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O.j. Ginther - One of the best experts on this subject based on the ideXlab platform.
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Up-regulation of endometrial oxytocin receptor is associated with the timing of Luteolysis in heifers with two and three follicular waves
Biology of Reproduction, 2020Co-Authors: Rafael R Domingues, O.j. Ginther, Victor E. Gomez-léon, M C WiltbankAbstract:Initiation of Luteolysis in ruminants is variable due to ill-defined mechanisms. Cycles of two follicular waves are shorter and have earlier Luteolysis than three-wave cycles. This study validated a cytobrush technique for evaluating dynamics of endometrial gene expression and associated changes in mRNA with timing of Luteolysis, based on circulating progesterone and ultrasound-determined changes in blood flow and volume of corpus luteum (CL). On day 8 (ovulation = day 0), Holstein heifers were randomized into two groups: cytobrush group (n = 9) had an endometrial sample collected every 48 h from day 8 until end of Luteolysis (CL blood flow
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up regulation of endometrial oxytocin receptor is associated with the timing of Luteolysis in heifers with two and three follicular waves
Biology of Reproduction, 2020Co-Authors: Rafael R Domingues, O.j. Ginther, Victor E Gomezleon, M C WiltbankAbstract:Initiation of Luteolysis in ruminants is variable due to ill-defined mechanisms. Cycles of two follicular waves are shorter and have earlier Luteolysis than three-wave cycles. This study validated a cytobrush technique for evaluating dynamics of endometrial gene expression and associated changes in mRNA with timing of Luteolysis, based on circulating progesterone and ultrasound-determined changes in blood flow and volume of corpus luteum (CL). On day 8 (ovulation = day 0), Holstein heifers were randomized into two groups: cytobrush group (n = 9) had an endometrial sample collected every 48 h from day 8 until end of Luteolysis (CL blood flow Luteolysis (n = 5). Concentrations of progesterone, CL blood flow, CL volume, and the frequency of two and three-wave cycles were similar between groups. Endometrial mRNA for progesterone receptors and estradiol receptors 1 and 2 was greater on day 8 and decreased thereafter similarly in two and three-wave cycles. Oxytocin receptor mRNA increased earlier in two vs three-wave cycles (day 14 vs 18), and the increase was associated with the onset of Luteolysis. In conclusion, the cytobrush technique allowed in vivo collection of multiple endometrial samples during the estrous cycle. Endometrial mRNA expression of steroid receptors did not explain the variability in timing of onset of Luteolysis in heifers while the later onset of Luteolysis in three-wave cycles was associated with later up-regulation of oxytocin receptor mRNA.
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relationships among nitric oxide metabolites and pulses of a pgf2α metabolite during and after Luteolysis in mares
Theriogenology, 2015Co-Authors: O.j. Ginther, C A Wolf, J M Baldrighi, J M GreeneAbstract:Abstract Hourly circulating concentrations of a PGF2α metabolite (PGFM), progesterone (P4), and LH were obtained from a reported project, and concentrations of nitric oxide (NO) metabolites (NOMs; nitrates and nitrites) were determined in eight mares. Unlike the reported project, hormone concentrations were normalized to the peak of the first PGFM pulse of Luteolysis (early Luteolysis), second PGFM pulse (late Luteolysis), and a pulse after Luteolysis. The duration of Luteolysis was 23.1 ± 1.0 hours, and the peak of the first and second PGFM pulses occurred 6.5 ± 0.9 and 14.8 ± 0.8 hours after the beginning of Luteolysis. Concentration of P4 decreased progressively within and between the PGFM pulses Changes were not detected in LH concentration in association with the PGFM pulses. Concentration of NOMs was greater (P
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173 USE OF CORPUS LUTEUM AREA AS A PREDICTOR OF ONGOING FUNCTIONAL Luteolysis IN DAIRY HEIFERS
