Product Of Membrane Lipid Peroxidation Research Articles

Photooxidation Tolerance Characters of a New Purple Pepper

Huai Zi (HZ) is a new purple mutant of green pepper (PI 631133) that is obtained from the United States Department of Agriculture. The net photosynthetic rate (P N), chlorophyll fluorescence parameters, antioxidant substances, antioxidant enzymes, photosystem 1 (PS1) and PS2 activities were studied through methyl viologen (MV) treatment. The results showed that the P N, actual photochemical efficiency of PS2 (ΦPS2), photochemical quenching coefficient (qP), PS1 and PS2 activities in HZ were lower than those in green pepper. HZ had a stronger ability to eliminate reactive oxygen species(O2 •−) and accumulated less malondialdehyde (MDA) (a membrane lipid peroxidation product) than did green pepper, and had a higher content of antioxidants and antioxidant enzyme activity. This suggests that the lower light energy absorption and higher thermal dissipation and antioxidant activity of HZ contributed to a more stable PS2 photosynthetic capacity, which resulted in photooxidation tolerance. Hence, our study strongly suggests that pepper hybrids can achieve a modest ratio of chlorophyll and anthocyanin content, high P N and resistance to photooxidation, improving yield and resistance to adverse environments.

Oxidative damage of rat liver mitochondria during exposure to t-butyl hydroperoxide. Role of Ca2 + ions in oxidative processes

AimsThe present study was designed for further evaluation of the biochemical mechanism of hepatic mitochondrial dysfunction under oxidative damages induced by organic hydroperoxide, tert-butyl hydroperoxide (tBHP), for estimation of the molecular targets impaired during oxidative stress, and for investigation of the role of Ca2+ ions in mitochondrial oxidative reactions and of the protective effect of melatonin during mitochondrial peroxidative damage. Main methodsMitochondria were isolated by differential centrifugation from the rat liver. The effects of tBHP exposure, EDTA, Ca2+ ions and melatonin on mitochondrial respiratory activity, mitochondrial enzyme activities and redox status were measured. Key findingsThe present study provides evidence that tBHP (at low concentrations of 0.02–0.065mM, in EDTA-free medium) induced uncoupling of the oxidation and phosphorylation processes and decreased the efficiency of the phosphorylation reaction. This effect depended on the respiratory substrate used. The presence of EDTA prevented oxidative impairment of mitochondrial respiration, but Ca2+ ions in the medium enhanced oxidant-induced mitochondrial damage considerably. In the presence of 0.5mM EDTA, tBHP (at high concentrations, 0.5–2mM) considerably oxidized mitochondrial reduced glutathione, enhanced accumulation of membrane lipid peroxidation products and mixed protein–glutathione disulfides and led to an inhibition of oxoglutarate dehydrogenase and succinate dehydrogenase. SignificanceDirect oxidative modification of enzymatic complexes of the respiratory chain and mitochondrial matrix, mitochondrial reduced glutathione depletion, protein glutathionylation, membrane lipid peroxidation and Ca2+ overload are the main events of mitochondrial peroxidative damages. Experiments in vitro demonstrated that melatonin inhibited the mitochondrial peroxidative damage, preventing redox-balance changes and succinate dehydrogenase inactivation.

Carbonylation of mitochondrial aconitase with 4-hydroxy-2-(E)-nonenal: Localization and relative reactivity of addition sites

Mass spectrometry was used to investigate the effects of exposing mitochondrial aconitase (ACO2) to the membrane lipid peroxidation product, 4-hydroxy-2-(E)-nonenal (HNE). ACO2 was selected for this study because (1) it is known to be inactivated by HNE, (2) elevated concentrations of HNE-adducted ACO2 have been associated with disease states, (3) extensive structural information is available, and (4) the iron–sulfur cluster in ACO2 offers a critical target for HNE adduction. The aim of this study was to relate the inactivation of ACO2 by HNE to structural features. Initially, Western blotting and an enzyme activity assay were used to assess aggregate effects and then gel electrophoresis, in-gel digestion, and tandem mass spectrometry (MS/MS) were used to identify HNE addition sites. HNE addition reaction rates were determined for the most significant sites using the iTRAQ approach. The most reactive sites were Cys358, Cys421, and Cys424, the three iron–sulfur cluster-coordinating cysteines, Cys99, the closest non-ligated cysteine to the cluster, and Cys565, which is located in the cleft leading to the active site. Interestingly, both enzyme activity assay and iTRAQ relative abundance plots appeared to be trending toward horizontal asymptotes, rather than completion.

