CHANGES IN FIBROBLAST GROWTH FACTOR 9 (FGF9) mRNA IN GRANULOSA AND THECA CELLS OF DOMINANT AND SUBORDINATE FOLLICLES DURING THE FIRST OVARIAN FOLLICULAR WAVE IN CATTLE

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 561-585-Ovarian & Uterine Function II
Basic/Clinical
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-566
Luis F Schutz*, Morgan L Totty, Nicole B Schreiber, John N Gilliam, John R Evans, Jeffrey A Williams and Leon J Spicer
Oklahoma State University, Stillwater, OK
Fibroblast growth factor 9 (FGF9) has been detected in mammalian granulosa cells (GC), theca cells (TC) and stromal cells of ovaries. Treatment of bovine GC and TC with exogenous FGF9 down-regulated hormone-stimulated steroidogenesis and steroidogenic enzyme gene expression (1, 2). Whether endogenous production of FGF9 by ovarian follicular cells changes during follicular growth in monotocous mammals such as cattle and humans is unknown. This study was designed to characterize FGF9 gene expression in GC and TC during development of bovine dominant follicles. Estrous cycles of cattle were synchronized with two injections of prostaglandin F (11 days apart) and then cattle (n = 16) were ovariectomized on day 3 or day 6 post-ovulation during dominant follicle growth and selection, as assessed by rectal ultrasonography.  Ovaries were collected, follicular fluid (FFL) was aspirated, and GC and TC were collected for RNA isolation. Follicles were categorized as small (< 5 mm), medium (5-8 mm) or large (8-22 mm) in GC, and medium (5-8 mm) or large (8-17 mm) in TC.  Estradiol (E2) and progesterone (P4) levels were measured by radioimmunoassay in FFL of small, medium and large ovarian follicles. Quantitative RT-PCR results indicated greater (P < 0.05) FGF9 gene expression in TC (230 ± 45 relative abundance) than in GC (84 ± 39 relative abundance) regardless of follicle size.  FGF9 mRNA abundance in GC was greater (P < 0.05) in medium (169 ± 37 relative abundance, n = 78) than in large (39 ± 10 relative abundance, n = 36) follicles and was 8-fold greater in E2-inactive (FFL E2 < P4) versus E2-active (FFL E2 > P4) follicles.  Also in GC, FGF9 mRNA abundance increased (P < 0.05) in E2-inactive follicles from day 3 to 6 post-ovulation (i.e., during atresia of E2-inactive follicles) but did not change in E2-active follicles during the same period (i.e., during growth of E2-active follicles). In TC, FGF9 mRNA did not change (P > 0.10) between day 3 or 6 post-ovulation.  GC FGF9 mRNA abundance was negatively correlated (P < 0.01) with FFL E2 (r = -0.76) and E2/P4 ratio (r = -0.58) and positively correlated (P < 0.05) with P4 (r = 0.18). TC FGF9 mRNA abundance was negatively correlated (P < 0.05) with E2 (r = -0.26) and E2/P4 ratio (r = -0.24), but not significantly correlated with P4. Taken together, these results indicate that FGF9 may play a role in regulating atresia and steroidogenesis of bovine ovarian follicles.

(1) Schreiber NB and Spicer LJ, Endocrinology 2012; 153:4491-501.  (2) Schreiber NB et al., J Endocrinol 2012; 215:167-75.

Nothing to Disclose: LFS, MLT, NBS, JNG, JRE, JAW, LJS

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: (Supported by NIH Grant R15-HD-066302)