Reproduction Fertility and Development, 2013Co-Authors: Guilherme Pugliesi, F. L. V. Pinaffi, O.j. GintherAbstract:The beginning of functional Luteolysis in cattle ranges from Days 16–19 (Day 0 = ovulation). During functional Luteolysis, luteal size and blood flow decrease in heifers. The wide range of beginning of Luteolysis and the low sensitivity of quick progesterone (P4) assays preclude targeting an individual for a specific period of Luteolysis. The present study aimed to evaluate the changes in area and blood flow of corpus luteum (CL) during spontaneous Luteolysis and test the hypothesis that a decrease in CL area (cm2) is more efficient in targeting the luteolytic period than using a specific day postovulation. Blood sampling and ultrasound scanning of CL were done every 12 h from Days 13–22 in dairy heifers (Holstein) and was used for a retrospective study (Experiment 1; n = 6 heifers). The P4 concentrations, maximum CL area, and the percentage of CL area with coloured signals of blood flow were centralized to 12-h sample when the end of Luteolysis (P4
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173 use of corpus luteum area as a predictor of ongoing functional Luteolysis in dairy heifers
Reproduction Fertility and Development, 2013Co-Authors: Guilherme Pugliesi, F. L. V. Pinaffi, O.j. GintherAbstract:The beginning of functional Luteolysis in cattle ranges from Days 16–19 (Day 0 = ovulation). During functional Luteolysis, luteal size and blood flow decrease in heifers. The wide range of beginning of Luteolysis and the low sensitivity of quick progesterone (P4) assays preclude targeting an individual for a specific period of Luteolysis. The present study aimed to evaluate the changes in area and blood flow of corpus luteum (CL) during spontaneous Luteolysis and test the hypothesis that a decrease in CL area (cm2) is more efficient in targeting the luteolytic period than using a specific day postovulation. Blood sampling and ultrasound scanning of CL were done every 12 h from Days 13–22 in dairy heifers (Holstein) and was used for a retrospective study (Experiment 1; n = 6 heifers). The P4 concentrations, maximum CL area, and the percentage of CL area with coloured signals of blood flow were centralized to 12-h sample when the end of Luteolysis (P4 < 1 ng mL–1) was detected. The percentage decrease in CL area and blood flow between Day 13 and the 12-h sample before the end of Luteolysis were calculated. In Experiment 2, a blood sampling and transrectal ultrasonography of CL were performed every 8 h starting on Day 14 to determine the beginning and end of functional Luteolysis (n = 20 heifers). The hour of detection of Luteolysis was defined as the scan at 8-h intervals when maximum CL area decreased by 25 or 12.5% on Day 14. Based on P4 concentrations, the preluteolytic, luteolytic, and postluteolytic periods in each heifer were identified. The area and blood flow were measured by a duplex B-mode and pulse-wave colour Doppler ultrasound instrument. In Experiment 1, the retrospective study indicated a 25% decrease in CL area and 65% decrease in blood flow 12 h before the end of functional Luteolysis. In Experiment 2, the 25% and 12.5% CL area decrease from Day 14 occurred, respectively, on Days 18.1 ± 0.6 and 17.2 ± 0.5 postovulation. The hypothesis that a decrease in CL area is more efficient in targeting ongoing Luteolysis than using a specific day postovulation was supported. This was indicated by the greater (P < 0.05) frequency of heifers detected in luteolytic period (12 of 20 heifers) using the criteria of a 12.5% decrease in CL area than using a specific day (Table 1). Using a day postovulation for obtaining heifers in the luteolytic phase was only 0 to 30% effective for targeting Luteolysis. In conclusion, the technique of using an ultrasonic 12.5% reduction in CL area is a good tool to detect ongoing Luteolysis and may be useful as an experimental design to study factors related to the luteolytic period in cattle. Table 1.Percentage values of heifers in preluteolytic, luteolytic, or postluteolytic periods according to a decrease in CL area criteria or a day postovulation Supported by grants from FAPESP (2012/04004-8 to GP).
R R Araujo - One of the best experts on this subject based on the ideXlab platform.
