+ Site Statistics
+ Search Articles
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ PDF Full Text
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn

+ Translate
+ Recently Requested

Effect of follicular fluid and inhibin immunoneutralization on FSH-induced preovulatory follicle growth in the ewe

Effect of follicular fluid and inhibin immunoneutralization on FSH-induced preovulatory follicle growth in the ewe

Journal of Endocrinology 131(3): 401-409

The potential direct ovarian effects of neutralization of inhibin, which increases, and follicular fluid treatment, which inhibits, follicle development in normal ewes was investigated in a sheep model in which endogenous FSH and LH secretion was suppressed thus removing any potential effects of treatment-induced alterations in endogenous FSH or LH secretion. Eighteen Welsh Mountain ewes were treated with two agonist implants containing 3.3 mg buserelin giving a total of 6.6 mg buserelin per animal. During week 5 of treatment all ewes were given a 72-h continuous infusion of ovine FSH (5 micrograms/h) starting it 09.00 h. Six ewes were treated with antiserum to the 1-26 alpha peptide fragment of porcine inhibin 0 h and 24 h after the start of the FSH infusion, and a further six ewes were treated with charcoal-stripped ovine follicular fluid (oFF) as a source of inhibin, at 09.00 and 17.00 h throughout the 72 h of FSH infusion. The plasma concentrations of both FSH and LH were significantly reduced in all ewes after 5 weeks of treatment with buserelin, and no large follicles > 2.5 mm in diameter were present. Treatment with inhibin antiserum or oFF had no effect, compared with control ewes, on the plasma concentrations of either FSH or LH during the FSH infusion period. After 72h of FSH infusion there was no difference in the number of small follicles (< 2.5 mm in diameter) or large follicles (> 2.5 mm in diameter) or the size of the largest follicles between control ewes and ewes treated with either inhibin antiserum or oFF. However, large oestrogenic follicles from ewes treated with oFF secreted significantly (P < 0.01) more testosterone in vitro and had a significantly (P < 0.01) higher follicular fluid concentration of testosterone than both control ewes and ewes treated with inhibin antiserum. These results show that the effects of inhibin immunization in increasing follicle growth and oFF in inhibiting follicle growth in normal sheep are not related to a direct effect of these treatments on the ovary, but are mediated by the effects of treatment on the plasma concentrations of FSH. The effect of oFF in increasing thecal androgen production suggests an increase in thecal sensitivity to LH. In the sheep model used in the present study, pulsatile LH secretion was abolished and large follicles were induced to develop under the influence of FSH in the presence of only basal concentrations of LH. The results suggest a potential interaction between oFF components and pulsatile LH secretion in modulating FSH-induced preovulatory follicle growth through an alteration in thecal sensitivity to LH.

(PDF emailed within 0-6 h: $19.90)

Accession: 002082535

Download citation: RISBibTeXText

PMID: 1783887

DOI: 10.1677/joe.0.1310401

Related references

Immunoneutralization of transforming growth factor alpha present in bovine follicular fluid prevents the suppression of the follicle-stimulating hormone-induced production of estradiol by bovine granulosa cells cultured in vitro. Biology of Reproduction 57(2): 341-346, 1997

Impairment in follicle-stimulating hormone secretion by different treatments with follicular fluid as a source of inhibin blocks the ability of pulsatile luteinizing hormone to induce preovulatory surges of gonadotropins in prepubertal ewe lambs. Biology of Reproduction 54(2): 387-393, 1996

Human preovulatory follicular fluid: inhibin and free steroids related to optimal follicular maturation in ovarian stimulation regimes and possible function in ovulation. Human Reproduction 7(6): 765-769, 1992

Correlation of human follicular fluid inhibin activity with spontaneous and induced follicle maturation. Journal of Clinical Endocrinology and Metabolism 58(4): 704-709, 1984

Immunoneutralization of inhibin in cycling rats increases follicle-stimulating hormone secretion, stimulates the ovary and attenuates progesterone receptor-dependent preovulatory luteinizing hormone secretion. Neuroendocrinology 91(4): 291-301, 2010

Effect of fshp on day 1 on the estrous cycle on follicle number and concentrations of inhibin in follicular fluid in heifers. Theriogenology 36(6): 1049-1058, 1991

Effect of dominant follicle persistence on follicular fluid oestradiol and inhibin and on oocyte maturation in heifers. Journal of Reproduction and Fertility 116(2): 293-304, 2000

Effect of FSHp on day 1 of the estrous cycle on follicle number and concentrations of inhibin in follicular fluid in heifers. Theriogenology 36(6): 1049-1057, 1991

Effect of follicular atresia on inhibin production by bovine granulosa cells in vitro and inhibin concentrations in the follicular fluid. Journal of Reproduction and Fertility 72(1): 1-8, 1984

Effect of acute immunoneutralization of inhibin in ewes during the late luteal phase of the oestrous cycle on ovarian hormone secretion and follicular development during the subsequent follicular phase. Journal of Reproduction and Fertility 104(2): 337-345, 1995

Follicular fluid levels of inhibin A, inhibin B, and activin A levels reflect changes in follicle size but are not independent markers of the oocyte's ability to fertilize. Fertility and Sterility 85(6): 1723-1729, 2006

Increase of follicle cell LH binding and changes in the level of follicular fluid during the preovulatory period in the sow. Annales de Biologie Animale, Biochimie, Biophysique 19(6): 1655-1667, 1979

Recovery of follicular fluid and oocytes of mares by non surgical puncture of the preovulatory follicle. Theriogenology 25(1): 178, 1986

Effect of inhibin like substance isolated from porcine follicular fluid on the follicle stimulating hormone level in mouse serum and on follicle stimulating hormone binding to porcine granulosa cells. Fertility & Sterility 34(1): 55-57, 1980

Origin of the preovulatory follicle in Mouflon sheep (Ovis gmelini musimon) and effect on growth of remaining follicles during the follicular phase of oestrous cycle. Animal Reproduction Science 65(3/4): 265-272, 2001