Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2073992 | Animal Reproduction Science | 2010 | 5 Pages |
Abstract
The mechanism for a reported temporal association between ovulation and a transient disruption in the periovulatory increase in LH concentrations was studied in nine mares treated with human chorionic gonadotropin when the preovulatory follicle was â¥32 mm. Examinations for ovulation detection and blood collection were done at 2-h intervals and the results were retrospectively centralized to ovulation (Hour 0). Concentrations of LH began to increase (P < 0.03) rapidly at Hour â18, decreased (P < 0.04) between Hours 0 and 6, and again increased (P < 0.0001) after Hour 12. A progressive decrease (P < 0.0001) in estradiol between Hours â30 and 24 was interrupted temporarily by an increase (P < 0.01) between Hours â2 and 0 and a decrease (P < 0.007) between Hours 0 and 2. Results indicated that a disruption and depression in the periovulatory LH surge occurred at the time of detected ovulation in mares and was temporally associated with a transient increase in estradiol during an overall progressive decline. The disruption in LH concentrations is attributable to the estradiol increase, based on a reported negative effect of estradiol on LH. The source of the circulating estradiol was likely from the discharge of estradiol-laden follicular fluid into the abdomen during ovulation and rapid absorption of estradiol into the circulation.
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Authors
O.J. Ginther, M. Almamun, A.K.M. Shahiduzzaman, M.A. Beg,