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role of follicular estradiol 17beta in timing of Luteolysis in heifers
Biology of Reproduction, 2009Co-Authors: R R Araujo, O.j. Ginther, Jair C Ferreira, Miller Palhao, M C WiltbankAbstract:The hypothesis was tested that estradiol (E2) from the ovarian follicles controls time of Luteolysis. Time of Luteolysis was evaluated by multiple measures of corpus luteum (CL) structure (area, volume) and function (progesterone [P4], luteal blood flow). The hypothesis for experiment 1 was that repeated ablation of follicles would reduce circulating E2 and delay Luteolysis. Heifers were randomly assigned on Day 9 (Day 0 = ovulation) to three groups. All follicles ≥4 mm were ablated on Day 9 (group FA9; n = 6); Days 9–15 (group FA15; n = 6); or Days 9–21 (group FA21; n = 7). As expected, follicular ablation delayed (P < 0.001) the rise in circulating E2 and peak E2 concentrations (FA9, Day 17.6 ± 0.7; FA15, Day 20.3 ± 0.3; FA21, Day 24.9 ± 0.3). Luteolysis (based on each measure) was delayed (P < 0.005) by repeated ablation of follicles, with earlier Luteolysis (based on P4 decrease) in FA9 (Day 15.2 ± 0.8) than FA15 (Day 16.5 ± 0.4), and a further delay in FA21 (Day 18.3 ± 0.5). The hypothesis of experiment 2 was that exogenous treatment with E2 would stimulate prostaglandin F2alpha (PGF) secretion and prevent the delay in Luteolysis associated with follicular ablations. Follicles ≥4 mm were ablated from Day 9 to Day 17 (n = 15). Heifers were treated on Days 13 and 15 with 1.0 mg of estradiol benzoate (FAE2; n = 7) or vehicle (FAV; n = 8). Treatment with E2 induced PGF secretion (detected by PGF metabolite) and induced earlier (P < 0.02) Luteolysis in FAE2 than in FAV, whether determined by circulating P4 or by area, volume, or blood flow of CL. In summary, ablation of follicles (≥4 mm) delayed and treatment with E2 hastened Luteolysis in heifers with ablated follicles. Thus, these results are consistent with an essential role for follicle E2 in timing of Luteolysis.
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characterisation of pulses of 13 14 dihydro 15 keto pgf2alpha pgfm and relationships between pgfm pulses and luteal blood flow before during and after Luteolysis in mares
Reproduction Fertility and Development, 2008Co-Authors: O.j. Ginther, Jair C Ferreira, B L Rodrigues, R R AraujoAbstract:Blood collections for characterising 13,14-dihydro-15-keto-PGF2alpha (PGFM) pulses in mares and colour-Doppler examinations for estimating percentage of corpus luteum with blood-flow signals were done hourly for a 24-h session on Day 15 (ovulation = Day 0; n = 13 mares) or during 12-h sessions from Days 12 to 16 (n= 10 mares). Luteolysis was defined as extending from the beginning of a precipitous decrease in progesterone until progesterone was <2 ng mL–1. Comparisons were made among preLuteolysis, Luteolysis, and postLuteolysis. Greater prostaglandin F2α activity (mean PGFM concentration per session) occurred during Luteolysis than during preLuteolysis and postLuteolysis. Statistically-detected PGFM pulses were smaller during preLuteolysis with a highly variable interval from the last pulse to the beginning of Luteolysis. Either two or three pulses were detected in each 24-h session during Luteolysis and postLuteolysis, after excluding three of eight sessions with no pulses during postLuteolysis. Statistically, 17% of pulses during postLuteolysis were prominent outliers. The nadir-to-nadir interval during a pulse (5 h), the peak-to-peak interval between pulses (9 h), and the resulting 4-h gap between pulses were similar during and after Luteolysis. The decrease in progesterone encompassed the PGFM pulses, without a detectable fluctuation during a pulse. The percentage of corpus luteum with blood-flow signals did not change during the ascending portion of a PGFM pulse and decreased within 2 or 3 h after the peak, even during preLuteolysis. Results indicated that a reported increase in luteal blood flow in heifers during the ascending portion of a PGFM pulse does not occur in mares.
