DISTRIBUTION OF OESTRONE AND OESTRADIOL-17β IN SOW OVARIES

1963 ◽  
Vol 44 (4) ◽  
pp. 529-535 ◽  
Author(s):  
Torleiv Lunaas
Keyword(s):  
Follicular Fluid ◽  
Luteal Phase ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Corpora Lutea ◽  
Luteal Tissue ◽  
Low Levels ◽  
The Absolute ◽  
Residual Tissue ◽  
Highly Correlated

ABSTRACT The contents of oestrone and oestradiol-17β were estimated in component parts of sow ovaries representative of the follicular and luteal phase of the oestrous cycle and also in whole juvenile ovaries. The values obtained of the sum total oestrone and oestradiol-17β in the follicular fluid and in the corresponding residual tissue were highly correlated. The proportions of oestradiol-17β tended to be larger in the follicular fluid than in the tissue (mean percentage: 84.3 and 69.6 respectively). In ovaries from the luteal phase of the oestrous cycle the oestrogen levels were generally lower than in ovaries from the follicular phase. Whereas no difference was found between the very low levels of oestrone in the corpora lutea and in the remainder of the ovary containing small follicles, the levels of oestradiol-17β differed significantly, being lower in the luteal tissue. Within each category of ovaries the absolute levels of the oestrogens were very variable. The results are discussed in relation to the pattern of urinary oestrone excretion in the sow during the oestrous cycle.

Source of ovarian inhibin secretion during the oestrous cycle of the sheep

1989 ◽  
Vol 123 (2) ◽  
pp. 181-188 ◽  
Author(s):  
G. E. Mann ◽  
A. S. McNeilly ◽  
D. T. Baird
Keyword(s):  
Corpus Luteum ◽  
Luteal Phase ◽  
Venous Blood ◽  
Contralateral Side ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Secretion Rate ◽  
Antral Follicles ◽  
Luteal Tissue

ABSTRACT The source of inhibin secretion by the ovary in the sheep at different stages of the oestrous cycle was investigated by in-vivo cannulation of the ovarian veins. Twenty-four Scottish Blackface ewes were allocated to four groups of six ewes, i.e. those operated on during the luteal phase (day 10), and those operated on during the follicular phase 24–30, 36 and 60 h following an injection of 125 μg cloprostenol on day 10 of the luteal phase. Samples of jugular and timed ovarian venous blood were collected under anaesthesia before and after enucleation of the corpus luteum. Ovaries were then removed and follicles dissected out. Following injection of cloprostenol, luteal regression occurred as indicated by a fall in the secretion of progesterone. The concentration of inhibin in jugular venous plasma and its ovarian secretion rate were similar at all stages of the follicular phase and during the luteal phase. In contrast, the secretion rate of oestradiol rose from 2·68 ±0·73 pmol/min during the luteal phase to 8·70± 2·24 pmol/min 24 h after injection of cloprostenol (P<0·05). Following enucleation of the corpus luteum the secretion rate of progesterone fell from 809 ± 270 pmol/min to 86 ± 30 pmol/min (P<0·001). There was also a smaller, artifactual fall in the secretion rate of oestradiol following enucleation of the corpus luteum, which was of similar size to a fall seen in the secretion rate of inhibin. This resulted in a significant (P<0·001) fall in the ratio of progesterone to inhibin, while the oestradiol to inhibin ratio remained unchanged. The secretion rate of inhibin from ovaries containing luteal tissue was similar to that from the contralateral side without luteal tissue (1·41±0·30 compared with 1·32±0·30 ng/min), while ovaries with large antral follicles secreted significantly (P< 0·001) more inhibin than those with no follicles ≥3 mm (2·28 ± 0·36 compared with 0·25 ±0·06 ng/min). From these results we conclude that, in the sheep, large antral follicles are responsible for most, if not all, the secretion of inhibin by the ovary at all stages of the oestrous cycle, and that the corpus luteum secretes little or no immunoactive or bioactive inhibin. Due to the fact that, unlike inhibin, the secretion rate of oestradiol rises during the follicular phase of the cycle, when the concentration of FSH is suppressed, it seems likely that oestradiol rather than inhibin is the major ovarian factor modulating the change in FSH secretion seen at this stage of the oestrous cycle. Journal of Endocrinology (1989) 123, 181–188

