scholarly journals Cyclic changes in the responsiveness of regressing corpora lutea to the luteolytic effects of prolactin in rats

Reproduction ◽  
2001 ◽  
pp. 411-417 ◽  
Author(s):  
F Gaytan ◽  
C Bellido ◽  
C Morales ◽  
JE Sanchez-Criado
Keyword(s):  
Corpus Luteum ◽  
Fold Increase ◽  
Oestrous Cycle ◽  
Corpora Lutea ◽  
Apoptotic Cells ◽  
Experimental Conditions ◽  
Lytic Effect ◽  
Steroidogenic Cells ◽  
Cyclic Changes ◽  
Apoptotic Effects

In cyclic rats, apoptosis of luteal cells during structural luteolysis occurs cyclically at the transition from pro-oestrus to oestrus in response to the preovulatory prolactin surge. This finding indicates that cyclic changes in apoptosis during luteolysis are dependent on prolactin surge cyclicity. In this study, the effects of prolactin on structural luteolysis were studied under different experimental conditions in relation to the phase of the oestrous cycle. In rats treated with prolactin at metoestrus and dioestrus, apoptosis did not occur in regressing corpora lutea, whereas in rats treated with prolactin on the morning of pro-oestrus, a 12.3-fold and 3.4-fold increase were observed in the number of apoptotic cells in regressing corpora lutea of the current and previous oestrous cycles, respectively. However, when the preovulatory prolactin surge and hence the subsequent apoptotic burst were blocked, prolactin treatment at the dioestrus phase induced a 13-fold increase in the number of apoptotic cells and significant changes in the volume of the corpus luteum (38% decrease) and the number of steroidogenic cells per corpus luteum (70% decrease). The results of this study indicate that the responsiveness of the regressing corpus luteum to the pro-apoptotic effects of prolactin are dependent on the phase of the oestrous cycle and on the presence or absence of an apoptotic burst in response to the preovulatory prolactin surge on the evening of pro-oestrus. Steroidogenic cells surviving to the apoptotic burst during the transition from pro-oestrus to oestrus became refractory to the lytic effect of prolactin. Furthermore, these cells also responded to the luteotrophic effects of prolactin, reaching full morphological luteinization, as indicated by the rescue of regressing cyclic corpora lutea during pregnancy.

scholarly journals Progesterone on an oestrogen background enhances prolactin-induced apoptosis in regressing corpora lutea in the cyclic rat: possible involvement of luteal endothelial cell progesterone receptors

2000 ◽  
Vol 165 (3) ◽  
pp. 715-724 ◽  
Author(s):  
F Gaytan ◽  
C Morales ◽  
C Bellido ◽  
R Aguilar ◽  
Y Millan ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Corpus Luteum ◽  
Progesterone Receptors ◽  
Luteal Cell ◽  
Corpora Lutea ◽  
Apoptotic Cells ◽  
Lhrh Antagonist ◽  
Characteristic Features ◽  
Induced Apoptosis ◽  
Cyclic Changes

Preovulatory surges of both prolactin (PRL) and progesterone have been suggested to be necessary for the induction of apoptosis in the regressing corpus luteum of the cyclic rat. The aim of these experiments was to study whether the administration of PRL and/or progesterone on the morning of pro-oestrus reproduces the regressive changes that happen in the cyclic corpus luteum (CL) during the transition from pro-oestrus to oestrus, and to analyse the temporal relationships between two characteristic features of structural luteolysis (luteal cell apoptosis and accumulation of macrophages). Cyclic rats (treated at 0900 h with an LHRH antagonist to block LH secretion) were injected at 1000 h with PRL and progesterone and killed at 0, 30, 60, 90 and 180 min after treatment. The number of apoptotic cells increased progressively from 60 min after treatment onward in hormone-treated rats, whereas the number of macrophages did not change throughout the period of time considered. Rats injected with PRL plus progesterone showed significantly greater numbers of apoptotic cells than those injected with PRL alone. The luteolytic effects of progesterone were in keeping with the presence of luteal endothelial cells showing progesterone receptor (PR) immunoreactivity in pro-oestrus. Treatment of rats during dioestrus and pro-oestrus with the specific antioestrogens LY117018 and RU58668 decreased the luteolytic effects of PRL and progesterone and the number of luteal endothelial cells immunostained for PR. These results strongly suggest that the preovulatory PRL surge and the preovulatory increase in progesterone together trigger structural regression of the corpus luteum. This seems to be dependent on oestrogen-driven cyclic changes in PRs in luteal endothelial cells.