Effects of Cadmium on Physiological Parameters of the LichenEvernia PrunastriandRamalina Fastigiata

The aim of the study was to investigate in short term experiment the physiological effects and accumulation of cadmium in the lichens Evernia prunastri (L.) Ach. and Ramalina fastigiata (Pers.) Ach. Treatment of lichen thalli with 5, 25, 50 and 500 μM Cd solutions caused a significant decrease in chlorophyll a and b contents and production of membrane lipid peroxidation, expressed as MDA content. Severe negative physiological effects were observed at the highest Cd concentration (500 μM Cd). Cd content in treated lichens thalli increased gradually as Cd concentration increased in treatment solutions. It was concluded that Cd exposure causes physiological and oxidative stress, with higher damage to E. prunastri due to higher Cd content bounded at intracellular sites.

Black Tea Supplementation Improves Antioxidant Status in Rats Subjected to Oxidative Stress

The protective effect of black tea extract (BTE) against HgCl2-induced oxidative damage in Wistar rats was investigated. Rats were injected with HgCl2 (5 mg/kg body weight in 0.9% NaCl) to induce oxidative stress. The aqueous BTE (2.5%) was prepared from CTC (curl, tear, crush) grade tea. BTE was fed to control and HgCl2-treated rats by gavage at a dose of 1 ml/(100 g body weight d). Biomarkers of oxidative stress, such as the erythrocyte plasma membrane redox system (PMRS) activity, lipid peroxidation, and advanced oxidation protein products (AOPP), increased by 166, 31, and 373%, respectively, in response to HgCl2 treatment, while intracellular glutathione and plasma antioxidant potential, i.e. ferric reducing ability (FRAP) decreased by 75 and 22%, respectively. BTE protected the rats against HgCl2-induced oxidative damage and raised the antioxidant potential in control rats. Due to its strong antioxidant effect in vivo, black tea intake may provide a significant health-promoting effect to humans.

Potentiation of amyloid-β peptide neurotoxicity in human dental-pulp neuron-like cells by the membrane lipid peroxidation product 4-hydroxynonenal

Lipid peroxidation is generally considered as primarily implicated in the pathogenesis of Alzheimer's disease (AD); one of its more reactive end products, 4-hydroxynonenal (HNE), has been shown to cause neuron dysfunction and degeneration. HNE production in the brain is stimulated by the amyloid-β peptide (Aβ), whose excessive accumulation in specific brain areas is a hallmark of AD. Conversely, Aβ production is up-regulated by this multifunctional aldehyde. Findings reported here point to the ability of HNE and Aβ to interact, with consequent potentiation of Aβ’s cytotoxicity as determined in vitro using neuron-like cells derived from human dental-pulp progenitor cells. Preincubation of cells with the aldehyde markedly up-regulated Aβ uptake and intracellular accumulation, by overexpressing two of the three components of the plasma membrane multireceptor complex CD36/CD47/β1-integrin: experimental and clinical data indicate that intraneuronal accumulation of Aβ is an early event possibly playing a primary role in AD pathogenesis. That HNE-mediated overexpression of CD36 and β1-integrin, which plays a key role in HNE's potentiating Aβ neurotoxicity, in terms of necrosis, was confirmed when this effect was prevented by specific antibodies against the two receptors.

