Development of a fish cell culture model to investigate the impact of fish oil replacement on lipid peroxidation.

ABSTRACT

Fish oils are rich in omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA), predominantly 205n-3 and 226n-3, whereas vegetable oils contain abundant C(18)-PUFA, predominantly 183n-3 or 182n-6. We hypothesized that replacement of fish oils with vegetable oils would increase the oxidative stability of fish lipids. Here we have used the long established and easily cultivated FHM cell line derived from the freshwater fish species fathead minnow (Pimephales promelas) to test this hypothesis. The FHM cells were readily able to synthesize 205n-3 and 246n-3 from 183n-3 but 226n-3 synthesis was negligible. Also, they were readily able to synthesize 203n-6 from 182n-6 but 204n-6 synthesis was negligible. Mitochondrial ß-oxidation was greatest for 183n-3 and 205n-3 and the rates for 160, 182n-6, 226n-3 and 181n-9 were significantly lower. Fatty acid incorporation was predominantly into phospholipids (79-97%) with very little incorporation into neutral lipids. Increasing the fatty acid concentration in the growth medium substantially increased the concentrations of 183n-3 and 182n-6 in the cell phospholipids but this was not the case for 205n-3 or 226n-3. When they were subjected to oxidative stress, the FHM cells supplemented with either 205n-3 or 226n-3 (as compared with 183n-3 or saturated fatty acids) exhibited significantly higher levels of thiobarbituric reactive substances (TBARS) indicating higher levels of lipid peroxidation. The results are discussed in relation to the effects of fatty acid unsaturation on the oxidative stability of cellular lipids and the implications for sustainable aquaculture.