scholarly journals Immunohistological Localization and Expression of α-Actin in the Baboon (Papio anubis) Corpus Luteum

1997 ◽  
Vol 45 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Firyal S. Khan-Dawood ◽  
Jun Yang ◽  
M. Yusoff Dawood
Keyword(s):  
Corpus Luteum ◽  
Luteal Phase ◽  
Adherens Junctions ◽  
Tunica Albuginea ◽  
Corpora Lutea ◽  
Papio Anubis ◽  
Lh Surge ◽  
Luteal Cells ◽  
Steroidogenic Cells ◽  
E Cadherin

We have recently shown the presence of E-cadherin and of α- and γ-catenins in human and baboon corpora lutea. These are components of adherens junctions between cells. The cytoplasmic catenins link the cell membrane-associated cadherins to the actin-based cytoskeleton. This interaction is necessary for the functional activity of the E-cad-herins. Our aim therefore was to determine the presence of α-actin in the baboon corpus luteum, to further establish whether the necessary components for E-cadherin activity are present in this tissue. An antibody specific for the smooth muscle isoform of actin, α-actin, was used for these studies. The results using immunohistochemistry show that (a) α-actin is present in steroidogenic cells of the active corpus luteum, theca externa of the corpus luteum, cells of the vasculature, and the tunica albuginea surrounding the ovary. The intensity of immunoreactivity for α-actin varied, with the cells of the vasculature reacting more intensely than the luteal cells. A difference in intensity of immunoreactivity was also observed among the luteal cells, with the inner granulosa cells showing stronger immunoreactivity than the peripheral theca lutein cells. There was no detectable immunoreactivity in the steroidogenic cells of the atretic corpus luteum. However, in both the active and atretic corpora lutea, α-actin-positive vascular cells were dispersed within the tissue. (b) Total α-actin (luteal and non-luteal), as determined by Western blot analyses, does not change during the luteal phase and subsequent corpus luteum demise (atretic corpora lutea). (c) hCG stimulated the expression of α-actin and progesterone secretion by the early luteal phase (LH surge + 1–5 days) and midluteal phase (LH surge + 6–10 days) cells in culture, but only progesterone in the late luteal phase (LH surge + 11–15 days). The data show that α-actin is present in luteal cells and that its expression is regulated by hCG, thus suggesting that E-cadherin may form functional adherens junctions in the corpus luteum.

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.

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.

STEROID AND PROSTAGLANDIN SECRETION BY THE CORPUS LUTEUM, ENDOMETRIUM AND EMBRYOS OF CYCLIC AND PREGNANT PIGS

1979 ◽  
Vol 82 (3) ◽  
pp. 425-428 ◽  
Author(s):  
J. WATSON ◽  
C. E. PATEK
Keyword(s):  
Corpus Luteum ◽  
Late Stage ◽  
Oestrous Cycle ◽  
Corpora Lutea ◽  
Reproductive Tissues ◽  
Prostaglandin F

Prostaglandin F2α (PGF2α) secreted by the reproductive tissues of the pig in vitro was measured and it was found that the levels secreted by the corpus luteum and endometrium of early pregnant sows were significantly lower than those secreted by tissues during the late stage of the oestrous cycle. They were, however, comparable to levels secreted by tissues from the mid-stage of the oestrous cycle. Embryos also secreted significant amounts of PGF2α. Secretion of progesterone and oestradiol by the corpora lutea of both cyclic and pregnant pigs fell within accepted limits but embryos were also found to secrete significant amounts of oestradiol. The results suggest that luteal maintenance in the early pregnant pig is unlikely to be directly due to reduced synthesis of PGF2α.

