Is there a link between plasma progesterone 1-2 days before frozen embryo transfers (FET) and ART outcomes in frozen blastocyst transfers?

OBJECTIVE

To study the efficacy of combined administration of subcutaneous and vaginal progesterone for priming frozen blastocysts transfers, looking at progesterone levels and ART outcome.

DESIGN

Retrospective study.

SETTING PATIENTS

Three hundred and twenty frozen blastocyst transfer cycles conducted in 213 women aged up to 42 years, BMI between 18 and 30 kg/m², with anatomically normal uterus who underwent frozen embryo transfers (FETs) from February 2019 to December 2019 with a combined luteal-phase support (LPS) associating subcutaneous and vaginal progesterone. Patients with recurrent pregnancy loss (RPL) were excluded.

RESULTS

When using combined vaginal and subcutaneous LPS, SPL >10.50 ng/mL in 95% of cases, with a minimum value of 7.02 ng/mL. CPR, OPR, and global miscarriage rates were 38.4%, 30.9%, and 19.5%, respectively. Analyzing results per quartiles, revealed that miscarriage rates were significantly inferior, and IR were higher in the upper two quartiles of serum progesterone (>21.95 ng/mL) on the day before FET, while there was no difference in CPR and OPR.

CONCLUSIONS

We report ART outcome of frozen blastocyst transfers performed using a combination of vaginal and subcutaneous progesterone for LPS. ART results were honorable and SPL favorable 1-2 days before FET in 99% of cases.

Clinical comparison of ovarian stimulation and luteal support agents in patients undergoing GnRH antagonist IVF cycles

OBJECTIVE

To explore the comparative efficacy, safety, and tolerability of agents used for ovarian stimulation and luteal support when applied in a population of women undergoing in vitro fertilization (IVF) using a gonadotropin-releasing hormone (GnRH) antagonist protocol.

STUDY DESIGN

A phase 4, multicenter, randomized, open-label, exploratory clinical trial was performed at 7 assisted reproductive technology centers in the United States. Subjects included 173 women aged 18-42 years with a documented history of infertility who were undergoing IVF. Subjects were randomized to treatment with highly purified human menopausal gonadotropin (HP-hMG) or recombinant human follicle-stimulating hormone (rhFSH) for ovarian stimulation and progesterone vaginal inserts (PVIs) or intramuscular injection of progesterone in oil (PIO) for luteal support. Protocols for IVF followed the standard practices of participating centers within the parameters of the study.

RESULTS

Biochemical, clinical, and ongoing pregnancy rates were the main outcome measures. Ongoing pregnancy rates for individual treatment groups ranged from 44.0-46.9%. No statistically significant differences were observed in pregnancy outcomes for the comparisons of HP-hMG vs. rhFSH or PVI vs. PIO. All study medications were generally safe and well tolerated.

CONCLUSION

In this study HP-hMG and rhFSH were equally effective for ovarian stimulation during GnRH antagonist IVF cycles. Both PVI and PIO are viable options for luteal support.

[Mexican National Consensus on Assisted Reproduction Treatment]

BACKGROUND

It is estimated that 15% of couples living in industrialized countries are infertile, ie have failed to conceive, reproductive age, after 12 months ormore of regular intercourse without contraception. During the past decade has increased the demand for fertility treatments because they believe are moreeffective now.

OBJECTIVE

To unify the therapeutic approach and service to patients and set a precedent for a Mexican Official Standard respect and support for the legislation of these procedures.

METHOD

Consensus by technical experts group panel with the participation of 34 national centers accredited for use in assisted reproduction. He organized seven workshops with the following themes: 1) selection of patients for assisted reproduction treatment, 2) schemes controlled ovarian stimulation for assisted reproduction techniques of high complexity, 3) preparation and egg retrieval technique, 4) transferembryo; 5) luteal phase supplementation; 6) indications and techniques of cryopreservation and 7) informed consent. Each table had a coordinator who wrote and presented the findings to the full, it made a number of observations until they reached unanimity of criteria, which are reflected in this document.

