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1 April 2009 Necessity of Sequential Pulses of Prostaglandin F2alpha for Complete Physiologic Luteolysis in Cattle
O. J. Ginther, R. R. Araujo, M. P. Palhão, B. L. Rodrigues, M. A. Beg
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Abstract

The luteolytic effects of exogenous prostaglandin F2alpha (PGF) that did and did not simulate natural 13,14-dihydro-15-keto-PGF (PGFM) pulses were studied during mid-diestrus in 42 Holstein heifers. Plasma concentrations of PGF were assessed by assay of PGFM. In experiment 1, a single intrauterine injection of 4.0 mg of PGF into the uterine horn ipsilateral to the corpus luteum resulted in a precipitous progesterone decline, whereas sequential injections of 0.25 or 1.0 mg every 12 h resulted in a stepwise decrease (P < 0.05) following each injection. A progesterone increase occurred during the first 5 min before the luteolytic decrease but only for the 4.0-mg dose. From the results of experiment 2, a 2-h intrauterine infusion of a total of 0.5 mg of PGF was judged to best simulate a natural PGFM pulse. In experiment 3, simulation of sequential pulses at 12-h intervals resulted in a continuous precipitous decrease in progesterone to <1 ng/ml by the beginning of the fourth simulated pulse. In contrast, a single simulated pulse resulted in a 6-h progesterone decrease to a constant concentration for 3 days after treatment, followed by a return to control concentrations. The mean ± SEM interval between the pretreatment and posttreatment ovulations was shorter (P < 0.05) in the group with sequential simulated pulses (14 ± 1 day) than in the group with a single pulse (21 ± 1 day). Results indicated that excessive PGF doses may stimulate nonphysiologic progesterone responses and supported the hypothesis that sequential PGF pulses are required to stimulate natural luteolysis in cattle.

O. J. Ginther, R. R. Araujo, M. P. Palhão, B. L. Rodrigues, and M. A. Beg "Necessity of Sequential Pulses of Prostaglandin F2alpha for Complete Physiologic Luteolysis in Cattle," Biology of Reproduction 80(4), 641-648, (1 April 2009). https://doi.org/10.1095/biolreprod.108.072769
Received: 14 August 2008; Accepted: 1 December 2008; Published: 1 April 2009
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