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E-GEOD-41735 - To elucidate the role of estradiol- 17β (E2) in the regulation of corpus luteum function
Released on 23 October 2012, last updated on 29 October 2012
Corpus luteum (CL) is a transient endocrine tissue formed from the remnants of the ovarian follicle after ovulation. In response to gonadotropin surge, the ovulating follicle undergoes dramatic changes in expression of genes and differentiation of follicular cells into luteal cells. In several species, of the several genes that are down- regulated post ovulation, Cyp19A1 that codes for aromatase, essential for biosynthesis of estradiol- 17β (E2), also get down- regulated but appears to get up- regulated at later time points in the estrous cycle to have critical role in E2 secretion. In primates and rodents, higher expression and higher E2 levels has been observed in CL. Surprisingly, in the recently carried out gene expression profiling of PGF2α- induced luteolysis studies in the bovine species [GSE27961], it was observed that expression of one of the earliest genes that was down- regulated was Cyp19A1 in the CL. However, the specific role of E2 in the regulation of CL function remains poorly defined. Thus, in the present study, efforts were made to examine the temporal changes in the global gene expression profile in the CL of pregnant rats after treatment with aromatase inhibitor (AI), Anastrozole, and E2 supplementation. The results obtained will further expand our knowledge on E2 target/responsive genes and the basic mechanism(s) that regulates the CL function. Key words: CL, E2, AI, Gene expression The objective of this study was to identify the effect of E2 deprivation and supplementation on CL function and temporal changes in the transcriptome of pregnant rat CL during day 12 to 16 of pregnancy following E2 deprivation by Anastrozole (AI, Aromatase inhibitor) treatment in pregnant rats, AI (1mg/ kg bw orally) treatment beginning on day 12 daily for 4 days. In the E2 supplementation experiments, together with AI, the rats were treated with E2 (10µg/ day s.c.). CL tissues were collected on day 12 (no treatment; n=3 animals/ time point), day 16 (vehicle treatment; n=3 animals/ time point), day 16 (AI treatment; n=3 animals/ time point) and day 16 (AI+ E2 treatment; n=3 animals/ time point) to examine gene expression changes associated with E2 deprivation and recovery in the system. Following retrieval of CL from the ovary, corpora lutea were flash frozen in liquid nitrogen and stored at -70oC for the purpose of RNA isolation. The isolated RNA was labelled and hybridized to Affymetrix GeneChip® Rat Gene 1.0 ST arrays as per the manufacturer’s instructions.
transcription profiling by array
SUDESHNA TRIPATHY <email@example.com>, R Medhamurthy, S Tripathy