Effects of coenzyme Q10 treatment on antioxidant pathways in normal and streptozotocin-induced diabetic rats

Coenzyme Q10 is an endogenous lipid soluble antioxidant. Because oxidant stress may exacerbate some complications of diabetes mellitus, this study investigated the effects of subacute treatment with exogenous coenzyme Q10 (10 mg/kg/day, i.p. for 14 days) on tissue antioxidant defenses in 30-day streptozotocin-induced diabetic Sprague-Dawley rats. Liver, kidney, brain, and heart were assayed for degree of lipid peroxidation, reduced and oxidized glutathione contents, and activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase. All tissues from diabetic animals exhibited increased oxidative stress and disturbances in antioxidant defense when compared with normal controls. Treatment with the lipophilic compound coenzyme Q10 reversed diabetic effects on hepatic glutathione peroxidase activity, on renal superoxide dismutase activity, on cardiac lipid peroxidation, and on oxidized glutathione concentration in brain. However, treatment with coenzyme Q10 also exacerbated the increase in cardiac catalase activity, which was already elevated by diabetes, further decreased hepatic glutathione reductase activity, augmented the increase in hepatic lipid peroxidation, and further increased glutathione peroxidase activity in the heart and brain of diabetic animals. Subacute dosing with coenzyme Q10 ameliorated some of the diabetes-induced changes in oxidative stress. However, exacerbation of several diabetes-related effects was also observed.     

Melatonin prevents oxidative stress and inhibits reactive gliosis induced by hyperhomocysteinemia in rats

Homocysteine (Hcy), an independent risk factor for atherosclerosis, undergoes auto-oxidation and generates reactive oxygen species, which are thought to be main cause of Hcy neurotoxicity. However, the mechanisms leading to neurodegenerative disorders are poorly understood because studies that have investigated the potential neurotoxicity of hyperhomocysteinemia in vivo are scarce. The purpose of this study was to test whether daily administration of methionine, which induces hyperhomocysteinemia, causes glial hyperactivity, and also to investigate the protective effects of melatonin on the brain tissue against oxidative stress of Hcy in rats. There was a significant development of oxidative stress as indicated by an increase in malondialdehyde + 4-hydroxyalkenals in hippocampus and cortex of hyperhomocysteinemic rats, whereas significant reduction was found in the activity of glutathione peroxidase (GSH-Px). Co-treatment with melatonin inhibited the elevation of lipid peroxidation and significantly increased GSH-Px activity in the brain regions studied. Western blot analysis revealed an increase in glial fibrillary acidic protein (GFAP) contents both in hippocampus and frontal cortex (p < 0.001) of hyperhomocysteinemic rats compared to the controls. Administration of melatonin significantly decreased GFAP contents in hippocampus and cortex (p < 0.05). S100B contents increased only in frontal cortex in hyperhomocysteinemic rats compared to the control (p < 0.01) and was inhibited by melatonin treatment (p < 0.01). The present findings show that Hcy can sensitize glial cells, a mechanism which might contribute to the pathogenesis of neurodegenerative disorders, and further suggest that melatonin can be involved in protecting against the toxicity of Hcy by inhibiting free radical generation and stabilizing glial cell activity.     

Effect of coenzyme Q10 intake on endogenous coenzyme Q content, mitochondrial electron transport chain, antioxidative defenses, and life span of mice