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temporal associations among pulses of 13 14 dihydro 15 keto pgf2alpha luteal blood flow and Luteolysis in cattle
Biology of Reproduction, 2007Co-Authors: O.j. Ginther, Luciano Andrade Silva, R R AraujoAbstract:Abstract Luteal blood flow was studied in heifers by transrectal color-Doppler ultrasound. Data were normalized to the decrease in plasma progesterone to <1 ng/ml (Day 0 or Hour 0). Blood flow in the corpus luteum (CL) was estimated by the percentage of CL area with color flow signals. Systemic prostaglandin F2alpha (PGF) treatment (25 mg; n = 4) resulted in a transient increase in CL blood flow during the initial portion of the induced decrease in progesterone. Intrauterine treatment (1 or 2 mg) was done to preclude hypothetical secondary effects of systemic treatment. Heifers were grouped into responders (Luteolysis; n = 3) and nonresponders (n = 5). Blood flow increased transiently in both groups; induction of increased blood flow did not assure the occurrence of Luteolysis. A transient increase in CL blood flow was not detected in association with spontaneous Luteolysis when examinations were done every 12 h (n = 6) or 24 h (n = 10). The role of PGF pulses was studied by examinations every hour during...
Ben Aernouts - One of the best experts on this subject based on the ideXlab platform.
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validation of a novel milk progesterone based tool to monitor Luteolysis in dairy cows timing of the alerts and robustness against missing values
Journal of Dairy Science, 2019Co-Authors: Ines Adriaens, Olivier Martin, Wouter Saeys, Bart De Ketelaere, Nicolas Charles Friggens, Ben AernoutsAbstract:ABSTRACT Automated monitoring of fertility in dairy cows using milk progesterone is based on the accurate and timely identification of Luteolysis. In this way, well-adapted insemination advice can be provided to the farmer to further optimize fertility management. To properly evaluate and compare the performance of new and existing data-processing algorithms, a test data set of progesterone time-series that fully covers the desired variability in progesterone profiles is needed. Further, the data should be measured with a high frequency to allow rapid onset events, such as Luteolysis, to be precisely determined. Collecting this type of data would require a lot of time, effort, and budget. In the absence of such data, an alternative was developed using simulated progesterone profiles for multiple cows and lactations, in which the different fertility statuses were represented. To these, relevant variability in terms of cycle characteristics and measurement error was added, resulting in a large cost-efficient data set of well-controlled but highly variable and farm-representative profiles. Besides the progesterone profiles, information on (the timing of) Luteolysis was extracted from the modeling approach and used as a reference for the evaluation and comparison of the algorithms. In this study, 2 progesterone monitoring tools were compared: a multiprocess Kalman filter combined with a fixed threshold on the smoothed progesterone values to detect Luteolysis, and a progesterone monitoring algorithm using synergistic control, PMASC, which uses a mathematical model based on the luteal dynamics and a statistical control chart to detect Luteolysis. The timing of the alerts and the robustness against missing values of both algorithms were investigated using 2 different sampling schemes: one sample per cow every 8 h versus 1 sample per day. The alerts for Luteolysis of the PMASC algorithm were on average 20 h earlier compared with the ones of the multiprocess Kalman filter, and their timing was less sensitive to missing values. This was shown by the fact that, when 1 sample per day was used, the Kalman filter gave its alerts on average 24 h later, and the variability in timing of the alerts compared with simulated Luteolysis increased with 22%. Accordingly, we postulate that implementation of the PMASC system could improve the consistency of Luteolysis detection on farm and lower the analysis costs compared with the current state of the art.
