Effect of a synthetic gonadotropin-releasing hormone on plasma concentrations of luteinizing hormone in ponies
Ginther, O.J.; Wentworth, B.C.
American Journal of Veterinary Research 35(1): 79-81
1974
ISSN/ISBN: 0002-9645 PMID: 4588644 Document Number: 81601
Single injections (400 mu g) of a synthetic gonadotropin-releasing hormone were given intravenously to 4 pony mares during late anoestrus and intravenously or subcutaneously to 3 and 4 mares resp. on the 2nd day of oestrus. In anoestrous mares, plasma concentrations of LH in the 1st post-treatment sample (5 min) were significantly higher than the plasma values before treatment. The concentration increased gradually for 15 min after treatment and remained high (approx. twice the pre-treatment value) until 50 min after treatment. Beginning 1 h after treatment, the concentration gradually decreased, and at 2.5 h, the concentration was not significantly different from the pre-treatment value. In oestrous mares treated intravenously there was an apparent gradual increase in LH concentrations for the first 10-20 min, high values for approx. 2 h (approx. twice the pre-treatment value), and then a gradual decrease to a concentration at 3 h that was not significantly different from the pre-treatment value. In oestrous mares treated subcutaneously, the LH concentration was highest 1 h after treatment and decreased over the next 8 h. Treatment of oestrous mares did not significantly alter follicular development or time of ovulation.