Impairment of Brain Mitochondrial Oxidative Phosphorylation Accompanying Vitamin E Oxidation Induced by Iron or Reactive Nitrogen Species: A Selective Review

Vancomycin induces reactive oxygen species-dependent apoptosis via mitochondrial cardiolipin peroxidation in renal tubular epithelial cells

Vancomycin (VCM) is a first-line antibiotic for serious infections caused by methicillin-resistant Staphylococcus aureus. However, nephrotoxicity is one of the most complaint in VCM therapy. We previously reported that VCM induced apoptosis in a porcine proximal tubular epithelial cell line (LLC-PK1), in which mitochondrial complex I may generate superoxide, leading to cell death. In the present study, VCM caused production of mitochondrial reactive oxygen species and peroxidation of the mitochondrial phospholipid cardiolipin that was reversed by administration of the mitochondrial uncoupler carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP). FCCP also significantly suppressed VCM-induced depolarization of the mitochondrial membrane and apoptosis. Moreover, the lipophilic antioxidant vitamin E and a mitochondria-targeted antioxidant, mitoTEMPO, also significantly suppressed VCM-induced depolarization of mitochondrial membrane and apoptosis, whereas vitamin C, n-acetyl cysteine, or glutathione did not provide significant protection. These findings suggest that peroxidation of the mitochondrial membrane cardiolipin mediated the VCM-induced production of intracellular reactive oxygen species and initiation of apoptosis in LLC-PK1 cells. Furthermore, regulation of mitochondrial function using a mitochondria-targeted antioxidant, such as mitoTEMPO, may constitute a potential strategy for mitigation of VCM-induced proximal tubular epithelial cell injury.

Chronic variable stress impairs energy metabolism in prefrontal cortex and hippocampus of rats: prevention by chronic antioxidant treatment

Since chronic stress has been used widely for studying clinical depression and that brain energy metabolism and oxidative stress might be involved in the pathophysiology of this illness, the objective of this study was investigate the activities of pyruvate kinase, complex II and IV (cytocrome c oxidase) in hippocampus and prefrontal cortex of rats submitted to chronic variable stress. We also evaluated if vitamins E and C administration could prevent such effects. During 40 days adult rats from the stressed group were subjected to one stressor per day, at a different time each day, in order to minimize predictability. The stressed group had gained less weight while its immobilization time in the forced swimming test was greater than that of the control group. Results showed that stressed group presented an inhibition in the activities of complex II and cytochrome c oxidase in prefrontal cortex, while in hippocampus just complex IV was inhibited. Pyruvate kinase activity was not altered in stressed group when compared to control. Vitamins E and C administration prevented the alterations on respiratory chain caused by stress. These data suggest that the impairment of energy metabolism and oxidative stress could be related with the pathogenic pathways in stress related disorders.

Role of vitamin E in preventing acute mercury toxicity in rat

We have examined the effect of both pre- and post-treatment of vitamin E on mercury induced acute toxicity in rats. Mercury (12μmol/kg b.w., single intraperitoneal injection) resulted in oxidative injury and metallothionein mRNA expression together with alterations in tissue histology and accumulation of mercury in the body organs. The ameliorating potential of vitamin E (24μmol/kg b.w., single intraperitoneal injection) was observed in mercury administered rats. Our findings indicate that vitamin E provides complete protection from mercury toxicity in the liver with both pre- and post-treatments. As mercury is nephrotoxic and neurotoxic, it is interesting to note that post-treatment of vitamin E showed more protection in the kidney compared to pre-treatment. In brain tissue, partial protection was observed on oxidative stress parameters. Our results thus suggest that post-treatment with vitamin E could be more beneficial than pre- treatment in mercury intoxication.

