Temporal and dose-dependent hepatic gene expression changes in immature ovariectomized mice following exposure to ethynyl estradiol.

D.R. Boverhof, K.C. Fertuck, L.D. Burgoon, J. E. Eckel, C. Gennings, T.R. Zacharewski

Abstract

Temporal- and dose-dependent changes in hepatic gene expression were examined in immature ovariectomized C57BL/6 mice gavaged with ethynyl estradiol (EE), an orally active estrogen. For temporal analysis, mice were gavaged every 24 hrs for 3 days with 100 µg/kg EE or vehicle and liver samples were collected at 2, 4, 8, 12, 24 and 72 hrs. Gene expression was monitored using custom cDNA microarrays containing 3067 genes/ESTs of which 393 exhibited a change at one or more time points. Functional gene annotation extracted from public databases associated temporal gene expression changes with growth and proliferation, cytoskeletal and extracellular matrix responses, microtubule based processes, oxidative metabolism and stress, and lipid metabolism and transport. In the dose-response study, hepatic samples were collected 24 hrs following treatment with 0, 0.1, 1, 10, 100 or 250 µg/kg EE. Thirty-nine of the 79 genes identified as differentially regulated at 24 hr in the time course study exhibited a dose response relationship with an average ED50 value of 47 ± 3.5 µg/kg. Comparative analysis indicated that many of the identified temporal and dose-dependent hepatic responses are similar to EE-induced uterine responses reported in the literature and in a companion study using the same animals. Results from these studies confirm that the liver is a highly estrogen responsive tissue that exhibits a number of common responses shared with the uterus as well as distinct estrogen mediated profiles. These data will further aid in the elucidation of the mechanisms of action of estrogens in the liver as well as in other classical and non-classical estrogen responsive tissues.

Supplementary Data

Time-course Dataset: Excel file (6.03MB) Text file (1.66MB)

Dose Response Dataset: Excel file (4.80MB) Text file (1.05MB)

Real-Time PCR Primers: Excel file (37.5KB) Text file (3.66KB)

Comparison of uterus and hepatic expression: Excel file (166KB) Text file (19.4KB)