Abstract: Increase in the cellular burden of oxidative stress is critically involved in various pathological manifestations of aging, including age-related neurological disorders. Dietary restriction can lower reactive oxygen species formation, and thereby lower oxidative damage in the brain. The brain consists of a diverse group of neurons with varying functions. However, attenuating role of dietary restriction on oxidative stress in different regions of brain is not well known. In the present study we demonstrated that by restricting diet intake for a period of six months, mice lowered the endogenous levels of oxidative stress markedly by decreasing lipid peroxidation and protein carbonyl contents in cerebral cortex, hippocampus and striatum regions of the brain. Based on these results we suggest that dietary restriction can significantly reduce oxidative stress in various regions of the brain by virtue of lowering endogenous levels of reactive oxygen species, which might prove beneficial for preserving normal brain function with age.
Abstract: Statins are widely used cholesterol-lowering agents that exert cholesterol-independent effects including antioxidative. The present study delineates the effects of statins, atorvastatin, and simvastatin on oxidative stress and functions of mitochondria that are the primary cellular sources of oxidative stress. In isolated rat liver mitochondria, both the statins prevented calcium-induced cytochrome c release, lipid peroxidation, and opening of the mitochondrial membrane permeability transition (MPT). Both the statins decreased the activity of mitochondrial nitric oxide synthase (mtNOS), lowered the intramitochondrial ionized calcium, and increased the
mitochondrial transmembrane potential. Our findings suggest that statins lower intramitochondrial ionized calcium that decreases mtNOS activity, lowers oxidative stress, prevents MPT opening, and prevents the release of cytochrome c from the mitochondria. These results provide a novel framework for understanding the antioxidative properties of statins and their effects on mitochondrial functions.
Abstract: Alzheimer’s disease is associated with synapse loss, memory dysfunction, and pathological accumulation of amyloid-β (Aβ) in plaques. However, an exclusively pathological role for Aβ is being challenged by new evidence for an essential function of Aβ at the synapse. Aβ protein exists in different assembly states in the central nervous system and plays distinct roles ranging from synapse and memory formation to memory loss and neuronal cell death. Aβ is present in the brain of symptom-free people where it likely performs important physiological roles. New evidence indicates that synaptic activity directly evokes the release of Aβ at the synapse. At physiological levels, Aβ is a normal, soluble product of neuronal metabolism that regulates synaptic function beginning early in life. Monomeric Aβ40 and Aβ42 are the predominant forms required for synaptic plasticity and neuronal survival. With age, some assemblies of Aβ are associated with synaptic failure and Alzheimer’s disease pathology, possibly targeting the N-methyl-D-aspartic acid receptor through the nicotinic acetylcholine receptor, mitochondrial Aβ alcohol dehydrogenase, and cyclophilin D. But emerging data suggests a distinction between age effects on the target response in contrast to the assembly state or the accumulation of the peptide. Both aging and Aβ independently decrease neuronal plasticity. Our laboratory has reported that Aβ, glutamate acid, and lactic acid are each increasingly toxic with neuron age. The basis of the age-related toxicity partly resides in age-related mitochondrial dysfunction and an oxidative shift in mitochondrial and cytoplasmic redox potential. In turn, signaling through phosphorylated extracellular signal-regulated protein kinases is affected along with an age-independent increase in phosphorylated cAMP response element-binding protein. This review examines the long-awaited functional impact of Aβ on synaptic plasticity.
Abstract: Overexpression of alpha-synuclein and oxidative stress has been implicated in the neuronal cell death in Parkinson's disease. Alpha-synuclein associates with mitochondria and excessive accumulation of alpha-synuclein causes impairment of mitochondrial functions. However, the mechanism of mitochondrial impairment caused by alpha-synuclein is not fully understood. We recently reported that alpha-synuclein associates with mitochondria and that overexpression of alpha-synuclein causes nitration of mitochondrial proteins and release of cytochrome c from the mitochondria [Parihar M.S., Parihar A., Fujita M., Hashimoto M., Ghafourifar P. Mitochondrial association of alpha-synuclein causes oxidative stress. Cell Mol Life Sci. 2008a;65:1272-1284]. The present study shows that overexpression of alpha-synuclein A53T or A30P mutants or wild-type in human neuroblastoma cells augmented aggregation of alpha-synuclein. Immunoblotting and immuno-gold electron transmission microscopy show localization of alpha-synuclein aggregates within the mitochondria of overexpressing cells. Overexpressing cells show increased mitochondrial reactive oxygen species, increased protein tyrosine nitration, decreased mitochondrial transmembrane potential, and hampered cellular respiration. These findings suggest an important role for mitochondria in cellular responses to alpha-synuclein.
