Ovarian follicular growth and development in heifers during and subsequent to chronic treatment with a GnRH agonist

2013 ◽  
Vol 100 (3) ◽  
pp. S323
Author(s):  
D.P.A.F. Braga ◽  
H. Irving-Rodgers ◽  
P.S. Baruselli ◽  
W.J. Aspden ◽  
E. Borges ◽  
...  
2011 ◽  
Vol 85 (Suppl_1) ◽  
pp. 675-675
Author(s):  
Julia M. Baldrighi ◽  
Manoel Francisco Sa Filho ◽  
Pietro Sampaio Baruselli ◽  
Jose Antonio Visintin ◽  
Mayra Elena Ortiz D'Avila Assumpcao

1994 ◽  
Vol 74 (4) ◽  
pp. 649-656 ◽  
Author(s):  
A. C. O. Evans ◽  
N. C. Rawlings

We studied the effects of reducing gonadotrophin secretion on ovarian follicular development in young prepubertal heifer calves. Calves received a GnRH agonist (n = 5, 15 mg of Leuprolide acetate, i.m.) or carrier (n = 5) at 8 and 12 w of age. Starting at 8 and 34 w of age, ovarian follicles were monitored daily for 17 d, and at 10, 15, 25 and 35 w of age, blood samples were collected every 15 min for 12 h for measurement of serum concentration of LH and FSH. GnRH agonist treatment did not affect the age and body weight at puberty (P > 0.05). Agonist treatment suppressed follicle numbers and in two heifers follicle emergence (growth above 4–5 mm) was blocked immediately. In three agonist-treated heifers, follicle emergence was blocked after one extended wave of follicular growth. At 34 w of age the pattern of ovarian follicular growth did not differ between groups but oestradiol secretion was lower in agonist-treated heifers. During agonist treatment basal and mean concentrations of FSH, and LH and FSH pulse amplitude were decreased but basal LH concentrations increased (P < 0.05). At 25 and 35 w of age some rebound in gonadotrophin secretion was seen.We concluded that disrupting gonadotrophin secretion in young prepubertal heifer calves by GnRH agonist treatment, suppressed ovarian follicular growth but that a rebound in gonadotrophin secretion prevented long term-effects on sexual development. Key words: Follicle stimulating hormone, gonadotrophin-releasing hormone, heifer calves, luteinising hormone ovarian follicles


2013 ◽  
Vol 80 (9) ◽  
pp. 999-1005 ◽  
Author(s):  
M.J. D'Occhio ◽  
F. Cremonesi ◽  
T.E. Trigg ◽  
W.J. Aspden ◽  
P.S. Baruselli

2018 ◽  
Vol 106 ◽  
pp. 1-14 ◽  
Author(s):  
Emilia Sinderewicz ◽  
Katarzyna Grycmacher ◽  
Dorota Boruszewska ◽  
Ilona Kowalczyk-Zięba ◽  
Joanna Staszkiewicz ◽  
...  

Reproduction ◽  
2010 ◽  
Vol 140 (2) ◽  
pp. 295-303 ◽  
Author(s):  
Jennifer L Juengel ◽  
Lisa J Haydon ◽  
Brigitta Mester ◽  
Brian P Thomson ◽  
Michael Beaumont ◽  
...  

IGFs are known to be key regulators of ovarian follicular growth in eutherian mammals, but little is known regarding their role in marsupials. To better understand the potential role of IGFs in the regulation of follicular growth in marsupials, expression of mRNAs encoding IGF1, IGF2, IGF1R, IGF-binding protein 2 (IGFBP2), IGFBP4 and IGFBP5 was localized by in situ hybridization in developing ovarian follicles of the brushtail possum. In addition, the effects of IGF1 and IGF2 on granulosa cell function were tested in vitro. Both granulosa and theca cells synthesize IGF mRNAs, with the theca expressing IGF1 mRNA and granulosa cell expressing IGF2 mRNA. Oocytes and granulosa cells express IGF1R. Granulosa and theca cells expressed IGFBP mRNAs, although the pattern of expression differed between the BPs. IGFBP5 mRNA was differentially expressed as the follicles developed with granulosa cells of antral follicles no longer expressing IGFBP5 mRNA, suggesting an increased IGF bioavailability in the antral follicle. The IGFBP protease, PAPPA mRNA, was also expressed in granulosa cells of growing follicles. Both IGF1 and IGF2 stimulated thymidine incorporation but had no effect on progesterone production. Thus, IGF may be an important regulator of ovarian follicular development in marsupials as has been shown in eutherian mammals.


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