The Concentration of Progesterone in the Peripheral Plasma of the Pregnant Ewe

Bassett, J. M.; Oxborrow, Tana J.; Smith, Ian D.; Thorburn, G. D.

doi:10.1677/joe.0.0450449

Cited by 199 publications

(101 citation statements)

References 20 publications

(30 reference statements)

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“…This is not the case in cavies where plasma progesterone levels during pregnancy can be divided into two phases (see above). (2) The highest progesterone concentration found in the plasma of the guinea-pig and cuis during pregnancy is certainly very much higher than those found in many other animals such as the pregnant hamster (25 ng/ml; Leavitt & Blaha, 1970), ewe (15 to 20 ng/ml; Bassett, Oxborrow, Smith & Thorburn, 1969;Fylling, 1970) and cow (8 ng/ml; Donaldson, Bassett & Thorburn, 1970). Thus, not to mention the high level of 513 ng/ml, even the progesterone concentrations (6-3 to 15 ng/ml) during the first 15 days in guinea-pigs Challis et al, 1971) and in G. musteloides (23 to 60 ng/ml) are, in fact, high levels and the progesterone requirement during the first 15 days' gestation in both species of cavy is, therefore, by no means low compared to these animals.…”

Section: Animals and Sample Collectionmentioning

confidence: 91%

Progesterone Levels During the Oestrous Cycle and Pregnancy in the Cuis, Galea Musteloides

Tam¹

1973

Reproduction

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Summary. The progesterone levels in arterial plasma, luteal and non-luteal ovarian tissues of the cuis, Galea musteloides, were determined at various stages of the oestrous cycle and pregnancy, using gas\p=m-\liquid chromatography with electron-capture detection. Plasma progesterone levels (8 to 18 ng/ml) during the oestrous cycle are lower than those found in pregnancy where they stayed at 23 to 60 ng/ml during the first 15 days. They rose to 513 ng/ml at Day 26 and thereafter gradually declined to 108 ng/ml a few days before parturition (Day 53). Within 24 hr after parturition, the level dropped to 23 ng/ml. During pregnancy, the pattern of changes in plasma progesterone levels and even the absolute concentrations (except for the first 15 days) resembled those of the guinea-pig. Progesterone concentration and content in the luteal tissue differed from those of the latter species. The results indicated that the maximal activity of the CL occurred between 20 and 30 days' gestation, the timing of which was again similar to that in the gui nea\x=req-\ pig. By comparison with other species, it was obvious that during gestation, both the guinea-pig and the cuis had very high plasma progesterone concentrations, and that gestation in these two animals could be divided into two phases according to these levels. The primary phase was the first 15 days when plasma progesterone was relatively low and the secondary phase was the latter half of gestation when the plasma progesterone concentration was at least fifteen times that of the primary phase. In both species, the establishment of the allantochorionic placenta occurred at the transition between these two phases when the plasma progesterone concentration was rising rapidly. The two phases probably represented stages where the requirement and metabolism of progesterone was widely different.

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Section: Animals and Sample Collectionmentioning

confidence: 91%

Progesterone Levels During the Oestrous Cycle and Pregnancy in the Cuis, Galea Musteloides

Tam¹

1973

Reproduction

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“…Moreover, the collapse of bovine placental progesterone production and an enhanced production of estrogens as a result of an increase in placental CYP17 activity was shown in in vitro studies (Schuler et al 1994). However, the signal cascade controlling the initiation of parturition in the cow must clearly be more complex than in the late pregnant sheep where the placenta is the sole significant source of progesterone (Denamur & Martinet 1955, Bassett et al 1969, Al-Gubory et al 1999, while in the cow it is the corpus luteum (Estergreen et al 1967, Day et al 1977a, 1977b, Chew et al 1979 with the prepartal decline in maternal progesterone levels clearly resulting from luteolysis (Hoffmann et al 1979). The bovine placenta contributes -if at all -only insignificantly to systemic maternal progesterone levels during late gestation (Comline et al 1974, Conley & Ford 1987 but is still capable of producing high local progesterone concentrations at the feto-maternal interface (Tsumagari et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Investigations into the mechanisms controlling parturition in cattle

