Antioxidant Systems in Poultry Biology: Superoxide Dismutase

Commercial poultry production is associated with various stresses responsible for decreasing productive and reproductive performance of growing chicks, breeders and commercial layers. A growing body of evidence shows that most of stresses in poultry production at the cellular level are associated with oxidative stress. Recently, a concept of the cellular antioxidant defense has been revised with special attention paid to cellular redox status maintenance and cell signaling. In fact, antioxidant systems of the living cell are based on three major levels of defense and superoxide dismutase (SOD) is shown to belong to the first level of the antioxidant defense network. Cellular antioxidant defenses are shown to include several options and vitagene activation in stress conditions is considered as a fundamental adaptive mechanism. The vitagene family includes various genes regulating synthesis of protective molecules including thioredoxins, sirtuins, heat shock proteins and SOD. However, by the time of writing no comprehensive review on the roles and effects of SOD in poultry biology has appeared. Therefore, the aim of this review is a critical analysis of the role of SOD in poultry biology with specific emphasis to its functions as an essential part of the vitagene network. From the analysis of the recent data related to SOD in poultry physiology and adaptation to stresses it is possible to conclude that: a) SOD as important vitagene is the main driving force in cell/body adaptation to various stress conditions. Indeed, in stress conditions additional synthesis of SOD is an adaptive mechanism to decrease ROS formation; b) If the stress is too high SOD activity is decreased and apoptosis is activated; c) there are tissue-specific differences in SOD expression which also depends on the strength of such stress-factors as heat, heavy metals, mycotoxins and other stressors; d) SOD is shown to provide an effective protection against lipid peroxidation in chicken embryonic tissues and semen; e) SOD is shown to be protective in heat and cold stress, toxicity stress as well as in other oxidative-stress related conditions in poultry production; f) there are complex interactions inside the antioxidant network of the cell/body to ensure an effective maintenance of homeostasis in stress conditions. Indeed, in many cases, nutritional antioxidants (vitamin E, selenium, carotenoids, phytochemicals, etc.) in the feed can increase SOD expression; g) nutritional means of SOD upregulation in stress conditions of poultry production and physiological and commercial consequences await further investigation; h) vitagene upregulation in stress conditions is emerging as an effective means for stress management.