Abstract: Subjects with Type II diabetes have increased plasma triglycerides (TG). Diabetic subjects also
are reported to have increased oxidative stress. In this study, we tested the hypothesis that
these two are related and suggest a mechanism by which oxidative stress might lead to
increased TG production. We suggest that under diabetic conditions, the activities of key
mitochondrial enzymes that are involved in citric acid cycle are reduced by oxidative stress. As
a result, acetate generated from pyruvate (PYR) is poorly utilized for energy production and at
the same time, oxidative stress would non-enzymatically decompose the cytoplasmic pyruvate
and generate increased levels of acetate. The combined results of the above are the increased
production and poor utilization of acetate which will be utilized for increased free fatty acid
(FFA) and TG production. In vitro incubation of liver mitochondria or primary hepatocytes with
oxidized linoleic acid (LOOH) or H2O2 resulted in a drastic decrease in activities of pyruvate
decarboxylase, aconitase and -keto glutarate dehydrogenase activities as compared to
controls. Livers from leptin receptor mutated Db/db (BKS.Cg-m +/+ Leprdb/J (Db/db) diabetic
mice also showed decreased mitochondrial citric acid cycle enzyme activities as compared to
livers from normal C57BL6 mice. Fatty acid synthesis was not affected when cells were
exposed to peroxides. Pyruvate, an alpha-keto acid was readily non-enzymatically converted into
acetate in the presence of LOOH or H2O2. These results show that, a) it is possible that in
diabetic conditions, pyruvate might be decomposed in the cytoplasm by LOOH or H2O2 to
generate increased levels of acetate, and b) pyruvate and acetate might be poorly utilized by
mitochondria by the citric acid cycle to provide energy. Together with the finding that fatty acid
synthesis is not affected by oxidative stress, we postulate that the increased cytoplasmic
acetate generated under diabetic oxidative stress might lead to increased free fatty acid and
triglyceride synthesis.
Abstract: Multiple sclerosis (MS) is a neurological disorder of the central nervous system characterized by demyelination and neurodegeneration. Although the pathogenesis of MS is not completely understood, various studies suggest that immune-mediated loss of myelin and mitochondrial dysfunction are associated with the disease. Mitochondria are one of the main cellular sources of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and play a pivotal role in many neuro-pathological conditions. Mitochondrial dysfunction leading to excessive production of ROS and RNS plays a significant role in the pathogenesis of MS, particularly in loss of myelin/oligodendrocyte complex. The present review summarizes critical role of mitochondria in the pathogenesis of MS. Further understanding of the role of mitochondria in MS may provide rationale for novel approaches to this disease and development of novel therapeutic maneuvers.
Abstract: A severe burn is associated with release of inflammatory mediators which ultimately cause local and distant pathophysiological effects. Mediators including Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) are increased in affected tissue, which are implicated in pathophysiological events observed in burn patients. The purpose of this article is to understand the role of oxidative stress in burns, in order to develop therapeutic strategies. All peer-reviewed, original and review articles published in the English language literature relevant to the topic of oxidative stress in burns in animals and human subjects were selected for this review and the possible roles of ROS and RNS in the pathophysiology of burns are discussed. Both increased xanthine oxidase and neutrophil activation appear to be the oxidant sources in burns. Free radicals have been found to have beneficial effects on antimicrobial action and wound healing. However following a burn, there is an enormous production of ROS which is harmful and implicated in inflammation, systemic inflammatory response syndrome, immunosuppression, infection and sepsis, tissue damage and multiple organ failure. Thus clinical response to burn is dependent on the balance between production of free radicals and its detoxification. Supplementation of antioxidants in human and animal models has proven benefit in decreasing distant organ failure suggesting a cause and effect relationship. We conclude that oxidative damage is one of the mechanisms responsible for the local and distant pathophysiological events observed after burn, and therefore anti-oxidant therapy might be beneficial in minimizing injury in burned patients.
Abstract: In the present study, we tested the significance of mitochondria for apoptosis upon exposure to tamoxifen and etoposide using two human breast cancer cell lines, MCF-7 and MDA-MB-231. We showed that both tamoxifen and etoposide induced apoptosis, increased intramitochondrial calcium and nitric oxide, and decreased mitochondrial transmembrane potential in both cell lines. Both drugs increased mitochondrial protein tyrosine nitration and caused release of cytochrome c from the mitochondria of both cell lines. This study suggests that tamoxifen and etoposide utilize a common mechanism to induce apoptosis in MCF-7 and MDA-MB-231 cells.
Abstract: The present study shows that rat liver and brain mitochondrial nitric oxide synthase (mtNOS) are functionally associated with mitochondrial respiratory chain complex I. When complex I is activated, mtNOS exerts high activity and generates nitric oxide, whereas inactivation of complex I leads mtNOS to abandon its NOS activity. Functional association of mtNOS with complex I is potentially important in regulating mtNOS activity and mitochondrial functions.