The main purpose of this study was to determine whether intake of coenzyme Q10, which can potentially act as both an antioxidant and a prooxidant, has an impact on indicators of oxidative stress and the aging process. Mice were fed diets providing daily supplements of 0, 93, or 371 mg CoQ10 /kg body weight, starting at 3.5 months of age. Effects on mitochondrial superoxide generation, activities of oxidoreductases, protein oxidative damage, glutathione redox state, and life span of male mice were determined. Amounts of CoQ9 and CoQ10, measured after 3.5 or 17.5 months of intake, in homogenates and mitochondria of liver, heart, kidney, skeletal muscle, and brain increased with the dosage and duration of CoQ10 intake in all the tissues except brain. Activities of mitochondrial electron transport chain oxidoreductases, rates of mitochondrial O2-* generation, state 3 respiration, carbonyl content, glutathione redox state of tissues, and activities of superoxide dismutase, catalase, and glutathione peroxidase, determined at 19 or 25 months of age, were unaffected by CoQ10 administration. Life span studies, conducted on 50 mice in each group, showed that CoQ10 administration had no effect on mortality. Altogether, the results indicated that contrary to the historical view, supplemental intake of CoQ10 elevates the endogenous content of both CoQ9 and CoQ10, but has no discernable effect on the main antioxidant defenses or prooxidant generation in most tissues, and has no impact on the life span of mice.     

Chronic Melatonin Administration Reduced Oxidative Damage and Cellular Senescence in the Hippocampus of a Mouse Model of Down Syndrome

Previous studies have demonstrated that melatonin administration improves spatial learning and memory and hippocampal long-term potentiation in the adult Ts65Dn (TS) mouse, a model of Down syndrome (DS). This functional benefit of melatonin was accompanied by protection from cholinergic neurodegeneration and the attenuation of several hippocampal neuromorphological alterations in TS mice. Because oxidative stress contributes to the progression of cognitive deficits and neurodegeneration in DS, this study evaluates the antioxidant effects of melatonin in the brains of TS mice. Melatonin was administered to TS and control mice from 6 to 12 months of age and its effects on the oxidative state and levels of cellular senescence were evaluated. Melatonin treatment induced antioxidant and antiaging effects in the hippocampus of adult TS mice. Although melatonin administration did not regulate the activities of the main antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase) in the cortex or hippocampus, melatonin decreased protein and lipid oxidative damage by reducing the thiobarbituric acid reactive substances (TBARS) and protein carbonyls (PC) levels in the TS hippocampus due to its ability to act as a free radical scavenger. Consistent with this reduction in oxidative stress, melatonin also decreased hippocampal senescence in TS animals by normalizing the density of senescence-associated β-galactosidase positive cells in the hippocampus. These results showed that this treatment attenuated the oxidative damage and cellular senescence in the brain of TS mice and support the use of melatonin as a potential therapeutic agent for age-related cognitive deficits and neurodegeneration in adults with DS.     

Distribution of Coenzyme Q Homologues in Brain

Ubiquinone (coenzyme Q₁₀), in addition to its function as an electron and proton carrier in mitochondrial electron transport coupled to ATP synthesis, acts in its reduced form (ubiquinol) as an antioxidant, inhibiting lipid peroxidation in biological membranes and protecting mitochondrial inner-membrane proteins and DNA against oxidative damage accompanying lipid peroxidation. Tissue ubiquinone levels are subject to regulation by physiological factors that are related to the oxidative activity of the organism: they increase under the influence of oxidative stress, e.g. physical exercise, cold adaptation, thyroid hormone treatment, and decrease during aging. In the present study, coenzyme Q homologues were separated and quantified in the brains of mice, rats, rabbits, and chickens using high-performance liquid chromatography. In addition, the coenzyme Q homologues were measured in cells such as NG-108, PC-12, rat fetal brain cells and human SHSY-5Y and monocytes. In general, Q₁ content was the lowest among the coenzyme homologues quantified in the brain. Q₉ was not detectable in the brains of chickens and rabbits, but was present in the brains of rats and mice. Q₉ was also not detected in human cell lines SHSY-5Y and monocytes. Q₁₀ was detected in the brains of mice, rats, rabbits, and chickens and in cell lines. Since both coenzyme Q and vitamin E are antioxidants, and coenzyme Q recycles vitamins E and C, vitamin E was also quantified in mice brain using HPLC-electrochemical detector (ECD). The quantity of vitamin E was lowest in the substantia nigra compared with the other brain regions. This finding is crucial in elucidating ubiquinone function in bioenergetics; in preventing free radical generation, lipid peroxidation, and apoptosis in the brain; and as a potential compound in treating various neurodegenerative disorders.     

