Body growth, mitochondrial enzymatic capacities and aspects of the antioxidant system and redox balance under calorie restriction in young turbot (Scophthalmus maximus, L.)

Calorie restriction (CR) without undernutrition has been found to enhance stress resistance and life span in endotherms and ectotherms. We investigated the effect of 30% reduction in food offering on growth, aerobic capacities and oxidative stress parameters in young turbot (Scophthalmus maximus, L.). No differences in body weight, length and hepatosomatic index between the ad libitum (AL)-fed and the CR group occurred after 55 days of diet application. Of the mitochondrial marker enzymes, only citrate synthase (CS) activity in the liver was reduced under CR, whereas muscle CS activity and cytochrome oxidase (CCO) activity in both tissues remained the same in both feeding groups. The concentration of reduced glutathione increased significantly during feeding in muscle of CR fish, resulting in a more reduced glutathione redox ratio (GSH/GSSG) compared with AL fish muscle. Thiobarbituric acid-reactive lipid hydroperoxides (lipid peroxidation) but not protein carbonyl content (protein oxidation) was significantly reduced in CR fish muscle. Liver oxidative stress parameters did not vary significantly between experimental feeding groups. We conclude that 30% CR over 8 weeks has no adverse effect on young turbot. On the contrary, CR supports a reduced tissue oxidation state and reduces accumulation of lipid peroxidation products in muscle at sustained muscular aerobic capacity.