Origin of 4-hydroxynonenal incubation-induced inhibition of dopamine transporter and Na+/K+ adenosine triphosphate in rat striatal synaptosomes

Interaction and binding mechanism of lipid oxidation products to sturgeon myofibrillar protein in low temperature vacuum heating conditions: Multispectroscopic and molecular docking approaches

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A comparative study of the effects of malondialdehyde and 4-hydroxy-2-nonenal on protein oxidation.

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Interaction mechanism between lipid oxidation production and protein at temperatures were firstly studied.

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Hydrogen bonding was the main driving force for bonding.

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Malondialdehyde had a strong ability to bind MP and accelerated protein oxidation.

In this work, the binding mechanism of myofibrillar protein (MP) with malondialdehyde and 4-hydroxy-2-nonenal under low temperature vacuum heating was investigated via multispectroscopic and molecular docking. The results showed that binding interaction and increasing temperature caused significant changes in the conformations as well as a decrease in the value of protein intrinsic fluorescence, surface hydrophobicity, and fluorescence excitation-emission matrix spectra. Furthermore, the decrease in α-helix and β-turn, increase in β-sheet and a random coil of MP, imply the MP molecules to be more unfolded. Isothermal titration calorimetry and molecular docking results showed that main driving force for binding with MP was hydrogen bond, and the binding ability of malondialdehyde was superior to that of 4-hydroxy-2-nonenal. Moreover, increasing the heating temperature was beneficial to the binding reaction and intensified the conformational transition of MP. These results will provide a reference for further studies on the lipid and protein interaction of sturgeon.

Stable expression of the human dopamine transporter in N27 cells as an in vitro model for dopamine cell trafficking and metabolism

Dopamine (DA) metabolism and cell trafficking are critical for the proper functioning of DA neurons. Disruption of these DA processes can yield toxic products and is implicated in neurological conditions including Parkinson's disease (PD). To investigate pathogenic mechanisms involving DA neurons, in vitro models that recapitulate DA metabolism and trafficking in vivo are crucial. N27 cells are a widely used model for PD; however, these cells exhibit little expression of the DA transporter (DAT) confounding studies of DA uptake and metabolism. This lack of adequate DAT expression calls into question the use of this cell line as a model to study DA cell trafficking and metabolism. To overcome this problem, we stably expressed the human DAT (hDAT) in N27 cells to develop cells that we named N27-BCD. This approach allows for characterization of toxicants that may alter DA metabolism, trafficking, and/or interactions with DAT. N27-BCD cells are more sensitive to the neurotoxins 1-methyl-4-phenylpyridinium (MPTP/MPP+) and 6-hydroxydopamine (6-OHDA). N27-BCD cells allowed for clear observation of DA metabolism, whereas N27 cells did not. Here, we propose that stable expression of hDAT in N27 cells yields a useful model of DA neurons to study the impact of altered DA cell trafficking and metabolism.

Curcumin nanoparticles ameliorate hepatotoxicity and nephrotoxicity induced by cisplatin in rats

The present work was conducted to investigate the effect of curcumin nanoparticles (CUR NPs) on cisplatin-induced hepatotoxicty and nephrotoxicity in rats. Rats were divided randomly into the following: control, rats treated daily with CUR NPs (50 mg/kg body wt/day) for 14 days, rats treated with a single dose of cisplatin (12 mg/kg body wt, i.p), and rats treated with a single dose of cisplatin followed by a daily administration of CUR NPs for 14 days. Cisplatin-induced hepato- and nephrotoxicity were evaluated by histological examinations and biochemical analyses of liver and kidney functions. Cisplatin induced significant increases in the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) and in the levels of bilirubin, urea, uric acid and creatinine. In addition, the levels of hepatic and renal lipid peroxidation (MDA), nitric oxide (NO), and serum tumor necrosis factor-α (TNF-α) increased significantly. However, cisplatin significantly decreased hepatic and renal reduced glutathione levels and renal Na⁺/K⁺-ATPase activity. Treatment with CUR NPs ameliorated almost all the biochemical changes induced by cisplatin and improved the histopathological alterations in liver and kidney. In conclusion, the present findings indicate that CUR NPs offered an effective protection against cisplatin-induced hepatotoxicity and nephrotoxicity through its antioxidant and anti-inflammatory properties.