EFFECT OF INTRA-UTERINE FOREIGN BODIES AND OF PROSTAGLANDIN ADMINISTRATION ON PROGESTERONE SECRETION DURING THE OESTROUS CYCLE OF THE GUINEA-PIG

1976 ◽  
Vol 70 (1) ◽  
pp. 39-45 ◽  
Author(s):  
F. R. BLATCHLEY ◽  
B. T. DONOVAN
Keyword(s):  
Guinea Pig ◽  
Corpus Luteum ◽  
Foreign Bodies ◽  
Glass Beads ◽  
Oestrous Cycle ◽  
Corpora Lutea ◽  
Blood Samples ◽  
Progesterone Secretion ◽  
Prostaglandin F

SUMMARY The response of the guinea-pig corpus luteum to the luteolytic influence of glass beads placed in the uterus, or to prostaglandin administration, was followed by assay of the progesterone content of blood samples collected daily. Following the introduction of glass beads into the uterus early in the cycle, the secretion of progesterone was curtailed. Treatment with prostaglandin F2α over days 4–6 or 6–8 of the cycle temporarily depressed progesterone release without shortening the life of the corpora lutea. When the drug was administered over days 8–10, 10–12 or 12–14 the depression in progesterone was not followed by any recovery. These observations indicate that the response of the corpora lutea to a luteolytic influence changes during the oestrous cycle.

THE EFFECT OF HYPOPHYSIAL STALK-SECTION ON THE CORPUS LUTEUM OF THE GUINEA-PIG

1971 ◽  
Vol 50 (4) ◽  
pp. 625-635 ◽  
Author(s):  
DOREEN V. ILLINGWORTH ◽  
J. S. PERRY
Keyword(s):  
Growth Rate ◽  
Guinea Pig ◽  
Corpus Luteum ◽  
Guinea Pigs ◽  
Oestrous Cycle ◽  
Corpora Lutea ◽  
Normal Cycle ◽  
Luteal Regression ◽  
Normal Regression ◽  
And Function

SUMMARY The effects of hypophysial stalk-section on the growth and function of the corpus luteum of the non-pregnant guinea-pig have been compared with the effects of hypophysectomy (as previously described) and with the effects of prolactin administered to hypophysectomized animals. Stalk-section soon after ovulation did not impair the growth of the corpora lutea nor their ability to secrete progesterone. Stalk-section before day 9 of the oestrous cycle prevented the normal regression of the corpora lutea; they continued to grow and 3 weeks after ovulation were as large as those of pregnant animals, or of non-pregnant hysterectomized guinea-pigs. The corpora lutea regressed irregularly during the following 2 weeks. When performed on, or later than day 9, stalk-section did not prevent luteal regression at the normal time. Administration of prolactin (10 i.u./day) to hypophysectomized guinea-pigs restored the growth-rate of the corpora lutea, which reached sizes comparable to those of the normal cycle, and those of stalk-sectioned animals, by 10 days after ovulation. Our results indicate that prolactin can have substantial luteotrophic activity in the guinea-pig.

Size distribution of steroidogenic and non-steroidogenic ovine luteal cells throughout pregnancy

2002 ◽  
Vol 75 (3) ◽  
pp. 427-432 ◽  
Author(s):  
Ş. Arikan ◽  
A. A. Yigit
Keyword(s):  
Corpus Luteum ◽  
Size Distribution ◽  
Early Stage ◽  
Wide Spectrum ◽  
Late Pregnancy ◽  
Corpora Lutea ◽  
Luteal Cells ◽  
Mean Diameter ◽  
The Mean ◽  
Steroidogenic Cells

AbstractThe present study examines the size distribution of ovine steroidogenic and non-steroidogenic luteal cells throughout pregnancy. Cells were isolated from corpora lutea collected from early (< 8 weeks), mid (9 to 14 weeks) or late (15 to 18 weeks) stages of pregnancy. Cells were stained for 3β-hydroxysteroid dehydrogenase (3β-HSD) activity, a marker for steroidogenic cells. Both 3β-HSD positive and β-HSD negative cells covered a wide spectrum of size ranging from 7 to 37 μm in diameter. There was a significant increase (P > 0·01) in mean diameter of non-steroidogenic luteal cells as pregnancy progressed. Mean diameter of 3β-HSD negative cells increased from 17·8 (s.e. 0·4) μm in the corpus luteum of early stage of pregnancy to 22·4 (s.e. 0·3) μm in the corpus luteum of advanced pregnancy. However, there was no significant increase in the mean diameter of 3β-HSD positive cells. Corpora lutea obtained from early stages of the pregnancy contained more steroidogenic cells than the cells obtained from mid and late pregnancy (P < 0·01). Percentage of 3β-HSD negative cells had increased 2·07-fold by 18 weeks of pregnancy when compared with the early stage of pregnancy. In contrast, percentage of 3β-HSD positive cells had decreased to 50% of starting values during the same period (P < 0·05). These results indicate that the ovine corpus luteum of pregnancy is morphologically dynamic over the course of pregnancy. Steroidogenic activity of luteal cells may decrease as pregnancy progresses, especially activity of the large luteal cells.

