecan-9-yl-xanthogenate (D609) is an inhibitor of phosphatidylcholine-specific phospholipase C, and this agent also has been reported to protect rodents against oxidative damage induced by ionizing radiation. Previously, we showed that D609 mimics glutathione (GSH) functions and that a disulfide is formed upon oxidation of D609 and the resulting dixanthate is a substrate for GSH reductase, regenerating D609. Considerable attention has been focused on increasing the intracellular GSH levels in many diseases, including Alzheimer's disease (AD). Amyloid beta-peptide [Abeta(1-42)], elevated in AD brain, is associated with oxidative stress and toxicity. The present study aimed to investigate the protective effects of D609 on Abeta(1-42)-induced oxidative cell toxicity in cultured neurons. Decreased cell survival in neuronal cultures treated with Abeta(1-42) correlated with increased free radical production measured by dichlorofluorescein fluorescence and an increase in protein oxidation (protein carbonyl, 3-nitrotyrosine) and lipid peroxidation (4-hydroxy-2-nonenal) formation. Pretreatment of primary hippocampal cultures with D609 significantly attenuated Abeta(1-42)-induced cytotoxicity, intracellular ROS accumulation, protein oxidation, lipid peroxidation and apoptosis. Methylated D609, with the thiol functionality no longer able to form the disulfide upon oxidation, did not protect neuronal cells against Abeta(1-42)-induced oxidative stress. Our results suggest that D609 exerts protective effects against Abeta(1-42) toxicity by modulating oxidative stress. These results may be of importance for the treatment of AD and other oxidative stress-related diseases.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Antineoplastic Agents; Apoptosis; Bridged-Ring Compounds; Cells, Cultured; Fluoresceins; Fluorescence; Hippocampus; Lipid Peroxidation; Neurons; Norbornanes; Oxidative Stress; Peptide Fragments; Protective Agents; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Thiocarbamates; Thiones; Type C Phospholipases