Recent advances in ovulation synchronization and superovulation in ...

Abstracts. II International Symposium on Animal Biology of Reproduction, Nov. 19-22, 2008, São Paulo, SP, Brazil.
Dominant follicle growth is interrupted by intrafollicular injection of FGF10 in cattle
B.G. Gasperin 1 , M.T. Rovani 1 , R. Ferreira 1 , J.F.C. Oliveira 1 , J. Buratini Jr 2 , C.A. Price 3 , P.B.D. Gonçalves 1
1 Laboratory of Biotechnology and Animal Reproduction, Federal University of Santa Maria, RS, Brazil; 2 Department of
Physiology, Institute of Biosciences, Sao Paulo State University, Botucatu, SP, Brazil; 3 Centre de Recherche en Reproduction
Animale, Université de Montréal, Québec, Canada.
Introduction
Fibroblast growth factor 10 (FGF10) is expressed by oocytes and theca cells from bovine antral follicles, and its
expression is negatively correlated with estradiol levels in the follicular fluid (1). FGF10 receptor (FGFR2IIIB) is
expressed by mural and cumulus granulosa cells (1,2) and corpus luteum (3). When added to granulosa cells culture,
FGF10 decreases estradiol secretion (1) and expression of angiotensin II receptor type 2 (AT2; 4). Thus, the aim of
this study was to test the hypothesis that FGF10 acts as an inhibitor of dominant follicle development around
deviation in cattle.
Materials and Methods
Eighteen cows were submitted to a hormonal protocol in order to induce a new follicular wave. Ovaries were daily
monitored and when the largest follicle reached the diameter of 7-8 mm, it was injected PBS (Control group; n = 3)
or human recombinant FGF10 at 100 ng/mL (FGF100 group; n = 4) or at 1,000ng/mL (FGF1,000 group; n = 3). The
injected amount was calculated based on the volume of follicular fluid estimated by a linear regression equation (5),
to obtain an adequate final concentration inside the follicle. After the injections, animals were daily monitored by
ultrasound during three days to evaluate effects on the follicular dynamics.
Results and Discussion
The intrafollicular injection of FGF10 at 100 or 1,000ng/mL interrupted follicular growth compared to control group
(Fig. 1). FGF10 was shown to be downregulated in theca cells of healthy steroidogenic follicles and to decrease
estradiol production of cultured granulosa cells without affecting cell proliferation (1). Recently, our group
demonstrated that angiotensin II signaling is necessary for the continuation of follicular growth near follicle
deviation (6), and that the expression of AT2 receptors is inhibited by FGF10 in cultured granulosa cells (4). Taken
together, these results suggest that FGF10 acts as an important regulator of follicular growth in cattle. We propose
that FGF10 expression needs to be suppressed in order to allow the continuation of follicle growth after deviation.
FOLLICULAR SIZE (mm)
14,0
13,0
12,0
11,0
10,0
9,0
8,0
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6,0
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4,0
Day: p=0.1
Group: p