title: A low level of dietary selenium has both beneficial and toxic effects and is protective against Cd-toxicity in the least killifish Heterandria formosa.
abstract: As an essential element, selenium (Se) is beneficial at low levels yet toxic at high levels. The present study assessed the effects of dietary exposure to Se in the least killifish Heterandria formosa, and investigated how this exposure influences the effects of a subsequent exposure to cadmium (Cd). The fish were pre-exposed to an environmentally relevant concentration (2 μg g(-1) dry wt) of dietary selenite (Se(4+)) or seleno-l-methionine (Se-Met) for 10 d. The same fish were then exposed to 0.5 mg L(-1) of Cd for 5 d. Both Se(IV) and Se-Met rapidly accumulated in H. formosa. Results for the two Se species were generally similar in this study. Fish exposed to Se had lower levels of lipid peroxidation (measured as levels of thiobarbituric acid reactive substances or TBARS) and a higher catalase (CAT) activity. In contrast, their Na(+)/K(+)-ATPase activity was reduced. The Cd exposure resulted in an increase in lipid peroxidation and decreases in the activities of catalase and Na(+)/K(+)-ATPase. The Cd-exposed H. formosa that were pre-exposed to Se had lower Cd body burdens, less lipid peroxidation, and higher catalase activity, than did fish not pre-exposed to Se. The Se exposure did not have a protective effect on the Cd-induced reduction in Na(+)/K(+)-ATPase activity. These results clearly demonstrate that a Se-enriched diet reduces some (but not all) forms of Cd-toxicity and that Se can simultaneously have beneficial and detrimental effects, making it difficult to predict the net outcome of changes in dietary Se levels for fish.
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Liaoning 110016, PR China. Electronic address: xielt@iae.ac.cn.
authors.forename: Lingtian
authors.initials: L
authors.lastname: Xie
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Liaoning 110016, PR China.
authors.forename: Xing
authors.initials: X
authors.lastname: Wu
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Liaoning 110016, PR China.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Chen
authors.affiliation: Inner Mongolia University for the Nationalities, Tongliao 028000, PR China. Electronic address: dongwu2002@hotmail.com.
authors.forename: Wu
authors.initials: W
authors.lastname: Dong
authors.affiliation: Department of Biology, University of Louisiana at Lafayette, P. O. Box 43602, Lafayette, LA 70504-3602, USA.
authors.forename: Alfy Morales
authors.initials: AM
authors.lastname: Cazan
authors.affiliation: Department of Biology, University of Louisiana at Lafayette, P. O. Box 43602, Lafayette, LA 70504-3602, USA.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Klerks
mesh_terms: D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D002374:Catalase / Q000378:metabolism; D003532:Cyprinodontiformes / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D005260:Female; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D020011:Protective Agents / Q000494:pharmacology / Q000633:toxicity; D020887:Selenious Acid / Q000494:pharmacology / Q000633:toxicity; D012645:Selenomethionine / Q000494:pharmacology / Q000633:toxicity; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D020011:Protective Agents; D017392:Thiobarbituric Acid Reactive Substances; D002104:Cadmium; D012645:Selenomethionine; D002374:Catalase; D000254:Sodium-Potassium-Exchanging ATPase; D020887:Selenious Acid
keywords: Dietary selenite; Dietary seleno-l-methionine; Heterandria formosa; Lipid peroxidation; Se-Cd interaction