4-Hydroxy-Trans-2-Nonenal in the Regulation of Anti-Oxidative and Pro-Inflammatory Signaling Pathways

Recent studies indicate that 4-hydroxy-trans-2-nonenal (HNE), a major oxidative stress triggered lipid peroxidation-derived aldehyde, plays a critical role in the pathophysiology of various human pathologies including metabolic syndrome, diabetes, cardiovascular, neurological, immunological, and age-related diseases and various types of cancer. HNE is the most abundant and toxic α, β-unsaturated aldehyde formed during the peroxidation of polyunsaturated fatty acids in a series of free radical-mediated reactions. The presence of an aldehyde group at C1, a double bond between C2 and C3 and a hydroxyl group at C4 makes HNE a highly reactive molecule. These strong reactive electrophilic groups favor the formation of HNE adducts with cellular macromolecules such as proteins and nucleic acids leading to the regulation of various cell signaling pathways and processes involved in cell proliferation, differentiation, and apoptosis. Many studies suggest that the cell-specific intracellular concentrations of HNE dictate the anti-oxidative and pro-inflammatory activities of this important molecule. In this review, we focused on how HNE could alter multiple anti-oxidative defense pathways and pro-inflammatory cytotoxic pathways by interacting with various cell-signaling intermediates.

Na+/K+-ATPase, acetylcholinesterase and glutathione S-transferase activities as new markers of postmortem interval in Swiss mice

Determining precisely the postmortem interval (PMI) is a key parameter for forensic researches, given that various physical, biochemical and metabolic changes begin to occur in the body after death. In the present study, the Na⁺/K⁺-ATPase, glutathione S-transferase (GST) and acetylcholinesterase (AChE) activities were evaluated. For this, male adult Swiss mice were killed by isoflurane inhalation anesthesia and divided into four groups according to time of death (0, 6, 24 and 48 h). The brain, liver, kidney and skeletal muscle tissues were removed. Our results revealed that at the time of 6 h, there was a decrease on Na⁺/K⁺-ATPase and GST activities in the brain and liver tissues, respectively. In addition, at this time point, an increase on renal GST activity was verified. At the time of 24 h, an increase on the cerebral AChE and renal GST activities was observed, while the cerebral Na⁺/K⁺-ATPase activity was decreased. Forty-eight hours after death, cerebral Na⁺/K⁺-ATPase and renal GST activities remained decreased and increased, respectively. In addition, no alteration was observed on the GST activity in the skeletal muscle and brain (in PMIs evaluated). The present study revealed that the brain and kidney (at the times of 24 and 48 h) were the tissues that suffered the most changes in almost all the enzymes evaluated. Our results demonstrated that enzyme activity assessments are reliable, easy-to-perform and low-cost determinations, and could be promising postmortem markers.

S-Adenosylmethionine Promotes Oxidative Stress and Decreases Na+, K+-ATPase Activity in Cerebral Cortex Supernatants of Adolescent Rats: Implications for the Pathogenesis of S-Adenosylhomocysteine Hydrolase Deficiency

S-Adenosylmethionine (AdoMet) concentrations are highly elevated in tissues and biological fluids of patients affected by S-adenosylhomocysteine hydrolase deficiency, who are clinically characterized by cerebral symptoms whose pathogenesis is still unknown. In the present work, we investigated the effects of AdoMet on redox homeostasis and on the activity of Na⁺, K⁺-ATPase in the cerebral cortex of young rats. AdoMet caused lipid peroxidation (increase of malondialdehyde concentrations) and protein oxidation (increase of carbonyl formation and decrease of sulfhydryl content). AdoMet also reduced the antioxidant defenses (reduced glutathione, GSH) and Na⁺, K⁺-ATPase activity. Furthermore, AdoMet-induced lipid peroxidation was fully prevented by the antioxidants trolox, melatonin, and resveratrol, and the decrease of GSH concentrations was abolished by trolox, suggesting the involvement of reactive oxygen species in these effects. In this context, AdoMet induced reactive oxygen (increase of 2',7'-dichloroflurescein-DCFH oxidation) but not nitrogen (nitrate and nitrite levels) species generation. Finally, the decrease of Na⁺, K⁺-ATPase activity provoked by AdoMet was totally prevented by trolox, implying a possible oxidation of cysteine groups of the enzyme that are critical for its function and highly susceptible to oxidative attack. It is also noted that adenosine and methionine did not alter the parameters evaluated, suggesting selective effects of AdoMet. Our data strongly indicate that disturbance of redox homeostasis caused by a major metabolite (AdoMet) accumulating in S-adenosylhomocysteine hydrolase deficiency may represent a deleterious mechanism of brain damage in this disease. Finally, reduction of Na⁺, K⁺-ATPase activity provoked by AdoMet may lead to impaired neurotransmission, but disturbance of this system should be better clarified in future studies.

Low Retinal Dehydrogenase 1 (RALDH1) Level in Prepubertal Boys with Autism Spectrum Disorder: A Possible Link to Dopamine Dysfunction?

Objective

Retinal dehydrogenase 1 (RALDH1) is a cytosolic enzyme which acts both as a source of retinoic acid (RA) and as a detoxification enzyme. RALDH1 has key functions in the midbrain dopaminergic system, which influences motivation, cognition, and social behavior. Since dopamine has been increasingly linked to autism spectrum disorder (ASD), we asked whether RALDH1 could contribute to the autistic phenotype. Therefore, we investigated for the first time the levels of RALDH1 in autistic patients. To further assess the detoxification function of RALDH1, we also explored 4-hydroxynonenal protein adducts (4-HNE PAs) and reduced glutathione (GSH) levels. Moreover, considering the effect of testosterone on RALDH1 expression, we measured the second to fourth digit ratio (2D:4D ratio) for both hands, which reflects exposure to prenatal testosterone.

Methods

Male patients with ASD (n=18; age, 62.9±4.3 months) and healthy controls (n=13; age, 78.1±4.9 months) were examined. Erythrocyte RALDH1, serum 4-HNE PAs and erythrocyte GSH levels were measured using colorimetric assays, and digit lengths were measured using digital calipers.

Results

We found significantly lower (−42.9%) RALDH1 levels in autistic patients as compared to controls (p=0.032). However, there was no difference in 4-HNE PAs levels (p=0.368), GSH levels (p=0.586), or 2D:4D ratios (p=0.246 in the left hand, p=0.584 in the right hand) between healthy controls and autistic subjects.

Conclusion

We concluded that a subset of autistic patients had a low RALDH1 level. These results suggest that low RALDH1 levels could contribute to the autistic phenotype by reflecting a dopaminergic dysfunction.

Neuroprotective and Therapeutic Effect of Caffeine on the Rat Model of Parkinson's Disease Induced by Rotenone

The present study aimed to investigate the protective and therapeutic effects of caffeine on rotenone-induced rat model of Parkinson's disease (PD). Rats were divided into control, PD model induced by rotenone (1.5 mg/kg intraperitoneally (i.p.) for 45 days), protected group injected with caffeine (30 mg/kg, i.p.) and rotenone for 45 days (during the development of PD model), and treated group injected with caffeine (30 mg/kg, i.p.) for 45 days after induction of PD model. The data revealed a state of oxidative and nitrosative stress in the midbrain and the striatum of animal model of PD as indicated from the increased lipid peroxidation and nitric oxide levels and the decreased reduced glutathione level and activities of glutathione-S-transferase and superoxide dismutase. Rotenone induced a decrease in acetylcholinesterase and Na⁺/K⁺-ATPase activities and an increase in tumor necrosis factor-α level in the midbrain and the striatum. Protection and treatment with caffeine ameliorated the oxidative stress and the changes in acetylcholinesterase and Na⁺/K⁺-ATPase activities induced by rotenone in the midbrain and the striatum. This was associated with improvement in the histopathological changes induced in the two areas of PD model. Caffeine protection and treatment restored the depletion of midbrain and striatal dopamine induced by rotenone and prevented decline in motor activities (assessed by open field test) and muscular strength (assessed by traction and hanging tests) and improved norepinephrine level in the two areas. The present study showed that caffeine offered a significant neuroprotection and treatment against neurochemical, histopathological, and behavioral changes in a rotenone-induced rat model of PD.

Oxidative Damage Precedes Nitrative Damage in Adriamycin-Induced Cardiac Mitochondrial Injury

The purpose of the present study was to determine if elevated reactive oxygen (ROS)/nitrogen species (RNS) reported to be present in adriamycin (ADR)-induced cardiotoxicity actually resulted in cardiomyocyte oxidative/nitrative damage, and to quantitatively determine the time course and subcellular localization of these postulated damage products using an in vivo approach. B6C3 mice were treated with a single dose of 20 mg/kg ADR. Ultrastructural damage and levels of 4-hydroxy-2-nonenal (4HNE)-protein adducts and 3-nitrotyrosine (3NT) were analyzed. Quantitative ultrastructural damage using computerized image techniques showed cardiomyocyte injury as early as 3 hours, with mitochondria being the most extensively and progressively injured subcellular organelle. Analysis of 4HNE protein adducts by immunogold electron microscopy showed appearance of 4HNE protein adducts in mitochondria as early as 3 hours, with a peak at 6 hours and subsequent decline at 24 hours. 3NT levels were significantly increased in all subcellular compartments at 6 hours and subsequently declined at 24 hours. Our data showed ADR induced 4HNE-protein adducts in mitochondria at the same time point as when mitochondrial injury initially appeared. These results document for the first time in vivo that mitochondrial oxidative damage precedes nitrative damage. The progressive nature of mitochondrial injury suggests that mitochondria, not other subcellular organelles, are the major site of intracellular injury.

4-Hydroxy-nonenal-A Bioactive Lipid Peroxidation Product

This review on recent research advances of the lipid peroxidation product 4-hydroxy-nonenal (HNE) has four major topics: I. the formation of HNE in various organs and tissues, II. the diverse biochemical reactions with Michael adduct formation as the most prominent one, III. the endogenous targets of HNE, primarily peptides and proteins (here the mechanisms of covalent adduct formation are described and the (patho-) physiological consequences discussed), and IV. the metabolism of HNE leading to a great number of degradation products, some of which are excreted in urine and may serve as non-invasive biomarkers of oxidative stress.

