Effects of varying dietary iodine supplementation levels as iodide or iodate on thyroid status as well as mRNA expression and enzyme activity of antioxidative enzymes in tissues of grower/finisher pigs.
OBJECTIVE
The objective of this study was to investigate the influence of high dietary iodine supply and different iodine sources on thyroid status and oxidative stress in target tissues of the thyroid hormones in fattening pigs.


METHODS
Eighty castrates (body weight: 33.3 ± 0.4 kg) were randomly allotted into five different treatments: The control diet contained 150 μg I/kg as KI, the other feeding groups were supplemented with 4,000 μg I/kg (as KI and KIO(3)) and 10,000 μg I/kg (as KI and KIO(3)), respectively. The mRNA expression levels of sodium/iodide symporter (NIS) and key antioxidant enzymes (Cu/Zn SOD, CAT, GPx) were analyzed in thyroid gland, liver, kidney, muscle, and adipose tissue sampled during slaughter. Furthermore, antioxidant enzyme activities and the effect on lipid peroxidation (MDA) were determined in liver and muscle.


RESULTS
In thyroid gland, a significant downregulation of NIS and Cu/Zn SOD mRNA expression was observed in high-iodine groups. In liver, a source effect on the mRNA expression of Cu/Zn SOD between KI and KIO(3) at 4,000 μg I/kg was shown. In contrast, not SOD but GPx activity was affected by iodine source with strongest downregulation in high KIO(3) group. In muscle, GPx activity was affected by both iodine source and dose, showing stronger downregulation in KI groups. In kidney and adipose tissue, oxidative stress parameters showed no or only unsystematic changes. However, variation in iodine supply had no effect on MDA concentrations.


CONCLUSIONS
NIS expression was significantly decreased with increased iodine supplementation, which is to ensure the thyroid gland function. However, the alleviating effect of iodine supplementation observed in antioxidant enzyme mRNA expression and activity did not reflect on the lipid peroxide level.
Institute of Animal Nutrition, Products, and Nutrition Physiology (APN), Department for Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Muthgasse 11, 1190, Vienna, Austria.
Qimeng
Q
Li
Christiane
C
Mair
Karl
K
Schedle
Isabella
I
Hellmayr
Wilhelm
W
Windisch
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001835:Body Weight; D019587:Dietary Supplements; D015536:Down-Regulation; D007452:Iodates / Q000008:administration & dosage*; D007454:Iodides / Q000008:administration & dosage*; D007455:Iodine / Q000008:administration & dosage*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008054:Lipid Peroxides / Q000032:analysis / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008315:Malondialdehyde / Q000032:analysis / Q000378:metabolism; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013552:Swine; D027981:Symporters / Q000235:genetics / Q000378:metabolism; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D013963:Thyroid Hormones / Q000378:metabolism; D000099209:Sodium-Iodide Symporters
D000975:Antioxidants; D007452:Iodates; D007454:Iodides; D007455:Iodine; D008054:Lipid Peroxides; D008315:Malondialdehyde; D012333:RNA, Messenger; D013482:Superoxide Dismutase; D027981:Symporters; D013963:Thyroid Hormones; D000099209:Sodium-Iodide Symporters