Experimental Infection by Brucella ovis: Changes in NTPDase, 5'-Nucleotidase and Acetylcholinesterase Associated Cerebral Oxidative Stres

Background: Changes in purinergic and cholinergic signaling have been demonstrated in various pathologies associated with inflammation; however, the changes in brucellosis caused by the Gram-negative coccobacillus Brucella ovis are not known. B. ovis is generally asymptomatic in sheep. Hepatosplenomegaly has been described in B. ovis, a non-zoonotic species, characterized by an extravascular inflammatory response. Purinergic system enzymes are closely involved with the modulation of the immune system, pro- and anti-inflammatory events. The objective of this study was to investigate the role of ectonucleotidases and cholinesterase’s in the brains of mice experimentally infected with B. ovis.Materials, Methods & Results: Forty-eight animals were divided into two groups: control (n = 24) and infected (n = 24). In group infected, 100 µL containing 1.3 x 107 UFC B. ovis /mL via intraperitoneal was used in inoculation. The brains were collected from the animals on days 7, 15, 30 and 60 post-infection (PI). We measured levels of TBARS (substances reactive to thiobarbituric acid) and ROS (reactive oxygen species) in the brain. The activity of NTPDase (using ATP and ADP as substrate) and 5'-nucleotidase (using AMP as substrate) were evaluated in brain in addition to histopathological analysis. No histopathological lesions were observed in the control group nor the infected group at days 7, 15, and 30 PI. However,multifocal areas with moderate microgliosis and inflammatory infiltrates in the cerebral cortex were observed at day 60 PI in the infected animals. B. ovis DNA was detected in brain. During the course of infection, B. ovis caused greater lipid peroxidation in the brains of infected animals than in the control group at day 60PI. No significant results were observed at 7, 15 or day 30 PI. Similarly, there was significantly more reactive oxygen species at day 60 PI in brains of infected animals than in the control group. NTPDase activity (using ATP and AMP as substrate) was lower at days 7 and 15 PI in infected animals than in control. However, during the course of infection there was an increase in NTPDase activity at day 60 PI in the infected group. The infected animals showed a decrease of 5´-nucleotidase (AMP as substrate) activity at days 7 and 30 PI. On the other hand, 5´-nucleotidase activity was greater on day 60 PI in the experimental group than in the control. The results suggest that nucleotide hydrolysis was low in the acute phase (up to day 30 PI) due to the decrease of NTPDase and 5´-nucleotidase activities. After day 60 PI, there was a reversal in enzyme activities, probably with concomitant increase of extracellular nucleotides. AChE activity in brain on days 30 and 60 PI compared to control.Discussion: Among the functions of NTPDase are inhibition of platelet aggregation, vascular homeostasis, modulation of inflammation and immune response, all via its regulation of extracellular concentrations of ATP, a pro-inflammatory molecule. E-NTPDase plays an important role in controlling lymphocyte function, including antigen recognition and activation of cytotoxic T cell effector functions, as well as the generation of signals. The enzyme E-5´-nucleotidase also exerts non-enzymatic functions, including induction of intracellular signaling and mediation of cell-cell adhesion and cell-matrix and migration. Levels of acetylcholine are regulated by cholinesterase enzymes that are present in cholinergic and noncholinergic tissues, as the acetylcholinesterase (AChE) is a membrane-bound enzyme, primarily found in the brain and cholinergic neurons, where it participates in the structural regulation of postsynaptic differentiation. The results demonstrated that the chronicity of infection by B. ovis causes oxidative damage and inflammation in the brain, as well as modulation of ectonucleotidases and AChE activities

The Protective Effects of an Adsorbent against Oxidative Stress in Quails Fed Aflatoxin-Contaminated Diet

