Role of antioxidant systems in induced nutritional pancreatic atrophy in chicken

Novel role and mechanism of glutathione peroxidase-4 in nutritional pancreatic atrophy of chicks induced by dietary selenium deficiency

Nutritional pancreatic atrophy (NPA) is a classical Se/vitamin E deficiency disease of chicks. To reveal molecular mechanisms of its pathogenesis, we fed day-old chicks a practical, low-Se diet (14 μg Se/kg), and replicated the typical symptoms of NPA including vesiculated mitochondria, cytoplasmic vacuoles, and hyaline bodies in acinar cells of chicks as early as day 18. Target pathway analyses illustrated a > 90% depletion (P < 0.05) of glutathione peroxidase 4 (GPX4) protein and up-regulated apoptotic signaling (cytochrome C/caspase 9/caspase 3) in the pancreas and(or) acinar cells of Se deficient chicks compared with Se-adequate chicks. Subsequently, we overexpressed and suppressed GPX4 expression in the pancreatic acinar cells and observed an inverse (P < 0.05) relationship between the GPX4 production and apoptotic signaling and cell death. Applying pull down and mass spectrometry, we unveiled that GPX4 bound prothymosin alpha (ProTalpha) to inhibit formation of apoptosome in the pancreatic acinar cells. Destroying this novel protein-protein interaction by silencing either gene expression accelerated H2O2-induced apoptosis in the cells. In the end, we applied GPX4 shRNA to silence GPX4 expression in chick embryo and confirmed the physiological relevance of the GPX4 role and mechanism shown ex vivo and in the acinar cells. Altogether, our results indicated that GPX4 depletion in Se-deficient chicks acted as a major contributor to their development of NPA due to the lost binding of GPX4 to ProTalpha and its subsequent inhibition on the cytochrome c/caspase 9/caspase 3 cascade in the acinar cells. Our findings not only provide a novel molecular mechanism for explaining pathogenesis of NPA but also reveal a completely new cellular pathway in regulating apoptosis by selenoproteins.

Selenium Deficiency-Induced Pancreatic Pathology Is Associated with Oxidative Stress and Energy Metabolism Disequilibrium

Selenium (Se) is an essential micronutrient that plays a crucial role in development and physiological processes. The present study aimed to investigate the effects of Se deficiency on pancreatic pathology and the potential mechanism in pigs. Twenty-four castrated male Yorkshire pigs were divided into two groups and fed a Se-deficient diet (0.007 mg Se/kg) or a Se-adequate diet (0.3 mg Se/kg) for 16 weeks. The serum concentrations of insulin and glucagon, Se concentration, histologic characteristics, apoptotic status, antioxidant activity, free radical content, and major metabolite concentrations were analyzed. The results showed that Se deficiency reduced the concentrations of insulin and glucagon in the serum and of Se in pancreas, decreased the number of islets and cells in the local islets, and induced pancreatic apoptosis. Se deficiency caused a redox imbalance, which led to an increase in the content of free radicals and decreased the activity of antioxidant enzymes. Of 147 targeted metabolites judged to be present in pancreas, only hypotaurine and D-glucuronic acid had differential concentrations with the false discovery rate < 0.05. Pathway analysis using metabolites with differential expression (unadjusted P < 0.05, fold change > 1.4 or < 0.67) found that 8 glycolytic metabolites were significantly increased by Se-deficient, whereas most of the tricarboxylic acid cycle and pentose phosphate pathway metabolites were not significantly changed. Our studies indicated that Se deficiency-induced pancreatic pathology was associated with oxidative stress and enhanced activity of glycolysis, which may provide gaining insight into the actions of Se as a diabetogenic factor.

Fishmeal replacement with Spirulina Platensis and Chlorella vulgaris in African catfish (Clarias gariepinus) diet: Effect on antioxidant enzyme activities and haematological parameters

This study explored fishmeal replacement with two freshwater microalgae: Spirulina Platensis and Chlorella vulgaris in African catfish (Clarias gariepinus) diet. The effect of inclusion of the two microalgae on biomarkers of oxidative stress, haematological parameters, enzyme activities and growth performance were investigated. The juvenile fish were given 3 distinct treatments with isonitrogenous (35.01-36.57%) and isoenergetic (417.24-422.27 Kcal 100 g^-1) diets containing 50% S. platensis (50SP), 75% S. platensis (75SP), 50% C. vulgaris (50CL), 75% C. vulgaris (75CL) and 100% fishmeal (100% FM) was used as the control diet. The result shows that all the diets substituted with both S. platensis, and C. vulgaris boosted the growth performance based on specific growth rate (SGR) and body weight gain (BDWG) when compared with the control diet. The feed conversion ratio (FCR) and protein efficiency ratio (PER) was significantly influenced by all the supplementations. The haematological analysis of the fish shows a significant increase in the value of red and white blood cells upon supplementation with 50SP and 50CL but decrease slightly when increased to 75SP and 75CL. Furthermore, the value of haematocrit and haemoglobin also increased upon supplementation with 50SP and 50CL but decrease slightly when increased to 75SP and 75CL. The white blood cell (WBC), red blood cell (RBC) increased, while total cholesterol (TCL), and Plasma glucose levels decreased significantly upon supplementation of algae. This is a clear indication that S. platensis and C. vulgaris are a promising replacement for fishmeal, which is a source protein in the C. gariepinus diet.

