1995 — 2000 |
Wiltbank, Milo C |
R29Activity Code Description: Undocumented code - click on the grant title for more information. R55Activity Code Description: Undocumented code - click on the grant title for more information. |
Prostaglandin Receptor Regulation in the Corpus Luteum @ University of Wisconsin Madison
Prostaglandins (PG) have an essential role in regulating ovarian function including key aspects of ovulation, luteinization, and luteal regression. Despite this central role in reproductive physiology the temporal and cellular patterns of expression for the PG receptors, as well as the hormonal regulation of this expression, have not been defined. With the recent cloning of the cDNAs for the various subtypes of PGE and PGF/2alpha receptors, an analysis of both the protein and mRNA for these receptors is possible. We have validated highly sensitive and quantitative assays for the PGF/2alpha receptor mRNA and protein as well as the measuring PGF/2alpha responsiveness. The research proposed in this application is designed to evaluate the mechanisms involved in expression of the PGF/2alpha receptors and responsiveness during luteinization and luteolysis. Our working hypotheses for these studies is that the LH surge, or other aspects of the luteinization process, induce the expression of PGF/2alpha receptors and PG-responsive intracellular pathways, thus, establishing the cellular mechanisms for ovulation, luteinization, and regression of the corpus luteum. The Specific Aims are: 1) Characterize the temporal pattern for the in vivo expression of PGF/2alpha receptors during late follicular and early luteal development. 2) Determine the role of cAMP-dependent protein kinase, progesterone, and de novo protein synthesis in the differentiation of PGF/2alpha responsiveness in cultured follicular cells. 3) Determine whether small luteal cells can be induced by forskolin or hCG to express FP receptors, a property indicative of the large luteal cell phenotype. Determine the intracellular effector systems involved in PGF/2alpha-induced stimulation of mRNA for PGH synthase-2 and inhibition of mRNA for the PGF/2alpha receptor. 4) Determine the response of early and mid-cycle corpora lutea to PGF/2alpha in terms of down regulation of PGF/2alpha receptors, secretion of oxytocin, induction of mRNA for PGHS-2, and inhibition of expression of mRNA for 3beta-Hydroxysteroid Dehydrogenase. These studies will advance our knowledge of physiologic, intracellular, and molecular mechanisms regulating the expression of mRNA, protein, and intracellular response pathways for the PGF/2alpha receptor. This will not only advance our current knowledge of reproductive physiology, but will allow for the rational development of contraceptives or infertility treatments that target prostaglandin action in the ovary.
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2003 — 2004 |
Wiltbank, Milo C |
R03Activity Code Description: To provide research support specifically limited in time and amount for studies in categorical program areas. Small grants provide flexibility for initiating studies which are generally for preliminary short-term projects and are non-renewable. |
Altered Physiology Resulting in Large Follicular Cysts. @ University of Wisconsin Madison
DESCRIPTION (provided by applicant): The development of follicular cysts has been detected in numerous mammalian species, including humans, suggesting that this reproductive abnormality may be due to an underlying physiological pathway that is fairly ubiquitous in mammals. The research in this proposal focuses on the physiology that underlies the development of large follicular cysts. The cow has been chosen as the animal model for studies of this abnormality because follicular cysts are fairly common in this species and have been extensively described in previous research. In addition, the cow is a mono-ovulatory species and has been a useful animal model for understanding follicular development particularly because key follicular events (follicular selection, ovulation) occur at similar follicular diameters in humans and cows. The studies in this proposal test a working model based on previous scientific research, as well as our recent studies on the physiology that underlies the development of follicular cysts. This model predicts that during each estrous cycle, the normal estradiol surge induces a physiological condition that resembles the condition that results in follicular cysts. However, this "physiological lesion" is removed by the increase in circulating progesterone following ovulation. This model is very appealing because it provides a generalized physiological explanation for the development of large follicular cysts. It may also provide an explanation for the varied clinical, environmental, and experimental situations that result in the development of follicular cysts as well as provide a rationale basis for the treatment of this disorder. However, it is prudent to test whether this physiological model has experimental validity prior to extensive studies on the specific cellular and molecular mechanisms that underlie this disorder or extrapolation of this working model into species other than the cow. Therefore, we propose two specific objectives that will use the bovine animal model to test whether a normal endogenous estradiol surge will result in the postulated physiological condition. Specific Objective I. Determine whether follicular cysts will develop following an endogenous estradiol and GnRH surge if the LH surge is blocked with a GnRH antagonist. Specific Objective II. Determine whether follicular cysts will develop following an endogenous estradiol, GnRH, and LH surge if the freshly ovulated follicle (corpus hemmoragicum) is removed.
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2007 — 2010 |
Wiltbank, Milo C |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Defining the Mechanisms Involved in Luteolysis @ University of Wisconsin-Madison
DESCRIPTION (provided by applicant): The corpus luteum (CL) has a critical role in reproductive physiology due to secretion of progesterone, a hormonal requirement for pregnancy in mammals. However, if pregnancy does not occur, CL undergo an intriguing process termed luteolysis that is characterized by decreased progesterone production and death of cells in the CL. This research explores the in vivo mechanisms of luteolysis. The intracellular signaling pathways and gene expression cascades associated with protection or sensitization to luteolysis will be defined. First, an analysis will be done of the transcriptosome (steady state mRNA concentrations) in the CL using bovine microarray analysis of about 20,000 different mRNA transcripts. A more systematic analysis will also be performed of the changes in the transcriptosome that are induced by the hormone causing luteolysis, prostaglandin F2alpha (PGF), in CL that have the ability to undergo luteolysis in response to PGF (luteolytic capacity) or in CL without luteolytic capacity. Second, an in vivo model will be validated that produces CL with a large fluid-filled cavity allowing intraluteal treatments and monitoring. This model is central to our future studies of luteolysis because, despite considerable effort, no in vitro system has been developed that fully mimics in vivo luteolysis making it difficult to validly explore intracellular signal transduction during luteolysis. This in vivo model will be used to explore 2 key intracellular pathways that may be central to luteolytic sensitivity. Novel hypotheses will be explored on the role of constitutively active protein kinase A (PKA) in high constitutive progesterone production and the changes in PKA during luteolysis. We will also examine the luteal responses "protected" from PGF action by high intraluteal progesterone and the role of this pathway in luteolytic sensitivity. SPECIFIC OBJECTIVE 1: Characterize luteolysis-induced changes in the transcriptosome of the CL. This Objective will use bovine microarrays and differential display to determine the changes in mRNA that are induced by PGF in CL with and without luteolytic capacity at 2 times after PGF treatment (1 h and 10 h). SPECIFIC OBJECTIVE 2: Characterize an in vivo model for intraluteal treatment of bovine CL. SPECIFIC OBJECTIVE 3: Determine the roles of PKA in luteal function and luteolytic capacity. Studies will explore how PKA may be involved in high luteal progesterone and luteolytic capacity. SPECIFIC OBJECTIVE 4: Determine the role of intraluteal progesterone in luteolytic capacity. Completion of this research will validate a new in vivo model for luteolysis and provide insight into the interactions of specific gene expression cascades and signal transduction pathways during luteolysis.
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