Progress 10/01/00 to 09/30/04
Outputs
The incidence of embryonal mortality reduces reproductive performance, and costs Virginia producers approximately $1.2 million in potential income each year. The objectives of this project were to determine 1) factors regulated during of PGF induced luteal regression, 2) the effects of the ratio of PGE to PGF on embryonic development during early pregnancy, and 3) the effects of IFN on PGDH expression in endometrial cells. Exp. 1 was to determine the expression of IGFBP-1, ECE-1, and prostaglandin production in the caprine CL during luteolysis. Estrus was synchronized and corpora lutea were collected on d 10 at 1, 2, or 4 h after either saline (1 ml) or PGF (5 mg). Data from this experiment indicate that PGF stimulates ECE-1, luteal prostaglandin enzyme production (PGHS-2 and PGFS), and IGFBP-1 production in the caprine CL. Exp. 2 was designed because previous data indicated PGE increased ovine embryonic hatching rate, and PGF reduced development of rabbit, bovine, and
rat embryos. On d 6 following estrus, embryos were flushed and incubated individually in TCM-199 with HEPES and BSA for 6 d at 38 C in a 5% CO:air atmosphere with one of the following treatments: 1) control, 2) PGE (7 ng/mL), 3) PGF (7 ng/mL), 4) low PGE:high PGF (3.5:14 ng/mL), 5) balanced PGE:PGF (7:7 ng/mL), or 6) high PGE:low PGF (14:3.5 ng/mL). Treatment with PGE reduced hatching rate (1/17; 6%), while the hatching rate of embryos treated with PGF (9/18; 50%), low PGE:high PGF (8/16; 50%), and balanced PGE:PGF (11/18; 61%) were similar to control (6/18; 33%). In contrast, both development of morula to blastocysts and hatching rate were increased with high PGE:low PGF (6/6; 100% and 13/18; 72%, respectively). All other treatments did not affect development of morula to blastocysts. Exp. 3 was to determine the effect of the embryonic product, IFN, on endometrial cell expression of PGDH. Endometrial cells were collected from does on day 6 of the estrous cycle, and cultured at 38 C
in 5% CO:air on filter inserts with Matrigel in 24-well plates. After the initial 24 h period, cells were treated with no hormone, estradiol (P;10-8 M), progesterone (P; 10-8 M), or E+P. Additionally, cells were cultured with or without IFN (50 microM). IFN decreased the production of PGF, and the response was greater with the addition of estrogen. Expression of PGDH was not affected by IFN treatment. Our results indicate that increasing concentrations of PGF in the uterus during blastocoele formation and embryonic hatching is not detrimental to embryonic development. The embryo derived IFN will decrease PGF secretion, but this effect does not appear to be related to an upregulation of the PGF metabolizing enzyme, PGDH. An increase in PGF during pregnancy may initiate luteolysis, and reduce progesterone output by increasing production of endothelin-1 (ECE-1) and PGF (PGHS-2), and inhibiting IGF-I activity (IGFBP-1). Understanding the role of prostaglandins in early pregnancy may help
to understand the cause of early embryonal mortality.
Impacts
Embryonic mortality reduces the potential number of animals born by 20 to 40%, resulting a reduction of Virginia sheep and goat producer profit by approximately $1.2 million each year. The information generated from these studies on the processes involved in embryo development and uterine function is needed to develop the methods to reduce embryonic mortality and boost producer profit potentials
Publications
- Sayre, BL. 2004. Effects of prostaglandins E and F on early embryonic development in the goat. Small Rumin. Res. (submitted for review).
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Progress 01/01/03 to 12/31/03
Outputs
Luteal regression is initiated by prostaglandin (PG) F from the uterus. Maintenance of luteal function is necessary for continued embryonic development. An embryonic signal for maintenance of pregnancy is necessary by day 16 after mating. Interferon-tau (IFN-tau) is secreted by the caprine conceptus between days 15 and 18 of pregnancy. In the cow, the endometrium expresses high affinity receptors for IFN-tau, and IFN-tau binding acts to reduce PGF pulse amplitude. The antiluteolytic effects of IFN-tau are intrauterine, not systemic, and thus seem to be indirect. IFN-tau inhibits the action of estrogen on endometrial tissue. The rate-limiting step in metabolism of prostaglandins of the E and F series is catalyzed by 15-hydroxyprostaglandin dehydrogenase (PGDH). In the absence of PGDH, PGF remains biologically active. Estradiol appears to inhibit PGDH activity, while progesterone appears to increase activity. Embryonic production of INF-tau may inhibit estrogen receptor
and actions, and maintain pregnancy through the stimulation or prevention of the loss of endometrial PGDH activity. Endometrial cells have been collected from d6 of the estrous cycle of goats, isolated, and cultured. Established cell cultures were treated with saline or IFN-tau for 0, 24, 48, 72, 96 or 120 hours. Cells and media were collected for determination of PGDH mRNA and PGF concentrations. Laboratory analyses are underway and results will be forthcoming in the near future.
Impacts
Embryonic mortality reduces the potential number of animals born by 20 to 40 percent, resulting a reduction of Virginia sheep and goat producer profit by approximately $1.2 million each year. The information generated from these studies on the processes involved in embryo development and uterine function is needed to develop the methods to reduce embryonic mortality and boost producer profit potentials
Publications
- Sayre, BL, MPL Dismann, and JP Tritschler. 2003. Effects of prostaglandins E and F on early embryonic development in the goat. J. Anim. Sci. 81(Suppl. 2):16.
