Glutathione peroxidases in poultry biology: Part 2. Modulation of enzymatic activities

It is known that glutathione peroxidase (GSH-Px) belongs to the first and second levels of the antioxidant network and is involved in the regulation of many important cellular pathways including maintenance of the redox balance and signalling. In poultry the GSH-Px family includes four Se-dependent forms of the enzyme, however only GSH-Px1 and GSH-Px4 are well characterised and have received substantial attention as important enzymes participating in chicken adaptation to commercially-relevant stresses. The aim of this review is to analyse the current data on relationships between various stress conditions and the GSH-Px activity in poultry with special emphasis to selenium status and nutritional supplements. Indeed, the published literature indicates that there is a range of different nutritional (Se supplementation, antioxidants, plant extracts, probiotics, drugs, mycotoxins) and environmental (temperature stress, transportation, disease) factors modulating GSH-Px activity and/or expression in different tissues from poultry. These inducible enzymes are involved in adaptation to stress and Se supplementation in optimal concentrations whereby form is key for antioxidant system maintenance under stress conditions in commercial poultry production.