Disturbance of energy and redox homeostasis and reduction of Na+,K+-ATPase activity provoked by in vivo intracerebral administration of ethylmalonic acid to young rats

Ethylmalonic acid (EMA) accumulation occurs in various metabolic diseases with neurological manifestation, including short acyl-CoA dehydrogenase deficiency (SCADD) and ethylmalonic encephalopathy (EE). Since pathophysiological mechanisms responsible for brain damage in these disorders are still poorly understood, we investigated the ex vivo effects of acute intrastriatal administration of EMA on important parameters of energy and redox homeostasis in striatum from young rats. We evaluated CO(2) production from glucose, glucose utilization and lactate production, as well as the activities of the citric acid cycle (CAC) enzymes, the electron transfer chain (ETC) complexes II-IV (oxidative phosphorylation, OXPHOS) and synaptic Na(+),K(+)-ATPase. We also tested the effect of EMA on malondialdehyde (MDA) levels (marker of lipid oxidation) and reduced glutathione (GSH) levels. EMA significantly reduced CO(2) production, increased glucose utilization and lactate production, and reduced the activities of citrate synthase and of complexes II and II-III of the ETC, suggesting an impairment of CAC and OXPHOS. EMA injection also reduced Na(+),K(+)-ATPase activity and GSH concentrations, whereas MDA levels were increased. Furthermore, EMA-induced diminution of Na(+),K(+)-ATPase activity and reduction of GSH levels were prevented, respectively, by the antioxidants melatonin and N-acetylcysteine, indicating that reactive species were involved in these effects. Considering the importance of CAC and ETC for energy production and Na(+),K(+)-ATPase for the maintenance of the cell membrane potential, the present data indicate that EMA compromises mitochondrial homeostasis and neurotransmission in striatum. We presume that these pathomechanisms may be involved to a certain extent in the neurological damage found in patients affected by SCADD and EE.

4-Hydroxynonenal in the pathogenesis and progression of human diseases

Metastable aldehydes produced by lipid peroxidation act as 'toxic second messengers' that extend the injurious potential of free radicals. 4-hydroxy 2-nonenal (HNE), a highly toxic and most abundant stable end product of lipid peroxidation, has been implicated in the tissue damage, dysfunction, injury associated with aging and other pathological states such as cancer, Alzheimer, diabetes, cardiovascular and inflammatory complications. Further, HNE has been considered as a oxidative stress marker and it act as a secondary signaling molecule to regulates a number of cell signaling pathways. Biological activity of HNE depends on its intracellular concentration, which can differentially modulate cell death, growth and differentiation. Therefore, the mechanisms responsible for maintaining the intracellular levels of HNE are most important, not only in the defense against oxidative stress but also in the pathophysiology of a number of disease processes. In this review, we discussed the significance of HNE in mediating various disease processes and how regulation of its metabolism could be therapeutically effective.

Disruption of ion-trafficking system in the cochlear spiral ligament prior to permanent hearing loss induced by exposure to intense noise: possible involvement of 4-hydroxy-2-nonenal as a mediator of oxidative stress

Noise-induced hearing loss is at least in part due to disruption of endocochlear potential, which is maintained by various K⁺ transport apparatuses including Na⁺, K⁺-ATPase and gap junction-mediated intercellular communication in the lateral wall structures. In this study, we examined the changes in the ion-trafficking-related proteins in the spiral ligament fibrocytes (SLFs) following in vivo acoustic overstimulation or in vitro exposure of cultured SLFs to 4-hydroxy-2-nonenal, which is a mediator of oxidative stress. Connexin (Cx)26 and Cx30 were ubiquitously expressed throughout the spiral ligament, whereas Na⁺, K⁺-ATPase α1 was predominantly detected in the stria vascularis and spiral prominence (type 2 SLFs). One-hour exposure of mice to 8 kHz octave band noise at a 110 dB sound pressure level produced an immediate and prolonged decrease in the Cx26 expression level and in Na⁺, K⁺-ATPase activity, as well as a delayed decrease in Cx30 expression in the SLFs. The noise-induced hearing loss and decrease in the Cx26 protein level and Na⁺, K⁺-ATPase activity were abolished by a systemic treatment with a free radical-scavenging agent, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, or with a nitric oxide synthase inhibitor, N^ω-nitro-L-arginine methyl ester hydrochloride. In vitro exposure of SLFs in primary culture to 4-hydroxy-2-nonenal produced a decrease in the protein levels of Cx26 and Na⁺, K⁺-ATPase α1, as well as Na⁺, K⁺-ATPase activity, and also resulted in dysfunction of the intercellular communication between the SLFs. Taken together, our data suggest that disruption of the ion-trafficking system in the cochlear SLFs is caused by the decrease in Cxs level and Na⁺, K⁺-ATPase activity, and at least in part involved in permanent hearing loss induced by intense noise. Oxidative stress-mediated products might contribute to the decrease in Cxs content and Na⁺, K⁺-ATPase activity in the cochlear lateral wall structures.

