Estrogen status alters tissue distribution of oral dose of 75Se-selenite and enhances hepatic levels of SelP mRNA, GPx mRNA, GPx activity, and Se

Abstract

An association between male and female sex hormones and selenium (Se) status has been reported in animals and humans. These relationships may be important relative to the use of selenium in hormone related diseases such as breast cancer. The purpose of this study was to examine the effect of estrogen status on the tissue distribution of Se and mRNA levels of selenoprotein P (SelP) and glutathione peroxidase (GPx) in liver. 60 µCi of 75Se as selenite was orally administered to each bilaterally ovariectomized rat 5 weeks after implantation with either placebo pellet (OVX) or pellet with estradiol (OVX+E2). Blood and tissues were collected 1, 3, 6, and 24 h after dosing. Differences (P<0.05) in 75Se in blood, liver, heart, kidney, spleen, brain, and thymus were noted at certain times. Plasma SelP in OVX+E2 group contained a greater percentage of 75Se at 3, 6 and 24 h compared to OVX group (P<0.05); 75Se in plasma GPx also was greater in OVX+E2 compared to OVX group at 24 h (P<0.05). Real-time RT-PCR analysis showed that both hepatic SelP mRNA (0.93 vs. 0.50) and GPx mRNA (2.81 vs. 2.24) were significantly greater in OVX+E2 group than in OVX group. These results suggest that estrogen status affects distribution of ingested Se in tissue- and time-dependent manners, as well as the expression of hepatic SelP and GPx at both protein and mRNA level. (Supported by the OARDC Grant OHO00201).