Biomarkers of oxidative and nitrosative damage in Alzheimer's disease and mild cognitive impairment

Alzheimer's disease (AD) is the most common type of dementia in the elderly. Products of oxidative and nitrosative stress (OS and NS, respectively) accumulate with aging, which is the main risk factor for AD. This provides the basis for the involvement of OS and NS in AD pathogenesis. OS and NS occur in biological systems due to the dysregulation of the redox balance, caused by a deficiency of antioxidants and/or the overproduction of free radicals. Free radical attack against lipids, proteins, sugars and nucleic acids leads to the formation of bioproducts whose detection in fluids and tissues represents the currently available method for assessing oxidative/nitrosative damage. Post-mortem and in-vivo studies have demonstrated an accumulation of products of free radical damage in the central nervous system and in the peripheral tissues of subjects with AD or mild cognitive impairment (MCI). In addition to their individual role, biomarkers for OS and NS in AD are associated with altered bioenergetics and amyloid-beta (Abeta) metabolism. In this review we discuss the main results obtained in the field of biomarkers of oxidative/nitrosative stress in AD and MCI in humans, in addition to their potential role as a tool for diagnosis, prognosis and treatment efficacy in AD.

Ecophysiological determinations of antioxidant enzymes and lipoperoxidation in the blood of White Stork Ciconia ciconia from Poland

The aim of this study was to investigate the activity of antioxidant enzymes in the blood of White Stork Ciconia ciconia chicks (aged 19-54 days) in Poland in 2006. We took under consideration superoxide dismutase (SOD), catalase (CAT), ceruloplasmine (CP), glutathione peroxidase (GPx), glutathione reductase (GR) and the content of thiobarbituric acid-reactive substances (malondialdehyde) in polluted (copper manufacture), suburban areas, at the Odra meadows, and at swamps near Baltic Sea in the Pomeranian region. We examined the levels of Na, K, Ca, Mg, Fe, Zn, Cu, Mn, Co, Cd, and Pb and compared ecophysiological determinations for developing storks. Blood samples of wing venous were collected from 91 chicks from 33 nests. The degree of activity of antioxidant enzymes studied has been different in White Stork chicks' blood from Poland regions, as a rule. We have stated a relatively high level of CAT, GPx, SOD, and GR activity and malondialdehyde (MDA) content in chicks from polluted areas. However, relative value for GR in storks from Odra meadows was considerably higher (about 112 nmol NADPH(2)/min ml) than those in chicks from other environments (56-84 nmol on average). Relatively high levels of CAT, CP, and GPx (2.7 mkM/min l, 22.2 mg/l, and 3.8 nmol GSH/min ml, respectively) were also stated in chicks nested in swamps near Baltic Sea. Simultaneously, we have stated differences (p<0.02-p<0.001) in the level of elements (besides Ca) in blood of young storks from the studied areas. We found a high level of toxic metals, e.g. Cd, either from swamps near Baltic Sea (2.7 mg/kg) or from Głogów smelter (2.2mg/kg), whilst Pb concentration was high in chicks from Głogów (7.2 mg/kg). Cd and Pb levels in blood of chicks were different in individuals from each region (p<0.001). Birds from a smelter have the highest level of these elements, whereas the lowest one was stated in chicks from Odra meadows (Cd: 1.45, Pb: 0.84 mg/kg). Thus, Cd could be a useful marker of response for polluted stress. We also observed a relatively high level of Mg in chicks from both Pomeranian (7000 mg/kg) and polluted (about 6000 mg/kg) areas. Potassium, zinc, and cobalt levels were highest in chicks from suburbs (4.65, 10.1, and 2.7 mg/kg, respectively) and polluted regions (3.8, 9.7, and 5.6 mg/kg, respectively), whilst Cu and Mn were highest in those from polluted (10.9 and 47.6 mg/kg, respectively) and Pomeranian regions (11 and 42.2 mg/kg, respectively). Concentrations of Na, K, and Ca in chicks from Głogów smelter (143.2, 3.8, and 115.9 mg/kg, respectively) were often similar to those from Odra meadows (147.8, 3.6, and 112.5 mg/kg, respectively). This was probably due to a similar degree of homeostatic regulations of an organism. The levels of Mg, Fe, Zn, and Cu were often different (p<0.02-p<0.001) in the blood of White Stork chicks from the studied areas. Co, Pb, and Cd levels were higher (p<0.001) in chicks from Głogów smelter than in those from Odra meadows. It is evidence for importance of anthropopression, which influenced the course of biogeochemical processes and the bioaccumulation of toxic metals locally. This takes place also in chicks from swamps near Baltic Sea, in which the level of Cd was high (2.7 mg/kg); so we can state the high intensity of intoxication in this region. We can conclude that the use of hematological research assesses the condition of birds and might give a positive association with miscellaneous environmental loads. The high concentration of toxic heavy metals involved greater intensity of antioxidant enzymes' activity. Environmental intoxication causes an increase of lipoperoxidation intensity in growing chicks and changes the response of their immunological system.

