The effect of dietary antioxidants on lipofuscin accumulation in the crustacean brain

Lipofuscin accumulation is associated with ageing at the subcellular level. A strong correlation between lipofuscin and age has been found in crustaceans using histological techniques. This association has been proposed as the basis for a methodology to age crustaceans and in some cases lipofuscin levels were found to be better correlated with age than size. The experiment presented here was designed to test the potential effect of diet, in particular dietary antioxidants, on lipofuscin accumulation and age estimation.The shrimp, Penaeus japonicus, was reared in an aquaculture facility and fed commercial pellets with modified vitamins C and E contents. One group was fed with levels of vitamins C and E of 1000 and 150 mg/kg, respectively, and another group with 2500 and 5000 mg/kg, respectively. The experiment started when the shrimp were 19 weeks old. Samples were obtained at this point and at ages 33 and 43 weeks. Lipofuscin was measured in the nerve cords (antennal neuropils and oesophageal connectives) in an area adjacent to the brain.Dietary antioxidants significantly affected lipofuscin levels. High vitamin content in the diet resulted in lower percentage of the observed area covered with lipofuscin, lower lipofuscin granule density and lower average granule size. Gender had no effect on any of these variables and granule size did not significantly change within each treatment. Lipofuscin area and granule density increased with age in both vitamin treatments.These results suggest that age estimation using lipofuscin indices may be biased when: (1) wild populations are dispersed over diverse environments; (2) the age estimation of wild individuals is based on the results obtained using laboratory-reared individuals.