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short communication validation of a novel milk progesterone based tool to monitor Luteolysis in dairy cows using cost effective on farm measured data
Journal of Dairy Science, 2019Co-Authors: Ines Adriaens, Wouter Saeys, Bart De Ketelaere, Katleen Geerinckx, Ben AernoutsAbstract:ABSTRACT The progesterone (P4) monitoring algorithm using synergistic control (PMASC) uses luteal dynamics to identify fertility events in dairy cows. This algorithm employs a combination of mathematical functions describing the increasing and decreasing P4 concentrations during the development and regression of the corpus luteum and a statistical control chart that allows identification of Luteolysis. The mathematical model combines sigmoidal functions from which the cycle characteristics can be calculated. Both the moment at which Luteolysis is detected and confirmed by PMASC, as well as the model features themselves, can be used to inform the farmer on the fertility status of the cows.
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validation of a novel milk progesterone based tool to monitor Luteolysis in dairy cows timing of the alerts and robustness against missing values
bioRxiv, 2019Co-Authors: Ines Adriaens, Olivier Martin, Wouter Saeys, Bart De Ketelaere, Nicolas Charles Friggens, Ben AernoutsAbstract:Automated monitoring of fertility in dairy cows using milk progesterone is based on the accurate and timely identification of Luteolysis. In this way, well-adapted insemination advice can be provided to the farmer to further optimize his fertility management. To properly evaluate and compare the performance of new and existing data-processing algorithms, a test dataset of progesterone time-series that fully covers the desired variability in progesterone profiles is needed. Further, the data should be measured with a high enough (and equidistant) frequency to allow rapid onset events, such as Luteolysis, to be precisely determined. Collecting this type of data would require a lot of time, effort and budget. In the absence of such data, an alternative was developed using simulated progesterone profiles for multiple cows and lactations, in which the different fertility statuses were represented. To these, relevant variability in terms of cycle characteristics and measurement error was added, resulting in a large cost-efficient dataset of well-controlled but highly variable and farm-representative profiles. Besides the progesterone profiles, information on (the timing of) Luteolysis was extracted from the modelling approach and used as a reference for the evaluation and comparison of the algorithms. In this study, two progesterone monitoring tools were compared: a multiprocess Kalman filter combined with a fixed threshold to detect Luteolysis, and a progesterone monitoring algorithm using synergistic control (PMASC), which uses a mathematical model based on the luteal dynamics and a statistical control chart to detect Luteolysis. The timing of the alerts and the robustness against missing values of both algorithms were investigated using two different sampling schemes: one sample per cow every eight hours versus one sample per day. The alerts for Luteolysis of the PMASC algorithm were on average 20 hours earlier compared to the ones of the multiprocess Kalman filter, and their timing was less sensitive to missing values. This was shown by the fact that, when one sample per day was used, the Kalman filter gave its alerts on average 24 hours later, and the variability in timing of the alerts compared to simulated Luteolysis increased with 22%. Accordingly, we postulate that implementation of the PMASC system could improve the consistency of Luteolysis detection on farm and lower the analysis costs.
L A Penny - One of the best experts on this subject based on the ideXlab platform.
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Monocyte chemoattractant protein 1 in Luteolysis
Reviews of Reproduction, 2000Co-Authors: L A PennyAbstract:Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokine family of cytokines which are involved in leukocyte physiology and trafficking. Interest in the role of inflammatory cells and their cytokine products in Luteolysis has been increasing and there is mounting evidence demonstrating that MCP-1 is involved in Luteolysis. Cell sources of MCP-1, such as endothelial cells, are abundant in late stage luteal tissue. Increased amounts of mRNA encoding MCP-1 are found after Luteolysis in sheep, pigs, cows, rats and women and its up-regulation is associated with an increase in macrophages within the corpus luteum, indicating that MCP-1 may act as an inflammatory mediator during luteal regression. Luteolytic substances (prolactin in rats and prostaglandin F2alpha in ruminants) appear to be involved in increased expression of MCP-1 within the corpus luteum, although it is unclear whether this is a direct or indirect effect. Cytokines produced within the corpus luteum around Luteolysis may also be involved in regulating MCP-1 expression. The field of chemokine biology is expanding rapidly and MCP-1, as well as other chemokines yet to be investigated, may prove to be an important link between the hormonal and cellular events within the corpus luteum around the time of Luteolysis.