Changes in the secretion of LH pulses, FSH and prolactin during the preovulatory phase of the oestrous cycle of the ewe and the influence of treatment with bovine follicular fluid during the luteal phase

1988 ◽  
Vol 116 (1) ◽  
pp. 123-135 ◽  
Author(s):  
J. M. Wallace ◽  
G. B. Martin ◽  
A. S. McNeilly
Keyword(s):  
Follicular Fluid ◽  
Luteal Phase ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Ovarian Follicles ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Ovulation Rate ◽  
The Other ◽  
Lh Secretion

ABSTRACT It has previously been shown that treatment of ewes with bovine follicular fluid (bFF) throughout the luteal phase of the oestrous cycle lowers plasma levels of FSH but increases the frequency and amplitude of the pulses of LH. Under these conditions, ovarian follicles grow to a maximum diameter of 2·7 mm and have a reduced capacity to release oestradiol. We have examined the nature of the gonadotrophin signals controlling follicular development in the normally cycling ewe and have investigated the effects of previous exposure to bFF on these signals and the follicular responses to them. Control ewes (n = l) were injected i.v. with 9 ml bovine serum and treated ewes were injected with 9 ml bFF, twice daily from days 1 to 10 of the luteal phase (day 0 = oestrus). The ewes were injected with prostaglandin analogue on day 11 of the cycle to induce luteolysis and the gonadotrophin patterns were studied in blood sampled from these animals every 10 min for up to 72 h during the subsequent follicular phase. Following luteolysis (and the end of bFF treatment), LH pulse frequency increased rapidly in both groups and reached 1 pulse/h within 6 h. Thereafter, pulse frequency increased marginally and reached 1 pulse/50 min by the onset of the LH surge. This pattern was not affected by previous treatment with bFF. In the control ewes, the amplitude of the LH pulses did not change significantly following luteolysis or at any time during the follicular phase, while the levels of FSH declined slowly until the onset of the surge. In the treated ewes, on the other hand, there was an immediate increase in both LH pulse amplitude and the concentration of FSH immediately after the end of bFF treatment at luteolysis, and they remained above control levels for 24 and 16 h respectively. Plasma prolactin levels did not appear to change around the time of luteolysis but showed a marked and significant diurnal rhythm (nadir around noon and peak around midnight) in both groups. The concentrations of prolactin were significantly (P<0·001) lower and the preovulatory peak was delayed and reduced in the bFF-treated ewes relative to controls. The onset of oestrus was also significantly (P<0·01) delayed by bFF treatment, but the ovulation rates did not differ between the groups. Furthermore, comparisons within or between groups revealed no significant relationships between any of the variables of plasma LH secretion during the follicular phase and the subsequent ovulation rate. These observations provide a complete description of gonadotrophin patterns during the follicular phase of the ewe and confirm the suggestion that an increase in LH pulse frequency is the major driving force behind the follicular growth that ultimately leads to ovulation. On the other hand, it appears most unlikely that the pattern of LH secretion during the follicular phase has any influence on ovulation rate. The levels of FSH declined in the period leading up to the preovulatory surge, presumably as a consequence of rising peripheral levels of oestrogen (and/or inhibin). We also expected LH pulse amplitude to decline during the follicular phase because it has been proposed that pulse amplitude is also controlled by oestrogen. The absence of any significant fall in amplitude suggests that hypotheses about the control of LH secretion drawn from studies with ovariectomized ewes require further verification in the intact ewe. The effect of bFF on prolactin levels probably reflects the low rates of secretion of oestradiol by the small ovarian follicles in these ewes. J. Endocr. (1988) 116, 123–135

THE SHEEP CORPUS LUTEUM SECRETES INHIBIN

1988 ◽  
Vol 116 (3) ◽  
pp. R3-R5 ◽  
Author(s):  
C. G. Tsonis ◽  
D. T. Baird ◽  
B. K. Campbell ◽  
R. Leask ◽  
R. J. Scaramuzzi
Keyword(s):  
Corpus Luteum ◽  
Luteal Phase ◽  
Venous Blood ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Luteal Tissue ◽  
Two Stages

ABSTRACT An experiment was performed in 20 Merino ewes in which ovarian venous blood was collected by venepuncture at surgery and at two stages of the oestrous cycle. The ovarian venous concentrations of inhibin, oestradiol-17β and progesterone were determined. The results demonstrate that during the luteal phase of the oestrous cycle the ovarian venous blood draining an ovary containing luteal tissue contains significantly more inhibin bioactivity than ovarian venous blood from an ovary not containing luteal tissue. During the follicular phase the concentration of inhibin bioactivity in ovarian venous blood was reduced compared with the luteal phase. From this data we conclude that the sheep corpus luteum secretes inhibin bioactivity into the ovarian venous blood.

Seasonal and steroid-dependent effects on the modulation of LH secretion in the ewe by intracerebroventricularly administered β-endorphin or naloxone

1989 ◽  
Vol 122 (2) ◽  
pp. 509-517 ◽  
Author(s):  
R. J. E. Horton ◽  
H. Francis ◽  
I. J. Clarke
Keyword(s):  
Breeding Season ◽  
Luteal Phase ◽  
Pulse Frequency ◽  
Opioid Peptide ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Opioid Antagonist ◽  
Endogenous Opioid ◽  
Endogenous Opioid Peptide ◽  
Lh Secretion

ABSTRACT The natural opioid ligand, β-endorphin, and the opioid antagonist, naloxone, were administered intracerebroventricularly (i.c.v.) to evaluate effects on LH secretion in ovariectomized ewes and in ovariectomized ewes treated with oestradiol-17β plus progesterone either during the breeding season or the anoestrous season. Ovary-intact ewes were also studied during the follicular phase of the oestrous cycle. Jugular blood samples were taken at 10-min intervals for 8 h and either saline (20–50 μl), 100 μg naloxone or 10 μg β-endorphin were injected i.c.v. after 4 h. In addition, luteal phase ewes were injected i.c.v. with 25 μg β-endorphin(1–27), a purported endogenous opioid antagonist. In ovariectomized ewes, irrespective of season, saline and naloxone did not affect LH secretion, but β-endorphin decreased the plasma LH concentrations, by reducing LH pulse frequency. The effect of β-endorphin was blocked by administering naloxone 30 min beforehand. Treating ovariectomized ewes with oestradiol-17β plus progesterone during the breeding season reduced plasma LH concentrations from 6–8 μg/l to less than 1 μg/l. In these ewes, saline did not alter LH secretion, but naloxone increased LH pulse frequency and the plasma concentrations of LH within 15–20 min. During anoestrus, the combination of oestradiol-17β plus progesterone to ovariectomized ewes reduced the plasma LH concentrations from 3–5 μg/l to undetectable levels, and neither saline nor naloxone affected LH secretion. During the follicular phase of the oestrous cycle, naloxone enhanced LH pulse frequency, which resulted in increased plasma LH concentrations; saline had no effect. In these sheep, β-endorphin decreased LH pulse frequency and the mean concentrations of LH, and this effect was prevented by the previous administration of naloxone. The i.c.v. administration of β-endorphin(1–27) to luteal phase ewes did not affect LH secretion. These data demonstrate the ability of a naturally occurring opioid peptide to inhibit LH secretion in ewes during the breeding and non-breeding seasons, irrespective of the gonadal steroid background. In contrast, whilst the gonadal steroids suppress LH secretion in ovariectomized ewes during both seasons, they only appear to activate endogenous opioid peptide (EOP)-mediated inhibition of LH secretion during the breeding season. Furthermore, these data support the notion that LH secretion in ovariectomized ewes is not normally under the control of EOP, so that naloxone has no effect. Journal of Endocrinology (1989) 122, 509–517

Protein kinase C in uterine and systemic arteries during ovarian cycle and pregnancy

1991 ◽  
Vol 260 (3) ◽  
pp. E464-E470 ◽  
Author(s):  
R. R. Magness ◽  
C. R. Rosenfeld ◽  
B. R. Carr
Keyword(s):  
Blood Flow ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Luteal Phase ◽  
Follicular Phase ◽  
Ovarian Cycle ◽  
Corpora Lutea ◽  
Kinase C ◽  
Estrogen Production ◽  
Systemic Artery

Elevated uterine blood flow is associated with increases in local estrogen-to-progesterone ratios during the follicular phase of the ovarian cycle and late pregnancy. Because protein kinase C (PKC) activation increases arterial tone, decreased PKC activity may mediate vasodilation. Therefore, we determined uterine (UA) and systemic artery (SA, omental) PKC activity (pmol.mg protein-1.min-1) during the follicular (n = 6), early luteal (n = 4), and late luteal (n = 3) phases of the sheep ovarian cycle, and at 110 +/- 3 (n = 4) and 130 +/- 1 (n = 8) (+/- SE) days of ovine gestation. The stage of the ovarian cycle was verified by the presence of follicles (high estrogen) or corpora lutea (high progesterone) on the ovary and by plasma estrogen and progesterone concentrations. UA-PKC activity (pmol.mg protein-1.min-1) during the follicular phase was 100 +/- 18 and increased progressively to 155 +/- 28 during the early luteal phase and to 219 +/- 37 (P less than 0.05) during the late luteal phase; SA-PKC activity was unchanged. A local utero-ovarian relationship was observed, i.e., UA-PKC activity was lower (P less than 0.001) in UA ipsilateral to ovaries with only follicles (105 +/- 14) when compared with UA adjacent to ovaries with corpora lutea (224 +/- 26), which was similar to SA-PKC activity (184 +/- 35). UA-PKC activity fell from 344 +/- 70 at 110 days to 109 +/- 12 at 130 days gestation (P less than 0.05); SA-PKC activity was unchanged. During the ovarian cycle and latter one-third of ovine pregnancy, increased estrogen production is associated with decreased UA-PKC activity; thus local ovarian and placental steroids may alter PKC activity, thereby regulating UA tone and blood flow.

A comparative study of the corpus luteum

1995 ◽  
Vol 7 (3) ◽  
pp. 303 ◽  
Author(s):  
RT Gemmell
Keyword(s):  
Corpus Luteum ◽  
Luteal Phase ◽  
Secretory Granules ◽  
Hormonal Control ◽  
Egg Laying ◽  
Oestrous Cycle ◽  
Corpora Lutea ◽  
Embryonic Diapause ◽  
Alternative Reproductive Strategy ◽  
Uterine Development

The corpus luteum (CL) is a transitory organ which has a regulatory role in reproduction. Sharks, amphibians and reptiles have corpora lutea that produce progesterone which influences the rate of embryonic development. The egg-laying monotremes and the two major mammalian groups, eutherian and marsupial, have a CL that secretes progesterone. Most eutherians have allowed for the uterine development of their young by extending the length of the oestrous cycle and the CL or placenta actively secretes progesterone until birth. Gestation in the marsupial does not extend beyond the length of an oestrous cycle and the major part of fetal development takes place in the pouch. Where the extension of the post-luteal phase in the eutherian has allowed for the uterine development of young, the marsupial has extended the pre-luteal phase of the oestrous cycle and has evolved an alternative reproductive strategy, embryonic diapause. The mechanism for the secretion of hormones from the CL has been controversial for many years. Densely-staining secretory granules have been observed in the CL of sharks, marsupials and eutherians. These granules have been reported to contain relaxin, oxytocin or mesotocin, and progesterone. A hypothesis to suit all available data is that all hormones secreted by the CL are transported within such granules. In conclusion, although there are obvious differences in the mode of reproduction in the two main mammalian groups, it is apparent that there is a great deal of similarity in the hormonal control of regression of the CL and parturition.

Aromatase activity in the mare ovary during estrous cycle. Measurement of endogenous steroids and of their in vitro inhibitory effect

1993 ◽  
Vol 129 (6) ◽  
pp. 536-542 ◽  
Author(s):  
Hakima Amri ◽  
Pierre Silberzahn ◽  
Ihsan Al-Timimi ◽  
Jean-Luc Gaillard
Keyword(s):  
Follicular Fluid ◽  
Luteal Phase ◽  
Physiological Role ◽  
Inhibitory Effect ◽  
Aromatase Activity ◽  
Estrogen Production ◽  
Estrogen Synthesis ◽  
Luteal Tissue ◽  
Endogenous Steroids

This present study was undertaken to clarify estrogen synthesis in the mare ovary. First of all, an evaluation of endogenous steroid contents was carried out in the follicular fluid and in the luteal tissue at different stages of the luteal phase. Radioimmunoassays were performed after separation and purification of each hormone by chromatography. High amounts of conjugated (0.9 mg/l) and unconjugated (4 mg/l) estradiol-17β were found in the follicular fluid of the large follicules (50 mm). These concentrations of estrogens decreased drasticaly in the luteal tissue, and only low levels of circulating estrogens are found during the luteal phase. On the other hand, a high aromatization ability has been evidenced in the cyclic corpus luteum in vitro. In an attempt to clarify the regulation of estrogen synthesis, we have tested the inhibitory effect of several endogenous steroids on equine ovarian aromatase activity. 5α-Dihydrotestosterone appeared to be the most potent competitive inhibitor (Ki= 181 nmol/l) of aromatase activity, while the addition of a 3-sulfate group induced a slump in the inhibitory potency of estrone (Ki= 397 nmol/l vs 2206 nmol/l) and dehydroepiandrosterone (Ki = 291 nmol/l vs 6157 nmol/l). The physiological role of these conjugated steroids has not been known until now; we suggest that they would play a role in protecting aromatase from inhibition, in vivo. The high amounts of progesterone found in the luteal tissue (1.3 g/kg of proteins) might play a role in the regulation of estrogen production either by suppressing the induction of aromatase synthesis or by inhibiting the activity of the enzyme complex.

CHANGES IN THE DENSITY AND PROGESTERONE CONTENT OF LUTEAL TISSUE IN THE EGYPTIAN BUFFALO DURING THE OESTROUS CYCLE

1967 ◽  
Vol 39 (2) ◽  
pp. 163-171 ◽  
Author(s):  
A. S. EL-SHEIKH ◽  
FRANÇOIS B. SAKLA ◽  
SAFAA O. AMIN
Keyword(s):  
Corpus Luteum ◽  
Cell Volume ◽  
Distribution System ◽  
Oestrous Cycle ◽  
Luteal Cell ◽  
Corpora Lutea ◽  
Luteal Cells ◽  
Functional Changes ◽  
Parallel Increase ◽  
Luteal Tissue

SUMMARY The histological and functional changes of 31 corpora lutea of Egyptian buffaloes during the various phases of the oestrous cycle were studied. The volumes of the corpora lutea were calculated, the volume per cell, the cell volume and the volume of the intercellular spaces were estimated from transverse serial sections stained with haematoxylin and eosin, Mallory's triple stain or van Gieson's stain. The nuclear volumes were also determined and the cytoplasmic volume was calculated. The progesterone content was estimated using column absorption chromatography and a counter-current distribution system. It was concluded that the luteal cells increase both in volume and in number due to mitosis. The luteal cells decrease in volume after the 15th day after ovulation, the cells lose their distinct outlines in the regressive stage and disappear completely in the corpus albicans. There was a parallel increase in luteal cell volume and progesterone content until the 15th post-ovulatory day followed by a decrease in the regressive phase and disappearance of the hormone in the corpus albicans. A highly significant correlation (r = +0·875) was found between the progesterone content and the cytoplasmic volume. Progesterone concentration/g. luteal tissue increased from the corpus haemorrhagicum to the mature corpus luteum, decreased in the regressive corpus luteum and completely disappeared in the corpus albicans.

Studies of the luteinization process in the rat: follicular and luteal adenylate cyclase responsiveness to catecholamines

1987 ◽  
Vol 114 (2) ◽  
pp. 171-177 ◽  
Author(s):  
Gunnar Selstam ◽  
Ensio Norjavaara ◽  
Sten Rosberg ◽  
Knut Nordenström ◽  
Jan-Erik Damber ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Luteal Phase ◽  
Follicular Phase ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Significant Response ◽  
Corpora Lutea ◽  
Preovulatory Follicles ◽  
The Subject ◽  
Catecholamine Responsiveness

Abstract. The subject of the study was the development of follicular and luteal catecholamine responsiveness during the periovulatory period. Follicles and corpora lutea and granulosa cells were obtained from the PMSG ovulatory model and adenylate cyclase activity measured in membrane fractions. In the earlier part of the follicular phase (48 h and 26 h before ovulation) no response to noradrenalin on follicular and granulosa cell adenylate cyclase activity was seen. A small but significant response to noradrenalin was observed from 18 h before until 3 h after ovulation. The response to noradrenalin on luteal adenylate cyclase activity increased markedly with time and reached a maximum 39–57 h after ovulation. After this time the luteal response to noradrenalin decreased with luteal age. The effect of LH was less than that of noradrenalin during the early luteal phase, and in contrast to noradrenalin, increased with luteal age. The combined effects of LH and noradrenalin were not additive. In order to test whether gonadotropins could induce a noradrenalin response, injections of LH and FSH were given to the animals two days before ovulation. LH, but not FSH, induced a small but significant response to noradrenalin 16 h later. The present investigation has shown that ovarian responsiveness to catecholamines appears in preovulatory follicles followed by a marked increase in luteal catecholamine responsiveness. This development could at least partly occur under the influence of LH.

scholarly journals Effect of ram introduction on the oestrous cycle of springbok ewes (Antidorcas marsupialis)

Reproduction ◽  
2002 ◽  
pp. 509-513 ◽  
Author(s):  
DC Skinner ◽  
SD Cilliers ◽  
JD Skinner
Keyword(s):  
Maximum Concentration ◽  
Luteal Phase ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Arid Environments ◽  
Wild Ungulates ◽  
Plasma Progesterone ◽  
Before And After ◽  
Antidorcas Marsupialis

Springbok are aseasonally breeding wild ungulates that inhabit arid environments, and interest has been shown in domesticating them for agricultural purposes. The present study was conducted for husbandry purposes to determine the effect of introducing a vasectomized ram to an isolated herd of springbok ewes (n = 9). Blood was collected from ewes every third day, before and after introduction of a vasectomized ram. Ewes were subjected to the ram for 42 days. Plasma progesterone was measured by radioimmunoassay and was used to establish the stage of the oestrous cycle. After introduction of the ram, the variation in the timing of the follicular phase between ewes was clearly reduced, compressing the spread of oestrus in the springbok ewes from 11 to 3 days. In seven of the nine ewes, the ram was introduced during the luteal phase of the oestrous cycle, causing this cycle to be significantly longer in duration (P < 0.05) and to have a higher maximum concentration of progesterone (P < 0.001) than cycles before and after introduction of the ram. This finding implies that the mechanism of synchronization operates through a luteotrophic effect. These results indicate that rams may be used successfully to synchronize breeding in springbok.

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