Includes bibliographical references (leaves 143-165) / xiii, 168 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Reports on studies undertaken to examine the physiological basis of the known ability of lupin grain to increase ovulation rate in the ewe. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, Waite Agricultural Research Institute, 1989

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Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains vi, 86 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 75-85).

Graduation date: 1991

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains vii, 68 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 46-68).

Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; vii, 71 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains vi, 84 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 76-83).

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains vi, 45 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 40-45).

Inadequate concentrations of progesterone during gestation can result in impaired embryonic growth and losses. These losses may be attributed to an overactive mechanism of progesterone catabolism or improper luteal function, which results in low concentration of progesterone. Progesterone catabolism occurs to the greatest extent by the liver, which holds a vast supply of cytochrome P450 enzymes and aldo-keto reductases that are involved in steroid inactivation. Insulin is a hormone produced by the pancreas that is involved in glucose uptake and metabolism. Progesterone catabolism is decreased in the presence of elevated insulin levels. Lipoic acid is a naturally occurring antioxidant and multienzyme cofactor which has been shown to increase insulin sensitivity and enhance glucose uptake in a number of species. The objectives of the current experiments were to 1) determine if administering a racemic mixture of lipoic acid by gavage at a dose of 32 mg/kg BW would increase peripheral progesterone concentrations, decrease progesterone clearance rates, or modulate cytochrome P450 2C (CYP2C), cytochrome P450 3A (CYP3A), or aldo-keto reductase 1 C (AKRIC) hepatic enzyme activity, and 2) determine if dosing lipoic acid directly into the rumen at 32 mg/kg BW or 64 mg/kg BW would increase progesterone in the blood, decrease progesterone clearance rates, or modulate insulin. In the first trial, Katahdin cross ovariectomized ewes were randomly assigned to a control or a lipoic acid treatment group. In this experiment, a controlled internal drug release (CIDR) device was inserted in all ewes and serum samples were collected daily for five days to determine progesterone. Liver biopsies were performed on day 10 to measure CYP2C, CYP3A, and AKRI C activity. Following liver biopsies, CIDRs were removed and an intensive blood sampling was performed to measure progesterone decay from peripheral circulation. We found that while lipoic acid does not have an effect on peripheral progesterone concentrations or hepatic enzyme activity, lipoic acid supplemented ewes have decreased progesterone clearance rates compared to control ewes. In the second trial, ovariectomized Katahdin cross ewes were randomly assigned to a control, low lipoic acid (32 mg/kg BW), or a high lipoic acid (64 mg/kg BW) treatment group. A CIDR was inserted in all ewes and blood samples were taken daily for 4 days. Following CIDR removal on day 11, an intensive blood sampling was performed to measure progesterone decay from peripheral circulation. One week following CIDR removal, ewes underwent an intravenous glucose tolerance test. It was found that lipoic acid supplementation did not affect progesterone concentrations, progesterone clearance, or insulin area under the curve. There was a treatment effect such that high lipoic acid dosed ewes had higher area under the curve for glucose when compared to control and low lipoic acid dosed ewes. Although no differences in progesterone concentrations were seen in the second trial, we speculate that the administration method rather than the efficacy of lipoic acid may account for the lack of differences observed. This theory is based on evidence from our first trial that oral lipoic acid supplementation did in fact reduce progesterone catabolism, as well as published data demonstrating that ruminally dosed lipoic acid is less effective than the equivalent oral dose.

The exact mechanisms controlling uterine secretion of prostaglandin F₂α (PGF₂α) are not known. This study (Experiments 1, 2 and 3) was conducted to evaluate the relationships of progesterone and estrogen to changes in 13,14-dihydro-15-keto-prostaglandin F₂α (PGFM) and PGF₂α in ewes. Experiment 1 was designed to determine whether a radioimmunoassay (RIA) for progesterone would detect pessary-released 6α-methyl-17α-hydroxy-progesterone (MPA; n=3) and oral 17α-acetoxy-6-methyl-16-methylene-4, 6-pregnadiene-3, 20 dione (MGA; n=3) in blood plasma of ovariectomized ewes. Neither progestogen treatment interfered with the RIA. Experiment 2 was conducted to answer the question: Do MPA-containing pessaries delay luteolysis in intact ewes? Ewes were treated with MPA containing (n=10) or blank pessaries (controls; n=8) from d 7 and until d 18 of the estrous cycle for control and until d 22 for MPA-treated ewes; d 0 was the day of estrus. Blood samples were collected from the jugular vein throughout the experiment. Pessaries containing MPA did not affect the timing of luteolysis (d 15.4 ± .2), but they prolonged (P<.O5) the interestrous interval (17.5 d for control vs 24.1 d for MPA-treated ewes). Experiment 3 was designed to study the relationships among progesterone, estrogen, PGFM and PGF₂α in ewes. Ewes were treated with MPA-containing (n=7; 60 mg), progesterone-containing (n=8i 45 mg) or blank pessaries (n=8) from d 7 until d 20 of the estrous cycle. From d 14 and continuing until 24 h after estrus, jugular and vena caval blood samples were collected during two sampling periods daily. Plasma was assayed for progesterone, estrogen, PGFM and PGF₂α. Treatment did not affect the profiles of change in concentration of progesterone, PGFM and jugular PGF₂α, but treatment affected (P < .05) estrogen and vena caval PGF₂α profiles. Overall, treatment affected (P < .05) the mean concentrations of estrogen, progesterone, PGFM and PGF₂α. sampling site (jugular vs. vena cava) affected (P < .0001) the mean concentration of progesterone, estrogen and PGF₂α, but site did not affect PGFM concentrations. Hormonal relationships associated with changes in release of PGF₂α were evaluated. Estrogen seemed to be the primary hormone controlling PGF₂α release. In conclusion, MPA treatment did not delay the timing of luteolysis, but it increased the interestrous interval. Of the compounds measured, estrogen accounted for the greatest proportion of the variation in PGF₂α release in ewes around the time of luteolysis. / Master of Science