Nutritional requirements of meat-type and egg-type ducks: what do we know?

The demand for duck meat, duck eggs, and associated products is increasing each year. Classic and modern selection programs have been applied to enhance the economic traits of ducks to satisfy the requirements of consumers and enhance the incomes of producers. The nutritional requirements of unselected ducks may not be adequate, however, to fulfill the potential productivity performance of modern birds, including both meat-type and egg-type ducks. In particular, an imbalanced diet is associated with low productive performance and signs of nutritional deficiency (if insufficient nutrients are supplied), as well as with high feed costs and manure problems that reflect flock health and welfare (if excessive nutrients are supplied). Thus, the main aim of this review is to summarize the results of previous studies that estimated the nutrient requirements of meat-type and egg-type ducks in order to evaluate current knowledge and to identify further issues that need to be addressed. In addition, the results obtained in previous studies are compared in order to understand how to lower commercial feed costs, fulfill the genetic potential of selected ducks, protect the environment from pollution, and satisfy the welfare and health needs of ducks.

The Protective Effects of Different Sources of Maternal Selenium on Oxidative Stressed Chick Embryo Liver

The experiment was conducted to investigate the protective effects of different sources of maternal selenium (Se) on oxidative stressed chick embryo. A total of 270 Lingnan Yellow broiler breeders were randomly allocated into three treatments with five replicates for 18 birds each. Breeders were fed with basal diet (BD) including 0.04 mg/kg Se or BD supplemented with sodium selenite (SS) or selenomethionine (SM) at a level of 0.15 mg Se/kg. The rearing experiment lasted for 8 weeks after an 8-week pre-test. Twenty eggs were collected from each replicate during the last 10-day, then incubated in a commercial incubator. On embryonic 17th, fertile eggs were transferred into 39.5 °C temperature stimulation for 6 h. Afterward, five eggs were randomly selected from each replicate for collecting chick embryo sample. The results showed that Se supplementation in the diet of breeders resulted in lower reactive oxygen species (ROS), heat shock protein 70 (HSP70), malondialdehyde (MDA), carbonyl and 8-hydroxydeoxyguanosine (8-OHdG) concentrations and higher glutathione peroxidase (GPx), total superoxide dismutase (T-SOD), and catalase (CAT) activities in heat stress treated chick embryo (P < 0.05), and ROS, MDA, carbonyl, 8-OHdG concentrations in SM treatment were lower than those in SS treatment (P < 0.05). Se supplementation elevated cellular glutathione peroxidase (GPx1) mRNA level and activity, cytoplasmic thioredoxin reductase (TrxR1) activity and selenoprotein P (SelP) mRNA and protein level (P < 0.05), and maternal SM showed a higher value than maternal SS in upregulating GPx1, TrxR1, and SelP mRNA levels as well as GPx1 and TrxR1 activities or SelP protein level (P < 0.05). This study indicated that maternal Se can enhance antioxidative capacity and reduce ROS concentration and oxidative damage by upregulating the expression of antioxidative selenoprotein, and maternal SM is superior to SS in heat stress treated chick embryo.

Effects of transport stress and rest before slaughter on blood parameters and meat quality of ducks

Zhu, Z., Chen, Y., Huang, Z., Zhang, Y., Xu, Q., Tong, Y., Zhai, F., Chang, G. and Chen, G. 2014. Effects of transport stress and rest before slaughter on blood parameters and meat quality of ducks. Can. J. Anim. Sci. 94: 595–600. Ducks have been transported to be slaughtered at centralized locations since the 2013 avian influenza A (H7N9) epidemics in China. It is unavoidable that a certain amount of stress will occur during the transportation. We investigated the effects of transport stress and rest before slaughter on blood parameters and meat quality in ducks. Pekin ducks (42 d old) were randomly divided into six groups. Each group had five replicates, with four ducks in each replicate. The experimental design included the variables transport time and rest time before slaughter. Transport distance categories were short-distance (1 h transport; n=20), medium-distance (2 h transport; n=20) and long-distance (3 h transport; n=20) transport. Rest time was categorized as short (0.5 h; n=20) or long (2 h; n=20) periods of rest. Blood samples and meat samples were collected after transport or after the post-transport rest period. Blood indicators (triiodothyronine, thyroxine, insulin, glutamic-pyruvic transaminase, aspartate transaminase, creatine kinase, and glutathione peroxidase) were measured using enzyme-linked immunosorbent assay (ELISA) kits. Meat quality characteristics (meat component, pH, malondialdehyde, and protein carbonyl) were also measured. Triiodothyronine, thyroxine, aminotransferase, glutamic-oxaloacetic transaminase, creatine kinase, glutathione peroxidase, pH, malondialdehyde, and protein carbonyl values changed significantly in ducks exposed to the medium-distance transport treatment. Stress indicators improved and meat quality returned to normal by the end of a 2-h pre-slaughter rest. These results indicate that a 2-h transport causes serious stress in ducks. A 2-h rest before slaughter mitigates these adverse effects.

