www.elsevier.de/jtemb Journal of Trace Elements Trace Elements in Medicine and Biology Journal of Trace Elements in Medicine and Biology 18 (2004) 89–97 SELENIUM SPECIAL Effects of selenium deficiency on fatty acid metabolism in rats fed fish oil-enriched diets $ Klaus Sch . afer a, * , Antonios Kyriakopoulos b , Hildegard Gessner b , Tilman Grune c , Dietrich Behne b a Institute of Animal Nutrition, Freie Universit . at Berlin, Berlin, Germany b Department Molecular Trace Element Research in the Life Sciences, Hahn-Meitner-Institut Berlin, Berlin, Germany c Department of Physical Medicine and Rehabilitation, Humboldt Universit . at Berlin, Berlin, Germany Received 15 September 2003; accepted 16 March 2004 Abstract The hepatic fatty acid metabolism was investigated in rats stressed by selenium deficiency and enhanced fish oil intake. Changes in the composition of lipids, peroxides, and fatty acids were studied in the liver of rats fed either a Se- deficient (8 mg Se/kg) or a Se-adequate (300 mg Se/kg) diet, both rich in n-3 fatty acid-containing fish oil (100 g/kg diet) and vitamin E (146mg alpha-tocopherol/kg diet). The two diets were identical except for their Se content. Se deficiency led to a decrease in hair coat density and quality as well as to changes in liver lipids, individual lipid fractions and phospholipid fatty acid composition of the liver. The low Se status did reduce total and reduced glutathione in the liver but did not affect the hepatic malondialdehyde level. In liver phospholipids (PL), Se deficiency significantly reduced levels of palmitic acid [16:0], fatty acids of the n-3 series such as DHA [22:6 n-3], and other long-chain polyunsaturates C-20–C-22, but increased n-6 fatty acids such as linoleic acid (LA) [18:2 n-6]. Thus, the conversion of LA to arachidonic acid was reduced and the ratio of n-6/n-3 fatty acids was increased. As in liver PL, an increase in the n-6/n- 3 ratio was also observed in the mucosal total fatty acids of the small intestine. These results suggest that in rats with adequate vitamin E and enhanced fish oil intake, Se deficiency affects the lipid concentration and fatty acid composition in the liver. The changes may be related to the decreased levels of selenoenzymes with antioxidative functions. Possible effects of Se on absorption, storage and desaturation of fatty acids were also discussed. r 2004 Elsevier GmbH. All rights reserved. Keywords: Selenium; Fish oil; Lipid metabolism; Phospholipid fatty acid composition; Oxidative stress Introduction Previous results from animal studies indicated that the n-3 fatty acids abundant in fish oil are essential for normal growth and development [1] and recent human studies suggested that they might have beneficial effects on human health [2,3]. Polyunsaturated fatty acids (PUFA) such as arachidonic acid (AA, 20:4 n-6), eicosapentaenoic acid (EPA, 20:5 n-3), and docosahex- aenoic acid (DHA, 22:6 n-3) are vital components of phospholipids (PL) in the membrane. The C-20 carbon ARTICLE IN PRESS $ Parts of the study were presented at the 1st International FESTEM Symposium on Trace Elements and Minerals in Medicine and Biology 2001, May 16–19, Venice, Italy. Sch . afer K, Behne D, Kyriakopoulos A, Gessner H, Grune T—Effect of selenium on antioxidant defense and phospholipid fatty acid metabolism in rats fed diets enriched with fish oil. *Corresponding author. Tel.: +49-30-8385-3302; fax: +49-30-8385- 5938. E-mail address: ksch@zedat.fu-berlin.de (K. Sch . afer). 0946-672X/$-see front matter r 2004 Elsevier GmbH. All rights reserved. doi:10.1016/j.jtemb.2004.03.003