Ozone ameliorates age-related oxidative stress changes in rat liver and kidney: Effects of pre- and post-ageing administration

The ageing process is known to be accompanied by increased oxidative stress and compromised antioxidant defenses. Controlled ozone administration has been shown to be effective in various pathophysiological conditions with an underlying oxidative burden. However, its effect on the biochemical alterations associated with the ageing process has been rarely studied. Therefore, the present work was carried out to study the role of ozone in counteracting the state of oxidative stress associated with ageing in rat liver and kidneys using two experimental models. In the pre-ageing model, ozone was administered prior to the onset of ageing at adulthood and continued after the start of the ageing process (3-month-old rats until the age of 15 months). While in the post-ageing model, ozone was administered after ageing has begun and lasted for one month (14-month-old rats until the age of 15 months). The pre-ageing ozone administration effectively reduced lipid and protein oxidation markers, namely, malondialdehyde and protein carbonyl levels and decreased lipofuscin pigment deposition in rat liver and kidneys. Moreover, it significantly restored hepatic and renal reduced glutathione (GSH) contents and normalized cytosolic hepatic glutathione peroxidase activity. Similar but less pronounced effects were observed in the post-ageing ozone-treated group. Nevertheless, in the latter model ozone administration failed to significantly affect liver and kidney lipofuscin levels, as well as kidney GSH contents. These data provide evidences for potentially positive effects of pre-ageing ozone therapy in neutralizing chronic oxidative stress associated with ageing in rat liver and kidneys.     

Increased oxidative stress in patients with amyotrophic lateral sclerosis and the effect of edaravone administration

Objectives and methods: Compared to age-matched healthy controls (n?=?55), patients with amyotrophic lateral sclerosis (ALS) (n?=?26) showed increased oxidative stress as indicated by a significantly increased percentage of oxidized coenzyme Q10 (%CoQ10) in total plasma coenzyme Q10, a significantly decreased level of plasma uric acid, and a significantly decreased percentage of polyunsaturated fatty acids in total plasma free fatty acids (FFA). Therefore, the efficacy of edaravone, a radical scavenger, in these ALS patients was examined.

Results and discussion: Among 26 ALS patients, 17 received edaravone (30?mg/day, one to four times a week) for at least 3 months, and 13 continued for 6 months. Changes in revised ALS functional rating scale (ALSFRS-R) were significantly smaller in these patients than in edaravone-untreated ALS patients (n?=?19). Edaravone administration significantly reduced excursions of more than one standard deviation from the mean for plasma FFA levels and the contents of palmitoleic and oleic acids, plasma markers of tissue oxidative damage, in the satisfactory progress group (ΔALSFRS-R?≥?0) as compared to the ingravescent group (ΔALSFRS-R?<??5). Edaravone treatment increased plasma uric acid, suggesting that it is an effective scavenger of peroxynitrite. However, edaravone administration did not decrease %CoQ10. Therefore, combined treatment with agents such as coenzyme Q10 may further reduce oxidative stress in ALS patients.     

Age-Related Regional Changes in Hydroxyl Radical Stress and Antioxidants in Gerbil Brain