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immune cells and cytokine production in the bovine corpus luteum throughout the oestrous cycle and after induced Luteolysis
Reproduction, 1999Co-Authors: L A Penny, D G Armstrong, T A Bramley, R Webb, R A Collins, E D WatsonAbstract:Immune cells and their cytokine products have powerful local effects within body tissues. There has been great interest in the potential role of these cells, not only during destruction of the corpus luteum but also during its functional lifespan. In this study, lymphocytes, macrophages and major histocompatibility complex class II molecules were quantified using immunohistochemistry and the reverse transcription-polymerase chain reaction was used to detect mRNA for tumour necrosis factor α and interferon γ within corpora lutea from three groups of cows: (1) corpora lutea collected at an abattoir and assessed visually into four stages (stage I (days 1-5), stage II (days 6-12), stage III (days 13-18) and stage IV (days 19-21) of the oestrous cycle); (2) corpora lutea collected around natural Luteolysis (days 14-20); and (3) corpora lutea collected 6, 12 and 24 h after prostaglandin F 2α -induced Luteolysis. The numbers of T lymphocytes (CD5 + and CD8 + ) were significantly higher (P < 0.05) at stage IV and from day 16 onwards, before functional Luteolysis. There were significantly higher numbers (P < 0.01) of macrophages at stages I, III and IV compared with stage II in visually staged tissue. Major histocompatibility complex class II molecules were increased (P < 0.05) at stages I and IV compared to stage II and at all times after induced Luteolysis. Using reverse transcription- polymerase chain reaction, mRNA encoding tumour necrosis factor α and interferon γ was detected in all luteal tissue collected around natural Luteolysis and after induced Luteolysis. These findings, particularly the increase in T lymphocytes before functional Luteolysis, provide further evidence of a significant role for the immune system in affecting reproductive function in cows.
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expression of monocyte chemoattractant protein 1 in the bovine corpus luteum around the time of natural Luteolysis
Biology of Reproduction, 1998Co-Authors: L A Penny, D G Armstrong, T A Bramley, E D Watson, G Baxter, C O Hogg, H Kindahl, R WebbAbstract:Monocyte chemoattractant protein (MCP-1) is a specific chemoattractant for monocytes/macrophages that could have a role in the influx of macrophages into the corpus luteum (CL) during structural Luteolysis. In this study, reverse transcription-polymerase chain reaction and in situ hybridization were used to investigate MCP-1 mRNA expression in CL collected from 18 heifers between Days 15 and 20 of the estrous cycle. There was expression of mRNA encoding MCP-1 in luteal tissue from all cows; however, expression was greater in animals that had undergone Luteolysis at the time of CL collection as compared to animals in which the CL was still functional. Similarly, in situ hybridization showed greater expression of mRNA encoding MCP-1 in CL after functional Luteolysis. There was also evidence of increased MCP-1 mRNA expression in an animal with a functional CL where the systemic concentration of prostaglandin F 2α metabolite was high at the time of tissue collection. T lymphocyte populations, identified by immunohistochemistry, had a distribution similar to that of cells expressing MCP-1 mRNA within the CL, but other cell types were also involved. These results demonstrate an increase in MCP-1 mRNA after functional Luteolysis in the cow, which may be related to the influx of macrophages that occurs at this time.
Jair C Ferreira - One of the best experts on this subject based on the ideXlab platform.