The relationship between oxidative stress and post-translational modification of the dopamine transporter in bipolar disorder

Bipolar disorder (BD) has been consistently associated with altered levels of oxidative stress markers, although the cause and consequences of these alterations remain to be elucidated. One of the main hypotheses regarding the pathogenesis of mania involves increased dopaminergic transmission. In this review, the authors aim to discuss a potential mechanism by which increased oxidative stress inhibits the uptake of dopamine through the post-translational modification of the dopamine transporter and its implications for BD. Within the next 5 years, the authors believe that the mechanisms of dopamine transporter oxidation and its impact on the pathophysiology of BD will be elucidated, which may open avenues for the development of more specific interventions for the treatment of this debilitating illness.

4-Hydroxy-2-nonenal, a reactive product of lipid peroxidation, and neurodegenerative diseases: a toxic combination illuminated by redox proteomics studies

SIGNIFICANCE

Among different forms of oxidative stress, lipid peroxidation comprises the interaction of free radicals with polyunsaturated fatty acids, which in turn leads to the formation of highly reactive electrophilic aldehydes. Among these, the most abundant aldehydes are 4-hydroxy-2-nonenal (HNE) and malondialdehyde, while acrolein is the most reactive. HNE is considered a robust marker of oxidative stress and a toxic compound for several cell types. Proteins are particularly susceptible to modification caused by HNE, and adduct formation plays a critical role in multiple cellular processes.

RECENT ADVANCES

With the outstanding progress of proteomics, the identification of putative biomarkers for neurodegenerative disorders has been the main focus of several studies and will continue to be a difficult task.

CRITICAL ISSUES

The present review focuses on the role of lipid peroxidation, particularly of HNE-induced protein modification, in neurodegenerative diseases. By comparing results obtained in different neurodegenerative diseases, it may be possible to identify both similarities and specific differences in addition to better characterize selective neurodegenerative phenomena associated with protein dysfunction. Results obtained in our laboratory and others support the common deregulation of energy metabolism and mitochondrial function in neurodegeneration.

FUTURE DIRECTIONS

Research towards a better understanding of the molecular mechanisms involved in neurodegeneration together with identification of specific targets of oxidative damage is urgently required. Redox proteomics will contribute to broaden the knowledge in regard to potential biomarkers for disease diagnosis and may also provide insight into damaged metabolic networks and potential targets for modulation of disease progression.

Naringenin ameliorates Alzheimer's disease (AD)-type neurodegeneration with cognitive impairment (AD-TNDCI) caused by the intracerebroventricular-streptozotocin in rat model

Oxidative stress is involved in Alzheimer's disease (AD)-type neurodegeneration with cognitive impairment (AD-TNDCI) as well as age related cognitive deficit. The present study was designed to investigate the pre-treatment effects of naringenin (NAR), a polyphenolic compound on cognitive dysfunction, oxidative stress in the hippocampus, and hippocampal neuron injury in a rat model of AD-TNDCI. The rats were pre-treated with NAR at a selective dose (50mg/kg, orally) for 2 weeks followed by intracerebroventricular-streptozotocin (ICV-STZ) (3mg/kg; 5μl per site) injection bilaterally. Behavioral alterations were monitored after 2 weeks from the lesion using passive avoidance test and Morris water maze paradigm. Three weeks after the lesion, the rats were sacrificed for measuring non-enzymatic [4-hydroxynonenal (4-HNE), malonaldehyde (MDA), thiobarbituric reactive substances (TBARS), hydrogen peroxide (H(2)O(2)), protein carbonyl (PC), reduced glutathione (GSH)] content and enzymatic [glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT) and Na(+)/K(+)-ATPase] activity in the hippocampus, and expression of choline acetyltransferase (ChAT) positive neuron, and histopathology of hippocampal neurons. The non-enzymatic level and enzymatic activity was significantly increased and decreased, respectively, with striking impairments in spatial learning and memory, loss of ChAT positive neuron and severe damage to hippocampal neurons in the rat induced by ICV-STZ. These abnormalities were significantly improved by NAR pre-treatment. The study suggests that NAR can protect against cognitive deficits, neuronal injury and oxidative stress induced by ICV-STZ, and may be used as a potential agent in treatment of neurodegenerative diseases such as AD-TNDCI.