- Sayre, BL, S Wildeus, MPL Dismann, and JR Collins. 2004. Genetic and environmental effects on phenotypic expression of myotonia in the Myotonic goat. J. Anim. Sci. (Proceedings of the Southern Section ASAS Annual Meeting) : (submitted and accepted for publication).
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Progress 01/01/02 to 12/31/02
Outputs
Luteal regression is initiated by prostaglandin (PG) F from the uterus. Maintenance of luteal function is necessary for continued embryonic development. Likewise, uterine prostaglandins may directly affect the development of the embryo. Previous data indicated PGE increased ovine embryonic hatching rate, and PGF reduced development of rabbit, bovine, and rat embryos. The objective of this experiment was to determine the effects of PGE and PGF on embryonic development of caprine embryos. Embryos were incubated for 6 d with one of the following treatments: 1) control, 2) PGE, 3) PGF, 4) low PGE:high PGF, 5) balanced PGE:PGF, or 6) high PGE:low PGF. Treatment with PGE reduced hatching rate (1/17; 6%), while the hatching rate of embryos treated with PGF (9/18; 50%), low PGE:high PGF (8/16; 50%), and balanced PGE:PGF (11/18; 61%) were similar to control (6/18; 33%). In contrast, both development of morula to blastocysts and hatching rate were increased with high PGE:low
PGF (6/6; 100% and 13/18; 72%, respectively). All other treatments did not affect development of morula to blastocysts. Based on the literature, PGF was expected to reduce hatching rates, and PGE was expected to increase hatching rates. In contrast, in this experiment PGE reduced embryonic hatching rate, and PGF had no effect. While high concentrations of PGE with PGF improved hatching rates, increased concentrations of PGF did not affect embryonic development. Further studies are needed to elucidate the roles of PGE and PGF on regulation of embryonic blastocoele formation and hatching.
Impacts
Embryonic mortality reduces the potential number of animals born by 20 to 40%, resulting a reduction of Virginia sheep and goat producer profit by approximately $1.2 million each year. The information generated from these studies on the processes involved in embryo development and luteal function is needed to develop the methods to reduce embryonic mortality and boost producer profit potentials
Publications
- Sayre, BL and MPL Dismann. 2002. Early expression of insulin-like growth factor binding protein-1 and endothelin converting enzyme-1 after treatment with PGF in goats. J. Anim. Sci. 80(Suppl. 2):18.
- Sayre, BL, MPL Dismann, and JP Tritschler. 2003. Effects of prostaglandins E and F on early embryonic development in the goat. J. Anim. Sci. (Proceedings of the Southern Section ASAS Annual Meeting) : (submitted and accepted for publication).
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Progress 01/01/01 to 12/31/01
Outputs
Luteal regression is initiated by prostaglandin PGF from the uterus. Maintenance of luteal function is necessary for continued embryonic development. Likewise, uterine prostaglandins may directly affect the development of the embryo. The first experiment was designed to determine the expression of insulin-like growth factor binding protein-1 (IGFBP-1), endothelin-1 (ET-1) converting enzyme-1 (ECE-1), and prostaglandin production in the caprine CL and the timing of expression in relation to other luteal factors during the process of luteolysis. Estrus was synchronized and corpora lutea were collected on d 10 at 1, 2, or 4 h after either saline (1 ml) or PGF (5 mg). Corpora lutea were split with one half homogenized in TriReagent for collection of total RNA for determination of gene expression with RT-PCR, and one half homogenized in saline for determination of hormone concentrations. Data from this experiment indicate that PGF stimulates ECE-1, luteal prostaglandin
enzyme production (PGHS-2 and PGFS), and IGFBP-1 production in the caprine CL. These factors likely inhibit luteal progesterone production, which is necessary for embryonic development. Experiment 2 was designed to determine the effect of various levels of PGE and PGF on early embryonic development. Embryos were collected from synchronized, superovulated does on d 5 or 6 of pregnancy, and incubated with one of six treatments: control, PGE (7 ng/ml), PGF (7 ng/ml), low PGE:PGF (1:4), balanced PGE:PGF (1:1), or high PGE:PGF (4:1), in 500 ml of Ham's F10 with BSA and antibiotic/antimycotic at 37 degree C for 6 days. During this experiment, the superovulation protocol did not induce superovulation, probably due to an ineffective batch of FSH. Thus, insufficient numbers of embryos were collected to determine differences between treatments. Another replicate of this experiment will be performed and the data combined.
Impacts
Embryonic mortality reduces the potential number of animals born by 20 to 40%, resulting a reduction of Virginia sheep and goat producer income by approximately $1.2 million each year. The information generated from these studies on the processes involved in embryo development and luteal function is needed to develop the methods to reduce embryonic mortality and boost producer income potentials
Publications
- Sayre, BL and MPL Dismann. 2002. Early expression of insulin-like growth factor binding protein-1 and endothelin converting enzyme-1 after treatment with PGF in goats. J. Anim. Sci. (Proceedings of the Southern Section ASAS Annual Meeting)
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Progress 01/01/00 to 12/31/00
Outputs
No Progress Reported.
Impacts
(N/A)
Publications
- No publications reported this period
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