Shenavai

Preissing²,

Hoffmann³

et al. 2012

Reproduction

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A pronounced increase in fetal cortisol concentrations stimulating an increase in estrogen production at the expense of progesterone precursors in the placenta, luteolysis, and progesterone withdrawal is considered as a key event during the complex signal cascade leading to the initiation of parturition in cattle. However, there are many questions concerning the exact functional and/or temporal relationships between these individual processes which finally result in the expulsion of the calf and the timely release of the placenta. Thus, parturition was induced in 270-day pregnant cows using the progesterone receptor blocker aglepristone (group AG, nZ3), the prostaglandin F 2a analog cloprostenol (group PG, nZ4), and the glucocorticoid dexamethasone (group GC, nZ4) to characterize the effect on maternal steroid and prostaglandin levels and to identify immediate subsequent changes in placental morphology and gene expression as compared with untreated controls sampled on day 272 (group D272, nZ3) and cows during normal parturition (group NT, nZ4). All calves of the treatment groups were born on days 271-272, whereas gestational length in NT cows was 280.5G1.3 days. However, none of the treatments significantly induced the prepartal remodeling of placentomes characterized by a decline in trophoblast giant cells and reduction of the caruncular epithelium. Data on placental CYP17 and COX2 expression confirm that these key enzymes are upregulated by GC, whereas placental aromatase expression was not affected by any treatment. Maternal progesterone and prostaglandin profiles suggest differential effects of the treatments on luteal function and placental or uterine prostaglandin production. The results provide new information on the initiation of parturition in cattle but raise many new questions.

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“…The capacity of the uterus to grow and differentiate in response to circulating ovarian steroid hormones may be determined, in part, by the level of high-affinity E2 and P receptors in uterine cytoplasm (see Clark and Peck 1979 for a review). Except during the first and last 4-7 days of pregnancy, gestation in the ewe is characterized by (1) maternal peripheral serum P levels which are not less than those seen during the luteal phase of the oestrous cycle and which between days 50 and 120 increase to levels 2-5 times those seen during the luteal phase of the cycle; and (2) extremely low maternal peripheral serum levels of unconjugated oestrogens (Bassett et al 1969;Charnley et al 1973; Robertson and Smeaton 1973;Tsang 1978).…”

Section: Introductionmentioning

confidence: 99%

Uterine and Placental Growth: RNA and Protein Metabolism and Steroid Hormone Receptor Levels in the Endometrium, Whole Uterus and Cotyledons during Pregnancy in the Ewe

Miller¹,

Stone²

1981

Aust. Jnl. Of Bio. Sci.

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Some aspects of uterine and placental growth have been examined during pregnancy in the ewe. Changes in in vitro rates of protein synthesis, RNA:DNA and protein:DNA ratios and the tissue concentration of DNA in intercaruncular endometrium and caruncles/cotyledons between days 0 (oestrus) and 112 of pregnancy were compared with corresponding changes in the concentrations of high-affinity cytosol receptors for oestradiol and progesterone in whole uterus and caruncles/maternal cotyledons. Rapid growth of the intercaruncular endometrium between days 28 and 112 and of the developing cotyledons between days 28 and 84 occur in the presence of tissue levels of both steroid receptors that are extremely low in relation to the corresponding levels seen in the uterus at oestrus. If uterine responses to steroid hormones are regulated by the amounts of specific receptor present in the tissue, the results support the concept that uterine growth after day 28 of pregnancy results primarily from the physical stimulus of the growing conceptus rather than from the actions of endogenous steroid sex hormones.

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The Concentration of Progesterone in the Peripheral Plasma of the Pregnant Ewe

Cited by 199 publications

References 20 publications

Progesterone Levels During the Oestrous Cycle and Pregnancy in the Cuis, Galea Musteloides

Progesterone Levels During the Oestrous Cycle and Pregnancy in the Cuis, Galea Musteloides

Investigations into the mechanisms controlling parturition in cattle

Uterine and Placental Growth: RNA and Protein Metabolism and Steroid Hormone Receptor Levels in the Endometrium, Whole Uterus and Cotyledons during Pregnancy in the Ewe

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