Estrogen-Induced Lh Release in Progesterone-Treated Ovariectomized Ewes

Yuthasastrakosol, P.; Simaraks, S.; Palmer, W. M.; Howland, B. E.

doi:10.4141/cjas74-068

Cited by 14 publications

(5 citation statements)

References 25 publications

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“…Progesterone has been found to be at basal levels throughout anoestrus with some elevations occurring before the first behavioural oestrus of the breeding season (Thorburn et al, 1969). Reeves, Tarnavsky & Chakraborty (1974) (1974) and the sheep (Yuthasastrakosol, Howland, Simaraks & Palmer, 1974). was used at an initial dilution of 1:100,000.…”

Section: Introductionmentioning

confidence: 99%

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Luteinizing Hormone, Oestrogen and Progesterone Levels in Peripheral Serum of Anoestrous and Cyclic Ewes as Determined by Radioimmunoassay

Yuthasastrakosol¹,

Palmer²,

Howland³

1975

Reproduction

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Summary. Jugular vein blood was collected daily from four mature ewes throughout anoestrus and the first oestrous cycle of the breeding season until 4 days after the second oestrus. The levels of oestrogen, progesterone and LH were determined by radioimmunoassay. There were fluctuations in the LH level throughout most of the observed anoestrous period with a mean \ m=+-\ S.E. value of 2\m=.\3\ m=+-\ 0\m=.\9 ng/ml. High LH values of 20\m=.\0, 41\m=.\2and 137\m=.\5 ng/ml were observed in three ewes on Day \m=-\24of anoestrus. A brief minor rise in progesterone level was also observed around this period. Progesterone levels were consistently low (0\m=.\11 \ m=+-\ 0 \ m= . \ 0 1 ng/ml) before Day \m=-\25of anoestrus. A major rise occurred on Day \m=-\12 of anoestrus and this was followed by patterns similar to those that have been previously reported for the oestrous cycle of the ewe. Random fluctuations of oestrogens deviating from a mean level of 4\m=.\40 \ m=+-\ 0\m=.\1 pg/ml were observed during anoestrus and the mean level during the period from the first to the second oestrus was 5\m=.\2\ m=+-\ 0\m=.\3 pg/ml. A wel l \x=req-\ defined peak of 13\m=.\3\ m=+-\ 0\m=.\7 pg/ml was seen in all ewes on the day of the second oestrus. Results of the present study suggest that episodic releases of LH occur during anoestrus and periods of low luteal activity. The fluctuations in LH levels, as observed during the period of low luteal activity, i.e. before Day \m=-\25 of anoestrus, were less pronounced during the periods of high luteal activity. The view that luteal activity precedes the first behavioural oestrus of the breeding season is supported.

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Section: Introductionmentioning

confidence: 99%

“…The RIA procedure for serum progesterone was that of Abraham, Swerdloff, Tulchinsky & Odell (1971) as modified by Yuthasastrakosol et al (1974) and was used without column chromatography. A highly specific (Niswender, 1973) anti-progesterone-6jS-BSA serum (No.…”

Section: Introductionmentioning

confidence: 99%

Luteinizing Hormone, Oestrogen and Progesterone Levels in Peripheral Serum of Anoestrous and Cyclic Ewes as Determined by Radioimmunoassay

Yuthasastrakosol¹,

Palmer²,

Howland³

1975

Reproduction

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“…The sensitivity of this method in our laboratory is 0· 15 ng/ml, which corresponds to approximately 95 % binding of labelled hormone when binding in tubes containing no labelled hormone is expressed as 100%. Serum progesterone was measured by the radioimmunoassay as described by Abraham, Swerdloff, Tulchinsky & Odell (1971) and modified by Yuthasastrakosol, Howland, Simaraks & Palmer (1974). The method had a coefficient of variation of 7-5 % and the lower limit of sensitivity was determined to be 0-05 ng.…”

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confidence: 99%

Release of LH in anoestrous and cyclic ewes

Yuthasastrakosol¹,

Palmer²,

Howland³

1977

Reproduction

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“…The concentration of progesterone in serum was determined by radioimmunoassay (RIA) following Yuthasastrakosol et al (1974). Briefly, extraction was accomplished by combining 250 µI of serum with 750 µI of phosphate-buffered saline (PBS, pH 7.2) and 5.5 ml of ethyl ether.…”

Section: Methodsmentioning

confidence: 99%

Progesterone levels and reproductive status of white whales (De/phinapterus leucas) from the Canadian Arctic

Stewart

1994

Meddr Grønland. Biosci

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Serum progesterone levels were compared to the presence and size of ovaries, corpora lutea and fetuses in white whales sampled at three sites in the eastern Canadian Arctic. Generally, a progesterone level greater than 3.00 ng/ml indicated a pregnancy although there was some overlap in the range of values with mature, nonpregnant whales. This overlap may be an artifact of sample management or may indicate failed or failing pregnancies. Data are not available to test these hypothesis. Progesterone concentration was not significantly correlated with ovarian mass, corpus luteum mass or fetus mass. Ovaries of immature whales were significantly smaller than those of mature-but-notpregnant and pregnant whales.

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Estrogen-Induced Lh Release in Progesterone-Treated Ovariectomized Ewes

Abstract: Yurneslsrurosor, P., Howr.rNo, B. E., Srlren-lrs, S. AND PeI-uEn, W. M. 1974. Estrogen-induced LH release in progesterone-treated ovariectomized ewes.Can. J. Anim. Sci For personal use only.

Cited by 14 publications

References 25 publications

Luteinizing Hormone, Oestrogen and Progesterone Levels in Peripheral Serum of Anoestrous and Cyclic Ewes as Determined by Radioimmunoassay

Luteinizing Hormone, Oestrogen and Progesterone Levels in Peripheral Serum of Anoestrous and Cyclic Ewes as Determined by Radioimmunoassay

Release of LH in anoestrous and cyclic ewes

Progesterone levels and reproductive status of white whales (De/phinapterus leucas) from the Canadian Arctic

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