Multifunctionality of antioxidant system in insects

Abstract

Amount of reactive oxygen species (ROS) produced in tissues of vertebrates is regulated by their elimination through coordinate action and level of enzymatic (SODs - superoxide dismutases, CAT-catalase, GSH-Px - glutathione peroxidase, GSTs - glutathione-S-transferases and GR - glutathione reductase) and non-enzymatic (glutahione, ascorbate and tocopherols) antioxidant (AO) components. Different from vertebrates, incest species lack selenium-dependent GSH-Px and posses active enzymatic ascorbate recycling pathway serving to eliminate hydrogen peroxide. Moreover, the sites of ROS generation in insect cells are compartmentalized and dislocated within the cells. Consequently, AO components are widely distributed at subcellular level. The mode of the regulation of AO components functioning in insects has been studied in diverse insect species employing different agents acting as inducers of oxidative stress, as well as during reproduction, development and ageing. The results reported so far showed that incest AO system is very flexible and dynamically organized. Besides, it has been demonstrated that this system operates not only to eliminate extensive ROS but also to recompose particular ROS which express direct physiological effects (e.g. hydrogen peroxide and nitric oxide) and to establish optimal redox state.