Placental production of progesterone in ovariectomized goats treated with a synthetic progestagen to maintain pregnancy

Sheldrick, E. L.; Ricketts, A. P.; Flint, A. P. F.

doi:10.1530/jrf.0.0600339

Cited by 29 publications

(14 citation statements)

References 23 publications

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“…Polymorpho- , and about Day 130 in the goat (Sheldrick, Ricketts & Flint, 1980 Morris & Sass (1966). This is consistent with the highly permeable nature of the endothelial vessels of the corpus luteum (Morris & Sass, 1966;Smith, Mclntosh & Morris, 1970 Na, and Cl in afferent utero-ovarian and uterine lymph resembled those in plasma, confirming the integrity of the cannulated tissues, but consistent small differences were found in Na, which was higher, and Cl, which was lower, in lymph than in plasma.…”

Section: Introductionsupporting

confidence: 64%

Anatomy of the utero-ovarian lymphatic network and the composition of afferent lymph in relation to the establishment of pregnancy in the sheep and goat

Staples¹,

Fleet²,

Heap³

1982

Reproduction

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Summary. Lymphatic vessels draining the uterus and ovaries were located within the mesometrium and along the utero-ovarian pedicle by injection of marker dyes into the uterine wall and/or ovary of sheep and goats. Afferent lymphatics drained from the uterus towards the utero-ovarian pedicle and alongside the uterine artery, while 4\p=n-\12ovarian lymphatics emerged from the sub-ovarian plexus. A complex lymphatic network was formed in the region of the utero-ovarian pedicle by anastomosis between uterine and ovarian lymphatics. Mixed lymph carried in ducts alongside the uterine artery and in the utero-ovarian pedicle drained into the medial iliac node(s) and lumbo-aortic nodes, respectively. There was no evidence for retrograde lymph flow between the uterus and ovaries, but the close proximity of utero-ovarian lymphatics and the ovarian artery may provide an additional pathway for countercurrent diffusion of prostaglandin F-2\g=a\.Afferent lymph collected after chronic cannulation of utero-ovarian ducts ipsilateral to an ovary bearing a corpus luteum contained a mean progesterone concentration which was 10-to 1000-fold higher than that in jugular vein plasma between 15 and 45 days of gestation. Uterine lymph collected after cannulation of utero-ovarian ducts followed by ipsilateral ovariectomy had a progesterone value equivalent to that in plasma. Protein concentration in utero-ovarian and uterine lymph was between 85 and 90% of that of plasma, while Na concentration was slightly higher, and Cl concentration slightly lower than that of plasma. The concentration of K was similar in both biological fluids, confirming that tissue damage of cannulated vessels was negligible. Cell numbers in utero-ovarian and ovarian lymph were low (200 leucocytes/mm3) and consisted mostly of lymphocytes (>94%). These studies show that leucocytes in lymph are exposed to a high concentration of progesterone, and possibly other related steroids, in the utero\x=req-\ ovarian network which is adjacent to an ovary containing a corpus luteum.

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Section: Introductionsupporting

confidence: 64%

Anatomy of the utero-ovarian lymphatic network and the composition of afferent lymph in relation to the establishment of pregnancy in the sheep and goat

Staples¹,

Fleet²,

Heap³

1982

Reproduction

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“…At this stage of gestation the fetal cortisol concentration, which is the signal for parturition, is rising [5,8]. It has been suggested that cortisol of fetal origin may act on the placenta to promote production of estrogen or PGF 2␣ [2,4,5,14,16,17]. While estrogen has traditionally been thought to exert its luteolytic action via a stimulatory influence on PGF 2␣ , neither PGF 2␣ concentrations nor pulse frequency increased during this time.…”

Section: Discussionmentioning

confidence: 99%

Pulsatile Output of Prostaglandin F2α Does Not Increase Around the Time of Luteolysis in the Pregnant Goat1

