Antioxidant enzymatic defenses and oxidative damage in Dentex dentex fed ondifferent dietary macronutrient levels

摘要

A wide range of antioxidant mechanisms are present in fish maintaining an adequate "oxidative balance". Whenthis balance tilts in favor of the oxidant agents "oxidative stress" arises with detrimental effects in molecules ofgreat biological importance. Little has been reported about the influence of different dietary energy sources onantioxidant defenses in fish. The influence of different dietary macronutrient combinations on the key antioxidantenzyme activity, the oxidative damage to lipids and proteins and the possible modifications in the SODisoenzymatic pattern were evaluated in liver, white muscle, heart and erythrocytes of common dentex (Dentexdentex). Four experimental diets with different protein:lipid:carbohydrate ratios (43/16/28; 43/24/4; 38/19/28and 38/24/13) were formulated. In general, neither different dietary macronutrient levels nor the interactionamong them induces substantial modifications in enzymatic antioxidant defense mechanisms. Two constitutiveSOD isoforms, CuZn-SOD I and Mn-SOD, were detected in the tissues analyzed in all experimental groups,independently of diet formulation, but, a third SOD isoenzyme, CuZn-SOD II seems to be induced in white muscleby higher dietary protein levels. Densitometric analyses of western blotting membranes revealed higher CuZn-SOD expression in the heart of dentex fed on lower dietary protein levels, although these differences did notcorrelate with the SOD activity. Finally, a direct relation exists between the lipid or protein intake level andoccurrence of oxidative damage in different tissue components.