Tiago Boeira Salomon

Antioxidant enzymes activities and protein damage in rat brain of both sexes

The theory of free radicals and accumulation of damages suggests that the reactive species of oxygen play a key role in the context of aging. Thus, for the best understanding of the aging process, the study of antioxidant defenses has to be considered as part of gerontology. The present work evaluated the enzymatic activity of the enzymes catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), and measured the amount of oxidative damage in proteins (carbonyl groups) in brains of rats of both sexes in the ages of 3-, 6-, 12- and 20-months. The results suggest that the patterns of activity and accumulation of damages can be sex-specific and related to the cycle of reproductive life of the organism.

Alpha-lipoic acid restores tear production in an animal model of dry eye.

The tear film comprises a major mechanism for protection of the ocular surface against harmful external agents. Disruption of tear production can lead to dry eye syndrome, causing damage ranging from mild discomfort to scarring of the ocular surface with irreversible vision impairment. The production of tears by the lacrimal gland is influenced by neuroendocrine, hormonal, and immunological factors. Reactive oxygen and nitrogen species play an important role in its regulation. We assessed the effects of oxidative stress on antioxidant defenses in the lacrimal gland and ocular surface in ovariectomized rats supplemented with n-3 polyunsaturated fatty acids (n-3 PUFA) and alpha-lipoic acid (ALP). We found that n-3 PUFA did not measurably influence oxidative stress, but ALP had site-specific pro-oxidant and antioxidant effects, and was an important influence on ocular surface dry eye improvement. As an index of oxidative damage to proteins and lipids, we measured levels of carbonyl and malondialdehyde (MDA), respectively. Enzymatic antioxidant defenses were measured as total superoxide dismutase (tSOD) and glutathione peroxidase (GPx), and non-enzymatic defenses were estimated by vitamin C, total glutathione, and indirect oxide nitric levels. PUFA and ALP treatment restored lacrimal production with resulting improvement in the dry eye Schirmer test in all supplemented groups. The results indicated that reactive oxygen species resulting from oxidative stress in the lacrimal gland did not play an important role in dry eye through reactive oxygen species; however, alpha-lipoic acid altered the metabolism of reactive nitrogen species, causing increased activity of lacrimal peroxidase and improved lacrimal production.

Pulmonary antioxidant defences and protein damage during the ageing process of both sexes.

The free radical theory holds that the senescence is caused by oxidative damage that results from an imbalance between reactive oxygen and nitrogen species (RONS) and antioxidant defences. Hence, it plays an important role in the field of gerontology. We evaluated, in male and female rats, the activities of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), and total superoxide dismutase (tSOD), as well as oxidative protein damage in pulmonary tissue at 3, 6, 12, and 20 months of age. The results show an increase in the activities of all antioxidant enzymes at 12 months of age in female rats, suggesting an association with the reproductive life cycle. Protein damage in female pulmonary tissues did not change significantly throughout the ageing process. In male rats, the activity of GPx in 20 months of age showed an inter‐gender increase, while the tSOD and GPx showed higher activities in 20 months of age in the intra‐gender analysis. The male lung showed higher protein damage at 6 months of age. These findings suggest that antioxidant enzymatic activity is connected to the reproductive life cycle. Copyright

Oxidative stress in testis of animals during aging with and without reproductive activity

The free radical theory of aging postulates that an imbalance between reactive oxygen species (ROS) and reactive nitrogen species (RNS) and antioxidant defenses is important in senescence. To address this issue and gain insight into the aging process, we have evaluated the antioxidant defenses and have assessed oxidative damage in testis tissues in aging male rats. In order to relate aging and reproduction, animals with and without reproductive activity were studied. In reproductive animals the results showed a progressive increase in antioxidant enzyme activity until 12 months of age followed by an abrupt fall at 24 months. In non-reproductive animals, antioxidant activity was stable through 12 months of age, but again, fell abruptly at 24 months of age. In addition, increased aconitase activity and increased testosterone levels were found among reproductively active animals. The data demonstrate the existence of metabolic differences in testis of reproductively experienced animals and reproductively naïve animals.

