Influence of resveratrol and resveratol enriched extracts on endogenous synthesis longchained omega-3-fatty acids - Studies in cell culture in vitro and in rainbow trout and seabass in aquaculture

• Applicants: Professor Dr. Gerald Rimbach; Professor Dr. Carsten Schulz
• Subject Area: Animal Breeding, Animal Nutrition, Animal Husbandry
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 251894753

Eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) belong to the long-chain polyunsaturated fatty acid family (LCPUFA) and exhibit significant health benefits in humans. Both fatty acids are centrally involved in the regulation of triglyceride levels, inflammatory processes and neuronal development. Fish is the major source for LCPUFA in human diets. Fish grown in aquaculture has to be supplemented with dietary LCPUFA to maintain fish health and product quality as conversion rates of dietary alpha-linolenic acid to EPA and DHA are poor both in freshwater fish species and especially in seawater fish species. Thus innovative strategies are needed to improve endogenous LCPUFA synthesis in aquaculture fish species. Delta6-desaturation seems to be the rate-limiting step in LCPUFA-synthesis. Delta6-desaturase converts alpha-linolenic acid into stearidonic acid which is further processed to EPA and DHA. We have identified the stilbene resveratrol as a potent inducer of delta6-desaturation in cultured hepatocytes. Resveratrol enhanced delta6-desaturase mRNA and protein levels as well EPA/DHA concentrations in hepatocytes in vitro. Within this grant proposal we aim to investigate the impact of resveratrol on LCPUFA metabolism in vivo. To this end rainbow trouts (fresh water) and sea bass (seawater) will be supplemented with resveratrol at varying water temperatures. We will measure delta6-desaturase, EPA/DHA levels and fatty acid composition in plasma, liver and filet in fish. Furthermore underlying molecular mechanisms by which resveratrol affects EPA and DHA synthesis will be examined in vitro in D11-trout hepatocytes. D11-cells will be treated with non-cytotoxic concentrations of resveratrol for the determination of fatty acid spectra and delta6-desaturase activities. Furthermore RNAi and electro mobility shift assays will be used to identify putative transcription factors (PPARalpha, STAT, HNF1, RXR, ER) involved in the resveratrol mediated induction of delta6-desaturase.

• DFG Programme: Research Grants