Exploring the biology of lipid peroxidation-derived protein carbonylation

The sustained overproduction of reactive oxygen and nitrogen species results in an imbalance of cellular prooxidant-antioxidant systems and is implicated in numerous disease states, including alcoholic liver disease, cancer, neurological disorders, inflammation, and cardiovascular disease. The accumulation of reactive aldehydes resulting from sustained oxidative stress and lipid peroxidation is an underlying factor in the development of these pathologies. Determining the biochemical factors that elicit cellular responses resulting from protein carbonylation remains a key element to developing therapeutic approaches and ameliorating disease pathologies. This review details our current understanding of the generation of reactive aldehydes via lipid peroxidation resulting in protein carbonylation, focusing on pathophysiologic factors associated with 4-hydroxynonenal-protein modification. Additionally, an overview of in vitro and in vivo model systems used to study the physiologic impact of protein carbonylation is presented. Finally, an update of the methods commonly used in characterizing protein modification by reactive aldehydes provides an overview of isolation techniques, mass spectrometry, and computational biology. It is apparent that research in this area employing state-of-the-art proteomics, mass spectrometry, and computational biology is rapidly evolving, yielding foundational knowledge concerning the molecular mechanisms of protein carbonylation and its relation to a spectrum of diseases associated with oxidative stress.

Effect of oxidative stress induced by paradoxical sleep deprivation on the activities of Na+, K+-ATPase and acetylcholinesterase in the cortex and hippocampus of rat

Several studies revealed the importance of paradoxical sleep as a homeostatic mechanism by which the brain can control oxidative stress. The aim of the present study is to investigate the effect of 72 h of paradoxical sleep deprivation on the oxidative stress markers and its insults on the activities of Na(+), K(+)-ATPase and acetylcholinesterase in the cortex and hippocampus of albino rat. Animals were subjected to paradoxical sleep deprivation for 72 h. At the end of the experiment, the rats were sacrificed, and catalase activity, levels of reduced glutathione, lipid peroxidation, and nitric oxide were assayed together with the activities of Na(+), K(+)-ATPase and acetylcholinesterase in the cortex and hippocampus. The present study revealed a significant increase in lipid peroxidation accompanied by a significant decrease in reduced glutathione in the cortex and hippocampus. Na(+), K(+)-ATPase decreased significantly in both areas. However, acetylcholinesterase showed a significant increase in the investigated brain regions. The present data showed that 72 h of paradoxical sleep deprivation induced oxidative stress in the cortex and hippocampus. It could be suggested that the inhibition of Na(+), K(+)-ATPase and the increased acetylcholinesterase activity may underlie memory impairment, increased brain excitability, and anxiety induced by paradoxical sleep deprivation.

Increased oxidative stress in the anterior cingulate cortex of subjects with bipolar disorder and schizophrenia

BACKGROUND

Recent studies indicate the presence of mitochondrial dysfunction in brains of subjects with bipolar disorder (BD). Because the mitochondrial electron transport chain is a major source for production of reactive oxygen species that cause oxidative stress, we sought to determine in the present study if BD is associated with oxidative stress.

METHODS

Postmortem anterior cingulate brain sections from subjects with BD, major depressive disorder (MDD), or schizophrenia, and from nonpsychiatric, non-neurologic comparison controls were generously provided by the Stanley Foundation Neuropathology Consortium. Oxidative stress was determined by analyzing 4-hydroxynonenal (4-HNE), a major product of lipid peroxidation. The level of 4-HNE was determined by measuring 4-HNE protein adducts using immunohistochemistry.

RESULTS

We found that 4-HNE levels were significantly increased by 59% in BD subjects and by 47% in schizophrenia subjects, but not in MDD subjects, when compared with controls. Levels of 4-HNE were negatively correlated with pH in all 60 subjects. When pH was used as covariate, 4-HNE levels were still significantly increased in BD subjects when compared with controls. Further, 4-HNE levels were significantly correlated with pH values only in BD subjects, but not in MDD, schizophrenia, or control subjects.

CONCLUSIONS

Oxidative damage in the brain may contribute in part to the pathological process in BD and schizophrenia. This finding also suggests antioxidative stress as a probable alternative approach to the pharmacological treatment of these psychiatric disorders.

