Activation by Corticosteroids of Steroid Metabolizing Enzymes in Ovine Placental Explants in Vitro

Ricketts, A. P.; Galil, Aharon; Ackland, Nicola; Heap, R. B.; Flint, A. P. F.

doi:10.1677/joe.0.0850457

Cited by 39 publications

(20 citation statements)

References 16 publications

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“…Progesterone was measured in lymph and plasma by the radioimmunoassay procedure described by Ricketts, Galil, Ackland, Heap & Flint (1980). Progesterone was extracted from 50 pi appropriately diluted lymph or plasma by shaking for 10 min with 5 ml petroleum ether (b.p.…”

Section: Introductionmentioning

confidence: 99%

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

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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: Introductionmentioning

confidence: 99%

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

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“…Oestrogens were characterized by recrystallization to constant specific radioactivity, or by the formation of derivatives (oestrone 3-monoacetate and oestradiol-3,17-diacetate) followed by re-chromatography. The techniques of acetylation, hydrolysis, chromatography and counting of radioactivity have been described elsewhere (Challis et al, 1973;Ricketts et al, 1980 (Kidder, Casida & Grummer, 1955;Gardner, First & Casida, 1963;Frank, Bazer, Thatcher & Wilcox, 1977). It has been proposed that a mechanism by which blastocyst oestrogen production may prolong luteal function in early pregnancy may involve a redirection of uterine prostaglandin (PG) secretion away from uterine venous blood towards the uterine lumen, thereby protecting the corpus luteum from the luteolytic effect of PGF-2a .…”

Section: Introductionmentioning

confidence: 99%

Oestrogen production by blastocyst and early embryonic tissue of various species

Gadsby¹,

Heap²,

Burton³

1980

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138

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“…Increasing cortisol stimulates the conversion of androgen to oestrogen in the placenta which triggers uterine contractility, governing the initiation of labour (Flint et al, 1975;Ricketts et al, 1980;Leung et al, 1999;Jenkin and Young, 2004). Prostaglandins are also an important component of labour as they contribute to cervical ripening, fetal maturation (along with cortisol), expression of uterine oxytocin receptors, etc.…”

mentioning

confidence: 99%

Synchronisation of lambing with low doses of dexamethasone in Chios ewes — Short communication

Tsiligianni¹,

Ntovolou

Amiridis

2008

Acta Veterinaria Hungarica

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The purpose of the present study was to investigate the feasibility of improving the synchronisation of lambing after oestrus synchronisation and artificial insemination (AI). To this end, low doses of dexamethasone 21-isonicotinate (DEX) alone or in combination with prostaglandin F 2a (PG) were used in five treated groups (n = 20 each) and one control group (n = 136) of Chios ewes. On day 143 of pregnancy 1.5 mg DEX was given in Group 5, while on day 146 the following treatments were applied: 0.0375 mg PG in Groups 4 and 5, and 1, 1.5 and 2 mg of DEX in ewes of Groups 1, 2 and 3, respectively. The control ewes received no treatment. The 1.5 and 2 mg dose of DEX was more effective in synchronising labour as regards the treatment to lambing interval and the proportion of ewes that gave birth within 3 days. However, obstetrical manipulations were needed, and dead lambs were born when 2 mg DEX was used. It was concluded that lambing can be safely synchronised in Chios ewes with 1.5 mg DEX given on day 146, without affecting the viability of lambs and without parturition complications. Key words: Synchronisation of lambing, dexamethasone, prostaglandinsSynchronising parturitions and consequently shortening the lambing period would be of economic benefit for sheep producers (better management of newborn lambs and the pre-and postpartum ewe, eradication of maedi-visna on the basis of the artificial feeding of newborn lambs) and could improve the welfare of the stock.

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Activation by Corticosteroids of Steroid Metabolizing Enzymes in Ovine Placental Explants in Vitro

Cited by 39 publications

References 16 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

Oestrogen production by blastocyst and early embryonic tissue of various species

Synchronisation of lambing with low doses of dexamethasone in Chios ewes — Short communication

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