P4‐298: The histidine analogue hydraide reduces BETA‐AMYLOID 42 levels and gamma‐secretase activity in a model of Alzheimer's disease

Membrane lipid peroxidation product 4-hydroxynonenal (HNE) is important therapeutic target for several neurodegenerative diseases because it is neurotoxic and has been implicated in the pathogenesis of alzheimer's disease, Parkinson's diease, amyotrophic lateral sclerosis, and stroke. We recently reported that a histidine analogue (AG/01), which is highly effective in scavenging HNE and significantly protects against focal ischemia-induced brain damage. We now report that anti-amyloidogenic and neuroprotective ability of the histidine analogue was investigated in the triple-transgenic Alheimer's disease model mice (3xTg-AD mice). HNE-mediated beta-secretase and gamma-secretase activities, abeta production, and modification of gamm-secretase activities, Abeta production, and modification of gamma-secretase were reduced in the presence of the histidine analogue. The histidine analogue histidyl hydraide was also effective in reducing Abeta42 levels, gamma-secretase activity, and HNE modification of gamma-secretase substrate receptor Nicastrin in the brains of 3xTg-AD mice. These findings suggest a therapeutic potential for HNE-scavenging agents in the treatment of alzheimer's disease. Western blot Animals and treatment with the histidine analog histidyl hydrazide (AG/01) The histidine analog histidyl hydrazide (AG/01) reduces the Aβ42/Aβ40 ratio, γ-secretase activity, and HNE-modified Nct in the brains of AD mice. These findings suggest a therapeutic potential for HNE-scavenging agents in the treatment of alzheimer's disease.

Rat liver mitochondrial damage under acute or chronic carbon tetrachloride-induced intoxication: Protection by melatonin and cranberry flavonoids

In current societies, the risk of toxic liver damage has markedly increased. The aim of the present work was to carry out further research into the mechanism(s) of liver mitochondrial damage induced by acute (0.8g/kg body weight, single injection) or chronic (1.6g/ kg body weight, 30days, biweekly injections) carbon tetrachloride – induced intoxication and to evaluate the hepatoprotective potential of the antioxidant, melatonin, as well as succinate and cranberry flavonoids in rats.Acute intoxication resulted in considerable impairment of mitochondrial respiratory parameters in the liver. The activity of mitochondrial succinate dehydrogenase (complex II) decreased (by 25%, p<0.05). Short-term melatonin treatment (10mg/kg, three times) of rats did not reduce the degree of toxic mitochondrial dysfunction but decreased the enhanced NO production.After 30-day chronic intoxication, no significant change in the respiratory activity of liver mitochondria was observed, despite marked changes in the redox-balance of mitochondria. The activities of the mitochondrial enzymes, succinate dehydrogenase and glutathione peroxidase, as well as that of cytoplasmic catalase in liver cells were inhibited significantly. Mitochondria isolated from the livers of the rats chronically treated with CCl4 displayed obvious irreversible impairments. Long-term melatonin administration (10mg/kg, 30days, daily) to chronically intoxicated rats diminished the toxic effects of CCl4, reducing elevated plasma activities of alanine aminotransferase and aspartate aminotransferase and bilirubin concentration, prevented accumulation of membrane lipid peroxidation products in rat liver and resulted in apparent preservation of the mitochondrial ultrastructure. The treatment of the animals by the complex of melatonin (10mg/kg) plus succinate (50mg/kg) plus cranberry flavonoids (7mg/kg) was even more effective in prevention of toxic liver injury and liver mitochondria damage.

Oxidative lipid modification of nicastrin enhances amyloidogenic γ‐secretase activity in Alzheimer’s disease

The cause of elevated level of amyloid β-peptide (Aβ42) in common late-onset sporadic [Alzheimer's disease (AD)] has not been established. Here, we show that the membrane lipid peroxidation product 4-hydroxynonenal (HNE) is associated with amyloid and neurodegenerative pathologies in AD and that it enhances γ-secretase activity and Aβ42 production in neurons. The γ-secretase substrate receptor, nicastrin, was found to be modified by HNE in cultured neurons and in brain specimens from patients with AD, in which HNE-nicastrin levels were found to be correlated with increased γ-secretase activity and Aβ plaque burden. Furthermore, HNE modification of nicastrin enhanced its binding to the γ-secretase substrate, amyloid precursor protein (APP) C99. In addition, the stimulation of γ-secretase activity and Aβ42 production by HNE were blocked by an HNE-scavenging histidine analog in a 3xTgAD mouse model of AD. These findings suggest a specific molecular mechanism by which oxidative stress increases Aβ42 production in AD and identify HNE as a novel therapeutic target upstream of the γ-secretase cleavage of APP.