Effect of hypermethioninemia on some parameters of oxidative stress and on Na(+),K (+)-ATPase activity in hippocampus of rats

In the present study we investigated the effect of chronic administration of methionine, a metabolite accumulated in many inherited pathological conditions such as methionine adenosyltransferase deficiency and homocystinuria, on some parameters of oxidative stress, namely thiobarbituric acid reactive substances (TBARS), catalase activity and total thiol content, as well as on Na(+),K(+)-ATPase activity in rat hippocampus. For chronic treatment, rats received subcutaneous injections of methionine (1.34-2.68 mumol/g of body weight), twice a day, from the 6th to the 28th day of age and controls received saline. Animals were killed 12 h after the last injection. Results showed that chronic hypermethioninemia significantly increased TBARS, decreased Na(+),K(+)-ATPase activity but did not alter catalase and total thiol content. Since chronic hypermethioninemia altered TBARS and Na(+),K(+)-ATPase activity at 12 h after methionine administration, we also investigated the effect of acute administration of this amino acid on the same parameters studied after chronic methionine administration. For acute treatment,29-day-old rats received one single injection of methionine (2.68 mumol/g of body weight) or saline and were killed 1, 3 or 12 h later. Results showed that rats subjected to acute hypermethioninemia presented a reduction of Na(+),K(+)-ATPase activity and an increase in TBARS when the animals were killed at 3 and 12 h, but not at 1 h, after methionine administration. These data indicate that hypermethioninemia increases lipid peroxidation which may, at least partially, explain the effect of methionine on the reduction in Na(+),K(+)-ATPase activity. If confirmed in human beings, our findings could suggest that the induction of oxidative stress and the inhibition of Na(+),K(+)-ATPase activity caused by methionine might contribute to the neurophysiopathology observed in patients with severe hypermethioninemia.

Lactic acidosis progressively impairs dopamine uptake in rat striatal synaptosomes by a mechanism partially independent of the Na+/K+-ATPase dysfunction

Previous experiments reported that incubation of rat striatal synaptosomes with lactic acid (pH 5.5) resulted in an inhibition of dopamine (DA) uptake partially mediated by free radical damage. Since the DA uptake process is highly dependent on the functionality of Na+/K+-ATPase, the present study investigated whether this inhibition of DA uptake could be related to an alteration of the Na+/K+-ATPase activity. Striatal lactic acidosis was performed by direct addition of lactic acid in the incubation medium to obtain a pH as close as possible to that observed in ischemia. Acidosis (pH 5.5) induced a progressive decline in the specific DA uptake and a decrease of Na+/K+-ATPase activity in striatal synaptosomes. However, whereas loss of Na+/K+-ATPase activity was totally prevented by Trolox, a powerful antioxidant, DA uptake remained partially inhibited. Taken together, these data suggest that acidosis, in a degree encountered during ischemia, alters the high-affinity DA uptake in part by a mechanism that does not involve a Na+/K+ pump deficiency.

Role of mitogen-activated protein kinases in 4-hydroxy-2-nonenal-induced actin remodeling and barrier function in endothelial cells

In vivo and in vitro studies indicate that 4-hydroxy-2-nonenal (4-HNE), generated by cellular lipid peroxidation or after oxidative stress, affects endothelial permeability and vascular tone. However, the mechanism(s) of 4-HNE-induced endothelial barrier function is not well defined. Here we provide evidence for the first time on the involvement of mitogen-activated protein kinases (MAPKs) in 4-HNE-mediated actin stress fiber formation and barrier function in lung endothelial cells. Treatment of bovine lung microvascular endothelial cells with hydrogen peroxide (H(2)O(2)), as a model oxidant, resulted in accumulation of 4-HNE as evidenced by the formation of 4-HNE-Michael protein adducts. Exposure of cells to 4-HNE, in a dose- and time-dependent manner, decreased endothelial cell permeability measured as transendothelial electrical resistance. The 4-HNE-induced permeability changes were not because of cytotoxicity or endothelial cell apoptosis, which occurred after prolonged treatment and at higher concentrations of 4-HNE. 4-HNE-induced changes in transendothelial electrical resistance were calcium independent, as 4-HNE did not alter intracellular free calcium levels as compared with H(2)O(2) or diperoxovanadate. Stimulation of quiescent cells with 4-HNE (1-100 microm) resulted in phosphorylation of ERK1/2, JNK, and p38 MAPKs, and actin cytoskeleton remodeling. Furthermore, pretreatment of bovine lung microvascular endothelial cells with PD 98059 (25 microm), an inhibitor of MEK1/2, or SP 600125 (25 microm), an inhibitor of JNK, or SB 202190 (25 microm), an inhibitor of p38 MAPK, partially attenuated 4-HNE-mediated barrier function and cytoskeletal remodeling. These results suggest that the activation of ERK, JNK, and p38 MAP kinases is involved in 4-HNE-mediated actin remodeling and endothelial barrier function.

Basic aspects of the biochemical reactivity of 4-hydroxynonenal

4-hydroxynonenal (HNE), a major lipid peroxidation product of n-6 polyunsaturated fatty acids, which was discovered by the late Hermann Esterbauer, is a remarkable trifunctional molecule. Both the hydroxy group and the conjugated system consisting of a C=C double bond and a carbonyl group contribute to the high reactivity of HNE. Most of the biochemical effects of HNE can be explained by its rapid reactions with thiol and amino groups. Among the primary reactants for HNE are the amino acids cysteine, histidine and lysine, which--either free or protein-bound--undergo readily Michael additions to the C=C bond. After this primary reaction, which confers rotational freedom to the C2-C3 bond, secondary reactions may occur involving the carbonyl and the hydroxy group. Primary amines may alternatively react with the carbonyl group to form Schiff bases. Reactions which do not fit into this scheme are the oxidation and the reduction respective of the carbonyl group and the epoxidation of the C=C double bond. Examples will be presented for the interaction of HNE with various classes of biomolecules such as proteins and peptides, lipids and nucleic acids and the biochemical consequences will be discussed.