Abstract— The levels of hydroxyl radicals and oxidized GSH have been examined as indices of oxidative stress in young (3 months), middle-aged (15 months), and old (20–24 months) gerbil brain hippocampus, cortex, and striaturn. The hydroxyl radical stress was estimated by measuring the salicylate hydroxyl radical trapping products 2,5-and 2,3-dihydroxybenzoic acid. The stress was significantly higher in all three brain regions in middle-aged and old gerbils versus young animals (66.0%). Regional comparisons showed that the stress was significantly higher in cortex than in either the hippocampus or striatum of the middle-aged and old gerbils (32.0%). The ratio of oxidized to total GSH also increased progressively in middle-aged and old animals in all three brain regions (p < 0.05, 41.1%), further indicating a general age-related increase in oxidative stress. Parallel to this age-related increase in oxidative stress, a significant, albeit slight (8%), decrease in neuronal number in hippocampal CA1 region was observed in both the middle-aged and old animals. Possible differences in antioxidant levels were also examined. Total GSH levels were similar across age groups (variance <12%). However, the regional comparison showed that it was highest in striatum in all age groups. The levels of a-tocopherol (vitamin E) were significantly higher in the middle-aged and old animals in all three regions (70.4%). Vitamin E was highest in the hippocampus and the differences between the hippocampus and the cortex and striatum increased with age. Although of a lesser magnitude, significant increases in hippocampal total ascorbic acid level were also noted with age (p < 0.05, 10%). Ascorbic acid was the most regionally specific of the three antioxidants examined, with hippocampus > cortex > striatum for all age groups. The difference in ascorbic acid level between hippocampus and cortex also increased with age (64.4%). The results suggest that the general age-related, regionally specific increases in oxidative stress stimulate the accumulation of antioxidants. It is interesting that the hippocampus, which is selectively vulnerable to various insults such as ischemia, epilepsy, and insulin-induced hypoglycemia, exhibits the greatest age-related increase in vitamin E and ascorbic acid, perhaps reflective of a greater impact of the progressive increase in baseline oxidative stress.     

Chronic melatonin treatment prevents age-dependent cardiac mitochondrial dysfunction in senescence-accelerated mice

Heart mitochondria from female senescence-accelerated (SAMP8) and senescence-resistant (SAMR1) mice of 5 or 10 months of age, were studied. Mitochondrial oxidative stress was determined by measuring the levels of lipid peroxidation, glutathione and glutathione disulfide and glutathione peroxidase and reductase activities. Mitochondrial function was assessed by measuring the activity of the respiratory chain complexes and ATP content. The results show that the age-dependent mitochondrial oxidative damage in the heart of SAMP8 mice was accompanied by a reduction in the electron transport chain complex activities and in ATP levels. Chronic melatonin administration between 1 and 10 months of age normalized the redox and the bioenergetic status of the mitochondria and increased ATP levels. The results support the presence of significant mitochondrial oxidative stress in SAM mice at 10 months of age, and they suggest a beneficial effect of chronic pharmacological intervention with melatonin, which reduces the deteriorative and functional oxidative changes in cardiac mitochondria with age.     

Melatonin prevents oxidative stress and inhibits reactive gliosis induced by hyperhomocysteinemia in rats

Homocysteine (Hcy), an independent risk factor for atherosclerosis, undergoes auto-oxidation and generates reactive oxygen species, which are thought to be main cause of Hcy neurotoxicity. However, the mechanisms leading to neurodegenerative disorders are poorly understood because studies that have investigated the potential neurotoxicity of hyperhomocysteinemia in vivo are scarce. The purpose of this study was to test whether daily administration of methionine, which induces hyperhomocysteinemia, causes glial hyperactivity, and also to investigate the protective effects of melatonin on the brain tissue against oxidative stress of Hcy in rats. There was a significant development of oxidative stress as indicated by an increase in malondialdehyde + 4-hydroxyalkenals in hippocampus and cortex of hyperhomocysteine mic rats, whereas significant reduction was found in the activity of glutathione peroxidase (GSH-Px). Co-treatment with melatonin inhibited the elevation of lipid peroxidation and significantly increased GSH-Px activity in the brain regions studied. Western blot analysis revealed an increase in glial fibrillary acidic protein (GFAP) contents both in hippocampus and frontal cortex (p < 0.001) of hyperhomocysteinemic rats compared to the controls. Administration of melatonin significantly decreased GFAP contents in hippocampus and cortex (p < 0.05). S100B contents increased only in frontal cortex in hyperhomocysteinemic rats compared to the control (p < 0.01) and was inhibited by melatonin treatment (p < 0.01). The present findings show that Hcy can sensitize glial cells, a mechanism which might contribute to the pathogenesis of neurodegenerative disorders, and further suggest that melatonin can be involved in protecting against the toxicity of Hcy by inhibiting free radical generation and stabilizing glial cell activity.     