Induction of ROS generation by fluconazole in Candida glabrata: activation of antioxidant enzymes and oxidative DNA damage

In this study, we assessed the generation of reactive oxygen species (ROS) induced by subinhibitory concentration of fluconazole in susceptible and resistant Candida glabrata strains at stationary growth phase and measured their oxidative responses parameters: glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione-S-transferase (GST), consumption of hydrogen peroxide, and total glutathione, as well as oxidative damage in lipids, proteins, and DNA. Data showed that fluconazole increased generation of ROS and GPx and SOD enzymatic activity in treated cells; however, these enzymatic activities did not differ between resistant and susceptible strains. Susceptible strains exhibited higher GST activity than resistant, and when susceptible cells were treated with fluconazole, GST activity decreased. Fluconazole treatment cause oxidative damage only in DNA. There are a possible participation of ROS, as organic peroxides and O2(•-), in antifungal mechanism of fluconazole, which results in higher GPx and SOD enzymatic activities and oxidative DNA damage in C. glabrata.

Blood markers of oxidative stress predict weaning failure from mechanical ventilation

Patients undergoing mechanical ventilation (MV) often experience respiratory muscle dysfunction, which complicates the weaning process. There is no simple means to predict or diagnose respiratory muscle dysfunction because diagnosis depends on measurements in muscle diaphragmatic fibre. As oxidative stress is a key mechanism contributing to MV‐induced respiratory muscle dysfunction, the aim of this study was to determine if differences in blood measures of oxidative stress in patients who had success and failure in a spontaneous breathing trial (SBT) could be used to predict the outcome of MV. This was a prospective analysis of MV‐dependent patients (≥72 hrs; n = 34) undergoing a standard weaning protocol. Clinical, laboratory and oxidative stress analyses were performed. Measurements were made on blood samples taken at three time‐points: immediately before the trial, 30 min. into the trial in weaning success (WS) patients, or immediately before return to MV in weaning failure (WF) patients, and 6 hrs after the trial. We found that blood measures of oxidative stress distinguished patients who would experience WF from patients who would experience WS. Before SBT, WF patients presented higher oxidative damage in lipids and higher antioxidant levels and decreased nitric oxide concentrations. The observed differences in measures between WF and WS patients persisted throughout and after the weaning trial. In conclusion, WF may be predicted based on higher malondialdehyde, higher vitamin C and lower nitric oxide concentration in plasma.

Oxidative stress in the kidney of reproductive male rats during aging.

Reproduction alters the male physiology. We performed a comprehensive examination of oxidative stress in the kidneys of male rats with (experienced) or without (naïve) reproductive activity during aging. Oxidative stress was assessed by measuring the activity of catalase, glutathione peroxidase, glutathione S-transferase, and superoxide dismutase, and by measuring protein carbonylation, lipid peroxidation, nitrite and nitrate levels, vitamin C levels, and glutathione (total, reduced, and oxidized forms) levels, and metabolism was accessed by aconitase activity in kidney tissue, as well as testosterone and estradiol levels in serum. Reproductively active animals exhibited increased testosterone levels and altered metabolism. Aging affects tissues and organs and contributes to their functional decline. Elderly naïve rats showed high nitrite and nitrate levels. The experienced rats had less damage in elderly ages, probably because they had higher antioxidant amount and antioxidant enzyme activities at earlier ages, which would have avoided oxidative damage seen in naïve group, and because of the metabolism decline. Glutathione increase in naïve elder rats probably was induced for direct protection against oxidative damage and indirect protection by higher glutathione peroxidase and glutathione S-transferase activities. Linear regression shows that lipid peroxidation levels explained vitamin C levels (B standardized value of 0.42), indicating that vitamin C was properly produced or recruited into kidneys to combat lipid peroxidation. Catalase activity reflected the protein carbonylation and lipid peroxidation levels (B standardized values of 0.28 and 0.48). These results add comprehensive data regarding changes in oxidative stress during aging, and suggest an explanation for the costs of reproduction.

Treatment of oxidative stress in brain of ovariectomized rats with omega-3 and lipoic acid.

