Iron Dextran treatment does not induce serum protein carbonyls in the newborn pig

Authors: Caperna, Thomas; Shannon, Amy; Blomberg, Le Ann; Garrett, Wesley; Ramsay, Timothy

Submitted to: Cambridge University Press
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2011
Publication Date: 8/19/2011
Citation: Caperna, T.J., Shannon, A.E., Blomberg, L., Garrett, W.M., Ramsay, T.G. 2011. Iron Dextran treatment does not induce serum protein carbonyls in the newborn pig. Cambridge University Press: Animal. 6(1):79-86.

Interpretive Summary: Oxidation of serum proteins leads to addition of carbonyl molecules to the proteins which alters their function and has long been associated with stress-related disease processes. This process is initiated by the presence of reactive oxygen radicals and is enhanced by the presence of trace metals, especially iron. Because all piglets born in modern production facilities receive supplemental iron injections at birth in the form of iron dextran to prevent anemia, we were interested in determining whether treatment with recommended levels of iron would contribute to the formation of oxidized proteins. Protein carbonyls in serum, were chemically converted to colored compounds so that they could be quantified by spectrophotometry. To identify specific carbonylated proteins, serum protein carbonyls were chemically modified with biotin which could be separated by electrophoresis and visualized by staining with fluorescent stain. To identify individual proteins, stained spots were cut from the two dimensional gels and were analyzed by mass spectrometry. All of the major serum proteins were found to have some level of protein oxidation. The total quantity of oxidized proteins was not different when treated and untreated pigs were compared, even though circulating iron was elevated at least four fold. With few exceptions, the distribution of proteins which were oxidized, were also similar. Our data support the use of iron dextran for prevention of anemia in neonatal pigs and further show that the administration of iron does not lead to excessive oxidation of serum proteins.

Technical Abstract: Oxidation of serum proteins can lead to carbonyl formation which alters their function and is often associated with stress-related diseases. Since it is recommended that all pigs reared in modern production facilities be given supplemental iron at birth to prevent anemia, and metals can catalyze the carbonylation of proteins, the primary objective of this study was to determine if standard iron dextran treatment was associated with enhanced serum protein oxidation in newborn piglets. Piglets were treated with 100 mg of iron dextran intramuscularly either on the day of birth or on the third day after birth. Blood samples were collected from piglets 48 or 96 hr after treatment and serum was harvested. For quantification, serum protein carbonyls were converted to hydrazones with dinitrophenyl hydrazine and analyzed spectrophotometrically. To identify and determine relative distribution of carbonylated proteins, serum protein carbonyls were derivatized with biotin hydrazide, separated by 2D PAGE, stained with FITC-avidin and identified by mass spectrometry. The standard iron dextran treatment, was associated with no increase (P>.05) in total oxidized proteins if given either on the first or third day of life. In addition, with a few noted exceptions, the overall distribution and identification of oxidized proteins was similar between control and iron-dextran-treated pigs. These results indicate that while iron-dextran treatment is associated with a marked increase in circulating iron, it does not appear to specifically induce the oxidation of serum proteins.