Tissue specific oxidative stress profile in relation to glycaemic regulation in mice

BACKGROUND

Diabetes mellitus is a metabolic disorder characterized by hyperglycaemia resulting from uncontrolled glucose regulation. Reactive oxygen species are recognized as one link between hyperglycaemia and diabetic complications. Studies have shown that diabetes mellitus is associated with decreases in antioxidant potential and increased formation of free radicals leading to oxidative stress. The present study was undertaken because an unequivocal demonstration that control of hyperglycaemia can reduce oxidative stress is still lacking.

METHODS

In the present study, we investigated oxidative stress profile of normal, streptozotocin-induced diabetic, insulin-treated and untreated diabetic animals. On the one hand, oxidative damage caused to lipids, proteins and DNA was measured. On other hand, antioxidant defense was measured in terms of specific activities of antioxidant enzymes (AOEs) and antioxidant molecules.

RESULTS

It was observed that the damage to lipids, proteins and DNA caused by free radicals increased in diabetic animals compared with that in controls. In diabetic animals not treated with insulin, damage to all biological molecules increased further significantly (p ≤ 0.005). Changes in AOEs from different tissues were complex depicting a varied AOE level in different tissues. Insulin treatment significantly improved the oxidative stress profile in all tissues studies.

CONCLUSIONS

The control of hyperglycaemia improves oxidative stress profile, that is, the ability of cells to cope up with oxidative stress.

Combined effects of muscular dystrophy, ecological stress, and selenium on blood antioxidant status in broiler chickens

The results obtained in this study demonstrated that experimentally induced alimentary muscular dystrophy (MD) in Cobb 500 broiler chickens resulted in increased plasma concentrations of malondialdehyde (MDA), deviations in activities of erythrocyte antioxidant enzymes Cu,Zn-SOD (decrease), and CAT (increase) as well as reduction in plasma concentrations of trace elements Cu, Zn, and Se in affected birds. These data evidenced the presence of oxidative stress in birds with MD, reared both under conditions of ecological comfort and ecological stress. The increased MDA and САТ levels and the reduced Cu,Zn-SOD, Cu, Zn, and Se concentrations in healthy chickens reared under unfavorable microclimatic conditions such as higher air temperature and humidity, higher ammonia concentrations, and lower light intensity were indicative about an induced ecological stress. After the 10-day oral treatment with a selenium-containing preparation, the levels of MDA, Cu,Zn-SOD, CAT, Cu, Zn, and Se attained their normal values in chickens with MD, reared under ecologically comfortable conditions. According to our results, ecological stress was shown to exert independently a significant adverse effect upon the levels of the studied parameters and possibly to be a cause for their slower and not complete normalization despite the selenium therapy in experimental broiler chickens.

Differential effects of sodium selenite and nano-Se on growth performance, tissue se distribution, and glutathione peroxidase activity of avian broiler

The present research evaluated differential effects of sodium selenite and nano-Se on growth performance, tissue Se distribution, and glutathione peroxidase (GSH-Px) activity of avian broiler. Broilers were randomly segregated into 12 groups so that three replicates were available for each of the three treatments (T-1, T-2, and T-3) and control groups. The control groups were fed basal diets without Se addition. T-1, T-2, and T-3 were fed with diets containing 0.2 mg kg(-1) sodium selenite, 0.2 mg kg(-1) nano-Se, and 0.5 mg kg(-1) nano-Se, respectively. Compared with the control, Se supplementation remarkably improved daily weight gain and survival rate and decreased feed conversion ratio (P < 0.05). However, no significant difference was observed between T-1, T-2, and T-3. The tissue Se content was significantly higher (P < 0.05) in Se-supplemented groups than the control, and T-3 showed the highest. Furthermore, higher Se content was observed in liver, and there was a significant difference (P < 0.05) compared with that in muscle. As for serum and hepatic GSH-Px activities, Se supplementation remarkably improved GSH-Px activity (P < 0.05), and there was no significant difference (P > 0.05) between treatments (T-1, T-2, and T-3).

