The relationship between uric acid and its oxidative product allantoin: a potential indicator for the evaluation of oxidative stress in birds (original) (raw)
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Allantoin, the oxidation product of uric acid is present in chicken and turkey plasma
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2003
Urate oxidase is not present in birds yet allantoin, a product of this enzyme, has been measured in birds. Studies were designed to compare the concentrations of plasma purine derivatives in chickens and turkeys fed inosine-supplemented diets. The first study consisted of 12 male chicks that were fed diets supplemented with 0.6 mol inosine or hypoxanthine per kilogram diet from 3-to 6-week-old. Study 2 consisted of 12 turkey poults (toms) fed inosine-supplemented diets (0.7 molykg) from 6-to 8-week-old. Plasma allantoin and oxypurines concentrations were measured weekly using high performance liquid chromatography. Plasma uric acid (PUA) in chickens fed inosine-supplemented diets increased from 0.31 to 1.34 mM (P-0.05) at the end of week 2. In turkeys, those fed control diet had 0.17 mM PUA concentration compared to 0.3 mM in those fed the inosine diet at week 2 (P-0.05). Allantoin concentration increased in chickens from week 1 to 2 while a decrease was observed in turkeys (P-0.005) for both treatments. These data show that allantoin is present in turkey and chicken plasma. The presence of allantoin in avian plasma is consistent with uric acid acting as an antioxidant in these species. ᮊ
Avian Pathology, 2002
To study the uricolytic properties of urate oxidase in granivorous and carnivorous birds, experiments were conducted in pigeons (Columba livia domestica) and Red-tailed Hawks (Buteo jamaicensis). Plasma concentrations of allantoin and uric acid were determined at various times in experimental groups before and after receiving 100, 200, and 600 U/kg urate oxidase once daily and were compared with controls. All regimens caused a significant decrease in plasma uric acid concentrations within 2 days after the first administration, when compared with controls. Furthermore, both doses used in Red-tailed Hawks (200 and 100 U/kg) caused a significant postprandial suppression of plasma uric acid concentrations. Plasma allantoin concentrations were significantly higher when compared with controls. The ability of urate oxidase to prevent the physiological postprandial hyperuricaemia in Redtailed Hawks and to reduce plasma uric acid concentrations to undetectable levels, shows the great potential of this drug for treating avian hyperuricaemia.
Comparison of Plasma Uric Acid Levels in Five Varieties of the Domestic Turkey, Meleagris gallopavo
Poultry Science, 2006
Plasma uric acid (PUA) is a consensus physiological biomarker for many phenotypes in vertebrates because it is a reliable indicator for processes such as oxidative stress and tubular function. In birds, it is considered a major antioxidant and is also the primary endproduct of nitrogen metabolism. Despite this importance, knowledge of baseline levels of PUA in physiologically normal birds, including the turkey, Meleagris gallopavo, is limited. Here, we compared PUA levels in a total of 106 apparently normal male and female birds at 8 and 32 wk of age from 5 strains of the domestic turkey, including Bourbon Red, Narragansett, Blue Slate, Royal
Oxidative stress, circulating antioxidants, and dietary preferences in songbirds
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2013
Oxidative stress is an unavoidable consequence of metabolism and increases during intensive exercise. This is especially problematic for migratory birds that metabolize fat to fuel long-distance flight. Birds can mitigate damage by increasing endogenous antioxidants (e.g. uric acid) or by consuming dietary antioxidants (e.g. tocopherol). During flight, birds may increase protein catabolism of lean tissue which may increase circulating uric acid and many birds also consume an antioxidant-rich frugivorous diet during autumn migration. We evaluated three related hypotheses in a migratory passerine: (1) protein consumption is positively related to circulating antioxidants, (2) a dietary oxidative stressor [i.e. polyunsaturated fatty acid (PUFA)] influences antioxidant capacity and oxidative damage, and (3) oxidative stress influences dietary antioxidant preferences. White-throated Sparrows (Zonotrichia albicollis) consuming a high protein diet increased circulating uric acid; however, uric acid, antioxidant capacity, and oxidative stress did not differ between birds consuming a high PUFA versus a low PUFA diet, despite increased oxidative damage in high PUFA birds. Birds did not prefer antioxidant-rich diets even when fed high PUFA, low protein. We conclude that White-throated Sparrows successfully mitigated oxidative damage associated with a high PUFA diet and mounted an endogenous antioxidant response independent of uric acid, other circulating antioxidants, and dietary antioxidants.