SCOPE Postmenopausal women are often affected by a group of metabolic disorders related to oxidative stress. Alternative treatments that can improve the quality of life of these women have been the subject of recent studies. The objective of this study was to evaluate the response to oxidative stress in the brains of rats following ovariectomy, and to determine enzymatic and nonenzymatic antioxidant responses when the animals received 3 months of dietary supplementation. METHODS AND RESULTS Ovariectomy produced changes in antioxidant profiles characterized by reductions in glutathione S-transferase activity, H2 O2 consumption, superoxide dismutase activity, and vitamin C levels and increases in protein carbonylation. Docosahexaenoic fatty acid (DHA) supplementation restored these parameters to normal values and increased values of other antioxidants (glutathione peroxidase and total glutathione). However, DHA supplementation also increased protein carbonylation and lipid peroxidation. Eicosapentaenoic acid supplementation produced no changes in antioxidants, but decreased lipid peroxidation. Lipoic acid supplementation increased consumption of H2 O2 and decreased protein carbonylation and lipid peroxidation. CONCLUSION These results suggest that the antioxidant response to omega-3 varies in different tissues, and in this study DHA treatment had a prooxidant effect in the brain. Lipoic acid treatment, on the other hand, had a protective effect, reducing markers of oxidative damage.

Effects of lipoic acid and n-3 long-chain polyunsaturated fatty acid on the liver ovariectomized rat model of menopause

BACKGROUND Bilateral ovariectomy is an experimental model used to analyse the effects of menopause and develop strategies to mitigate the deleterious effects of this condition. Supplementation of the diet with antioxidants has been used to reduce potential oxidative stress caused by menopause. The purpose of the study was to analyse the effects of α-lipoic acid (LA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), dietary supplementation on oxidative stress in the livers of ovariectomized rats. METHODS In this study, we evaluated the effect of dietary supplementation with LA, DHA and EPA for a period of 16 weeks on oestrogen levels and oxidative stress biomarkers in the livers of ovariectomized 25 three-month-old rats. RESULTS Serum oestrogen levels were lower after ovariectomy but were not altered by dietary treatments. LA was capable of acting in the liver, recovering the activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase, and reducing protein oxidative damage. Moreover, LA supplementation reduced nitrite and nitrate levels. DHA and EPA recovered the antioxidant activity of cytosolic and mitochondrial superoxide dismutase, decreasing protein oxidation. Protection against lipid oxidation differed between treatments. The DHA-treated group showed increased levels of the lipid peroxidation biomarker malondialdehyde compared to the ovariectomized group. However, malondialdehyde levels were not altered by EPA treatment. CONCLUSIONS The results suggest that the antioxidant response varies among evaluated supplementations and all supplements were able to alter enzymatic and non-enzymatic antioxidants in the livers of ovariectomized rats. DHA presented the most evident antioxidant effect, decreasing protein and lipid damage.

Redox changes in the brains of reproductive female rats during aging

Abstract Reproduction is a critical and demanding phase of an animals life. In mammals, females usually invest much more in parental care than males, and lactation is the most energetically demanding period of a females life. Here, we tested whether oxidative stress is a consequence of reproduction in the brains of female Wistar rats. We evaluated the activities of glutathione peroxidase, glutathione S‐transferase, and superoxide dismutase; H2O2 consumption; protein carbonylation; NO2 & NO3 levels; and total glutathione, as well as sex hormone levels in brain tissue of animals at 3, 6, 12, and 24 months of age. Animals were grouped according to reproductive experience: breeders or non‐breeders. Most of the studied parameters showed a difference between non‐breeders and breeders at 12 and 24 months. At 24 months of age, breeders showed higher superoxide dismutase activity, H2O2 consumption, glutathione peroxidase activity, and carbonyl levels than non‐breeders. In 12‐month‐old non‐breeders, we observed a higher level of H2O2 consumption and higher superoxide dismutase and glutathione peroxidase activities than breeders. By evaluating the correlation network, we found that there were a larger number of influential nodes and positive links in breeder animals than in non‐breeders, indicating a greater number of redox changes in breeder animals. Here, we also demonstrated that the aging process caused higher oxidative damage and higher antioxidant defenses in the brains of breeder female rats at 24 months, suggesting that the reproduction process is costly, at least for the female brain. This study shows that there is a strong potential for a link between the cost of reproduction and oxidative stress. Graphical abstract Schematic representation of the changes observed during aging in the brains of breeder and non‐breeder animals. The size of the font represents the correlations between variables: 6 correlations (36 pt font), 5 correlations (28 pt font), 4 correlations (22 pt font), 3 correlations (18 pt font), 2 correlations (14 pt font), and 1 correlation (12 pt font.) Figure. No Caption available. HighlightsA simultaneous increase in reproduction and longevity are limited by trade‐offs.Aging increases oxidative damage and antioxidant defenses in the brains of breeders.The correlation network indicates that the redox profile changed mainly in breeders.Most of the parameters differ between non‐breeders and breeders at 12 and 24 months.