Circulating lipoproteins and tissue lipids: Effects of gemfibrozil on lipid metabolism in rainbow trout

Lipids support crucial functions in teleost fish, including the production of energy; lipoproteins support the movement of lipids through the vascular system. The objective of this thesis was to determine if gemfibrozil (GEM), a mammalian PPARalpha agonist pharmaceutical, could alter the circulating lipoproteins and tissue lipid metabolism in the rainbow trout, Oncorhynchus mykiss. Injections of GEM lowered the concentration of lipoproteins and changed their size distribution, lipid and fatty acid content. These changes were associated with an increased lipoprotein lipase transcript level but not activity. GEM increased liver size but did not affect its lipid content nor the activities or transcript levels of its PPARs and mitochondrial/peroxisomal enzymes. This thesis provides evidence that the pharmacological effects of GEM are conserved across vertebrates. Furthermore, the decreased plasma lipids and altered lipoprotein composition demonstrated here may be relevant sublethal indicators of exposure to PPARalpha agonists present in the aquatic environment