Effect of selenium deficiency on the antioxidative status and muscle damage in growing turkeys

An experiment investigated the effect of different selenium supplementations on the antioxidant defence system and on the occurrence of muscle dystrophy in growing turkeys. Newly hatched male turkeys (B.U.T. Big 6) were divided into eight groups of 18 turkeys each and fed either a basal diet (selenium < 0.010 mg/kg diet), or the basal diet supplemented with 0.10; 0.15; 0.20; 0.25; 0.30; 0.35 or 0.40 mg selenium/kg diet in the form of sodium selenate. Vitamin E was adequately supplemented in all diets. After 35 days, muscle damage parameters including aspartate aminotransferase, creatine kinase, creatine kinase M and B were significantly increased in the selenium deficient Group I. A significant reduction of weight gain, feed consumption and selenium dependent glutathione peroxidase activity was also observed in the liver of selenium deficient birds. The ratio of oxidised glutathione (GSSG) to total glutathione (tGSH) was substantially altered in the selenium deficient Group I as well as in Group II (0.10 mg selenium/kg feed). The activity of glutathione reductase (GR) and glutathione-S-transferase (GST) was not affected by selenium deficiency.

Differential susceptibility of chick and mouse islets to streptozotocin and its co-relation with islet antioxidant status

Species differences in susceptibility of islets to STZ in different mammals have been well documented. Likewise, failure of diabetes induction in birds by streptozotocin has been reported. We hypothesized that the susceptibility of islets to STZ treatment may be related to generation of reactive oxygen species (ROS) and their antioxidant defense mechanisms. To test this hypothesis, we measured the total ROS generated and estimated the damage caused to the chick islets due to STZ treatment, in terms of lipid peroxidation, protein carbonyl formation and DNA strand breaks and compared it with that of mouse islets. We also compared the activities of antioxidant enzymes like catalase, superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR) and amount of antioxidant molecules like reduced glutathione (GSH) and uric acid under control and STZ-treated conditions. These studies coupled with viability, functionality and presence of glucose transporter GLUT2 in chick and mouse islets clearly indicated that STZ treatment neither affects viability nor functionality of chick islets whereas those of mouse islets are affected significantly. Here we demonstrate for the first time a correlation between the generation of ROS on STZ treatment and antioxidant status with insensitivity of chick islets to STZ resulting into failure of diabetes induction in chick.

Selenium distribution in eggs of avian species

We studied the effect of egg mass of eight different avian species on Se distribution between egg components and the effect of incubation on Se accumulation by chicken eggshell and shell membrane. Eight groups of birds received a diet without Se supplementation. Unfertile eggs were collected after 35 days of feeding; yolk, albumen, shell and shell membrane were assayed separately for Se. All avian species studied showed identical Se concentration in yolk-albumen complex equal to 38.7 microg Se/100 g, reflecting a linear correlation between yolk-albumen mass and Se content. Shells and shell membrane Se accumulation showed quadratic correlation with the appropriate mass thus explaining unusually high Se concentration in ostrich shell and shell membrane, that reached values 1785 and 1904 microg Se/kg respectively. Incubation of fertile eggs decreased eggshell Se content, the effect being more expressed in eggs from hens fed sodium selenite compared to organic Se utilization (Sel-Plex). It was concluded that shell might be an additional Se source for an embryo.

Lipid peroxidation and antioxidant defence status during larval development and metamorphosis of giant prawn, Macrobrachium rosenbergii

In the present communication we studied the involvement of reactive oxygen species and alteration in antioxidant defence status during larval development and metamorphosis of giant prawn, Macrobrachium rosenbergii. Overall results indicate that there was a decline in endogenous lipid peroxidation level during larval development. Activity of superoxide dismutase was the lowest in early larval stages (Zoea-I and II) and thereafter increased in V and VI stages, followed by a decrease in the subsequent larval stages. Catalase and glutathione peroxidase did not exhibit specific pattern of changes during development. Reduced glutathione content exhibited an incremental increase during larval progression until metamorphosis. Ascorbic acid content of the larval tissue remained unaltered during development but a sharp fall was marked in its content in the post-larvae. Hence it is concluded that early larvae face high oxidative stress as evident from the high content of thiobarbituric acid reactive substances. This may be due to direct exposure of larvae to ambient oxygen of the water as well as their low antioxidant potential. However, during development with the augmentation in antioxidant reserve of the larval tissues a diminution in the oxidative stress was recorded. Thus it is presumed that antioxidant defences play an important role in providing protection to the developing larvae from oxidative assault during larval progression and metamorphosis.