Enhancement of Superoxide Dismutase and Catalase Activities and Salt Tolerance of Euhalophyte Suaeda salsa L. by Mycorrhizal Fungus Glomus mosseae

Arbuscular mycorrhizal (AM)-mediated plant physiological activities could contribute to plant salt tolerance. However, the biochemical mechanism by which AM fungi enhance salt tolerance of halophytic plants is unclear. A pot experiment was conducted to determine whether salt tolerance of the C3 halophyte Suaeda salsa was enhanced by the AM fungus Glomus mosseae. When 60-day-old S. salsa seedlings were subjected to 400 mmol L−1 NaCl stress for 35 days, plant height, number of leaves and branches, shoot and root biomass, and root length of G. mosseae-colonized seedlings were significantly greater than those of the nonmycorrizal seedlings. Leaf superoxide dismutase (SOD) activity at all sampling times (weekly for 35 days after salt stress was initiated) and leaf catalase (CAT) activity at 2 and 3 weeks after salt stress was initiated were also significantly enhanced in G. mosseae-colonized S. salsa seedlings, while the content of leaf malondialdehyde (MDA), a product of membrane lipid peroxidation, was significantly reduced, indicating an alleviation of oxidative damage. The corresponding leaf isoenzymes of SOD (Fe-SOD, Cu/Zn-SOD1, and Cu/Zn-SOD2) and CAT (CAT1 and CAT2) were also significantly increased in the mycorrhizal seedlings after 14 days of 400 mmol L−1 NaCl stress. Our results suggested that G. mosseae increased salt tolerance by increasing SOD and CAT activities and forming SOD and CAT isoforms in S. salsa seedlings.

Specific Lipid Peroxidation Products in Erythrocyte Membranes in Alzheimer´S Disease

Specific Lipid Peroxidation Products in Erythrocyte Membranes in Alzheimer´S Disease

Effect of Omega-3 Fatty Acids on Erythrocyte Membrane in Diabetic Rats

Background: Diabetes mellitus is a metabolic disease characterized by chronic hyperglycemia resulting from defects in insulin secretion, almost always with a major contribution from insulin resistance which may be affected by cell membrane fatty acids and phospholipids fractions. Aim: To evaluate the effects of omega-3 fatty acids on erythrocyte membrane and also in decreasing oxidative stress in diabetic rats. Material and Methods: Sixty healthy male albino rats weighting 180-200 g divided into five groups included: control, Omega-3, diabetic, prophylactic and treated groups. Fasting blood samples were collected from all groups for determination of fasting blood sugar, plasma insulin, erythrocyte membrane lipid profile, phospholipids fractions by HPLC, plasma and erythrocyte membrane lipid peroxidation product (malondialdehyde) and reduced glutathione. out. Results: Fasting blood sugar and plasma insulin sensitivity were improved by Omega-3 administration, also reduced glutathione improved by Omega-3 in both erythrocyte membrane and plasma, while, malondialdehyde decreased indicated the decrease of oxidative stress by Omega-3 administration. Conlusion: Omega-3 supplementation increased insulin sensitivity by improving cell membrane contents especially phospholipids fractions.

The balance between 4‐hydroxynonenal and intrinsic glutathione/glutathione S‐transferase A4 system may be critical for the epidermal growth factor receptor phosphorylation of human esophageal squamous cell carcinomas

