Reactive oxygen species (ROS)-mediated regulation of muscle texture in grass carp fed with dietary oxidants

Natural oxidant faba beans (FB) improve the muscle textural quality of grass carp (Ctenopharyngodon idellus). This study further explored the role and spatiotemporal dynamics of ROS during the 120-day process of texture quality change in grass carp fed with four feeds including commercial feed, FB only, FB and antioxidants (vitamin C and vitamin E), and commercial feed and oxidant (vitamin K3). The results showed that ROS (total ROS, H2O2, ·O2− and ·OH) time-dependently accumulated from intestine to blood, liver and muscle, improving the muscle texture by day 90 in grass carp fed solely with FB. Dietary antioxidants supplementation almost completely abolished the effect. It is notable that the textural quality and level of total ROS in the commercial feed and oxidant group supplemented vitamin K3 were higher than those of other three groups by day 60 (p < 0.05), suggesting that oxidant supplementation effectively improved the muscle textural quality of grass carp. Also, there was a positive feedback between ROS accumulation and production mainly in the mitochondria of tested organs as demonstrated by measuring the activity of the elevated electron transport chain (ETC) pathway, openness degree of mitochondrial membrane permeability transition pore (MPTP), and mitochondrial membrane potential (Δψ). These results validated the regulatory role of ROS in the improvement of muscle texture in grass carp fed with the natural oxidants and also demonstrated that oxidant supplementations (vitamin K3, or/and FB) have the potential to be applied to aquafeed for the improvement of muscle textural quality in freshwater fishes.