Gene profile analysis implicates Klotho as an important contributor to aging changes in brain white matter of the rhesus monkey

Conventional studies of brain changes in normal aging have concentrated on gray matter as the locus for cognitive dysfunction. However, there is accumulating evidence from studies of normal aging in the rhesus monkey that changes in white matter may be a more critical factor in cognitive decline. Such changes include ultrastructural and biochemical evidence of myelin breakdown with age, as well as more recent magnetic resonance imaging of global loss of forebrain white matter volume and magnetic resonance diffusion tension imaging evidence of increased diffusivity in white matter. Moreover, many of these white matter changes correlate with age-related cognitive dysfunction. Based on these diverse white matter findings, the present work utilized high-density oligonucleotide microarrays to assess gene profile changes associated with age in the white matter of the corpus callosum. This approach identified several classes of genes that were differentially expressed in aging. Broadly characterized, these genes were predominantly related to an increase in stress factors and a decrease in cell function. The cell function changes included increased cell cycle inhibition and proteolysis, as well as decreased mitochondrial function, signal transduction, and protein translation. While most of these categories have previously been reported in functional brain aging, this is the first time they have been associated directly with white matter. Microarray analysis has also enabled the identification of neuroprotective response pathways activated by age in white matter, as well as several genes implicated in lifespan. Of particular interest was the identification of Klotho, a multifunctional protein that regulates phosphate and calcium metabolism, as well as insulin resistance, and is known to defend against oxidative stress and apoptosis. Combining the findings from the microarray study enabled us to formulate a model of white matter aging where specific genes are suggested as primary factors in disrupting white matter function. In conclusion, the overall changes described in this study could provide an explanation for aging changes in white matter that might be initiated or enhanced by an altered expression of life span associated genes such as Klotho.

Antioxidant response and oxidative damage in brain cortex after high dose of pilocarpine

Pilocarpine is a cholinergic agonist capable to induce seizures and an epilepticus-like state in rodents. This status epilepticus (SE) is an useful animal model to study the development and understanding of the neuropathology, behavioural and electroencephalographic alterations of human temporal lobe epilepsy. It has been suggested a relationship between SE and reactive oxygen species (ROS) that can result in seizure-induced neurodegeneration. The aim of this study was to evaluate the existence of oxidative damage and the changes in the antioxidant system in cortex after administration of a high pilocarpine dose. Rats were injected with pilocarpine (350 mg/kg i.p.) or with saline as control and 2h after the animals were sacrificed. Malondialdehyde (MDA) levels, as marker of lipid peroxidation, significantly increased (64%) after pilocarpine treatment evidencing oxidative damage. Antioxidant enzyme activities--catalase (CAT), glutathione peroxidase (GP) and superoxide dismutase (SOD)--significantly increased in response to pilocarpine (28%, 28% and 21%, respectively). GP and Mn-SOD gene expression were induced by pilocarpine treatment. Vitamin E concentration in brain cortex decreased (15%) as result of pilocarpine administration. In conclusion, the high dose of pilocarpine, used in the present study, induces oxidative damage and increases antioxidant enzyme activities and expression in brain cortex. Moreover, increased lipid peroxidation produces the consumption of Vitamin E.