Abstract: Alpha-synuclein is a neuron-specific protein that contributes to the pathology of Parkinson's disease via mitochondria-related mechanisms. The present study investigated possible interaction of alpha-synuclein with mitochondria and consequences of such interaction. Using SHSY cells overexpressing alpha-synuclein A53T mutant or wild-type, as well as isolated rat brain mitochondria, the present study shows that alpha-synuclein localizes at the mitochondrial membrane. In both SHSY cells and isolated mitochondria, interaction of alpha-synuclein with mitochondria causes release of cytochrome c, increase of mitochondrial calcium and nitric oxide, and oxidative modification of mitochondrial components. These findings suggest a pivotal role for mitochondria in oxidative stress and apoptosis induced by alpha-synuclein.
Abstract: mAtNOS1 is a novel gene recently reported in mammalian cells with functions that are not fully understood. The present study generated human neuroblastoma SHSY cells over- and underexpressing mAtNOS1 and shows that mAtNOS1 is involved in regulating mitochondrial nitric oxide, mitochondrial transmembrane potential, protein tyrosine nitration, cytochrome c release, and apoptosis of those cells.
Abstract: Nitric oxide (NO) is a reactive radical synthesized by members of the NO synthase (NOS) family, including mitochondrial-specific NOS (mtNOS). Some of the assays used for the determination of cytoplasmic NOS activity have been utilized to detect mtNOS activity. However, it seems that many of those assays need to be adjusted and optimized to detect NO in the unique environment of mitochondria. Additionally, most mtNOS detection assays are designed and optimized for isolated mitochondria and may exert inherent pitfalls and limitations once used in living cells. This chapter describes several assays used commonly for mtNOS detection in isolated mitochondria and in mitochondria of live cells. Those include colorimetric and spectrophotometric methods, Griess reaction, radioassay, and polarographic and chemiluminescence assays. It also describes fluorescent-based assays for the detection of mitochondrial NO in live cells. Advantages and limitations of each assay are discussed.
Abstract: Age-related glutamate excitotoxicity depends in an unknown manner on active mitochondria, which are key determinants of the cellular redox potential. Compared with embryonic and middle-aged neurons, old-aged rat hippocampal neurons have a lower resting reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and a lower redox ratio (NAD(P)H/flavin adenine nucleotide). Glutamate treatment resulted in an initial increase in NAD(P)H concentrations in all ages, followed by a profound calcium-dependent, age-related decline in NAD(P)H concentration and redox ratio. With complex I of the electron transport chain inhibited by rotenone, treatment with glutamate or ionomycin only resulted in the increase in NAD(P)H fluorescence. High-performance liquid chromatography analysis of adenine nucleotides in brain extracts showed 50% less nicotinamide adenine dinucleotide (NADH) and almost twice as much oxidized nicotinamide adenine dinucleotide, demonstrating a more oxidized ratio in old than middle-aged brain. Resting glutathione content also declined with age and further decreased with glutamate treatment without accompanying changes in adenosine triphosphate levels. We conclude that age does not affect production of NADH by dehydrogenases but that old-aged neurons consume more NADH and glutathione, leading to a catastrophic decline in redox ratio.
Abstract: mAtNOS1 is a novel gene recently reported in mammalian genome with functions that are not fully understood. The present study shows that in human mammary adenocarcinoma MCF-7 cells, mAtNOS1 expression increases mitochondrial nitric oxide and calcium. Our study further shows that overexpression of mAtNOS1 induces apoptosis in MCF-7 cells by increasing mitochondrial protein tyrosine nitration and cytochrome c release. The present study suggests a novel function for mAtNOS1 in regulating mitochondrial nitric oxide and calcium and inducing apoptosis of MCF-7 cells.
Abstract: We recently demonstrated that mitochondrial nitric oxide synthase (mtNOS) functionally couples with mitochondrial respiratory chain complex I to produce nitric oxide [M.S. Parihar, R.R. Nazarewicz, E. Kincaid, U. Bringold, P. Ghafourifar, Association of mitochondrial nitric oxide synthase activity with respiratory chain complex I, Biochem. Biophys. Res. Commun. 366 (2008) 23-28]. The present report shows that inactivation of complex I leads mtNOS to become pro-oxidative. Our findings suggest a crucial role for mtNOS in oxidative stress caused by mitochondrial complex I inactivation.
