Progress 10/01/00 to 09/30/05
Outputs
Overall goals for this project were to examine development of follicles in postpartum dairy cows and/or in culture, and to assess the role of the FSH receptor in these processes. Techniques for collecting ovaries from cows, ewes and sows, aspirating oocytes and granulosa cells from follicles, methods of assessing health and/or developmental status of the follicles, and methods of measuring production of the FSH receptor have been developed and validated. Through the use of these techniques we have found that ovaries must be collected from slaughter facilities and processed for research within 2-4 hours if held at room temperature. In addition, results appear to confirm the idea that a growth factor type I form of the FSH receptor is involved in development of healthy follicles, while the G protein-coupled form of the FSH receptor is expressed throughout follicular development, although at a greatly reduced rate in atretic follicles. We also have preliminary evidence
that a dominant negative form of the FSH receptor may be involved in follicular atresia. Using immunohistochemistry, preliminary evidence indicates that expression of the growth factor type I form of the FSH receptor may be very low in bovine follicles. We have also found that FSH stimulates growth of tumorigenic mouse ovarian surface epithelial cells via a signal transduction pathway that involves Ca2+ influx and activation of the MAPK (mitogen-activated protein kinase) cascade.
Impacts
A cow that produces 100 pounds of milk per day (valued from $11-13/pound) that misses being rebred during the first two possible estrous cycles after parturition (a total of 42 days) may cost the producer a total of $462 to $546 in lost milk sales due to the delay in producing the next calf. Thus, a dairyman milking 500 cows could potentially lose up to $273,000 in milk sales if faced with this problem throughout the milking herd. Even missing a single estrous cycle postpartum (21 days total) could cost the hypothetical producer above as much as $136,500 on a whole-herd basis. A difficulty is that cows producing over 100 pounds of milk daily simply cannot consume enough nutrients to provide energy for milk production plus other processes such as reproduction. Therefore, an understanding of specific reproductive events such as oocyte maturation and development of follicles under these reduced energy conditions will allow researchers to develop better methods of estrus
induction/synchronization, as well as to allow the development of new hormonal or other interdictory strategies for enhancing fertility. In addition, our findings on tumor cells have potential implications for the therapy of ovarian cancer. Either the growth factor type FSH-R or the ion channel that mediates FSH-stimulated Ca2+ entry may represent an unexploited target for anticancer agents
Publications
- Li, Yong-Hai, Suhasini Ganta, Lisa Freeman. Follicle-stimulating hormone (FSH) stimulates proliferation of mouse ovarian surface eipithelial cells via a signaling pathway dependent upon Ca2+ influx. Society for the Study of Reproduction, 2005 Annual Meeting, Quebec City, Canada.
- Rozell, T.G., A.M. Monteiro, P.J. Baker and M. Mihm. Evidence for differential expression of FSH receptor exons 10 and 11 during follicular wave development in the cow. Society for the Study of Reproduction, 2005 Annual Meeting, Quebec City, Canada.
- Keller, A.E., D.M. Grieger, T.G. Rozell. 2004. Stage-specific expression of follicle stimulating hormone receptor variants during bovine folliculogenesis. Biol. Reprod. 70: (Suppl. 1), p. 160.
- McFee, R.M., R.M. Pohlmann, D.T. Clopton, R. Bott, T.G. Rozell and A.S. Cupp. 2004. Inhibition of VEGF Signal Transduction Arrests Vascular Development and Blocks Follicle Progression to the Pre-Antral Stage in Perinatal Rat Ovaries. Biol. Reprod. 70: (Suppl. 1), p. 160
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Progress 01/01/04 to 12/31/04
Outputs
Reproductive activity is a critical factor in the dairy producers ability to keep producing milk each year, and yet it is difficult to achieve good reproductive performance given the energy demands put on cows that are producing large amounts of milk. For this reason, a series of basic research studies have been designed to examine the effect of postpartum energy on the development of follicles in dairy cows. Follicle stimulating hormone (FSH) is known to play a critical role in this process, and new evidence indicates that the receptor for FSH may be altered at different times of the cycle or in response to reduced energy availability. In order to examine the role of the FSH receptor in postpartum fertility of dairy cows, several initial steps will have to be developed. Techniques for collecting ovaries from cows, aspirating oocytes and granulosa cells from follicles, methods of assessing health and/or developmental status of the follicles, and methods of measuring
production of the FSH receptor will first have to be developed and validated. Overall goals for this project are to examine development of follicles in postpartum dairy cows and/or in culture, and to assess the role of the FSH receptor in these processes. To date we have found that ovaries must be collected from slaughter facilities and processed for research within 2-4 hours if held at room temperature. We have also found that visual assessment of follicles can be done, and our methods were validated with progesterone assays of follicular fluid. In addition, results appear to confirm the idea that a growth factor type I form of the FSH receptor is involved in development of healthy follicles, while the G protein-coupled form of the FSH receptor is expressed throughout follicular development, although at a greatly reduced rate in atretic follicles. We are exploring the role of the growth factor type I FSH receptor in luteal formation We also have preliminary evidence that a dominant
negative form of the FSH receptor may be involved in follicular atresia. Using immunohistochemistry, preliminary evidence indicates that expression of the growth factor type I form of the FSH receptor may be very low in bovine follicles.