scholarly journals Cloning of pig prostaglandin F2alphaFP receptor cDNA and expression of its mRNA in the corpora lutea

Reproduction ◽  
2003 ◽  
pp. 53-64 ◽  
Author(s):  
U Boonyaprakob ◽  
JE Gadsby ◽  
V Hedgpeth ◽  
P Routh ◽  
GW Almond
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Oestrous Cycle ◽  
Small Cells ◽  
Predicted Amino Acid Sequence ◽  
Corpora Lutea ◽  
Reading Frame ◽  
Luteal Tissue ◽  
Fp Receptor ◽  
Steroidogenic Cells

Changes in the expression and localization of luteal mRNA for PGF(2alpha) (FP) receptors may be critical in determining the luteolytic action of PGF(2alpha) in pig corpora lutea. In this study, a full-length FP receptor (FPr) cDNA was isolated and cloned from pig corpora lutea. This isolate (GenBank accession no. U91520) contains an open reading frame of 1086 bases coding for a protein of 362 amino acids with seven potential transmembrane domains. The predicted amino acid sequence of this isolate was 83% identical to the FPr amino acid sequence of other species including sheep, cattle and humans. Northern blot analysis showed the presence of an FPr message of about 5 kb in mRNA from pig corpora lutea. Relatively weak FPr mRNA expression was detected on day 4 and day 7 of the oestrous cycle. The expression was greater (P < 0.05) on days 10, 13 and 15 than on days 4 and 7. In situ hybridization analysis revealed that mRNA for FPr was expressed predominantly in the steroidogenic large luteal subtype of cell, although there was some expression in small luteal cells, with histological appearance of steroidogenic small cells. Localization of hybridization signals of FPr was observed in luteal tissue at all stages examined. These data demonstrate that FPr is expressed in pig corpora lutea throughout the oestrous cycle and that upregulation of the FPr mRNA occurs when the corpora lutea becomes sensitive to PGF(2alpha). Direct luteal targets of PGF(2alpha) appear to be primarily large steroidogenic cells in this species.

CYTOCHROME P-450 ACTIVITY IN SHEEP CORPORA LUTEA DURING THE OESTROUS CYCLE

1973 ◽  
Vol 58 (3) ◽  
pp. 493-501 ◽  
Author(s):  
E. R. SIMPSON ◽  
C. R. JEFCOATE ◽  
R. A. COLLETT ◽  
R. B. LAND
Keyword(s):  
Corpus Luteum ◽  
Oestrous Cycle ◽  
Corpora Lutea ◽  
Mitochondrial Cytochrome ◽  
Specific Content ◽  
Substrate Complex ◽  
Chain Cleavage ◽  
Binding Spectra ◽  
Two Parameters ◽  
Cytochrome P 450

SUMMARY Cytochrome P-450 of mitochondria from the ovine corpus luteum was examined on different days throughout the oestrous cycle. Most, if not all, of the mitochondrial cytochrome P-450 appeared to be of the type involved in cholesterol side-chain cleavage, as determined by steroid binding spectra. The content of mitochondrial cytochrome P-450 in the corpus luteum changed considerably throughout the cycle, and closely paralleled the rise and fall of plasma progesterone concentration; the correlation between these two parameters was 0·96. This was largely a reflection of the changes in weight of the corpus luteum throughout the cycle, since the specific content of cytochrome P-450 changed much less dramatically. The percentage of the mitochondrial cytochrome P-450 present as the cholesterol—substrate complex remained constant throughout the cycle at about 25–30% of the total.

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