RESULTS

Patient selection for assisted reproduction techniques is the first step of the process. Proper selection lead to success, in the same way that a bad pick up for failure. In the case of egg donation the most important recommendation is that only one to two embryos transferred in order to reduce multiple pregnancy rates and maintaining high pregnancy rates.

Complex expression patterns support potential roles for maternally derived activins in the establishment of pregnancy in mouse

Maternal-fetal communications are critical for the establishment of pregnancy. Embryonic growth and differentiation factors produced by the oviduct and uterus play essential roles during the pre- and early post-implantation phases. Although several studies indicate roles for activin in embryonic development, gene-knockout studies have failed to identify a critical role in mammalian embryogenesis. We hypothesized that activin is produced by maternal tissues during the establishment of pregnancy, and thus maternally derived activin could compensate for the absence of embryonic activin in null homozygotes during critical developmental stages. We investigated the expression of inhibin alpha, activin betaA, and betaB subunits in the mouse oviduct and uterus during the estrous cycle and early pregnancy, and in the early conceptus. Inhibin alpha subunit was weakly expressed, while activin betaA and betaB subunits were strongly expressed in oviduct and uterus at estrous, and dramatically upregulated in the uterus on each day of pregnancy between days 3.5 and 8.5 post coitum. Prior to implantation, activin betaA and betaB subunits were immunolocalized to oviductal and uterine epithelial cells; following implantation they were expressed in the stroma, in a wave preceding decidualization. Later in pregnancy, activin betaA and betaB subunits were present in decidua basalis, trophoblast giant cells, and labyrinth zone of the developing placenta. Expression of activin betaA subunit was also detected in blastocysts and early post-implantation embryos. These data are consistent with a role for maternally derived activins in the support of the pre-implantation embryo, and during gastrulation and embryogenesis.

Beneficial effects of a high fibre diet on oocyte maturity and embryo survival in gilts

The present study examined the effects of feeding gilts a high fibre diet from the third post-pubertal oestrus until either day 19 of the same cycle or insemination at the following oestrus on oocyte maturity, embryo survival and associated changes in reproductive hormone concentrations. Gilts fed with the high fibre diet had lower circulating oestradiol concentrations on days 17, 18 and 19 of the cycle and increased LH pulse frequency on day 18. More oocytes recovered on day 19 from gilts receiving the high fibre diet were at metaphase II after 46-h culture in medium containing 10% of their own follicular fluid, despite fewer large (>7 mm) follicles in these gilts when compared with control animals. There was no effect of diet on ovulation rate, corpora lutea size or progesterone concentrations on days 10–12 after insemination, but embryo survival on days 27–29 after insemination was higher in gilts that received the high fibre diet. This study demonstrates that a high fibre diet that increases embryo survival also improves oocyte maturity and provides information on endocrine correlates that may shed light on underlying mechanisms.

Antioxidant enzymatic defence systems in sheep corpus luteum throughout pregnancy

The activities of copper, zinc-superoxide dismutase (SOD1), manganese SOD (SOD2), glutathione peroxidase (GPX), glutathione reductase (GSSG-R) and glutathione S-transferase (GST) were studied in sheep corpora lutea (CL) obtained on days 15, 40, 60, 80 and 128 of pregnancy. Maintained enzymatic activity of SOD1, SOD2, GPX, GSSG-R and GST were found in the sheep CL throughout pregnancy. Enzymatic activity of SOD1, GPX and GST increased significantly from day 15 to day 40 of pregnancy, and thereafter remained constant until day 128. SOD2 and GSSG-R activities were not different between any days of pregnancy examined. Apoptotic luteal cells identified by the terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick-end labelling were very rarely observed, and their incidence (less than 0.5%) was not different between days of pregnancy. These results showed that the activities of antioxidant enzymes in the sheep CL are subject to major changes during early pregnancy, suggesting that the CL of early pregnancy may be rescued from luteolysis through increasing activities of key antioxidant enzymes and inhibition of apoptosis. Maintained levels of antioxidant enzymes in the CL throughout pregnancy may be linked to reactive oxygen species continuously generated in the steroidogenically active luteal cells, and may be involved in the maintenance of luteal steroidogenic activity and cellular integrity.