Oxidative stress might participate in the carcinogenesis of human esophageal squamous cell carcinomas (hESCC). 4-Hydroxynonenal (HNE) is a major product of membrane lipid peroxidation with short life. It might act as an important mediator through the generation of adducts and activate epidermal growth factor receptor (EGFR) signaling. It is mainly trapped with glutathione (GSH) and catalyzed by glutathione S-transferases (GSTs). This study aimed to elucidate the possible participation of HNE, GSH/GST system, and EGFR signaling in hESCC development. Immunohistochemistry of HNE adducts, EGFR, and phosphorylated EGFR (pEGFR) was performed with hESCC specimens. The effect of HNE on the phosphorylation of EGFR and its downstream PhospholipaseCγ1 (PLCγ1) was investigated with KYSE30 cell-line. Pretreatment with GSH inducer N-acetylcysteine (NAC) or GSH inhibitor Buthionine sulfoximine (BSO) and mandatory transfection of hGSTA4 gene in KYSE30 were conducted to investigate the relationship between HNE and GSH/GST system. Immunoreactants of HNE adducts, EGFR, and pEGFR were increased in hESCC compared to non-cancerous epithelium with positive correlations. The treatment of HNE ligand-independently induced the phosphorylation of EGFR and PLCγ1 accompanying the diminishment of intracellular GSH level. NAC increased GSH contents but BSO decreased in dose-dependent manners. Reflecting changes in GSH, HNE-induced EGFR phosphorylation was suppressed by NAC, whereas it was promoted by BSO. Mandatory expression of hGSTA4 suppressed HNE-induced events. We first demonstrated that the ligand-independent activation of EGFR by the balance between the stimulation of HNE and the prevention of intrinsic GSH/GST system might participate in the development of hESCC.

Salicylic acid and heat acclimation pretreatment protects Laminaria japonica sporophyte (Phaeophyceae) from heat stress

Possible mediatory roles of heat acclimation and salicylic acid in protecting the sporophyte of marine macroalga Laminaria japonica (Phaeophyceae) from heat stress were studied. Heat stress resulted in oxidative injury in the kelp blades. Under heat stress significant accumulation of hydrogen peroxide (H2O2) and malonaldehyde (MDA), a membrane lipid peroxidation product, and a drastic decrease in chlorophyll a content were recorded. Activity of the enzymatic antioxidant system was drastically affected by heat stress. The activity of superoxide dismutase (SOD) was significantly increased while peroxidase (POD), catalase (CAT) and glutathione peroxidase (GPX) were greatly inhibited and, simultaneously, phenylalanine ammonia-lyase was activated while polyphenol oxidase (PPO) was inhibited. Both heat acclimation pretreatment and exogenous application of salicylic acid alleviated oxidative damage in kelp blades. Blades receiving heat acclimation pretreatment and exogenous salicylic acid prior to heat stress exhibited a reduced increase in H2O2 and MDA content, and a lower reduction in chlorophyll a content. Pretreatment with heat acclimation and salicylic acid elevated activities of SOD, POD, CAT, GPX and PPO. Considering these results collectively, we speculate that the inhibition of antioxidant enzymes is a possible cause of the heat-stress-induced oxidative stress in L. japonica, and enhanced thermotolerance may be associated, at least in part, with the elevated activity of the enzymatic antioxidant system.

Characteristics of Leaf Senescence in Rice Genotypes with Different Nitrogen Use Efficiencies

Although excessive use of N fertilizer can result in the rapid decrease of N use efficiency and other serious environment problems,N fertilizer is yet the most important and largest input in modern rice production. Previous researches have been demonstrated that variation in N use efficiency existed among rice genotypes. Therefore,it is of urgent importance to elucidate the physiological mechanism of rice N absorption and utilization for increasing N use efficiency. In this research,field experiment with 225 kg ha-1 N fertilizer application was carried out in 2006 on the farm of Yangzhou University,Jiangsu province,China. Twelve rice genotypes (six N efficient and six N inefficient) selected from one hundred and twenty rice cultivars grown in Yangzhou during 2004 and 2005 were adopted to investigate the characteristics of N absorption and accumulation. Compared with N inefficient genotypes,N efficient genotypes had more obvious advantages in N absorption rate,the amount and the percentage of N accumulation during the growth phases from elongating to heading and from heading to maturing. And of which the advantage during the growth phase from heading to maturing was particularly significant. Since rice organs aged and the plant physiological functions declined gradually from heading to maturing,the characteristics of rice senescence was then studied to understand the relationships between rice senescence and the N absorption and accumulation,and the N use efficiency. Results showed that,during the period of grain filling,the activities of superoxide dismutase (SOD),peroxidase (POD),and catalase (CAT) in flag leaf of N efficient genotypes were obviously higher than those of N inefficient genotypes. Contrarily,content of malondialdehyde (MDA),which is the product of membrane lipid peroxidation,was lower in N efficient genotypes than in N inefficient genotypes significantly. After the stage of full heading,N use efficiency was positively correlated to the activities of SOD,POD,and CAT in flag leaf of rice and negatively correlated to the content of MDA. So it reveals that,at late growth stages of rice,the activities of SOD,POD,and CAT of N efficient genotypes were higher than those of N inefficient genotypes in flag leaves,which could eliminate reactive oxygen species,inhibit the membrane lipid peroxidation and decrease the content of MDA more efficiently in N efficient rice genotypes. Therefore,compared with the N inefficient genotypes,the leaf senescence of N efficient genotypes was relatively slower,which could prolong the functional period of leaves,enhance the organic matter accumulation and improve the efficiency of N absorption and utilization.

