Transitional Gene Expression Profiling of Ovarian Follicle in Rats Treated with Indomethacin and RU486 (CBX258). unidentified

Background: Single dosage on the proestrus day of indomethacin (IM, dual inhibitor of cyclooxygenase 1 and 2) or RU486 (RU, progesterone receptor antagonist) can induce unruptured follicle (UF) in rats. However, the morphology of follicular epithelium is different, and those in IM-treated rats are close to normal corpus lutea, and those in RU-treated rats look like graafian follicle, i.e., theca cells and granulosa cells in IM-treated rats are larger than those in RU-treated rats, and the borderline between theca cell layer and granulosa cell layer is blurry in IM-treated rats, whereas it's distinct in RU-treated rats. In the previous study, we determined transitional gene expression profile of ovarian follicles in normal rats during ovulation. In the present study, we characterized the difference of gene expression profile between RU-treated and IM-treated rats. Materials and Methods: 21 female Crl:CD(SD) rats (8 weeks old) were used. Estrous phases of each animal was determined by vaginal smears for five consecutive days. RU (100 mg/kg) and IM (4 mg/kg) were orally administered at 10:00 and 15:00 on the proestrus day respectively, and ovaries were removed at 22:00 on the proestrus day and 10:00 on the estrus day, embedded in OCT compound and snapped frozen. Ovaries were also collected from untreated rats at 22:00 on the proestrus day, and 10:00 on the estrus day as a control. Each group consisted of three animals. Granulosa cell and theca cells of graafian follicle and peri-ovulatory follicle on the proestrus day, and post-ovulatory follicle were collected by Laser Micro Dissection technique, and total RNA was isolated from these follicles to be subjected to GeneChip (Affymetrix Rat 230.2.0 Array) analysis. Results and Discussion: Comparing transitional gene expression profiles of untreated rats with those of RU-treated and IM-treated rats, statistically significant changes of genes were identified. In IM-treated rats, genes for hyaluronan and proteoglycan link protein were down regulated, which may be related to insufficient follicle fluid production and seemed critical for rupture for follicles. In RU-treated rats, many genes involved in lipid metabolism and steroid synthesis were affected, which is thought to correspond to immaturity of follicular cells. In addition, down-regulation of endothelin-2 and a disintegrin and metalloproteinase with thrombospondin motif 1 and 9 are observed, which were known to be indispensable for ovulation. To analyze the difference of these profiles further, would make it possible to find genes or pathway which play important roles in the ovulatory impairment.