Age-related oxidative inactivation of Na+, K+-ATPase in rat brain crude synaptosomes

The study was undertaken to examine the status of Na(+), K(+)-ATPase in aged rat brain and to verify if any alteration of this enzyme in aged brain could be related to an oxidative damage. The crude synaptosomes from rat brain were exposed in vitro to an oxidative stress in the form of a combination of Fe(2+) (100 microM) and ascorbate (2 mM) for up to 2 h when increased lipid peroxidation (nearly four-fold), extensive protein carbonyl formation and a marked decrease of Na(+), K(+)-ATPase activity (approximately 88%) were observed. All these changes were prevented by the presence of a chain-breaking anti-oxidant, butylated hydroxytoluene (0.2 mM), in the incubation mixture. When the same crude synaptosomal membranes from the young (4-6 months) and aged (18-22 months) rat brains were analysed, a significant reduction of Na(+), K(+)-ATPase activity (nearly 48%) along with significantly elevated levels of lipid peroxidation products and protein carbonyls could be detected in the aged animals in comparison to young ones. The latter data in combination with the results of in vitro experiments imply that the age-related decline of rat brain Na(+), K(+)-ATPase activity is presumably the consequence of an enhanced oxidative damage in aging brain

Modulation of D1-like dopamine receptor function by aldehydic products of lipid peroxidation

Growing evidence indicates that aldehydic products of lipid peroxidation play an important role in the pathophysiology of neurodegenerative disorders such as Parkinson's disease. In the present study, modulation of D1-like receptor binding and function by saturated alkanals and unsaturated alkenals, 4-hydroxynonenal (4-HNE) and trans-2-nonenal (nonenal), was examined in rat striatal membranes. The 4-HNE and nonenal were most effective in modulating both the specific D1-like receptor binding and function as measured by adenylate cyclase activation. Inactivation of receptor binding and the depression of adenylate cyclase activity were partially prevented by protection of the D1/D5-receptor with the agonist (R)-SKF 38393 or the specific antagonist SCH 23390. 4-HNE inhibited adenylate cyclase activation by Gpp (NH)p and forskolin, indicating the modulation of Gsalpha and the catalytic subunit of adenylate cyclase, respectively. Our data suggests that aldehydic products of lipid peroxidation can directly modulate the binding and functional properties of D1/D5 receptors, as well as effector proteins within their signaling pathway.

Oxidative metabolite of dopamine, 3,4-dihydroxyphenylacetaldehyde, induces dopamine release from PC12 cells by a Ca2+-independent mechanism

3,4-dihydroxyphenylacetaldehyde (DOPALD), an oxidative metabolite of dopamine (DA), induced dose-dependent DA release from pheochromocytoma (PC12) cells without affecting leakage of lactate dehydrogenase from the cells. DOPALD-induced DA release was independent of extracellular Ca2+ concentration and was not blocked by nifedipine, an L-type Ca2+ channel antagonist. These results indicated a novel intrinsic role of DOPALD in dopaminergic nerve terminals that may take part in the activation of dopamine neurons.

Relationship between age-related increases in rat liver lipid peroxidation and bile canalicular plasma membrane fluidity

Aging is associated with increased cellular levels of lipid peroxides and reactive oxygen species. This increase in the radical species may affect membrane fluidity and consequently membrane functions. We attempted to determine whether age-related increases in lipid peroxide and reactive oxygen species levels affect the annular fluidity of the bile canalicular plasma membrane in young (2-3 weeks old), adult (20 weeks old) and old (100 weeks old) rats. Hepatic levels of lipid peroxides measured with thiobarbituric acid reactive substances (TBARS), reactive oxygen species and reduced glutathione were significantly higher in the old rats than in the young and adult rats. Arachidonic acid (AA) levels increased and docosahexaenoic acid (DHA) levels decreased in the isolated canalicular plasma membrane of the old rats, and the ratio of DHA to AA thus decreased significantly with rat aging. Hepatic TBARS levels correlated negatively with molar ratios of DHA to AA. The annular fluidity of the bile canalicular plasma membrane decreased significantly in the old rats compared with that in the young and adult rats. These results suggest that the age-related decrease in DHA content of the bile canalicular plasma membrane and the molar ratio of DHA to AA may be associated with age-related deterioration of membrane annular fluidity.