Nélson R. Carvalho

Protective action of ethanolic extract of Rosmarinus officinalis L. in gastric ulcer prevention induced by ethanol in rats.

The pathology of a gastric ulcer is complex and multifactorial. Gastric ulcers affect many people around the world and its development is a result of the imbalance between aggressive and protective factors in the gastric mucosa. In this study, we evaluated the ethanolic extract of Rosmarinus officinalis L. (eeRo); this plant, more commonly known as rosemary, has attracted the interest of the scientific community due to its numerous pharmacological properties and their potential therapeutic applications. Here, we tested the preventive effects of eeRo against gastric ulcer induced by 70% ethanol in male Wistar rats. In addition, we aimed to clarify the mechanism involved in the preventive action of the eeRo in gastric ulcers. Based on the analysis of markers of oxidative damage and enzymatic antioxidant defense systems, the measurement of nitrite and nitrate levels and the assessment of the inflammatory response, the eeRo exhibited significant antioxidant, vasodilator and antiinflammatory properties.

Swimming Training Induces Liver Mitochondrial Adaptations to Oxidative Stress in Rats Submitted to Repeated Exhaustive Swimming Bouts

Background and Aims Although acute exhaustive exercise is known to increase liver reactive oxygen species (ROS) production and aerobic training has shown to improve the antioxidant status in the liver, little is known about mitochondria adaptations to aerobic training. The main objective of this study was to investigate the effects of the aerobic training on oxidative stress markers and antioxidant defense in liver mitochondria both after training and in response to three repeated exhaustive swimming bouts. Methods Wistar rats were divided into training (n = 14) and control (n = 14) groups. Training group performed a 6-week swimming training protocol. Subsets of training (n = 7) and control (n = 7) rats performed 3 repeated exhaustive swimming bouts with 72 h rest in between. Oxidative stress biomarkers, antioxidant activity, and mitochondria functionality were assessed. Results Trained group showed increased reduced glutathione (GSH) content and reduced/oxidized (GSH/GSSG) ratio, higher superoxide dismutase (MnSOD) activity, and decreased lipid peroxidation in liver mitochondria. Aerobic training protected against exhaustive swimming ROS production herein characterized by decreased oxidative stress markers, higher antioxidant defenses, and increases in methyl-tetrazolium reduction and membrane potential. Trained group also presented higher time to exhaustion compared to control group. Conclusions Swimming training induced positive adaptations in liver mitochondria of rats. Increased antioxidant defense after training coped well with exercise-produced ROS and liver mitochondria were less affected by exhaustive exercise. Therefore, liver mitochondria also adapt to exercise-induced ROS and may play an important role in exercise performance.

New Therapeutic Approach: Diphenyl Diselenide Reduces Mitochondrial Dysfunction in Acetaminophen-Induced Acute Liver Failure

The acute liver failure (ALF) induced by acetaminophen (APAP) is closely related to oxidative damage and depletion of hepatic glutathione, consequently changes in cell energy metabolism and mitochondrial dysfunction have been observed after APAP overdose. Diphenyl diselenide [(PhSe)2], a simple organoselenium compound with antioxidant properties, previously demonstrated to confer hepatoprotection. However, little is known about the protective mechanism on mitochondria. The main objective of this study was to investigate the effects (PhSe)2 to reduce mitochondrial dysfunction and, secondly, compare in the liver homogenate the hepatoprotective effects of the (PhSe)2 to the N-acetylcysteine (NAC) during APAP-induced ALF to validate our model. Mice were injected intraperitoneal with APAP (600 mg/kg), (PhSe)2 (15.6 mg/kg), NAC (1200 mg/kg), APAP+(PhSe)2 or APAP+NAC, where the (PhSe)2 or NAC treatment were given 1 h following APAP. The liver was collected 4 h after overdose. The plasma alanine and aspartate aminotransferase activities increased after APAP administration. APAP caused a remarkable increase of oxidative stress markers (lipid peroxidation, reactive species and protein carbonylation) and decrease of the antioxidant defense in the liver homogenate and mitochondria. APAP caused a marked loss in the mitochondrial membrane potential, the mitochondrial ATPase activity, and the rate of mitochondrial oxygen consumption and increased the mitochondrial swelling. All these effects were significantly prevented by (PhSe)2. The effectiveness of (PhSe)2 was similar at a lower dose than NAC. In summary, (PhSe)2 provided a significant improvement to the mitochondrial redox homeostasis and the mitochondrial bioenergetics dysfunction caused by membrane permeability transition in the hepatotoxicity APAP-induced.

Butane-2,3-dionethiosemicarbazone: an oxime with antioxidant properties.

