Chapter 1: Antioxidant defence systems in animal health
In: Selenium in pig nutrition and healthDepartment of Hygiene and Poultry Sciences, Moscow State Academy of Veterinary Medicine and Biotechnology Named After K.I. Skryabin, 109472 Moscow, Russia.
Department of Microbiology and Biochemistry, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria.
Department of Animal Nutrition, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, 2103 Gödöllo, Hungary.
Saint-Petersburg State Academy of Veterinary Medicine, 196084 St. Petersburg, Russia.
Sumy National Agrarian University, 40000 Sumy, Ukraine.
Odessa National Academy of Food Technologies, 65039 Odessa, Ukraine.
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Redox (antioxidant-prooxidant) balance in the cell is an important determinant of various physiological functions. Indeed, oxidative stress occurs when this balance is disturbed due to overproduction of free radicals or compromised antioxidant defences. Free radical overproduction and oxidative stress are considered as a pathobiochemical mechanism involved in the initiation or progression phase of various diseases in farm animals, including pigs. Dietary antioxidants may be especially important in protecting against the development of the oxidative stress. The mechanisms by which natural antioxidants act at the molecular and cellular level include roles in gene expression and regulation, apoptosis, and signal transduction and antioxidants are involved in fundamental metabolic and homeostatic processes. Indeed, free radicals are now considered to take part in signal transduction in the cell and at least two well-defined transcription factors, NF-κB and Nrf2 have been identified to be regulated by the intracellular redox state. The regulation of gene expression by oxidants, antioxidants, and redox state has emerged as a novel subdiscipline in molecular biology that has promising implications for the feed industry and animal production. However, there are still many gaps in our knowledge of the basic molecular mechanisms of oxidative damage and antioxidant defences. Selenium in the form of SeCys is incorporated into 25 selenoproteins and more than half selenoproteins are involved in antioxidant defences and redox homeostasis maintenance being the ‘chief executive’ of the antioxidant defence network.