Impacts
A cow that produces 100 pounds of milk per day (valued from $11-13) that misses being rebred during the first two possible estrous cycles after parturition (a total of 42 days) may cost the producer a total of $462 to $546 in lost milk sales due to the delay in producing the next calf. Thus, a dairyman milking 500 cows could potentially lose up to $273,000 in milk sales if faced with this problem throughout the milking herd. Even missing a single estrous cycle postpartum (21 days total) could cost the hypothetical producer above as much as $136,500 on a whole-herd basis. A difficulty is that cows producing over 100 pounds of milk daily simply cannot consume enough nutrients to provide energy for milk production plus other processes such as reproduction. Therefore, an understanding of specific reproductive events such as oocyte maturation and development of follicles under these reduced energy conditions will allow researchers to develop better methods of estrus
induction/synchronization, as well as to allow the development of new hormonal or other interdictory strategies for enhancing fertility.
Publications
- von Stein F, Li Y, Mitchell KE, Freeman LC. (2004) PKA Inhibition of Granulosa Cell IKs Reflects the Absence of the AKAP Yotiao. Biophys J 86:130a.
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Progress 01/01/03 to 12/31/03
Outputs
Reproductive activity is a critical factor in the dairy producers ability to keep producing milk each year, and yet it is difficult to achieve good reproductive performance given the energy demands put on cows that are producing large amounts of milk. For this reason, a series of basic research studies have been designed to examine the effect of postpartum energy on the development of follicles in dairy cows. Follicle stimulating hormone (FSH) is known to play a critical role in this process, and new evidence indicates that the receptor for FSH may be altered at different times of the cycle or in response to reduced energy availability. In order to examine the role of the FSH receptor in postpartum fertility of dairy cows, several initial steps will have to be developed. Techniques for collecting ovaries from cows, aspirating oocytes and granulosa cells from follicles, methods of assessing health and/or developmental status of the follicles, and methods of measuring
production of the FSH receptor will first have to be developed and validated. Overall goals for this project are to examine development of follicles in postpartum dairy cows and/or in culture, and to assess the role of the FSH receptor in these processes. To date we have found that ovaries must be collected from slaughter facilities and processed for research within 2-4 hours if held at room temperature. We have also found that visual assessment of follicles can be done, and our methods were validated with progesterone assays of follicular fluid. In addition, results appear to confirm the idea that a growth factor type I form of the FSH receptor is involved in development of healthy follicles, while the G protein-coupled form of the FSH receptor is expressed throughout follicular development, although at a greatly reduced rate in atretic follicles. We also have preliminary evidence that a dominant negative form of the FSH receptor may be involved in follicular atresia. Using
immunohistochemistry, preliminary evidence indicates that expression of the growth factor type I form of the FSH receptor may be very low in bovine follicles.
Impacts
A cow that produces 100 pounds of milk per day (valued from $11-13) that misses being rebred during the first two possible estrous cycles after parturition (a total of 42 days) may cost the producer a total of $462 to $546 in lost milk sales due to the delay in producing the next calf. Thus, a dairyman milking 500 cows could potentially lose up to $273,000 in milk sales if faced with this problem throughout the milking herd. Even missing a single estrous cycle postpartum (21 days total) could cost the hypothetical producer above as much as $136,500 on a whole-herd basis. A difficulty is that cows producing over 100 pounds of milk daily simply cannot consume enough nutrients to provide energy for milk production plus other processes such as reproduction. Therefore, an understanding of specific reproductive events such as oocyte maturation and development of follicles under these reduced energy conditions will allow researchers to develop better methods of estrus
induction/synchronization, as well as to allow the development of new hormonal or other interdictory strategies for enhancing fertility.