Abstract: 12(S)-hydroxyeicosatetraenoic acid (12-HETE) is one of the metabolites of arachidonic acid involved in pathological conditions associated with mitochondria and oxidative stress. The present study tested effects of 12-HETE on mitochondrial functions. In isolated rat heart mitochondria, 12-HETE increases intramitochondrial ionized calcium concentration that stimulates mitochondrial nitric oxide (NO) synthase (mtNOS) activity. mtNOS-derived NO causes mitochondrial dysfunctions by decreasing mitochondrial respiration and transmembrane potential. mtNOS-derived NO also produces peroxynitrite that induces release of cytochrome c and stimulates aggregation of mitochondria. Similarly, in HL-1 cardiac myocytes, 12-HETE increases intramitochondrial calcium and mitochondrial NO, and induces apoptosis. The present study suggests a novel mechanism for 12-HETE toxicity.
Abstract: The objective of the present study was to delineate the molecular mechanisms for mitochondrial contribution to oxidative stress induced by hypoxia and reoxygenation in the heart. The present study introduces a novel model allowing real-time study of mitochondria under hypoxia and reoxygenation, and describes the significance of intramitochondrial calcium homeostasis and mitochondrial nitric oxide synthase (mtNOS) for oxidative stress. The present study shows that incubating isolated rat heart mitochondria under hypoxia followed by reoxygenation, but not hypoxia per se, causes cytochrome c release from the mitochondria, oxidative modification of mitochondrial lipids and proteins, and inactivation of mitochondrial enzymes susceptible to inactivation by peroxynitrite. These alterations were prevented when mtNOS was inhibited or mitochondria were supplemented with antioxidant peroxynitrite scavengers. The present study shows mitochondria independent of other cellular components respond to hypoxia/reoxygenation by elevating intramitochondrial ionized calcium and stimulating mtNOS. The present study proposes a crucial role for heart mitochondrial calcium homeostasis and mtNOS in oxidative stress induced by hypoxia/reoxygenation.
Abstract: Mitochondria are implicated in glutamate excitotoxicity by causing bioenergetic collapse, loss of Ca(2+) homeostasis, and generation of reactive oxygen species (ROS), all of which become increasingly important clinically with age. Little is known about how aging affects the relative importance of mitochondrial membrane potential (DeltaPsi(m)) and ROS production. To determine aging affects on DeltaPsi(m) and ROS production in individual somal and axonal/dendritic mitochondria, we compared ROS production while simultaneously monitoring DeltaPsi(m) before and after glutamate treatment of live neurons from embryonic (day 18), middle-aged (9-12 months), and old (24 months) rats. At rest, old neuronal mitochondria 1) showed a higher rate of ROS production that was particularly strong in axonal/dendritic mitochondria relative to that in middle-age neurons, 2) were more depolarized in comparison with neurons of other ages, and 3) showed no differences in ROS or DeltaPsi(m) as a function of distance from the nucleus. All DeltaPsi(m) grouped into three classes of high (less than -120 mV), medium (-85 to -120 mV), and low (greater than -85 mV) polarization that shifted toward the lower classes with age at rest. Glutamate exposure dramatically depolarized the DeltaPsi(m) in parallel with greatly increased ROS production, with a surprising absence of an effect of age or distance from the nucleus on these mitochondrial parameters. These data suggest that old neurons are more susceptible to glutamate excitotoxicity because of an insidious depolarization of DeltaPsi(m) and rate of ROS generation at rest that lead to catastrophic failure of phosphorylative and reductive energy supplies under stress.
Abstract: Brain cells are highly energy dependent for maintaining ion homeostasis during high metabolic activity. During active periods, full mitochondrial function is essential to generate ATP from electrons that originate with the oxidation of NADH. Decreasing brain metabolism is a significant cause of cognitive abnormalities of Alzheimer disease (AD), but it remains uncertain whether this is the cause of further pathology or whether synaptic loss results in a lower energy demand. Synapses are the first to show pathological symptoms in AD before the onset of clinical symptoms. Because synaptic function has high energy demands, interruption in mitochondrial energy supply could be the major factor in synaptic failure in AD. A newly discovered age-related decline in neuronal NADH and redox ratio may jeopardize this function. Mitochondrial dehydrogenases and several mutations affecting energy transfer are frequently altered in aging and AD. Thus, with the accumulation of genetic defects in mitochondria at the level of energy transfer, the issue of neuronal susceptibility to damage as a function of age and age-related disease becomes important. In an aging rat neuron model, mitochondria are both chronically depolarized and produce more reactive oxygen species with age. These concepts suggest that multiple treatment targets may be needed to reverse this multifactorial disease. This review summarizes new insights based on the interaction of mitoenergetic failure, glutamate excitotoxicity, and amyloid toxicity in the exacerbation of AD.
