Affiliations: Department of Animal Science, Cornell University, Ithaca, NY 14853, USA | Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
Note: [] To whom correspondence should be addressed: Department of Animal Science, 252 Morrison Hall, Cornell University, Ithaca, NY 14853, USA. Tel.: 607 254 4703; Fax: 607 255 9829; E‐mail: XL20@ cornell.edu.
Abstract: This study was to determine whether or not effects of the cellular glutathione peroxidase (GPX1) knockout on several Se‐dependent parameters in mice were tissue, dietary Se concentration, and selenoprotein specific. A 2\times3 factorial experiment was conducted with 18 GPX1 knockout mice [GPX1(-)] and 18 controls (3 weeks old, half males and females). These mice were fed a torula yeast diet supplemented with all‐rac‐\alpha ‐tocopheryl acetate (50 mg/kg of feed) and Se (sodium selenite) at 0, 0.5, or 3.0 mg/kg of feed for 6 weeks. Both kidney GPX1 mRNA levels and liver, kidney, lung, and testis total GPX activities, assayed using hydrogen peroxide, were affected (p< 0.001) by the GPX1 knockout and dietary Se concentrations, whereas kidney extracellular or plasma GPX (GPX3) mRNA levels and phospholipid hydroperoxide GPX (GPX4) activities in the four tissues were affected (p< 0.001) by only dietary Se concentrations. Total GPX activity in testis was reduced approximately 90% (p< 0.01) by the GPX1 knockout. Neither the GPX1 knockout nor the dietary Se concentrations affected mRNA levels of GPX4 in testis or selenoprotein P in kidney. Total liver Se concentrations were not different between the GPX1(-) and control mice at 0 mg Se/kg of feed, but were reduced (p< 0.01) by 61 and 64% in the GPX1(-) mice at 0.5 and 3.0 mg Se/kg of feed, respectively. These results not only confirm the independent expression of GPX3, GPX4, and selenoprotein P from that of GPX1, but also show similar effects of the GPX1 knockout on Se‐dependent parameters in mice between different dietary Se concentrations, tissues, and selenoproteins.
