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Dietary pesticide chlorpyrifos-methyl affects arachidonic acid metabolism including phospholipid remodeling in Atlantic salmon (Salmo salar L.)

Sanden, M., Olsvik, P.A., Søfteland, L., Rasinger, J.D., Rosenlund, G., Garlito, B., Ibáñez, M., Berntssen, M.H.G.
Aquaculture 2018 v.484 pp. 1-12
Salmo salar, aquaculture feeds, arachidonic acid, bile, biotransformation, chlorpyrifos-methyl, cholinesterase, diet, dietary exposure, dose response, enzyme activity, fish, hematocrit, ingredients, lipid metabolism, liver, metabolites, palmitic acid, phospholipids, spleen
The pesticide chlorpyrifos-methyl (CLP-m) has been identified in plant ingredients intended for aquaculture feed production. To investigate systemic effects of CLP-m with emphasis on lipid metabolism, post-smolt Atlantic salmon were fed in duplicate (n=2) either diets with no CLP-m (Control) or CLP-m at different concentrations (0.1, 1.0 or 8.0mgkg−1) for a total of 67days (Low, Medium, High). Fish in all groups almost doubled their weight during the feeding trial from 262±26g (mean±SD) to 465±64g (overall mean), with no significant effects on any growth parameters. There was a significant dose-dependent inhibition of plasma cholinesterase activity (BuChE) after 67days. The CLP-m biotransformation metabolite, TCP was detected in liver and bile, with low levels of the parent compound in the organs. Spleen somatic index decreased significantly with increasing dietary CLP-m intake. Hematocrit (%) decreased linearly with increasing dietary exposure to CLP-m after 30days of exposure, but this decrease was less at 67days of exposure. A significantly reduced content of arachidonic acid (ARA 20:4n−6), accompanied by a significantly increased content of the saturated fatty acid, palmitic acid (PA 16:0), was observed in liver phospholipids (PLs) with increasing dietary content of CLP-m. Major effects were seen on the PL classes in liver which showed a significantly decreased absolute content, possibly indicating inhibition of PL remodeling pathways or other membrane perturbation effects from CLP-m exposure. In conclusion, this study shows that the pesticide CLP-m is a relatively potent toxicant in Atlantic salmon, especially affecting liver PLs and ARA metabolism.