Oximes are compounds generally used to reverse the acetylcholinesterase (AChE) inhibition caused by organophosphates (OPs). The aim of this study was to examine the capacity of the butane-2,3-dionethiosemicarbazone oxime to scavenge different forms of reactive species (RS) in vitro, as well as counteract their formation. The potential antioxidant and toxic activity of the oxime was assayed both in vitro and ex vivo. The obtained results indicate a significant hydrogen peroxide (H2O2), nitric oxide (NO) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity at 0.275, 0.5 and 5microM of oxime, respectively (p< or =0.05). The oxime exhibited a powerful inhibitory effect on dihydroxybenzoate formation (25microM) (p< or =0.05) and also decreased deoxyribose degradation induced by Fe2+ and via Fenton reaction (0.44 and 0.66mM, respectively) (p< or =0.05). The oxime showed a significant inhibitory effect on sigma-phenantroline reaction with Fe2+ (0.4mM) suggesting a possible interaction between the oxime and iron. A significant decrease in the basal and pro-oxidant-induced lipid peroxidation in brain, liver, and kidney of mice was observed both in vitro and ex vivo (p< or =0.05). In addition, in our ex vivo experiments the oxime did not depict any significant changes in thiol levels of liver, kidney and brain as well as did not modify the delta-aminolevulinate dehydratase (delta-ALA-D) activity in these tissues. Taken together our results indicate an in vitro and ex vivo antioxidant activity of the oxime possibly due to its scavenging activity toward different RS and a significant iron interaction.

Therapeutic cold: An effective kind to modulate the oxidative damage resulting of a skeletal muscle contusion.

Abstract Muscular contusions affect the function of the skeletal muscle system. This study investigated the oxidative damage as well as the main morphological changes related to a skeletal muscle contusion in the gastrocnemius muscle of rats and also the capacity of therapeutic cold to modulate these parameters. The therapeutic cold modulated the increase of oxidative stress markers and also modulated the reduction in the antioxidants levels in the injured muscle. In enzyme assays, therapeutic cold was also effective in normalizing the muscle Na+/K+ and Ca2+ ATPases, lactate dehydrogenase and myeloperoxidase activities. Similarly, the lesioned non-treated animals presented evident impairments in the mitochondrial functions and in the muscle morphology which were diminished by the cold treatment. The therapeutic cold was able to modulate the oxidative damage possibly by its capacity to limit the inflammatory response intensity, to attenuate the impairment of the mitochondrial function and also to preserve the skeletal muscle morphology.

Protective effects of therapeutic cold and heat against the oxidative damage induced by a muscle strain injury in rats

Abstract The mechanisms of action of physical agents commonly used to treat skeletal muscle lesions are not well understood. In this study, we examined whether the modulation of oxidative stress is involved in the beneficial effects of cold and heat on gastrocnemius muscle strain injury. Adult male Wistar rats were submitted to a strain injury and treated with therapeutic agents in an isolated or combined form. Strain damage caused an increase in muscle and blood oxidative damage. We suggest that this oxidative damage might be related to the impairment of the muscle cell structure, since we observed a significant positive correlation between increased plasma creatine kinase activity and both oxidized dichlorofluoresceine and lipid peroxidation levels in muscle and blood. The intensity of the inflammatory response appears also to be an important factor in the genesis of oxidative damage immediately following a muscle strain injury. Therapeutic cold seems to be more effective in preventing the damage induced by a strain injury, possibly due to its capacity to control the impairment of muscle cell structure and to modulate the intensity of the inflammatory response that follows a muscle strain injury.

Reduction of Acute Hepatic Damage Induced by Acetaminophen after Treatment with Diphenyl Diselenide in Mice

In this study, the authors evaluated the ability of diphenyl diselenide (PhSe)2 to reverse acute hepatic failure induced by acetaminophen (APAP) in mice. The animals received an APAP dose of 600 mg/kg intraperitoneally (i.p.), and then 1 hour later, they received 15.6 mg/kg i.p. of (PhSe)2. Three hours after (PhSe)2 administration, the animals were sacrificed and blood and liver samples were collected for analysis. The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured. The levels of reduced glutathione (GSH) and oxidized glutathione (GSSG), thiobarbituric acid-reactive substances (TBARS), 2’,7’-dichlorofluorescein (DFC), catalase activity (CAT), and myeloperoxidase (MPO) activity were determined in the liver. A methyl-tetrazolium reduction (MTT) assay was also performed on the liver. Histopathological studies were conducted in all groups. Exposure of animals to APAP induced oxidative stress, increased lipid peroxidation (LPO), and the generation of reactive species, reduced the levels of GSH, and caused an increase in the MPO activity. Treatment with (PhSe)2 reduced LPO and the formation of reactive species and inhibited the processes of inflammation, reducing the hepatic damage induced by APAP. The results of this study show that (PhSe)2 is a promising therapeutic option for the treatment of acute hepatic failure.