Abstract: Diabetes mellitus is reported to impair the memory function in experimental animals. Since the mammalian hippocampus and cerebral cortex play a pivotal role in a diverse set of cognitive functions, such as novelty detection and memory, we examined the vulnerability of cortex and hippocampus regions of the brain to oxidative damage in streptozotocin (STZ) diabetic mice. We next examined the attenuating effect of extracts of Withania somnifera and Aloe vera on prevention of hippocampal and cortical cell degenerations. Doses of both plant extracts given to experimental animals were based on the evaluation of their total antioxidant activity and also their potency to reduce Fe(3+). We assayed lipid peroxidation (LPO) and protein carbonyl (PC) in both regions of the brain and observed the changes in memory and motor behavioral functions in diabetic and control mice. The results showed a significant (P < 0.05) increase in LPO and PC in hippocampus and cortical regions of STZ diabetic mice. We also found a significant impairment in both motor and memory behavioral functions in diabetic mice. However, when diabetic mice were supplemented with the extracts of Withania somnifera and Aloe vera, the oxidative damage in both brain regions was reduced as marked by a significant (p < 0.05) declines in both LPO and PC. The combination of extracts of Withania somnifera and Aloe vera was more effective in reducing oxidative damage in brain regions than the supplementation of single plant extract. The combination also lowered the blood glucose level in comparison to STZ diabetic mice. Memory impairment and motor dysfunction were also improved by the plant extracts supplementation. We conclude that impairments in the hippocampus and cortex in STZ diabetic mice are associated with an increased free radical mediated oxidative damage and that the supplementation of plant extracts showed preventive effects in attenuating oxidative damage in both brain regions possibly via antioxidative mechanisms.
Abstract: Excitotoxicity and oxidative stress are the major mechanisms of neuronal cell death in neurodegenerative disorders that occurs in both Alzheimer's and Parkinson's diseases. Reactive oxygen species (ROS) that are generated extracellularly and intracellularly by various mechanisms are among the major risk factors that initiate and promote neurodegeneration.Therefore, it is important to find the compound which retard or reverse the neuronal injury. We designed this study to investigate the potential of extract of Asparagus racemosus (AR) against kainic acid (KA)-induced hippocampal and striatal neuronal damage. The dose of AR extract given to experimental animals was based on the evaluation of its total antioxidant activity. Extract of AR displayed potent reductant of Fe(3+). The excitotoxic lesion in brain was produced by intra-hippocampal and intra-striatal injections of kainic acid (KA; 0.25 microg in a volume of 0.5 microl) to ketamine and xylazine (200 and 2 mg/kg b.w. respectively) anesthetized mice. The results showed impairment of hippocampus and striatal regions of brain after KA injection marked by an increase in lipid peroxidation and protein carbonyl content and decline in glutathione peroxidase (GPx) activity and reduced glutathione (GSH) content. The AR extract supplemented mice displayed an improvement in GPx activity and GSH content and reduction in membranal lipid peroxidation and protein carbonyl. We show that the minimizing effect of AR extract on oxidative damage in addition to the elevation of GPx activity and GSH content could eventually result in protective effect on the KA-induced excitotoxicity.
Abstract: Alzheimer's disease (AD) is a neurodegenerative disorder of the central nervous system associated with progressive cognitive and memory loss. Molecular hallmarks of the disease are characterized by extracellular deposition of the amyloid beta peptide (Abeta) in senile plaques, the appearance of intracellular neurofibrillary tangles (NFT), cholinergic deficit, extensive neuronal loss and synaptic changes in the cerebral cortex and hippocampus and other areas of brain essential for cognitive and memory functions. Abeta deposition causes neuronal death via a number of possible mechanisms including oxidative stress, excitotoxicity, energy depletion, inflammation and apoptosis. Despite their multifactorial etiopathogenesis, genetics plays a primary role in progression of disease. To date genetic studies have revealed four genes that may be linked to autosomal dominant or familial early onset AD (FAD). These four genes include: amyloid precursor protein (APP), presenilin 1 (PS1), presenilin 2 (PS2) and apolipoprotein E (ApoE). Plaques are formed mostly from the deposition of Abeta, a peptide derived from APP. The main factors responsible for Abeta formation are mutation of APP or PS1 and PS2 genes or ApoE gene. All mutations associated with APP and PS proteins can lead to an increase in the production of Abeta peptides, specifically the more amyloidogenic form, Abeta42. In addition to genetic influences on amyloid plaque and intracellular tangle formation, environmental factors (e.g., cytokines, neurotoxins, etc.) may also play important role in the development and progression of AD. A direct understanding of the molecular mechanism of protein aggregation and its effects on neuronal cell death could open new therapeutic approaches. Some of the therapeutic approaches that have progressed to the clinical arena are the use of acetylcholinesterase inhibitors, nerve growth factors, nonsteroidal inflammatory drugs, estrogen and the compounds such as antioxidants, neuronal calcium channel blockers or antiapoptotic agents. Inhibition of secretase activity and blocking the formation of beta-amyloid oligomers and fibrils which may inhibit fibrilization and fibrilization-dependent neurotoxicity are the most promising therapeutic strategy against the accumulation of beta-amyloid fibrils associated with AD. Furthermore, development of immunotherapy could be an evolving promising therapeutic approach for the treatment of AD.
