ISSN:
1573-5168
Keywords:
epithelial damage
;
fish
;
intestine
;
lipid digestibility
;
lipid droplets
;
lipid nutrition
;
lipoprotein synthesis
;
ultrastructure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Arctic char (Salvelinus alpinus L.) were fed over a three-week period with a commercial diet or one of seven casein-based diets. The latter were either lipid-free or supplemented with 50–200 g linseed oil kg−1 diet by dry weight, 160 g linseed oil and 40 g 14:0 or 160 g linseed oil and 40 g 16:0. Three fish having filled guts were sampled from each dietary group and analysed for ultrastructural changes in the pyloric caecum. Increasing the dietary lipid level increased the accumulation of lipid droplets in columnar absorptive enterocytes from about 9% of epithelial volume in fish fed a diet of 50 g linseed oil, to almost 61% in fish fed a diet of 200 g linseed oil. Replacing linseed oil in the diet with 14:0 (160 g linseed oil + 40 g 14:0 kg−1 diet) appeared to produce a smaller lipid loading (roughly 53%) but the difference was not statistically significant. However, replacing 40 g linseed oil with 40 g of 16:0 in the diet decreased lipid loading significantly to just under 10%. Epithelial damage to enterocytes was assessed using a ranking scale based on ultrastructural signs of cell and organelle swelling and degeneration. The extent of damage closely followed the level of lipid loading, being lowest in fish fed the lipid-free or low-lipid (damage index 0.07–0.13) diets, and highest in char maintained on a diet containing 200 g linseed oil (index 1.41). Replacing linseed oil with 14:0 (160 g linseed oil + 40 g 14:0) appeared to reduce the damage index to 0.77 but this was not significant. However, a significant reduction of the damage index to 0.27 was observed when linseed oil was replaced by 16:0. We conclude that higher dietary linseed oil promotes lipid droplet accumulation in enterocytes. The droplets are probably related to the amount of polyunsaturated fatty acids in the lipid. Intracellular droplet formation and cellular damage are both reduced by adding saturated fatty acids to the diet. This could be related to disruptions in the lipoprotein assembly rate. The cellular damages observed with high lipid diets are likely to be pathological and may lead to intestinal malfunction and represent a major infection route for pathogenic bacteria.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007879127182
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