Evaluation of the gene expression changes induced by 17-alpha-ethynyl estradiol in the immature uterus/ovaries of the rat using high density oligonucleotide arrays.
BACKGROUND
In a previous study, we determined the effects of 17-alpha-ethynyl estradiol (EE) on gene expression using microarrays that represented approximately 9,000 genes, which was the state of-the-art. Higher content arrays with almost double the number of genes have since become available. In order to better determine whether common sets of gene expression changes can be predictive of estrogenic activity, we have replicated the previous experiment using the more comprehensive microarray.


METHODS
Immature 20-day-old Sprague-Dawley rats were exposed to 0.1, 1, and 10 microg EE/kg/day ( subcutaneously [s.c.]), for four days, dosing from postnatal day (PND) 20-23). Changes in a more comprehensive expression level of 15,923 rat annotated genes and expressed sequence tags were evaluated on PND 24.


RESULTS
By comparing the response of the treatment groups versus controls using various statistical parameters, we determined that the expression of 1,394 genes showed a significant change with respect to control (p< or =0.0001), to at least one of the EE dosages. The tissues from animals exposed to 0.1 microg EE/kg/day showed changes in the expression of only 33 genes, whereas when they were exposed to 1 or 10 microg EE/kg/day, the expression of 409 and 548 genes was modified, respectively. A dose-dependent analysis indicated that 592 genes showed a robust and significant response to EE exposure (increased or decreased). Our analysis confirmed the regulation of previously identified estrogen-sensitive genes, and clearly identified novel mediators of estrogen actions, both in the uterus as well as in the ovary.


CONCLUSIONS
This compendium of genes represents the largest compilation of estrogen-responsive genes that has ever been identified for the immature uterus and ovary of any species, and can be used to generate testable hypothesis to improve the understanding of the molecular pathways associated with physiological and pathophysiological responses to exposure to chemicals with estrogenic properties.
Naciff
Jorge M
JM
Miami Valley Innovation Center, The Procter and Gamble Company, Cincinnati, Ohio 45253-8707, USA. naciff.jm@pg.com
Torontali
Suzanne M
SM
Overmann
Gary I
GI
Carr
Gregory J
GJ
Tiesman
Jay P
JP
Daston
George P
GP
D000818:Animals; D001681:Biological Assay; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000633:toxicity*; D004997:Ethinyl Estradiol / Q000633:toxicity*; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D007279:Injections, Subcutaneous; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D010053:Ovary / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014599:Uterus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
D004967:Estrogens; D012333:RNA, Messenger; D004997:Ethinyl Estradiol