Coenzyme Q10 supplementation alleviates pain in pregabalin-treated fibromyalgia patients via reducing brain activity and mitochondrial dysfunction

Although coenzyme Q10 (CoQ10) supplementation has shown to reduce pain levels in chronic pain, the effects of CoQ10 supplementation on pain, anxiety, brain activity, mitochondrial oxidative stress, antioxidants, and inflammation in pregabalin-treated fibromyalgia (FM) patients have not clearly elucidated. We hypothesised that CoQ10 supplementation reduced pain better than pregabalin alone via reducing brain activity, mitochondrial oxidative stress, inflammation, and increasing antioxidant levels in pregabalin-treated FM patients. A double-blind randomised placebo-controlled trial was conducted. Eleven FM patients were enrolled with 2 weeks wash-out then randomly allocated to 2 treatment groups; pregabalin with CoQ10 or pregabalin with placebo for 40 d. Then, patients in CoQ10 group were switched to placebo, and patients in placebo group were switched to CoQ10 for another 40 d. Pain pressure threshold (PPT), FM questionnaire, anxiety, and pain score were examined. Peripheral blood mononuclear cells (PBMCs) were isolated to investigate mitochondrial oxidative stress and inflammation at day 0, 40, and 80. The level of antioxidants and brain positron emission tomography (PET) scan were also determined at these time points. Pregabalin alone reduced pain and anxiety via decreasing brain activity compared with their baseline. However, it did not affect mitochondrial oxidative stress and inflammation. Supplementation with CoQ10 effectively reduced greater pain, anxiety and brain activity, mitochondrial oxidative stress, and inflammation. CoQ10 also increased a reduced glutathione levels and superoxide dismutase (SOD) levels in FM patients. These findings provide new evidence that CoQ10 supplementation provides further benefit for relieving pain sensation in pregabalin-treated FM patients, possibly via improving mitochondrial function, reducing inflammation, and decreasing brain activity.     

Cold-induced hyperthyroidism produces oxidative damage in rat tissues and increases susceptibility to oxidants

In this work, we investigated whether cold exposure-induced hyperthyroidism increases oxidative damage and susceptibility to oxidants of rat liver, heart and skeletal muscle. All tissues exhibited gradual increases in hydroperoxide and protein-bound carbonyl levels. Glutathione peroxidase activity increased in all tissues after 2 days and further increased in the muscle after 10 days of cold exposure. Liver glutathione reductase activity increased after 10 days of cold exposure, while heart and muscle activities were not modified. Vitamin E levels were not affected by cold, while coenzyme Q9 and coenzyme Q10 levels decreased in heart and muscle after 2-day cold exposure and were not further modified after 10 days. Liver coenzyme Q9 levels increased after 2 days whereas coenzyme Q10 levels increased after 10 days in the cold. The whole antioxidant capacity was lowered, while parameters positively correlated with susceptibility to oxidants were increased by cold. Lipid fatty acid composition was modified in all tissues. In particular, fatty acid unsaturation degree increased in heart and muscle. Cytochrome oxidase activity increased, suggesting an increased content of hemoproteins, which are able to generate .OH radical. This view was supported by the observation that the tissue susceptibility to H(2)O(2) treatment, which is strongly correlated to iron-ligand content, increased after cold exposure. In this frame, it is apparent that the increase in oxidative capacity, necessary for homeotherm survival in low temperature environments, has potential harmful effects, because it results in increased susceptibility to oxidative challenge.     

