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KMID : 1094020140310010019
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Journal of Veterinary Clinics
2014 Volume.31 No. 1 p.19 ~ p.24
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Emergences of LH Surge Affected by Different Progesterone Levels in Ovariectomized Goats
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Kim Seung-Joon
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Abstract
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The purpose of the present study was to determine the priming effects of progesterone that affect theemergence of LH surge mode secretion by three different progesterone levels. In previous studies, we have shownthat LH surge occurred in follicular levels of progesterone, whereas there was no surge mode secretion of LH andFSH in either the subluteal or luteal levels of progesterone. In this study, the hypothesis was that the priming effectsof progesterone on the timing of the LH surge induced by exogenous estradiol are same between subluteal and luteallevels of progesterone. Long-term ovariectomized Shiba goats that had received implants of estradiol capsules (Day0) and three different progesterone silastic packet inducing follicular, subluteal and luteal levels of progesterone weredivided into three groups such as non-P, low-P and high-P group. Blood samples were collected daily throughout theexperiment for the analysis of gonadal steroid hormone levels. On Day 7, all devices of progesterone packets wereremoved but estradiol capsules were maintained during the experiment, and blood samples were collected at 1 hr intervalfor 12 h from the time of progesterone removals to determine peripheral changes of estradiol and progesteroneconcentration. Then all animals were infused estradiol on the Day 7 after 13 h from the removals of progesteronedevices with a peristaltic pump into jugular vein at a rate of 3 μg/h for 36 h. For analysis of peripheral LH and estradiolconcentration, blood samples were collected via another jugular vein at 2 h intervals for 52 h (from 4 h before thestart of estradiol infusion to 48 h after the start of estradiol infusion). In all animals of the three groups treated withestradiol infusion, an LH surge was expressed but the peak time of LH surge was different. This time interval fromestradiol infusion until the peak of LH surge was gradually and significantly extended by the different levels ofprogesterone treated before estradiol infusions in the three groups.
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KEYWORD
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luteinizing hormone surge, progesterone, ovariectomized goat
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