Cryotherapy reduces skeletal muscle damage after ischemia/reperfusion in rats

The aim of this study was to analyze the effects of cryotherapy on the biochemical and morphological changes in ischemic and reperfused (I/R) gastrocnemius muscle of rats. Forty male Wistar rats were divided into control and I/R groups, and divided based on whether or not the rats were submitted to cryotherapy. Following the reperfusion period, biochemical and morphological analyses were performed. Following cryotherapy, a reduction in thiobarbituric acid‐reactive substances and dichlorofluorescein oxidation levels were observed in I/R muscle. Cryotherapy in I/R muscle also minimized effects such as decreased cellular viability, levels of non‐protein thiols and calcium ATPase activity as well as increased catalase activity. Cryotherapy also limited mitochondrial dysfunction and decreased the presence of neutrophils in I/R muscle, an effect that was corroborated by reduced myeloperoxidase activity in I/R muscle treated with cryotherapy. The effects of cryotherapy are associated with a reduction in the intensity of the inflammatory response and also with a decrease in mitochondrial dysfunction.

Effect of repeated restraint stress and clomipramine on Na+/K+-ATPase activity and behavior in rats

Activation of the limbic‐hypothalamic‐pituitary‐adrenal axis (LHPA) and the release of glucocorticoids are fundamental for the adaptive response and immediate survival of an organism in reaction to acute stimuli. However, high levels of glucocorticoids in the brain may produce neuronal injury and a decrease of Na+/K+‐ATPase activity, with effects on neurotransmitter signaling, neural activity, as well as the whole animal behavior. Clomipramine is a tricyclic antidepressant that inhibits the reuptake of serotonin and norepinephrine by indirect actions on the dopaminergic system and LHPA axis. Its chronic use increases the bodys ability to cope with stress; however, high doses can potentiate its side effects on memory, learning, and sensory motor function. The purpose of the present study was to compare the effect of repeated restraint stress and clomipramine treatment on Na+/K+‐ATPase activity and on the behavior of male rats. Changes in the behavioral response were evaluated by measuring the memory, learning, anxiety, and exploratory responses. Our results showed that exposure to repeated restraint stress reduced levels of Na+/K+‐ATPase in brain structures and changed short and long‐term memory, learning, and exploratory response when compared to the control group. Exposure to clomipramine treatment increased anxiety levels and reduced Na+/K+‐ATPase activity in the cerebral cortex as well as short term memory, learning, and exploratory response. In conclusion, the present results provide additional evidence concerning how repeated restraint stress and clomipramine chronically administered at higher dose levels affect the neural activity and behavior of male rats.

Inhibition of δ-aminolevulinate dehydratase is not closely related to the development of hyperglycemia in alloxan-induced diabetic mice

Alloxan is a compound widely used in models of diabetes mellitus due to its ability for damage insulin-producing β-cells. The aim of this study was to investigate acute (after 24h) and sub-acute (after seven days) effects of 200mg/kg alloxan administration on mice. Biochemical parameters as liver, kidney, and blood δ-ALA-D activity, total sulfhydryl content of hepatic and renal tissues, and hepatic and renal content of malondialdehyde (MDA) were evaluated. The histopathology of hepatic and renal tissues of alloxan-treated and control animals was carried out. Further, blood glucose levels were determined in an attempt to correlate alloxan-induced hyperglycemia with changes in thiol status. Results showed that mice exhibited a significant inhibition of hepatic and renal δ-ALA-D activity in addition to a significant decrease in total sulfhydryl groups of same tissues in both acute and sub-acute alloxan administrations. Moreover, alloxan-induced inhibition of δ-ALA-D activity was partly suppressed when enzymatic assay was performed in the presence of dithiothreitol, suggesting that inhibitory effect of alloxan on δ-ALA-D activity is, at least partially, related to the oxidation of the enzymes essential thiol groups. Blood δ-ALA-D activity was significantly inhibited only 24h after alloxan administration; however, at this time, a hyperglycemic status was not observed in animals. In contrast, a significant increase in blood glucose levels was observed seven days after alloxan administration. Despite of alterations in biochemical parameters, histological tissue examination of alloxan-treated mice revealed typical renal and hepatic parenchyma. Therefore, these results showed that acute toxic effects of alloxan are related, at least partially, to depletion of sulfhydryl groups, and do not closely relate to the development of hyperglycemia in mice.