Modulation of age‐related changes in oxidative stress markers and energy status in the rat heart and hippocampus: a significant role for ozone therapy

Oxidative stress emerges as a key player in the ageing process. Controlled ozone administration is known to promote an oxidative preconditioning or adaptation to oxidative stress. The present study investigated whether prophylactic ozone administration could interfere with the age‐related changes in the heart and the hippocampus of rats. Four groups of rats, aged about 3 months old, were used. Group 1 (Prophylactic ozone group) received ozone/oxygen mixture by rectal insufflations (0.6 mg/kg) twice/week for the first 3 months, then once/week till the age of 15 months. Group 2 (Oxygen group) received oxygen as vehicle for ozone in a manner similar to group 1. Group 3 (Aged control group) was kept without any treatment until the age of 15 months. A fourth group of rats (Adult control group) was evaluated at 3 months of age to provide baseline data. Ozone alleviated age‐associated redox state imbalance as evidenced by reduction of lipid and protein oxidation markers, lessening of lipofuscin deposition, restoration of glutathione levels in both tissues and normalization of glutathione peroxidase activity in the heart tissue. Ozone also mitigated age‐associated energy failure in the heart and the hippocampus, improved cardiac cytosolic Ca²⁺ homeostasis and restored the attenuated Na⁺, K⁺‐ATPase activity in the hippocampus of aged rats. These data provide new evidence concerning the anti‐ageing potential of prophylactic ozone administration. Copyright © 2012 John Wiley & Sons, Ltd.     

Effects of melatonin on oxidative stress and spatial memory impairment induced by acute ethanol treatment in rats

Melatonin has recently been suggested as an antioxidant that may protect neurons from oxidative stress. Acute ethanol administration produces both lipid peroxidation as an indicator of oxidative stress in the brain and impairs water-maze performance in spatial learning and memory tasks. The present study investigated the effect of melatonin against ethanol-induced oxidative stress and spatial memory impairment. The Morris water maze was used to evaluate the cognitive functions of rats. Thiobarbituric acid reactive substances (TBARS), which are the indicators of lipid peroxidation, and the activities of antioxidative enzymes (glutathione peroxidase and superoxide dismutase) were measured in the rat hippocampus and prefrontal cortex which form interconnected neural circuits for spatial memory. Acute administration of ethanol significantly increased TBARS levels in the hippocampus. Combined melatonin-ethanol treatment caused a significant increase in glutathione peroxidase activities and a significant decrease of TBARS in the rat hippocampus. In the prefrontal cortex, there was only a significant decrease of TBARS levels in the combined melatonin-ethanol receiving group as compared to the ethanol-treated group. Melatonin did not affect the impairment of spatial memory due to acute ethanol exposure, but melatonin alone had a positive effect on water maze performances. Our study demonstrated that melatonin decreased ethanol-induced lipid peroxidation and increased glutathione peroxidase activity in the rat hippocampus.     

Effects of combined quercetin and coenzyme Q(10) treatment on oxidative stress in normal and diabetic rats

Reactive oxygen species may be actively involved in the genesis of various pathological states such as ischemia-reperfusion injury, cancer, and diabetes. Our objective was to determine if subacute treatment with combined antioxidants quercetin and coenzyme Q(10) (10 mg/kg/day ip for 14 days) affects the activities of antioxidant enzymes in normal and 30-day streptozotocin-induced diabetic Sprague-Dawley rats. Quercetin treatment raised blood glucose concentrations in normal and diabetic rats, whereas treatment with coenzyme Q(10) did not. Liver, kidney, heart, and brain tissues were excised and the activities of catalase, glutathione reductase, glutathione peroxidase, superoxide dismutase, and concentrations of oxidized and reduced glutathione were determined. In the liver of diabetic rats, superoxide dismutase, glutathione peroxidase, and levels of both oxidized and reduced glutathione were significantly decreased from the nondiabetic control, and these effects were not reversed when antioxidants were administered. In kidney, glutathione peroxidase activity was significantly elevated in the diabetic rats as compared to nondiabetic rats, and antioxidant treatment did not return the enzyme activity to nondiabetic levels. In heart, catalase activity was increased in diabetic animals and restored to normal levels after combined treatment with quercetin and coenzyme Q(10). Cardiac superoxide dismutase was lower than normal in quercetin- and quercetin + coenzyme Q(10)-treated diabetic rats. There were no adverse effects on oxidative stress markers after treatment with quercetin or coenzyme Q(10) singly or in combination. In spite of the elevation of glucose, quercetin may be effective in reversing some effects of diabetes, but the combination of quercetin + coenzyme Q(10) did not increase effectiveness in reversing effects of diabetes.     