Acute temperature resistance threshold in heart mitochondria: Febrile temperature activates function but exceeding it collapses the membrane barrier

Purpose: Molecular mechanisms underlying hyperthermia-induced cellular injury are not fully understood. The aim of this study was to identify the components of mitochondrial oxidative phosphorylation affected by mild hyperthermia and to quantify the contribution of each component to changes in system behaviour.Methods: Temperature effects on the oxidative phosphorylation in isolated rat-heart mitochondria were assessed using modular kinetic analysis. Mitochondrial H2O2 production and lipid peroxidation were measured for estimation of temperature-induced oxidative damage.Results: The increase of temperature in the febrile range (40°C) slightly activated mitochondrial function through stimulation of the respiratory module, without affecting the kinetics of the proton leak and phosphorylation modules. At 42°C, state 3 respiration rate remained unchanged, the proton leak across the inner mitochondrial membrane was substantially increased, the respiratory module slightly inhibited, leading to decreased membrane potential (Δψ) and diminished ATP synthesis (16% lower phosphorylation flux). Increase of temperature above 42°C caused dissipation of Δψ and abolishment of ATP synthesis indicating complete uncoupling of oxidative phosphorylation. The changes in mitochondrial functions induced by incubation at 42°C were completely reversible in contrast to only partial recovery after incubation at higher temperature (45°C). Furthermore, hyperthermia stimulated the production of H2O2 and membrane lipid peroxidation with maximal rates observed at 40°C.Conclusions: We demonstrated for the first time that febrile temperature (40°C) activates mitochondrial energy supplying functions, whereas further temperature increase by only a few degrees leads to severe impairment of mitochondrial ability to maintain ΔΨ and synthesise ATP.

Modular kinetic analysis reveals differences in Cd2+ and Cu2+ ion‐induced impairment of oxidative phosphorylation in liver

Impaired mitochondrial function contributes to copper- and cadmium-induced cellular dysfunction. In this study, we used modular kinetic analysis and metabolic control analysis to assess how Cd(2+) and Cu(2+) ions affect the kinetics and control of oxidative phosphorylation in isolated rat liver mitochondria. For the analysis, the system was modularized in two ways: (a) respiratory chain, phosphorylation and proton leak; and (b) coenzyme Q reduction and oxidation, with the membrane potential (Delta psi) and fraction of reduced coenzyme Q as the connecting intermediate, respectively. Modular kinetic analysis results indicate that both Cd(2+) and Cu(2+) ions inhibited the respiratory chain downstream of coenzyme Q. Moreover, Cu(2+), but not Cd(2+) ions stimulated proton leak kinetics at high Delta psi values. Further analysis showed that this difference can be explained by Cu(2+) ion-induced production of reactive oxygen species and membrane lipid peroxidation. In agreement with modular kinetic analysis data, metabolic control analysis showed that Cd(2+) and Cu(2+) ions increased control of the respiratory and phosphorylation flux by the respiratory chain module (mainly because of an increase in the control exerted by cytochrome bc(1) and cytochrome c oxidase), decreased control by the phosphorylation module and increased negative control of the phosphorylation flux by the proton leak module. In summary, we showed that there is a subtle difference in the mode of action of Cd(2+) and Cu(2+) ions on the mitochondrial function, which is related to the ability of Cu(2+) ions to induce reactive oxygen species production and lipid peroxidation.

