Ovarian response and FSH profile in cows following injection of various doses of inhibin antiserum
1997
Akagi, S. (Kyushu National Agricultural Experiment Station, Nishigoshi, Kumamoto (Japan)) | Kaneko, H. | Nakanishi, Y. | Takedomi, T. | Watanabe, G. | Taya, K.
Dose effect of inhibin antiserum on ovarian response and hormonal profiles were investigated. On day 12 of the estrous cycle (day 0=estrus), 14 of 19 cows were given a single i.v. injection of 25 ml(n=4), 37.6 ml(n=5) or50 ml(n=5) antiserum against inhibin produced in a castrated male goat. The other 5 animals were given 50 ml castrated male goat serum (control serum). The animals in each group received a single i.m. injection of 0.5 mg prostaglandin F2alpha analogue (PG) 48 hr following the serum injection. The population of follicles and ovulation rate (estimated by the number of corpora lutea) were examined by ultrasonography. Administration of inhibin antiserum consistently resulted in a significant (p0.01) increase in plasma concentration of follicle-stimulating hormone (FSH) in inhibin-neutralized groups, although the increased FSH levels were sustained longer in 50-ml group than in the 25- and 37.5-ml groups. Levels in the circulating inhibin antibody titer wee positively correlated with dosage of inhibin antiserum. A large number of antral follicles (- 4mm in diameter) developed similarly after hypersecretion of FSH in all neutralized groups, coupled with a rise in plasma estradiol levels, while the number of large follicles (- 10 mm n diameter) on estrus showed a dose-dependent increase. Multiple ovulation (2 to 4) was recorded in all animals after injection of 50 ml inhibin antiserum, however all cows in the 25-ml group experienced only one ovulation and injection of 37.5 ml resulted in a variable number of ovulations (1 to 5). These results demonstrated that administration of inhibin antiserum on day 12, followed by injection of PG, was able to induce hypersecretion of FSH and subsequently multiple ovulations
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