Estradiol and tamoxifen reverse ovariectomy-induced physical inactivity in mice.

UNLABELLED: Decreased physical activity and increased body mass are associated with estrogen deficiency. PURPOSE: To determine whether estrogen or the estrogen analog, tamoxifen, could reverse those detrimental effects after surgical ovariectomy in mice. METHODS: Ten-week-old C57BL/6 mice were sham operated (sham, N = 6) or ovariectomized (OVX, N = 9). After 4 wk of voluntary wheel running, placebo (OVX-P) or 17beta-estradiol (OVX-E2) pellets were implanted and the mice ran an additional 4 wk. A second study followed in which mice received placebo, 17beta-estradiol, or tamoxifen (OVX-Tam) simultaneously with ovariectomies. Distances run per 24 h and body masses were analyzed by two-way ANOVA with repeated measures. RESULTS: During the initial 4 wk, OVX mice ran approximately 80% less and had approximately 20% greater body masses compared with sham mice (P < 0.001). Estradiol replacement quickly reversed the inactivity as OVX-E2 mice increased their running from 1.9 +/- 0.3 km x 24 h(-1) to 6.9 +/- 0.7 km within a week of replacement, which was equivalent to shams (8.1 +/- 0.7 km), whereas OVX-P mice ran only 0.5 +/- 0.2 km (P < 0.01). OVX-E2 mice tended to maintain body mass after estradiol replacement, whereas the OVX-P mice continued to increase mass. OVX mice that received tamoxifen had high running activity, approximately 9 km x 24 h(-1), and maintained body mass. CONCLUSION: The removal of ovarian hormones caused mice to become inactive and gain body mass. Hormone therapy in the form of 17beta-estradiol or tamoxifen rapidly stimulated voluntary wheel running and reversed body mass gains, indicating that estrogen receptor binding was involved in regulating physical activity.

Detection of recombinant human erythropoietin in urine by isoelectric focusing.

BACKGROUND: Doping with erythropoietic proteins such as recombinant human erythropoietin (rHuEPO) and darbepoetin alfa is a serious issue in sport. There is little information on the time course of detection of rHuEPO in urine and on methods to evaluate electrophoresis-based data. METHODS: We used a recently described isoelectric focusing method for detecting rHuEPO and endogenous EPO in urine obtained from individuals treated with placebo or epoetin alfa. The latter was administered subcutaneously at 50 IU/kg on days 0, 2, 4, 7, 9, 11, 14, 16, and 18. Blood and urine samples were collected during the morning of study days -3, 0, 2, 4, 7, 9, 11, 14, 16, and 18 and on days 2, 3, 4, and 7 postadministration. We developed visual and numerical (two-band ratio) techniques to evaluate the electropherograms for the presence of rHuEPO. RESULTS: Compared with the placebo group, the epoetin alfa-treated group responded with increases in hematocrit, reticulocytes, macrocytes, serum EPO, and serum soluble transferrin receptor. The electropherograms showed that the pattern of bands arising from urinary rHuEPO is different from that of endogenous urinary EPO. Both the two-band ratio and the visual technique detected rHuEPO in all 14 epoetin alfa-treated individuals 3 days after the last dose. On the 7th day after the last dose, both techniques detected rHuEPO in approximately one-half of the participants. rHuEPO was not detected in the placebo-treated individuals. CONCLUSIONS: The isoelectric focusing method detects rHuEPO in most urine samples collected 3 days after nine doses of epoetin alfa. The numerical two-band ratio was equivalent to a visual method for detecting rHuEPO in urine.