Changes in oxidative stress parameters in relation to age, growth and reproduction in the short-lived catarina scallop Argopecten ventricosus reared in its natural environment

Increase in oxidative damage and decrease in cellular maintenance is often associated with aging, but, in marine ectotherms, both processes are also strongly influenced by somatic growth, maturation and reproduction. In this study, we used a single cohort of the short-lived catarina scallop Argopecten ventricosus, to investigate the effects of somatic growth, reproduction and aging on oxidative damage parameters (protein carbonyls, TBARS and lipofuscin) and cellular maintenance mechanisms (antioxidant activity and apoptosis) in scallops, caged in their natural environment. The concentrations of protein carbonyls and TBARS increased steeply during the early period of fast growth and during reproduction in one-year-old scallops. However, oxidative damage was transient, and apoptotic cell death played a pivotal role in eliminating damage in gill, mantle and muscle tissues of young scallops. Animals were able to reproduce again in the second year, but the reduced intensity of apoptosis impaired subsequent removal of damaged cells. In late survivors low antioxidant capacity and apoptotic activity together with a fast accumulation of the age pigment lipofuscin was observed. Rates of oxygen consumption and oxidative stress markers were strongly dependent on somatic growth and reproductive state but not on temperature. Compared to longer-lived bivalves, A. ventricosus seems more susceptible to oxidative stress with higher tissue-specific protein carbonyl levels and fast accumulation of lipofuscin in animals surviving the second spawning. Superoxide dismutase activity and apoptotic cell death intensity were however higher in this short-lived scallop than in longer-lived bivalves. The life strategy of this short-lived and intensely predated scallop supports rapid somatic growth and fitness as well as early maturation at young age at the cost of fast cellular degradation in second year scallops.     

Possible antioxidant mechanism in melatonin reversal of aging and chronic ethanol-induced amnesia in plus-maze and passive avoidance memory tasks

Cognitive dysfunction is one of the most striking age-related impairments seen in human beings and animals. This impairment probably is due to the vulnerability of the brain cells to increased oxidative stress during aging process. Pineal hormone melatonin is reported to be an endogenous antioxidant, whose peak plasma level declines during aging and in Alzheimer's disease (AD). Present experiments were performed to study the possible effect of exogenously administered melatonin on cognitive performance of young, aged, or ethanol-intoxicated mice (an animal model for AD) using one trial step-down type of passive avoidance and elevated plus-maze task. Aged or chronic ethanol-treated mice showed poor retention of memory in step-down passive avoidance and in elevated plus-maze task. Chronic administration of melatonin (0.1-10 mg/kg, sc) for 30 d or its coadministration with ethanol (15% W/V, 2 g/kg perorally) for 24 d significantly reversed the age-induced or chronic ethanol-induced retention deficits in both the test paradigms. However, in both the memory paradigms chronic administration of melatonin failed to modulate the retention performance of young mice. Chronic administration of melatonin (0.1-10 mg/kg) for 30 d also reversed age-associated decline in forebrain total glutathione (tGSH) level. Chronic ethanol administration to young mice produced decline in forebrain tGSH level and enhanced brain lipid peroxidation, which was significantly reversed by coadministration of melatonin (10 mg/kg). The results of this study showed chronic melatonin treatment reverses cognitive deficits in aged and ethanol-intoxicated mice, which is associated with its antioxidant property.     

