GnRH receptors during various stages of the estrous cycle of the mare, and effects of GnRH treatment on plasma concentrations of gonadotropins in the normally cycling mare and in the acyclic mare /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | In Experiment I, forty-eight normally cycling mares, ages 3 to 20 yr and with a condition score of five or higher were utilized to determine FSH and LH release in response to various treatments of GnRH. Twenty-four mares displaying estrus and with a follicle of 30 mm or greater were assigned in groups of three to receive a GnRH injection of 32, 63, 125, 250, 500, 750, 1000, or 2000 μg GnRH. Twenty-four mares in the luteal phase of the estrous cycle (d 8-11) were assigned in groups of three to receive a GnRH injection of 16, 32, 63, 125, 250, 500, 750, or 1000 μg GnRH. Pre-treatment mean concentrations, post-treatment maximum concentrations, durations of the FSH and LH response, and areas under the curve for FSH and LH were determined. Within treatment variation was apparent (P <.05) for mares in estrus, and we conclude that the response to GnRH of mares in estrus cannot be predicted. Diestrous mares responded consistently to all treatments, and we conclude that the diestrous mare is capable of responding to extremely low levels of GnRH stimulation. Six acyclic mares, ages 7 to 27 yr and with a condition score of five or higher were utilized in Experiment II to determine FSH and LH release to a single injection of 1 μg/kg BW GnRH. Results from this experiment indicated that this group of acyclic mares released FSH and LH in response to GnRH. Therefore, acyclicity in this group was not due to pituitary dysfunction. Sixteen mares were sacrificed in Experiment III for analyses of pituitary tissue. Receptor concentrations were similar for the d 3, d 7, and d 15 groups. The d 0 group was omitted, as the Scatchard analysis for this group did not fall on the equilibrium portion of the curve. Association constants were different across groups in this study, and we conclude that association constants, but not receptor concentrations, change throughout the estrous cycle of the mare. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Physiology of reproduction." |
| Physical Description: | xiv, 179 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |