Faculty Opinions recommendation of Plasma progesterone secretion during gestation of the captive short-beaked echidna.

ABSTRACT Progesterone was determined and identified in human peripheral blood during the preovulatory period of the menstrual cycle, by combined isotope derivative and recrystallization analysis. The mean concentration of progesterone in 1.095 ml of plasma obtained 9 days before ovulation was 0.084 μg/100 ml. However, the mean concentration of progesterone in 1.122 ml of plasma obtained 4 days before ovulation was 0.279 μg/100 ml. These data demonstrate a source of progesterone secretion other than the corpus luteum. The higher plasma-progesterone concentration 4 days before ovulation may indicate progesterone secretion of the ripening Graafian follicle of the ovary.

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Delayed effect of low progesterone concentrations on bovine uterine PGF(2alpha) secretion in the subsequent oestrous cycle

Reproduction ◽

10.1530/rep.0.1220643 ◽

2001 ◽

pp. 643-648 ◽

Cited By ~ 32

Author(s):

A Shaham-Albalancy ◽

Y Folman ◽

M Kaim ◽

M Rosenberg ◽

D Wolfenson

Keyword(s):

Corpus Luteum ◽

Luteal Phase ◽

Oestrous Cycle ◽

Delayed Effect ◽

Plasma Progesterone ◽

Progesterone Secretion ◽

Progesterone Treatment ◽

Late Luteal Phase ◽

Subsequent Cycle ◽

Concentration Curves

Low progesterone concentrations during the bovine oestrous cycle induce enhanced responsiveness to oxytocin challenge late in the luteal phase of the same cycle. The delayed effect of low progesterone concentrations during one oestrous cycle on uterine PGF(2alpha) secretion after oxytocin challenge on day 15 or 16 of the subsequent cycle was studied by measuring the concentrations of the major PGF(2alpha) metabolite (13,14-dihydro-15-keto PGF(2alpha); PGFM) in plasma. Two experiments were conducted, differing in the type of progesterone treatment and in the shape of the low progesterone concentration curves. In Expt 1, progesterone supplementation with intravaginal progesterone inserts, with or without an active corpus luteum, was used to obtain high, or low and constant plasma progesterone concentrations, respectively. In Expt 2, untreated cows, representing high progesterone treatment, were compared with cows that had low but increasing plasma progesterone concentrations that were achieved by manipulating endogenous progesterone secretion of the corpus luteum. Neither experiment revealed any differences in plasma progesterone concentrations between the high and low progesterone groups in the subsequent oestrous cycle. In both experiments, both groups had similar basal concentrations of PGFM on day 15 (Expt 1) or 16 (Expt 2) of the subsequent oestrous cycle, 18 days after progesterone treatments had ended. In both experiments, the increases in PGFM concentrations in the low progesterone groups after an oxytocin challenge were markedly higher than in the high progesterone groups. These results indicate that low progesterone concentrations during an oestrous cycle have a delayed stimulatory effect on uterine responsiveness to oxytocin during the late luteal phase of the subsequent cycle. This resulting increase in PGF(2alpha) secretion may interfere with luteal maintenance during the early stages of pregnancy.

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PLASMA PROGESTERONE LEVELS IN GUINEA-PIGS ACTIVELY IMMUNIZED AGAINST PROSTAGLANDIN F2α, HYSTERECTOMIZED OR TREATED WITH INTRA-UTERINE INDOMETHACIN

Journal of Endocrinology ◽

10.1677/joe.0.0670081 ◽

1975 ◽

Vol 67 (1) ◽

pp. 81-88 ◽

Cited By ~ 15

Author(s):

N. L. POYSER ◽

E. W. HORTON

Keyword(s):

Bovine Serum Albumin ◽

Serum Albumin ◽

Guinea Pigs ◽

Bovine Serum ◽

Prostaglandin F2α ◽

Corpora Lutea ◽

Plasma Progesterone ◽

Progesterone Secretion ◽

Bovine Serum Albumin Conjugate ◽

Prostaglandin F

SUMMARY Five guinea-pigs actively immunized against a prostaglandin F2α(PGF2α)–bovine serum albumin conjugate showed elongated oestrous cycles. During these, corpora lutea were maintained in a functional secretory state as indicated by plasma progesterone levels. The results are compatible with the view that the PGF2α antibodies neutralized the PGF2α released from the uterus and thus prevented its normal luteolytic effect. Similar patterns of progesterone secretion were observed in two hysterectomized animals and in two animals with intra-uterine implants of indomethacin.

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Hypokalemia alters sex hormone and gonadotropin levels: evidence that FSH may be required for luteinization

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1998.275.6.e1037 ◽

1998 ◽

Vol 275 (6) ◽

pp. E1037-E1045

Author(s):

Francisco Tejada ◽

Asunción Cremades ◽

Manuel Avilés ◽

Maria T. Castells ◽

Rafael Peñafiel

Keyword(s):

Luteinizing Hormone ◽

Follicle Stimulating Hormone ◽

Combined Treatment ◽

Gonadotropin Releasing Hormone ◽

Sex Hormone ◽

Plasma Progesterone ◽

Progesterone Secretion ◽

Potassium Gradient ◽

Deficient Mice ◽

Estradiol Levels

Hypokalemia produced different effects on steroid sex hormone concentrations in plasma and ovary in the mouse. Estradiol levels were slightly increased, whereas circulating progesterone was markedly decreased in all estrous periods. The preovulatory surge of gonadotropins and the secondary surge of follicle-stimulating hormone (FSH) at estrus were also decreased, but basal levels of both gonadotropins were unaffected. Supplementation with luteinizing hormone (LH), FSH, or gonadotropin-releasing hormone (GnRH) at proestrus rapidly normalized plasma and ovarian progesterone levels at this stage of the estrous cycle. Plasma progesterone levels at diestrus were restored only by combined treatment, at the periovulatory stage, with LH and FSH or GnRH but not by LH or FSH alone. The results demonstrate a lack of steroidogenic activity in the corpus luteum of the potassium-deficient mice and, furthermore, that FSH plays an important role in luteinization in the hypokalemic mice. We conclude that alteration of the transcellular potassium gradient may affect the regulation of the periovulatory surge of gonadotropins and progesterone secretion, probably by altering the release of GnRH from the hypothalamus. In addition, the results suggest that FSH may play a certain role as a luteotropic hormone in mice.

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Effect of melatonin on the peripheral concentrations of LH and progesterone after oestrus, and on conception rate in ewes

Journal of Endocrinology ◽

10.1677/joe.0.1190523 ◽

1988 ◽

Vol 119 (3) ◽

pp. 523-530 ◽

Cited By ~ 25

Author(s):

J. M. Wallace ◽

J. J. Robinson ◽

S. Wigzell ◽

R. P. Aitken

Keyword(s):

Breeding Season ◽

Pulse Generator ◽

Ovulation Rate ◽

Melatonin Treatment ◽

Embryo Survival ◽

Plasma Progesterone ◽

Progesterone Secretion ◽

Endocrine Status ◽

Increased Activity ◽

Intra Uterine Insemination

ABSTRACT It has previously been shown that administration of the indoleamine melatonin to advance the breeding season of ewes is also associated with an increase in ovulation rate and subsequent litter size. Experiment 1 assessed whether, in ewes receiving melatonin to advance the breeding season, the indoleamine acts directly on the corpus luteum to enhance progesterone secretion or indirectly through increased activity of the hypothalamic pulse generator. Six ewes received 3 mg melatonin orally at 15.00 h daily from 22 March onwards, six were induced to ovulate during mid-anoestrus following withdrawal of a progestagen pessary and injection of exogenous gonadotrophin and six acted as naturally ovulating controls. First overt oestrus occurred between 17 May and 8 July in melatonin-treated ewes, between 21 October and 3 January in control ewes and on 8 July in all induced ewes. On days 2 and 10 after the first overt oestrus, melatonin-treated ewes had pulsatile LH activity characteristic of that measured in control ewes ovulating naturally during the breeding season. There was an absence of any pulsatile LH activity in the induced ewes. Progesterone concentrations between days 7 and 12 following oestrus were significantly higher in melatonin-treated than in control and induced ewes, suggesting a luteotrophic role for melatonin. Experiment 2 was carried out to determine whether administration of melatonin commencing after induced ovulation and insemination would alter the endocrine status of the ewe and thereby influence the establishment of pregnancy and embryo survival. Thirty-two anoestrous ewes were induced to ovulate on 29 June. Starting 24 h after intra-uterine insemination, 16 ewes were given melatonin daily for 60 days and 16 acted as controls. Daily LH concentrations were higher in melatonin-treated than in control ewes from days 2 to 22 after oestrus, while prolactin concentrations declined in melatonin-treated ewes over the same period. Plasma progesterone concentrations were enhanced in melatonin-treated ewes between days 4 and 9 following oestrus, yet ovulation rates were the same as for controls. Successful pregnancies occurred in 0·56 control (9 of 16) and 0·69 melatonin-treated (11 of 16) ewes. For these ewes the number of fetuses surviving to term as a proportion of ovulation rate was 0·43 and 0·51 for the control and melatonin treatment respectively. J. Endocr. (1988) 119, 523–530

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Attenuation of preovulatory gonadotrophin surges by epostane: a new inhibitor of 3β-hydroxysteroid dehydrogenase

Journal of Endocrinology ◽

10.1677/joe.0.1180059 ◽

1988 ◽

Vol 118 (1) ◽

pp. 59-68 ◽

Cited By ~ 22

Author(s):

L. V. DePaolo

Keyword(s):

Peak Plasma ◽

Plasma Concentrations ◽

Hydroxysteroid Dehydrogenase ◽

Inhibitory Effects ◽

Plasma Progesterone ◽

Ru 486 ◽

Progesterone Secretion ◽

Progesterone Antagonist

ABSTRACT Epostane, an inhibitor of 3β-hydroxysteroid dehydrogenase, was administered orally to pro-oestrous rats to evaluate further a possible role for preovulatory progesterone secretion in eliciting surges of LH and FSH. Whereas a dose of 10 mg epostane/kg had essentially no effects on preovulatory gonadotrophin surges and ovulation, 200 mg epostane/kg markedly attenuated LH and FSH surges and blocked ovulation. A dose of 50 mg epostane/kg exerted effects on LH and FSH surges and ovulation intermediate between those of doses of 10 and 200 mg/kg. Plasma concentrations of progesterone were significantly lower in all anovulatory epostane-treated rats at 18.00 and 22.00 h on pro-oestrus than those measured in vehicle-treated rats. Concurrent injection of 2 mg progesterone in rats given 200 mg epostane/kg restored gonadotrophin surges to normal, but consistently failed to reverse the inhibitory effects of epostane on ovulation. Peak plasma progesterone levels produced by the progesterone injections were eight- to tenfold higher than the highest levels measured in vehicle-treated rats during the afternoon of pro-oestrus. Insertion of progesterone capsules was less effective than injections of progesterone in restoring gonadotrophin surges to normal, even though peak plasma progesterone concentrations achieved after insertion of two 20 mm long progesterone capsules were double the peak progesterone concentrations measured in control rats. Nevertheless, taken together with recent reports showing attenuation of preovulatory gonadotrophin surges by the progesterone antagonist RU 486 (17β-hydroxy-11β-[4-dimethyl-aminophenyl]-17α-[prop-1-ynl]estra-4,9-diene-3-one), the present results provide support for a role of preovulatory progesterone secretion in enhancing oestrogen-dependent LH/FSH surges on pro-oestrus. J. Endocr. (1988) 118, 59–68

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Inhibition of progesterone secretion by a 3β-hydroxysteroid dehydrogenase inhibitor in late pregnant sheep

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y85-024 ◽

1985 ◽

Vol 63 (2) ◽

pp. 136-142 ◽

Cited By ~ 18

Author(s):

Graham Jenkin ◽

Geoffrey D. Thorburn

Keyword(s):

Hydroxysteroid Dehydrogenase ◽

Placental Lactogen ◽

Plasma Progesterone ◽

Progesterone Secretion ◽

Pregnant Sheep ◽

Plasma Estradiol ◽

Prostaglandin F ◽

Essential Prerequisite ◽

Estradiol 17Β

The role of progesterone in the initiation of parturition in the sheep is unclear. Whether a decrease in plasma progesterone is the essential prerequisite for the initiation of parturition or whether other factors also maintain uterine quiescence until delivery is not known. The effect of withdrawal of progesterone on the initiation of parturition has been investigated by intravenous administration of trilostane, a 3β-hydroxysteroid dehydrogenase Δ5−4 isomerase inhibitor, to late pregnant sheep. Twenty-five or 100 mg trilostane caused a precipitous decrease in plasma progesterone to about 30% of preinjection levels. Progesterone remained depressed for up to 7 days after treatment. 13,14-Dihydro-15-keto-prostaglandin F2α (PGFM) became elevated between 7 and 36 h after trilostane injection but gradually returned to preinjection levels during the subsequent 36 h, at a time when plasma progesterone was still depressed. Four of 11 animals treated with 100 or 200 mg trilostane aborted prematurely at a time when plasma PGFM was maximal and plasma progesterone minimal. There were no consistent changes in plasma estradiol-17β or ovine placental lactogen concentrations after treatment with trilostane. It is suggested that a decrease in plasma progesterone will cause a transient increase in plasma PGFM concentrations which can lead to the premature initiation of parturition. In some instances the myometrium does not appear to respond to the elevated PGFM concentrations even when the estrogen:progesterone ratio is elevated by a decrease in plasma progesterone.

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Relationship between plasma leptin concentration and reproductive function in dairy cows

Proceedings of the British Society of Animal Science ◽

10.1017/s175275620000658x ◽

2002 ◽

Vol 2002 ◽

pp. 2-2 ◽

Cited By ~ 1

Author(s):

GE Mann ◽

D Blache

Keyword(s):

Dairy Cows ◽

Post Partum ◽

Plasma Concentrations ◽

Reproductive Function ◽

Progesterone Concentration ◽

Metabolic Demand ◽

Plasma Progesterone ◽

Progesterone Secretion ◽

High Incidence ◽

Plasma Leptin

In modern dairy cows, poor fertility is an ever-increasing problem. Milk progesterone analysis has revealed that this poor fertility is associated with a high incidence of reproductive cycle problems during the post partum period and with reduced progesterone secretion following mating. One of the likely causes of these problems is the increasing metabolic demand placed on these cows by increasing milk yield. In recent years, the search for an endocrine link between nutritional status and reproductive function has focussed on leptin. The aim of the present study was to determine whether plasma concentrations of leptin differ between cows with and without post partum reproductive problems and to determine if any relationship exists between plasma leptin and post mating plasma progesterone concentration.

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CHANGES IN CONCENTRATIONS OF FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE, PROLACTIN AND PROGESTERONE IN THE PLASMA OF EWES DURING THE TRANSITION FROM ANOESTRUS TO BREEDING ACTIVITY

Journal of Endocrinology ◽

10.1677/joe.0.0750127 ◽

1977 ◽

Vol 75 (1) ◽

pp. 127-136 ◽

Cited By ~ 61

Author(s):

J. S. WALTON ◽

JUDITH R. McNEILLY ◽

A. S. McNEILLY ◽

F. J. CUNNINGHAM

Keyword(s):

Follicle Stimulating Hormone ◽

Plasma Concentrations ◽

Cyclic Activity ◽

Plasma Progesterone ◽

Progesterone Secretion ◽

Group A ◽

High Concentrations ◽

Group B ◽

Short Days

The plasma concentrations of FSH, LH, prolactin and progesterone were measured throughout anoestrus and during the resumption of cyclic activity in two groups of ewes. Group A was maintained under conditions of natural daylength throughout the experiment, whereas Group B was exposed to 6 h of light and 18 h of darkness, the change being made abruptly on the longest day. In those ewes kept on short days, oestrus and ovulation occurred 18·3 days (P < 0·05) and 23·4 days (P < 0·001) earlier than in the ewes under conditions of natural daylength. Ovulation preceded oestrus by 18·6 days and 23·1 days in Groups A and B respectively. The occurrence of ovulation was detected by the determination of plasma progesterone concentrations. In all ewes, progesterone levels were basal until the first ovulation when the pattern of secretion was typical of that seen during the oestrous cycle. In the 4 days before ovulation, the plasma progesterone concentration increased slowly to reach a maximum of 0·66 ± 0·12 (s.e.m.) ng/ml on day − 1. The first ovulation was associated with a substantial surge of LH. Similar release of LH, thought to be related to the increased progesterone secretion, was also observed on day −5. Sporadic release of LH was also found before this time in some animals. Plasma concentrations of FSH fluctuated randomly throughout anoestrus and during the transition to established oestrous cycles. These changes were not apparently related to ovulation. Throughout anoestrus, prolactin concentrations were raised but always declined before the time of ovulation. The fall in prolactin concentrations occurred sooner in the ewes on short days, pointing to a relationship with the decreased daylength. These data suggest that the return to oestrous cycles may be brought about by the removal of an antigonadotrophic effect exerted by high concentrations of prolactin in the blood during anoestrus.

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