Design and evaluation of a photoprotective compound able to release taurine under conditions of oxidative stress

Citation: IFSCC Magazine, 11 (2008) (2) 105–112Abstract: A novel photoprotective ingredient with anti‐oxidant and electrophilic scavenging properties was designed. A structure–activity relationship study was conducted in order to optimize its bioavailability, specifically its ability to reach deep layers of the skin that may be affected by ultraviolet radiation‐induced oxidative stress. A particular characteristic of this compound is its ability to release taurine upon reaction with some reactive oxygen species. In situ taurine formation may contribute to photoprotection. Preliminary in vitro experiments provide some evidence for effective protection against UVA‐induced oxidative stress. Scavenging of the electrophilic species 4‐hydroxynonenal, a highly cytotoxic end product of membrane lipid peroxidation, seems to be 2‐oxo‐1,3‐thiazolidine major photoprotective mechanism.Keywords: antioxidant, electrophilic species scavenging, photoprotection, structure‐activity relationship, taurinePaper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands

The photon emission, ATP level and motility of boar spermatozoa during liquid storage

Changes were studied in induced photon emission (as an indicator of oxidative stress), ATP level and sperm motility during seven day-storage of boar semen at 15 degrees C extended with the use of BTS extender. Photon emission was measured using a luminometer equipped with a cooled photomultiplier with a spectral response range from 370 to 620 nm. The time of storage had a significant effect on luminescence parameters (integral and peak max), intracellular ATP level and percentage of motile spermatozoa. The increase in luminescence parameters was paralleled by a decrease in ATP level and sperm motility. A significant correlation was found between the percentage of motile spermatozoa and integral (r=-0.27) and peak max (r=-0.31). ATP level was correlated with integral (r=-0.25) but not with peak max. Our results suggest that reactive oxygen species and products of cell membrane lipid peroxidation have a negative effect on ATP level and sperm motility. Induced luminescence assessment in combination with sperm motility and ATP level can give valuable information about the status and function of spermatozoa which may be relevant for predicting the fertilizing potential of the semen.

Cocoa procyanidins attenuate 4-hydroxynonenal-induced apoptosis of PC12 cells by directly inhibiting mitogen-activated protein kinase kinase 4 activity

Neurodegenerative disorders such as Alzheimer's disease (AD) are associated with oxidative stress, and it has been suggested that apoptosis is a crucial pathway in neuronal cell death in AD patients. 4-Hydroxynonenal (HNE), one of the aldehydic products of membrane lipid peroxidation, is reported to be elevated in the brains of AD patients and mediates the induction of neuronal apoptosis in the presence of oxidative stress. In this study, we investigated the HNE-induced apoptosis mechanism and the protective effects of the cocoa procyanidin fraction (CPF) and its major antioxidant procyanidin B2 against the apoptosis induced by HNE in rat pheochromocytoma (PC12) cells. HNE-induced nuclear condensation and increased sub-G1 fraction, both of which are markers of apoptotic cell death, were inhibited by CPF and procyanidin B2. Intracellular reactive oxygen species (ROS) accumulation was attenuated by pretreatment with CPF and procyanidin B2. CPF and procyanidin B2 also prevented HNE-induced poly(ADP-ribose) polymerase cleavage, antiapoptotic protein (Bcl-2 and Bcl-X L) down-regulation, and caspase-3 activation. Activation of c-Jun N-terminal protein kinase (JNK) and mitogen-activated protein kinase kinase 4 (MKK4) was attenuated by CPF and procyanidin B2. Moreover, CPF and procyanidin B2 bound directly to MKK4 and inhibited its activity. Data obtained with SP600125, a selective inhibitor of JNK, revealed that JNK is involved in HNE-induced apoptosis through the inhibition of PARP cleavage and caspase-3 activation in PC12 cells. Collectively, these results indicate that CPF and procyanidin B2 protect PC12 cells against HNE-induced apoptosis by blocking MKK4 activity as well as ROS accumulation.