Science of The Total Environment, 1995
The aim of this study was to explore the influence of diet on the development of interspecific differences in the detoxication capacity of the mixed function oxidase (MFO) system (monooxygenase) among birds. The role of MFO activity in the detoxication/bioaccumulation of organochlorines (e.g., PCBs) was also investigated. Seven different species of birds were analysed: the yellow-legged herring gull (Larus cuchinnans), black-headed gull (Lanes ridibundw), jackdaw (Coruus monedula), magpie (Pica pica), cormorant, (Phalacrocorax carbo), coot (Fulica atru) and sparrow (Passer itaaliue). These species have different feeding habits ranging from omnivorous species like the yellow-legged herring gull to specialist and stenophagic species Like the cormorant. This preliminary study confirms the relationship between feeding habits and evolutionary interspecific differences in MFO activity.
Scientific Reports
The high metabolic activity associated with endurance flights and intense fuelling of migrant birds may produce large quantities of reactive oxygen species, which cause oxidative damage. Yet it remains unknown how long-lived birds prepare for oxidative challenges prior to extreme flights. We combined blood measurements of oxidative status and enzyme and fat metabolism in Hudsonian godwits (Limosa haemastica, a long-lived shorebird) before they embarked on non-stop flights longer than 10,000 km during their northbound migrations. We found that godwits increased total antioxidant capacity (TAC) and reduced oxidative damage (TBARS) as the pre-migratory season progressed, despite higher basal metabolic rates before departure. Elevations in plasma β-hydroxybutyrate and uric acid suggest that lipid and protein breakdown supports energetic requirements prior to migration. Significant associations between blood mitochondrial cytochrome-c oxidase and plasma TAC (negative) and TBARS (positive...
Chemico-Biological Interactions, 1990
Uric acid is an end-product of purine metabolism in Man, and has been suggested to act as an antioxidant in vivo. Products of attack upon uric acid by various oxidants were measured by high performance liquid chromatography. Hypochlorous acid rapidly oxidized uric acid, forming allantoin, oxonic/ oxaluric and parabanic acids, as well as several unidentified products. HOCI could oxidize all these products further. Hydrogen peroxide did not oxidize uric acid at detectable rates, although it rapidly oxidized oxonic acid and slowly oxidized allantoin and parabanic acids. Hydroxyl radicals generated by hypoxanthine/xanthine oxidase or Fe2+-EDTA/H202 systems also oxidized uric acid to allantoin, oxonic/oxaluric acid and traces of parabanic acid. Addition of ascorbic acid to the Fe2+-EDTA/H202 system did not increase formation of oxidation products from uric acid, possibly because ascorbic acid can 'repair' the radicals resulting from initial attack of hydroxyl radicals upon uric acid. Mixtures of methaemoglobin or metmyoglobin and H202 also oxidized uric acid: allantoin was the major product, but some parabanic and oxonic/oxaluric acids were also produced. Caeruloplasmin did not oxidize uric acid under physiological conditions, although simple copper (Cu 2÷) ions could, but this was prevented by albumin or histidine. The possibility of using oxidation products of uric acid, such as allantoin, as an index of oxidant generation in vivo in humans is discussed.
Oxidative damage and anti-oxidant capacity in two migratory bird species at a stop-over site
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2007
We quantified in the garden warbler (Sylvia borin) and the barn swallow (Hirundo rustica), two long-distance migratory songbirds, the early oxidative damage (ROMs) and plasma anti-oxidant capacity (OXY) variation of individuals caught at a stop-over site after a sustained flight across the sea, during spring migration. Our main goal was to quantify the oxidative damage and anti-oxidant capacity variation in these two migratory species in relation to fat and muscle stores. The birds were sampled in Ponza, a small island along the migratory route of these species. The levels of ROMs and OXY did not show any differences between the two species and in general were higher in individuals with higher fat and protein stores. Nevertheless, the balance between ROMs and OXY was better in individuals in good condition. These patterns were similar in both species. No sex differences emerged for both ROMs and OXY in the barn swallow, the only species that could be sexed. Both markers of oxidative stress did not show any significant variation across a 30-min restrained experiment. These data are the first of this kind in wild birds in a migratory context and suggest that individuals in better condition are exposed to lower oxidative stress, providing an indirect evidence of the oxidative cost caused by prolonged flights.