Background: Contamination of crops with aflatoxin is considered a serious global threat to food safety, since potent carcinogenic, teratogenic, mutagenic and immunosuppressive effects of aflatoxins are well recognized. Recently, the use of adsorbents has been linked with protective effects against oxidative stress in several diseases. Thus, the aim of this study was to assess the occurrence of oxidative stress in quails (Coturnix coturnix) fed with aflatoxin-contaminated diet, as well as the protective effect of an adsorbent.Materials, Methods & Results: Twenty-eight quails were divided into four groups (n = 7): diet without additives (control; the group A), diet and adsorbent containing aluminosilicates (the group B), aflatoxin-contaminated diet (200 ppb) (the group C), and aflatoxin-contaminated diet (200 ppb) and adsorbent containing aluminosilicates (the group D). The composition of the adsorbent containing aluminosilicates was 0.3% based on yeast cell wall, silymarin, and bentonite. The animals received feed and water ad libitum during 20 days. At the end of the experimental period, total blood was collected by cardiac puncture in tubes without anticoagulant to obtain serum (centrifuged at 3500 g during 10 min) for later determination of biochemical parameters. The liver was placed in a solution of Tris–HCl 10 mM, pH 7.4 for TBARS (Thiobarbituric acid reactive substances), ROS (Reactive oxygen species), SOD (Superoxide dismutase) and CAT (Catalase) analysis. The hepatic tissue was gently homogenized in a glass potter in specific buffer, homogenated, and centrifuged at 10.000 g at 4ºC for 10 min to yield a supernatant (S1) used for analyses. Homogenate aliquots were stored at -80°C until utilization. Fragments of liver and intestine (5 cm) were collected for histopathological analyses. Between days 15 to 20 of the experiment, group C quails showed clinical signs, such as apathy, creepy feathers and reduced feed intake. At day 20 of experiment, macroscopically, the liver of quails belonging to the group C showed greenish yellow color differently from the other groups. Microscopically, no alterations were observed in the liver of animals in groups A and B. Severe diffuse microvacuolar degeneration (hydropic) of hepatocytes and small foci of necrosis in the liver were observed in the group C, as observed in the group D, but in a more moderate degree to microvacuolar degeneration. Seric total protein, albumin, globulin and uric acid levels decreased in the group C and D. The levels of alanine aminotransferase (ALT) increased in the group C, and the treatment with adsorbent was able to avoid this increment. Seric and hepatic reactive oxygen species and TBARS increased in the group C, and the treatment with adsorbent reduced theses parameters in the group D. Catalase (CAT) activity decreased, while ALA-D increased in the group C. The treatment with adsorbent was able to prevent CAT activity decrease, but it did not prevent the increase in ALA-D activity.Discussion: Aflatoxins are considered one of the most important problems in poultry production causing high economic losses to producers. In this study, the use of adsorbent showed a protective effect to hepatic tissue, minimizing histopathological lesions, as well as by preventing lipid peroxidation and exacerbated production of free radicals. Based on this data, aflatoxin intoxication causes hepatic oxidative stress that contributes directly to disease pathogenesis, and the addition of an adsorbent containing 0.3% based on bentonite, yeast cell wall and silymarin may be considered a new approach to prevent cellular and hepatic damage caused by aflatoxins

Experimental Infection by Brucella ovis: Changes in NTPDase, 5'-Nucleotidase and Acetylcholinesterase Associated Cerebral Oxidative Stres

Background: Changes in purinergic and cholinergic signaling have been demonstrated in various pathologies associated with inflammation; however, the changes in brucellosis caused by the Gram-negative coccobacillus Brucella ovis are not known. B. ovis is generally asymptomatic in sheep. Hepatosplenomegaly has been described in B. ovis, a non-zoonotic species, characterized by an extravascular inflammatory response. Purinergic system enzymes are closely involved with the modulation of the immune system, pro- and anti-inflammatory events. The objective of this study was to investigate the role of ectonucleotidases and cholinesterase’s in the brains of mice experimentally infected with B. ovis.Materials, Methods & Results: Forty-eight animals were divided into two groups: control (n = 24) and infected (n = 24). In group infected, 100 µL containing 1.3 x 107 UFC B. ovis /mL via intraperitoneal was used in inoculation. The brains were collected from the animals on days 7, 15, 30 and 60 post-infection (PI). We measured levels of TBARS (substances reactive to thiobarbituric acid) and ROS (reactive oxygen species) in the brain. The activity of NTPDase (using ATP and ADP as substrate) and 5'-nucleotidase (using AMP as substrate) were evaluated in brain in addition to histopathological analysis. No histopathological lesions were observed in the control group nor the infected group at days 7, 15, and 30 PI. However,multifocal areas with moderate microgliosis and inflammatory infiltrates in the cerebral cortex were observed at day 60 PI in the infected animals. B. ovis DNA was detected in brain. During the course of infection, B. ovis caused greater lipid peroxidation in the brains of infected animals than in the control group at day 60PI. No significant results were observed at 7, 15 or day 30 PI. Similarly, there was significantly more reactive oxygen species at day 60 PI in brains of infected animals than in the control group. NTPDase activity (using ATP and AMP as substrate) was lower at days 7 and 15 PI in infected animals than in control. However, during the course of infection there was an increase in NTPDase activity at day 60 PI in the infected group. The infected animals showed a decrease of 5´-nucleotidase (AMP as substrate) activity at days 7 and 30 PI. On the other hand, 5´-nucleotidase activity was greater on day 60 PI in the experimental group than in the control. The results suggest that nucleotide hydrolysis was low in the acute phase (up to day 30 PI) due to the decrease of NTPDase and 5´-nucleotidase activities. After day 60 PI, there was a reversal in enzyme activities, probably with concomitant increase of extracellular nucleotides. AChE activity in brain on days 30 and 60 PI compared to control.Discussion: Among the functions of NTPDase are inhibition of platelet aggregation, vascular homeostasis, modulation of inflammation and immune response, all via its regulation of extracellular concentrations of ATP, a pro-inflammatory molecule. E-NTPDase plays an important role in controlling lymphocyte function, including antigen recognition and activation of cytotoxic T cell effector functions, as well as the generation of signals. The enzyme E-5´-nucleotidase also exerts non-enzymatic functions, including induction of intracellular signaling and mediation of cell-cell adhesion and cell-matrix and migration. Levels of acetylcholine are regulated by cholinesterase enzymes that are present in cholinergic and noncholinergic tissues, as the acetylcholinesterase (AChE) is a membrane-bound enzyme, primarily found in the brain and cholinergic neurons, where it participates in the structural regulation of postsynaptic differentiation. The results demonstrated that the chronicity of infection by B. ovis causes oxidative damage and inflammation in the brain, as well as modulation of ectonucleotidases and AChE activities

