Effects of Contaminated Fish Oil on Hepatic FAS and HMGCR Gene Expression and Liver Function Enzyme Activities

Abstract

Concerns surrounding contamination with persistent organic pollutants (POPs) prompt caution in the consumption of fish and fish oil, despite their benefits on cardiovascular disease. The present study compared the effects of fish oil spiked with polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCs) to unmodified fish oil on hepatic gene expression of enzymes involved in lipid metabolism. Liver function enzyme levels were also examined. Thirty Sprague-Dawley rats were divided into three groups consuming a diet containing unmodified fish oil, fish oil spiked with POPs, or a control diet without fish oil. After 9 weeks of feeding, gene expression of fatty acid synthase (FAS) was significantly downregulated in both fish oil groups (P = 0.050) compared to control, while the unmodified fish oil group exhibited a tendency towards lower HMG-CoA reductase (HMGCR) transcription. This may explain the significantly lower levels of serum triglycerides in both fish oil groups (P = 0.002), while the unmodified fish oil group showed a tendency towards lower total cholesterol. Rats on the unmodified fish oil diet had significantly lower levels of lactate dehydrogenase (P = 0.040), while rats consuming diets with spiked fish oil exhibited significantly increased levels of alanine aminotransferase (P = 0.029). These findings point to differential genetic regulation from POP contamination and raise concerns surrounding liver damage during the consumption of spiked fish oils. Future studies should investigate the effects of a lengthened feeding time, varying contaminant doses, and interactions between contaminant mixtures and oils of varying composition. Supported by CHNR08-810, SDSU UGP and NUTR 302L class.