Publications
- Craig, RA, S Ganta, DM Grieger, LC Freeman, and TG Rozell (2003). Alternative splicing of the follicle stimulating hormone receptor: Examination of the novel growth factor type I and dominant negative alternate transcripts in bovine and porcine ovaries. Dom. Anim. Endocrinol.
- Pohlmann RM, DT Clopton, RM McFee, TG Rozell and AS Cupp (2003). Inhibition of Vascular Endothelial Growth Factor (VEGF) Signaling Blocks Follicle Progression in the Perinatal Rat Ovary. (Abstract Submitted to American Society of Animal Science, Midwest Meeting.
- Keller, DM Grieger, and TG Rozell (2003). Bovine follicles express different variant forms of the FSH receptor at different stages of follicular development. Biol. Reprod. 68: (Suppl. 1), p. 503.
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Progress 01/01/02 to 12/31/02
Outputs
Progress to date has involved the development and validation of assays to evaluate oocyte quality and production of the FSHR. PCR, immunoblotting, and immunohistochemistry have been used to localize splice variants of the FSHR to follicles and CL of cow and sow. Preliminary data were presented at the Society for the Study of Reproduction; a manuscript is in preparation. Funding for this project was solicited as part of a larger coordinated series of experiments from the National Science Foundation; however, funding was not approved. The project is currently funded by the KSU Agricultural Experiment Station, and further funding will be solicited from the Kansas Dairy Association. Components of the study were integrated into Dr. Freeman's application for competitive renewal of a NIH R01.
Impacts
Long postpartum intervals in high producing dairy cattle may cost producers thousands of dollars annually. It is critically important to understand the basic physiological mechanisms during this important period of a cow's productive life. Cows producing over 100 pounds of milk daily simply cannot consume enough nutrients to provide energy for milk production plus other processes such as reproduction. Therefore, an understanding of specific reproductive events such as oocyte maturation and development of follicles under these reduced energy conditions will allow researchers to develop better methods of estrus induction/ synchronization, as well as to allow the development of new methodologies for supplementing reproductive activity with reproductive and/or metabolic hormones.
Publications
- Craig, R.A., D.M. Grieger, L.C. Freeman and T.G. Rozell. Alternative splicing of the follicle stimulating hormone receptor: examination of the novel growth factor type-1 and dominant negative alternate transcripts in the bovine and porcine overy. Biol. Reprod 66(S1):134 (Abstract 89), 2002.
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Progress 01/01/01 to 12/31/01
Outputs
Dairy cows producing large amounts of milk typically fail to re-breed after calving, in large part due to the commitment for large amounts of available energy into milk production. To better understand the underlying reasons whereby high producing cows fail to rebreed, a research project has been initiated to examine the physiology of the ovary in response to in vitro and/or in vivo conditions that simulate those in the postpartum cow. Specifically, the goal is to describe the growth and quality of follicles and their enclosed oocytes in response to low amounts of available energy. To achieve this goal, oocyte quality and the production of follicle stimulating hormone receptors (FSHR) will be examined within follicles in culture where the environment can be closely controlled, and also in ovaries from postpartum dairy cows. Additional goals are to gain a better understanding of the role of the FSHR and variant forms of this receptor in the growth and development of
follicles and the cells within. In order to meet these goals, research has been initiated in collaboration between the primary investigators listed above to examine basic cellular events associated with production of the FSHR and their link to energy status of the animal and/or culture conditions. Progress to date has involved the development and validation of assays to evaluate oocyte quality and production of the FSHR. In collaboration with Dr. David Grieger, an assay has been developed to allow the identification of the precise type of FSHR that is being produced under different conditions. Using this assay, our laboratories were the first to identify two functional variants of the FSHR produced within bovine follicles.
Impacts
Long postpartum intervals in high producing dairy cattle may cost producers thousands of dollars annually. A cow producing 100 pounds of milk per day that misses being rebred during the first two possible estrous cycles after parturition may cost the producer a total of $420 to $504 in lost milk sales due to the delay in producing the next calf. Cows producing over 100 pounds of milk daily simply cannot consume enough nutrients to provide energy for milk production plus other processes such as reproduction. Understanding specific reproductive events such as oocyte maturation and development of follicles under these reduced energy conditions will allow researchers to develop better methods of estrus induction/synchronization of new methodologies for supplementing reproductive activity.
Publications
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