Abstract: Increasing evidence supports the role of excitotoxicity in neuronal cell injury. Thus, it is extremely important to explore methods to retard or reverse excitotoxic neuronal injury. In this regard, certain dietary compounds are beginning to receive increased attention, in particular those involving phytochemicals found in medicinal plants in alleviating neuronal injury. In the present study, we examined whether medicinal plant extracts protect neurons against excitotoxic lesions induced by kainic acid (KA) in female Swiss albino mice. Mice were anesthetized with ketamine and xylazine (200 mg and 2 mg/kg body wt. respectively) and KA (0.25 microg in a volume of 0.5 microl) was administered to mice by intra hippocampal injections. The results showed an impairment of the hippocampus region of brain after KA injection. The lipid peroxidation and protein carbonyl content were significantly (P < 0.05) increased in comparison to controls. Glutathione peroxidase (GPx) activity (EC 1.11.1.9) and reduced glutathione (GSH) content declined after appearance of excitotoxic lesions. As GPx and GSH represent a major pathway in the cell for metabolizing hydrogen peroxide (H2O2), their depletion would be expected to allow H2O2 to accumulate to toxic levels. Dried ethanolic plant extracts of Withania somnifera (WS), Convolvulus pleuricauas (CP) and Aloe vera (AV) dissolved in distilled water were tested for their total antioxidant activity. The diet was prepared in terms of total antioxidant activity of plant extracts. The iron (Fe3+) reducing activity of plant extracts was also tested and it was found that WS and AV were potent reductants of Fe3+ at pH 5 5. CP had lower Fe3+ reducing activity in comparison to WS and AV. Plant extracts given singly and in combination 3 weeks prior to KA injections resulted in a decrease in neurotoxicity. Measures of lipid peroxidation and protein carbonyl declined. GPx activity and GSH content were elevated in hippocampus supplemented with WS and combination of WS + CP + AV. However, when CP and AV were given alone, the changes in the GPx activity and GSH content were not significant. Although the major factors involved in these properties of phytochemicals remain to be specified, the finding of this study has suggested that phytochemicals present in plant extracts mitigate the effects of excitotoxicity and oxidative damage in hippocampus and this might be accomplished by their antioxidative properties.
Abstract: There is strong evidence that oxidative stress participates in the etiology of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. In the previous studies we have already shown that a combination of alpha-tocopherol and ascorbic acid protect neurons against tert-butyl hydroperoxide (t-BuOOH) induced neurotoxicity in different brain regions including hippocampus and mid brain. In this work, we examined the neuroprotective effect of low dose of adenosine against protein oxidation (protein carbonyls) in parallel with the level of reduced glutathione (GSH) in hippocampus and mid brain regions of mouse brain. The t-BuOOH was injected intraperitoneally in three concentrations (50, 100, 150 mg/kg b.w.) for 10 days. Results showed dose dependent increase in protein carbonyl (PC) in hippocampus and mid brain region. This increase was accompanied by a significant (p < 0.05) decline in GSH content in both brain regions of t-BuOOH treated mice. Adenosine (1 mg/kg b.w.) protected both hippocampus and mid brain neurons against protein oxidation as evidenced by reduction in protein carbonyl content. The GSH content was significantly (p < 0.05) increased after the treatment of adenosine in both brain regions. These data show that prior treatment with low dose of adenosine attenuates the oxidative protein damage with parallel increase in the GSH level in hippocampus and mid brain of t-BuOOH induced mice.
Abstract: Temperature induced superoxide anion radical (O2-) generation in vivo has been demonstrated in the gills of Heteropneustes fossilis by electron spin resonance (ESR) spin trapping. Temperature exposures from 25 degrees C to 37 degrees C for various times (1-4 hr) caused generation of O2- in the gill. The acid mucopolysaccharide test was conducted in gill sections during elevated temperatures. The results showed an increased activity of mucopolysaccharide in gills which indicate an increased mucus secretion in gills during elevated temperatures. The detectable stable levels of O2- in the gill at 32 and 37 degrees C temperature exposures point towards a probable role for this radical in the exudation of mucus under elevated temperature.