Oxidative Stress and Changes on the Adenosinergic System of Cats Infected by Feline Leukemia Virus (FeLV)

Background: The feline leukemia virus (FeLV) is clinically important retroviruses that infect domestic and wild feline worldwide, affecting more than 3 million cats representing a great risk for premature death. Some studies have demonstrated that oxidative stress, as well as the adenosinergic system, exert an important role in the pathogenesis of viral diseases. Oxidative stress is considered a disturbance in the antioxidant/oxidant status in favor of the excessive generation or lower removal of free radicals. Therefore, the aim of this study was to evaluate whether changes on the adenosinergic system and oxidative stress occurred in cats positives for feline leukemia virus (FeLV).Materials, Methods & Results: Forty-nine serum samples of cats (between 4 months and 13 years of age) seen at the Veterinary Hospital of the University of Santa Catarina State (UDESC - Lages, SC, Brazil) were used. Blood samples were collected from the jugular vein and stored in tubes without anticoagulant to obtain serum. An aliquot was used to detect both viral infections using the kit SNAP FIV/FeLV, that detects the p27 protein from FeLV and antibodies against the p24 protein from FIV. The test was performed according the manufacture’s recommendations. Based on this result, this study involved 20 FeLV negative cats, 20 FeLV positive symptomatic cats, and 9 FeLV positives asymptomatic cats. Serum samples were used to determine the activities of adenosine deaminase (ADA) and glutathione-S-transferase (GST), as well as thiobarbituric acid reactive substances (TBARS) and reactive oxygen levels (ROS). Seric ADA and GST activities, as well as TBARS (lipid peroxidation) and ROS (free radical) levels were determined spectrophotometrically according to the specific method. Seric ADA activity was increased in symptomatic animals compared to negatives and also to asymptomatic positive animals, and the same was observed for seric TBARS levels. On the other hand, GST activity decreased in the symptomatic and asymptomatic groups compared to the negative control group. No difference was observed regarding seric ROS levels.Discussion: The upregulation of seric ADA activity observed in this present study could contribute to the inflammatory process since it would decrease seric levels of Ado, a nucleoside with anti-inflammatory effects. Lipids, especially the polyunsaturated fatty acids, are sensitive to oxidation by free radicals, generating MDA, and cause to increase of TBARS levels. A significant negative correlation between lipid peroxidation and ADA activity in kidney samples of rats experimentally infected by protozoan, and these authors demonstrated that increase on lipid peroxidation is linked to decreased ADA activity. The reduction on seric GST activity can be explained since the antioxidant enzyme was unable to remove the excess of peroxides and superoxide anion, resulting on decreased cellular antioxidant activity. Based on these evidences, it is possible to conclude that symptomatic FeLV cats showed an upregulation on seric ADA activity associated to the impairment of the immune response, contributing to inflammatory processes. Moreover, FeLV symptomatic cats showed damage to lipids and an impairment on antioxidant/oxidant status, alterations compatible to oxidative stress and oxidative damage. In summary, these alterations contribute to the pathophysiology of FeLV infection, and can be used as markers of this disease