Changes in fibroblast growth factor 9 mRNA in granulosa and theca cells during ovarian follicular growth in dairy cattle.
Fibroblast growth factor 9 (FGF9) has been suggested to act as an antidifferentiation factor in cattle by reducing steroidogenesis and increasing cell proliferation in granulosa (GC) and theca (TC) cells. The objective of this study was to characterize FGF9 mRNA abundance in GC and TC during development of dominant follicles in dairy cattle. Estrous cycles of nonlactating dairy cattle were synchronized, and ovaries were collected on either d 3 to 4 (n=8) or 5 to 6 (n=8) postovulation for GC and TC RNA extraction from small (1-5mm), medium (5.1-8mm), and large (8.1-18mm) follicles for PCR analysis. The FGF9 mRNA abundance was greater in GC than in TC. In GC, FGF9 mRNA abundance was greater in small, medium, and large estrogen-inactive [i.e., concentrations of estradiol (E2)<progesterone (P4)] follicles than in large E2-active (i.e., concentrations of E2>P4) follicles at both early (d 3-4) and late (d 5-6) growing phases of first dominant follicle. Abundance of FGF9 mRNA increased in medium-sized follicles from early to late growing phase of the dominant follicle. In TC, FGF9 mRNA abundance was greater in large E2-inactive follicles than in large E2-active follicles on d 3 to 4 postovulation; no significant differences in TC FGF9 mRNA existed among follicle types on d 5 to 6 postovulation. Correlations among levels of follicular fluid hormones and FGF9 mRNA levels revealed significant negative correlations between GC FGF9 mRNA abundance and follicular fluid E2 (r=-0.68), free IGF-1 (r=-0.63), and E2-to-P4 ratio (r=-0.58). In summary, abundance of FGF9 mRNA in GC and TC increases in medium-sized follicles during development of dominant follicles and is less in dominant E2-active than subordinate E2-inactive follicles, suggesting that FGF9 signaling could contribute to normal follicle development and steroidogenesis in dairy cattle.
Department of Animal Science, Oklahoma State University, Stillwater 74078.
L F
LF
Schütz
Department of Animal Science, Oklahoma State University, Stillwater 74078.
N B
NB
Schreiber
Department of Veterinary Clinical Sciences, Oklahoma State University, Stillwater 74078.
J N
JN
Gilliam
Università degli Studi di Milano, Department of Health, Animal Science and Food Safety, Via Celoria 10, 20133 Milan, Italy.
C
C
Cortinovis
Department of Animal Science, Oklahoma State University, Stillwater 74078.
M L
ML
Totty
Università degli Studi di Milano, Department of Health, Animal Science and Food Safety, Via Celoria 10, 20133 Milan, Italy.
F
F
Caloni
Department of Animal Science, Oklahoma State University, Stillwater 74078.
J R
JR
Evans
Department of Animal Science, Oklahoma State University, Stillwater 74078. Electronic address: leon.spicer@okstate.edu.
L J
LJ
Spicer
D000818:Animals; D002417:Cattle; D004958:Estradiol; D005260:Female; D051525:Fibroblast Growth Factor 9; D006107:Granulosa Cells / Q000378:metabolism; D006080:Ovarian Follicle / Q000737:chemistry; D011374:Progesterone; D012333:RNA, Messenger / Q000378:metabolism; D013799:Theca Cells
D051525:Fibroblast Growth Factor 9; D012333:RNA, Messenger; D011374:Progesterone; D004958:Estradiol
fibroblast growth factor-9 (FGF9); follicle growth; granulosa cell; theca cell