Abstract: This study investigated the influence of starvation over seven days on avian thyroidal superoxide radical levels and superoxide dismutase activity profiles in the Indian rock pigeon Columba livia intermeida, in relation with iodine metabolism. The serum thyroid hormone profile was assayed to correlate the thyroidal redox status with the circulating thyroid hormone levels. The spin-trapping results suggest a role for thyroidal superoxide anion (O2.-) in causing a hypothyroid state in pigeons during long term energy withdrawal. Pigeons starved for 1 day generated superoxide and iodide free radicals in their thyroids, with a significant decrease in SOD activity. Regain of SOD activity in 2nd- and 3rd-day starved birds is marked by complete scavenging of radicals in the thyroid, suggesting the significance of SOD in thyroid glands as a potential antioxidant sink against reactive oxygen species, O2.- Resurgence of O2.- radicals with a parallel decrease in SOD activity in the thyroid gland on 5th- and 7th-day of starvation provides evidence of disruption of homeostasis between pro-oxidant and antioxidant states, leading to oxidative stress in avian thyroid during long-term calorie crisis. Following starvation both thyroid hormones thyroxine (T4) and triiodothyronine (T3) decreased, putting pigeons in a hypothyroid state. We argue that oxidative inactivation of thyroid peroxidase and other thyroid proteins by radical attack during starvation invoked oxidative stress, which could be one of the factors responsible for the hypothyroid state in pigeons.
Abstract: Reactive oxygen species (ROS) such as the superoxide anion radical (O2.-) hydrogen peroxide (H2O2) and hydroxyl radical (.OH) have been implicated in the pathophysiology of various states, including ischemia reperfusion injury, haemorrhagic shock, atherosclerosis, heart failure, acute hypertension and cancer. The free radicals, nitric oxide (NO) and O2.- react to form peroxynitrite (ONOO-), a potent cytotoxic oxidant. A potential mechanism of oxidative damage is the nitration of tyrosine residues of protein, peroxidation of lipids, degradation of DNA and oligonucleosomal fragments. Several mechanisms are responsible for the protection of the cells from potential cytotoxic damage caused by free radicals. Cells have developed various enzymatic and nonenzymatic defense systems to control excited oxygen species, however, a certain fraction escapes the cellular defense and may cause permanent or transient damage to nucleic acids within the cells, leading to such events as DNA strand breakage and disruption of Ca2+ metabolism. There is currently great interest in the possible role of ROS in causing DNA damage that leads to cancer and spontaneous mutations. A high rate of oxidative damage to mammalian DNA has been demonstrated by measuring oxidized DNA bases excreted in urine after DNA repair. The rate of oxidative DNA damage is directly related to the metabolic rate and inversely related to life span of the organism.
Abstract: Lipid peroxidation an outcome of free radicals activity has been hypothesized as one of the possible factor involved in the pathogenesis of neuronal damage. We investigated the effects of free radical scavengers, alpha-tocopherol (T) and ascorbic acid (A) combination (TA-combination) to attenuate tert-butyl hydroperoxide (t-BuOOH)-induced lipid peroxidation in different regions of mice brain. Examinations of effect of three regimens (100, 200, 300 mg/kg body weight) of t-BuOOH on mid brain, cerebellum, striatum, cortex and hippocampus revealed dose and time dependent increase in lipid peroxidation. We observed that prior supplementation of TA-combination reduced lipid peroxidation induced by t-BuOOH in every brain region. These findings suggest that TA-combination may play a vital role in protecting the brain tissue against free radicals.
Abstract: Superoxide Radical Induced Peroxidative Alteration of Avian Thyroid Cell Membrane Fluidity and Molecular Order of Phospholipid Bilayer Under Melatonin Implantation: a Spintrap and Spin-Label Study by EPR Spectroscopy
P. Prakash, P.G. Kumar1, M. Laloraya1, M.S. Parihar2
Govt. College Chachaura-Binaganj, Guna, (M.P.) India; 1The Population Council, Centre for Biomedical Research 1230 York Avenue, New York, 10021, USA; 2School of Studies in Zoology, Biochemistry Division, Vikram University, Ujjain (M.P.), 456010, India
(FAX: 91-0734-51231)
We investigated the effect of subcutaneous implants of melatonin, on O2· /SOD activity, lipid peroxidation, membrane fluidity and phospholipid molecular order in the thyroid glands of Columbia livia intermedia. We used spin trap PBN (N-t-butyl-alpha-phenylnitrone) for O2· trapping and to probe biophysical status. 16-doxyl stearate was used as the spinlabel during EPR spectroscopy. After two weeks of melatonin implantation:-
(1) O2· radicals were generated in plasma membranes and glandular homogenates of the thyroid gland. Significant increases (P<0.05) in lipid peroxidation and reduced (P<0.05) SOD activity were also observed during the treatment.
