Effect of immunization with bovine follicular fluid (BFF) on gonadotropin levels and ovulation rate in the ewe
1999
Barbas, J.P. | Mascarenhas, R.
Follicular fluid is rich in inhibin, a glicoprotein hormone that is produced by granulosa cells of ovarian follicles and contributes to the regulation of FSH secretion and ovulation. The neutralization of endogenous inhibin causes an increase of the ovulation rate in ewes. Since the isolation of inhibin from the follicular fluid is a very complex process, the objective of this work was to evaluate the effects of ewe immunization with bovine follicular fluid (BFF) on FSH and LH levels and on the rate of ovulation. BFF was treated with activated charcoal-dextran (SIGMA) for the elimination of steroids and concentrate through ultra filtration in Centrifugal Ultrafree-20 units (MILLIPORE). Three immunizations were carried out at 14 or 28 day intervals with 2 or 4 mg of total protein per application. The presence of anti-follicular fluid circulating antibodies was detected in all animals by using the Outcherlony immunodifusion technique from the second immunization. No significant variations were observed in mean concentrations of plasma FSH (4.14 ñ 1.85 ng/ml in nontreated ewes and 4.18 ñ 1.38 ng/ml in treated ewes). Similarly, no significant variations were observed in the amplitude of the LH pre-ovulatory peak or during the time in which this peak occurs relatively to the end of progestagen treatment or to the beginning of oestrus. However, BFF treated ewes showed higher ovulation rates when compared to placebo treated animals (1.45 ñ 0.50 and 1.14 ñ 0.35). Results suggest that the increase of the ovulation rate after BFF immunization may lead to a neutralization of endogenous inhibin, but causes no significant changes in plasma gonadotropin levels, follicular development and maturation control
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