Characterization of antioxidant systems, oxidation status and lipids in brain of wild-caught size-class distributed Aristeus antennatus (Risso, 1816) Crustacea, Decapoda

The objectives of the study were to characterize the enzymic antioxidant system (free radical scavenging enzymes such as catalase, superoxide dismutase, glutathione peroxidases, glutathione transferase and glutathione reductase), dietary antioxidants (vitamin E), the oxidation status (malondialdehyde (MDA) levels and the fluorescence intensity of lipid-soluble fluorescent products (LSFP)) and lipid composition (lipid classes and polyunsaturated fatty acids (PUFA) as pro-oxidants) in neural tissues from males and females of wild-caught size-class distributed blue and red marine shrimp Aristeus antennatus (Risso, 1816), trawled off the south coast of Spain. Moreover, the mechanisms that may result in the deposition of age-pigments in relation to the physiological age of this species in its natural environment were investigated. Three different size classes were defined for males and four for females, and differences were observed for the different variables measured between sexes. The proportion of polar lipids (primarily phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine) predominated over that of neutral lipids, increasing significantly in males but decreasing in females. However, cerebrosides increased significantly from size–age class I to III in males but no significant differences were observed in females. The fatty acid composition showed increases in monounsaturated fatty acids (particularly 18:1 and 24:1 isomers) and dimethyl acetals, but decreases in PUFA (primarily 22:6(n-3)) with increasing size–age in both sexes. The concentration of MDA (nmol g⁻¹ brain) did not present any marked trend with size–age in both sexes. In contrast, fluorescence intensity showed increasing trends in both sexes with increasing size–age, when expressed as % fluorescence brain⁻¹ (λ_ex/em 350–445 nm and λ_ex/em 400–455). However, when expressed as % fluorescence mg⁻¹ brain total lipid, only males presented an upward trend with size–age (λ_ex/em 400–455). The concentration of vitamin E (ng mg⁻¹ brain) did not show significant differences between different size–age classes within the same sex and showed a molar ratio of one molecule of vitamin E per approximately 200 molecules of PUFA in brain membranes. The antioxidant enzyme activities showed clearer patterns with increasing size–age in males than in females, with catalase and glutathione transferase presenting downward trends and superoxide dismutase and total glutathione peroxidase showing upward trends. The fluorescence analysis of brain LSFP was not a useful tool to separate the population into different size–age classes, although the different patterns encountered between sexes for the variables measured points to males as better subjects for this type of study.