Age-related changes in brain mitochondrial DNA deletion and oxidative stress are differentially modulated by dietary fat type and coenzyme Q₁₀

Mitochondria-related oxidative damage is a primary event in aging and age-related neurodegenerative disorders. Some dietary treatments, such as antioxidant supplementation or the enrichment of mitochondrial membranes with less oxidizable fatty acids, reduce lipid peroxidation and lengthen life span in rodents. This study compares life-long feeding on monounsaturated fatty acids (MUFAs), such as virgin olive oil, and n-6 polyunsaturated fatty acids, such as sunflower oil, with or without coenzyme Q₁₀ supplementation, with respect to age-related molecular changes in rat brain mitochondria. The MUFA diet led to diminished age-related phenotypic changes, with lipoxidation-derived protein markers being higher among the older animals, whereas protein carbonyl compounds were lower. It is noteworthy that the MUFA diet prevented the age-related increase in levels of mitochondrial DNA deletions in the brain mitochondria from aged animals. The findings of this study suggest that age-related oxidative stress is related, at the mitochondrial level, to other age-related features such as mitochondrial electron transport and mtDNA alterations, and it can be modulated by selecting an appropriate dietary fat type and/or by suitable supplementation with low levels of the antioxidant/electron carrier molecule coenzyme Q.     

Melatonin reduces glial reactivity in the hippocampus, cortex, and cerebellum of streptozotocin-induced diabetic rats

Hyperglycemia plays a critical role in the development and progression of diabetic neuropathy. One of the mechanisms by which hyperglycemia causes neural degeneration is via the increased oxidative stress that accompanies diabetes. Metabolic and oxidative insults often cause rapid changes in glial cells. Key indicators of this response are increased synthesis of glial fibrillary acidic protein (GFAP) and S100B, both astrocytic markers. In the present study, we examined glial reactivity in hippocampus, cortex, and cerebellum of streptozotocin (STZ)-induced diabetic rats by determining the expression of GFAP and S-100B and we evaluated the effect of melatonin on the glial response. Western blot measurement of contents in brain regions after 6 weeks of STZ-induced diabetes indicated significant increases in these constituents compared with those in nondiabetic controls. Administration of melatonin prevented the upregulation of GFAP in all brain regions of diabetic rats. Using GFAP immunohistochemistry, we observed an increase in GFAP immunostaining in the hippocampus of STZ-diabetic rats relative to levels in the control brains. Treatment with melatonin resulted in an obvious reduction of GFAP-immunoreactive astrocytes in hippocampus. Like GFAP, S100B levels also were increased in all three brain areas of diabetic rats, an effect also reduced by melatonin treatment. Finally, the levels of lipid peroxidation products were elevated as a consequence of diabetes, with this change also being prevented by melatonin. These results suggest that diabetes causes increased glial reactivity possibly due to elevated oxidative stress, and administration of melatonin represents an achievable adjunct therapy for preventing gliosis.     

Brain oxidative stress and selective behaviour of aluminium in specific areas of rat brain: potential effects in a 6-OHDA-induced model of Parkinson's disease

The ability of aluminium to affect the oxidant status of specific areas of the brain (cerebellum, ventral midbrain, cortex, hippocampus, striatum) was investigated in rats intraperitoneally treated with aluminium chloride (10 mg Al³⁺/kg/day) for 10 days. The potential of aluminium to act as an etiological factor in Parkinson's disease (PD) was assessed by studying its ability to increase oxidative stress in ventral midbrain and striatum and the striatal dopaminergic neurodegeneration induced by 6-hydroxydopamine in an experimental model of PD. The results showed that aluminium caused an increase in oxidative stress (TBARS, protein carbonyl content, and protein thiol content) for most of the brain regions studied, which was accompanied by a decrease in the activity of some antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase). However, studies in vitro confirmed the inability of aluminium to affect the activity of those enzymes. The reported effects exhibited a regional-selective behaviour for all the cerebral structures studied. Aluminium also enhanced the ability of 6-hydroxydopamine to cause oxidative stress and neurodegeneration in the dopaminergic system, which confirms its potential as a risk factor in the development of PD.