Ford

Thorburn

Caddy

et al. 1999

Biology of Reproduction

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Prostaglandin (PG) F(2alpha) secreted from the uterus is the luteolysin of the estrous cycle and is also believed to be responsible for luteolysis in the pregnant doe at term. We have reported that basal progesterone concentrations decrease before basal PGF(2alpha) concentrations increase, which is inconsistent with this view. In this study we investigated whether luteolysis is associated with increased frequency or amplitude of pulsatile PGF(2alpha) secretion in does over the last 2 wk of gestation. Progesterone concentrations decreased approximately 1 wk before parturition. There was no accompanying increase in PGF(2alpha) concentrations or pulse frequency, and those pulses that were observed were of lesser amplitude and duration than those that have been associated with luteolysis in cycling ewes. A small increase in PGF(2alpha) pulse frequency was identified during the 3 days before parturition, but this was not associated with any change in progesterone concentrations. The biological significance of these small changes in PGF(2alpha) pulse frequency is obscure, although the high concentration of this eicosanoid at labor may have been related to the final, precipitous decline in plasma progesterone concentrations. These findings do not support the notion that PGF(2alpha) is the principal luteolysin in the pregnant doe at term.

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“…The caprine placenta secretes approximately 8-11% of the progesterone found in the maternal circulation close to term [38][39][40]. Accordingly, it has been suggested that the preparturient increase in fetal cortisol concentrations induces the placental enzymes 17ao-hydroxylase and 3-hydroxysteroid dehydrogenase [31,40], which would redirect progesterone metabolism away from 5p3-pregnanediol (the major secreted progesterone metabolite in this species) and toward estrogen production. The resultant increase in the E/P ratio may then stimulate uterine production of PGF 2 , resulting in luteolysis and a consequent decrease in luteal progesterone production.…”

Section: Discussionmentioning

confidence: 99%

“…The plasma progesterone pool receives its main input from the corpus luteum with a minor (approximately 8-11%) contribution from the placenta [38][39][40]. We therefore assume that the large changes observed in arterial progesterone concentrations broadly reflect changes in luteal function.…”

Section: Discussionmentioning

confidence: 99%

Fetal and Maternal Endocrine Changes Approaching Parturition in the Goat: Lack of Evidence for Prostaglandins E2 and F2α as Signals for Luteolysis1

Ford

Young

Caddy

et al. 1998

Biology of Reproduction

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We investigated the temporal relationship of fetal cortisol secretion to circulating concentrations of fetal ACTH1-39 and its high-molecular weight precursors in goats. We also measured the concentrations of progesterone, estradiol-17beta estrone sulfate, prostaglandin (PG) E, PGF2alpha, and PGF2alpha metabolite (PGFM) in maternal arterial plasma over the last month of gestation. Prostaglandin concentrations were also measured in utero-ovarian venous plasma. There was a positive association between ACTH1-39 in fetal plasma and the prepartum surge in fetal cortisol that commenced 8 days before labor. The fetal cortisol surge was followed by a simultaneous decrease in maternal progesterone and an increase in plasma estrogens commencing 3-4 days before labor. No change in basal prostaglandin concentration occurred before this time. There was a positive veno-arterial difference of PGE and PGF2alpha across the uterine vascular bed, confirming the uteroplacental unit as a major source of these eicosanoids in the plasma of the pregnant doe. We conclude that the fetal signal for parturition precedes luteolysis by some 5 days and find no evidence of changes in the basal concentrations of PGE and PGF2alpha in maternal plasma at the time of luteolysis.

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Placental production of progesterone in ovariectomized goats treated with a synthetic progestagen to maintain pregnancy

Cited by 29 publications

References 23 publications

Anatomy of the utero-ovarian lymphatic network and the composition of afferent lymph in relation to the establishment of pregnancy in the sheep and goat

Anatomy of the utero-ovarian lymphatic network and the composition of afferent lymph in relation to the establishment of pregnancy in the sheep and goat

Pulsatile Output of Prostaglandin F2α Does Not Increase Around the Time of Luteolysis in the Pregnant Goat1

Fetal and Maternal Endocrine Changes Approaching Parturition in the Goat: Lack of Evidence for Prostaglandins E2 and F2α as Signals for Luteolysis1

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