(2) The thyroid cell membrane of control birds is in a relatively fluid state. Melatonin implantation induces a significant decrease (P<0.001) in fluidity and a simultaneous increase in phospholipid molecular order.
We conclude that in the pigeon, the phase transition of the thyroid cell membrane from a fluid to mosoic state under melatonin implantation is due to the peroxidative modification of the phospholipid bilayer under the influence of O2· radicals. Such an oxidative influence may account for melatonin-induced inhibition of avian thyroid function.
Abstract: Lipid peroxidation and ascorbic acid (AsA) contents were measured in the gill and air sac of male and female catfish, Heteropneustes fossilis, after exposure to temperatures (25-37 degrees C) at various times. Lipid peroxidation in gill and air sac biomembranes was enhanced on increasing the temperature from 25 to 37 degrees C for 60-240 min. In gill, the significant decline in AsA was observed only at 240 min exposed with different temperature range. In other exposure periods, the decline was nonsignificant. Air sac AsA was decreased significantly by exposure of 32 and 37 degrees C temperatures at various times. Lipid peroxidation and AsA contents after temperature exposure in gill and air sac of male and female fish showed no significant difference. The findings indicated an increased oxidative stress in gill and air sac of male and female fish after increased temperature exposure. The decline in AsA level supports its antioxidant role in relation to oxygen radicals.
Abstract: Avian Thyroidal Superoxide Radical and Superoxide Dismutase System: Role and Thyrotrophic Regulation with Reference to Iodine Metabolism
P. Prakash, P. Kumar G1, M. Laloraya1, M.S. Parihar2
Govt. College Chachaura-Binaganj, Guna, (M.P.) India; 1The Population Council, Centre for Biomedical Research 1230 York Avenue, New York, 10021, USA; 2School of Studies in Zoology, Biochemistry Division, Vikram University, Ujjain (M.P.), 456010, India
(FAX: 091-0734-51231)
Spin trap studies, using EPR spectroscopy, showed that the thyroid gland of the Indian rock pigeon Columba livia intermedia generates superoxide anion (O2·Â) radicals and its enzymic dismutation by superoxide dismutase (SOD) serves as an alternative hydrogen peroxide (H2O2) generating system to drive the H2O2 dependent and peroxidase mediated organic iodine biosynthesis. The O2· radical also mediates oxidative activation of thyroidal iodine to its free radical form, 1·Â. Some important findings of our study are:
(1) Thyroidal SOD is a constitutive enzyme with a dual role of protecting the gland from the degenerative influence of O2· and providing H2O2 as substrate for iodide peroxidase.
(2) The thyroidal O2·Â/SOD system is under thyrotropic modulation by TSH. TSH induces a simultaneous O2· burst and rise in SOD activity profile. A positive correlation between thyroidal SOD activity level and circulating thyroxine (T4) level and TSH treatment has been demonstrated, suggesting the conservation of iodine from O2· attack under adaptive increase in SOD.
Abstract: In human, goat and chick amniotic fluid the contents of lecithin, lysolecithin and phosphatidyl ethanolamine increase during embryonic development. The sphingomyelin content however, increased during the early period only and declined during the latter part of development.
Abstract: The total phospholipid (TPL) concentration in lung and amniotic fluid of chick increases with the advancement of incubation period. A positive correlation (r = 0.77) exists between the lung and amniotic fluid phospholipids. Highest value of TPL was observed at the end of incubation period. Interestingly, in few samples of both lung and amniotic fluid, low concentrations of TPL were also observed.
Abstract: The effects of reserpine (Serpasil) and chlorpromazine (Largactil) on preoptic area (POA), supraoptic nucleus (SON) and paraventricular nucleus (PVN) of hypothalamus were studied in female rats having 4-day normal oestrus cycle. 30 rats were treated with reserpine in three doses i.e. 0.5 mg, 1.0 mg and 1.5 mg/kg body weight, whereas 20 other rats were treated with chlorpromazine in two doses i.e. 5.0 mg and 10.0 mg/Kg body weight. Gomori positive neurosecretory neurons of the hypothalamus were studied by measuring the diameters of nuclei and cells of POA, SON and PVN. When compared to controls both drugs caused a significant (p less than 0.001 to p less than 0.05) decrease in the nuclear and cell size of the neurons.
Abstract: Total protein concentrations (TPC) in the human amniotic fluid, during 19 to 40 weeks of gestation, from normal and twins pregnancies were compared. In the normal pregnancies the protein concentrations were found to increase with progressing gestation, but to decrease gradually to the term. TPC fluctuations also showed a similar pattern in the twin pregnancies. There was no significant difference in the total protein contents between the normal and twin pregnancies, which probably indicates that the majority of the proteins originate from maternal source.