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role of follicular estradiol 17beta in timing of Luteolysis in heifers
Biology of Reproduction, 2009Co-Authors: R R Araujo, O.j. Ginther, Jair C Ferreira, Miller Palhao, M C WiltbankAbstract:The hypothesis was tested that estradiol (E2) from the ovarian follicles controls time of Luteolysis. Time of Luteolysis was evaluated by multiple measures of corpus luteum (CL) structure (area, volume) and function (progesterone [P4], luteal blood flow). The hypothesis for experiment 1 was that repeated ablation of follicles would reduce circulating E2 and delay Luteolysis. Heifers were randomly assigned on Day 9 (Day 0 = ovulation) to three groups. All follicles ≥4 mm were ablated on Day 9 (group FA9; n = 6); Days 9–15 (group FA15; n = 6); or Days 9–21 (group FA21; n = 7). As expected, follicular ablation delayed (P < 0.001) the rise in circulating E2 and peak E2 concentrations (FA9, Day 17.6 ± 0.7; FA15, Day 20.3 ± 0.3; FA21, Day 24.9 ± 0.3). Luteolysis (based on each measure) was delayed (P < 0.005) by repeated ablation of follicles, with earlier Luteolysis (based on P4 decrease) in FA9 (Day 15.2 ± 0.8) than FA15 (Day 16.5 ± 0.4), and a further delay in FA21 (Day 18.3 ± 0.5). The hypothesis of experiment 2 was that exogenous treatment with E2 would stimulate prostaglandin F2alpha (PGF) secretion and prevent the delay in Luteolysis associated with follicular ablations. Follicles ≥4 mm were ablated from Day 9 to Day 17 (n = 15). Heifers were treated on Days 13 and 15 with 1.0 mg of estradiol benzoate (FAE2; n = 7) or vehicle (FAV; n = 8). Treatment with E2 induced PGF secretion (detected by PGF metabolite) and induced earlier (P < 0.02) Luteolysis in FAE2 than in FAV, whether determined by circulating P4 or by area, volume, or blood flow of CL. In summary, ablation of follicles (≥4 mm) delayed and treatment with E2 hastened Luteolysis in heifers with ablated follicles. Thus, these results are consistent with an essential role for follicle E2 in timing of Luteolysis.
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characterisation of pulses of 13 14 dihydro 15 keto pgf2alpha pgfm and relationships between pgfm pulses and luteal blood flow before during and after Luteolysis in mares
Reproduction Fertility and Development, 2008Co-Authors: O.j. Ginther, Jair C Ferreira, B L Rodrigues, R R AraujoAbstract:Blood collections for characterising 13,14-dihydro-15-keto-PGF2alpha (PGFM) pulses in mares and colour-Doppler examinations for estimating percentage of corpus luteum with blood-flow signals were done hourly for a 24-h session on Day 15 (ovulation = Day 0; n = 13 mares) or during 12-h sessions from Days 12 to 16 (n= 10 mares). Luteolysis was defined as extending from the beginning of a precipitous decrease in progesterone until progesterone was <2 ng mL–1. Comparisons were made among preLuteolysis, Luteolysis, and postLuteolysis. Greater prostaglandin F2α activity (mean PGFM concentration per session) occurred during Luteolysis than during preLuteolysis and postLuteolysis. Statistically-detected PGFM pulses were smaller during preLuteolysis with a highly variable interval from the last pulse to the beginning of Luteolysis. Either two or three pulses were detected in each 24-h session during Luteolysis and postLuteolysis, after excluding three of eight sessions with no pulses during postLuteolysis. Statistically, 17% of pulses during postLuteolysis were prominent outliers. The nadir-to-nadir interval during a pulse (5 h), the peak-to-peak interval between pulses (9 h), and the resulting 4-h gap between pulses were similar during and after Luteolysis. The decrease in progesterone encompassed the PGFM pulses, without a detectable fluctuation during a pulse. The percentage of corpus luteum with blood-flow signals did not change during the ascending portion of a PGFM pulse and decreased within 2 or 3 h after the peak, even during preLuteolysis. Results indicated that a reported increase in luteal blood flow in heifers during the ascending portion of a PGFM pulse does not occur in mares.