Persistence of anti-zonae pellucidae antibodies following a single inoculation of porcine zonae pellucidae in the domestic equine

In this study of equids, we investigated the antibody response and the effect on the estrous cycle following a single inoculation of porcine zonae pellucidae (pZP) employing controlled-release methodology. We also investigated the use of two different water-soluble adjuvants as an alternative to oil-based adjuvants. Twenty-seven domestic mares were inoculated with various formulations of pZP and adjuvant. We showed that the anti-pZP antibodies generated as a result of the inoculations persisted for at least 43 weeks (length of the study). Of the various formulations used in the study, pZP and QS-21 water-soluble adjuvant, administered in combination with an emulsified preparation of pZP and Freund’s Complete Adjuvant generated a significantly (P < 0.05) higher titer of anti-pZP antibodies when compared with other formulations employing the water-soluble adjuvant, Carbopol. Hormone analyses for cyclicity indicated a high incidence and extended duration of persistent corpora lutea among the treated mares. The positive control group of mares receiving two standard inoculations of pZP and Freund’s Complete and Incomplete Adjuvants, as well as the placebo group of mares injected with QS-21 only, also exhibited high incidences of persistent corpora lutea. However, all mares eventually returned to normal cyclicity. The basis for the high incidence and extended duration of persistent corpora lutea was unexplained. The results demonstrate for the first time the persistent generation of anti-pZP antibodies following a single inoculation of pZP incorporated into a controlled-released preparation in the horse. This study further suggests that a single inoculation of pZP sequestered in a controlled-release lactide-glycolide polymer may serve as an alternative to traditional two-inoculation protocols for contraception investigations in the equine.

Alpha B-crystallin in corpora lutea of pseudopregnant rat

Localization sites and labeling intensity of alphaB-crystallin in corpus luteum (CL) of pseudopregnant rats has been studied using postembedding light and electron microscopical immunohistochemistry. At days 2 and 18 alphaB-crystallin labeling was found to be significantly higher compared with the luteal maintenance period (days 6 and 10). alphaB-crystallin localized both to luteal and interstitial cells of CL. At light microscopical level alphaB-crystallin labeling decreased during CL life span in the central area of luteal cells cytoplasm and increased in the peri-plasmalemmal area. Interstitial cells labeling was found to increase at day 6, followed by almost complete disappearance during functional luteolysis (days 15 and 18). Our results at electron microscopical level showed alphaB-crystallin to localize in cytoplasm with close relationship with endoplasmic reticulum, Golgi apparatus, mitochondria and also in nuclei of luteal and interstitial cells. At day 2 labeling of luteal cells was abundant in cytoplasm but weak in nuclei. During the luteal maintenance period and functional luteolysis labeling in luteal cells was relocalized to the peri-plasmalemmal and perinuclear areas. Labeling in nuclei of luteal cells was weak. At the same time (day 6) interstitial cells including nuclei showed strong labeling, which was significantly decreased during luteolysis. Immunohistochemically detectable tubulin decreased in CL tissue during CL life span allowing to suggest that alphaB-crystallin acts as chaperone, one possible role of which is to stabilize the cytoskeleton in different CL cell types during CL formation and active functioning.

Prostaglandin E(2) and F(2 alpha) production by equine conceptuses and concentrations in conceptus fluids and uterine flushings recovered from early pregnant and dioestrous mares

A growing equine conceptus must suppress the cyclical release of PGF(2 alpha) from the endometrium to effect maternal recognition of its presence in the uterus. Paradoxically, the conceptus itself secretes PGF(2 alpha), together with other prostaglandins. In this study, the PGF(2 alpha) and PGE(2) content of, and production in vitro by, day 10-32 equine conceptuses were measured and the influence of pregnancy on the concentrations of these prostaglandins in the uterine lumen was examined. In vitro, the release of both prostaglandins per mg conceptus tissue was very high on day 10 after ovulation and lower thereafter. However, while PGF(2 alpha) production decreased further after day 18 of gestation, PGE(2) production remained high until day 32. Prostaglandin concentrations in yolk sac fluid were unaffected by gestational age and PGE(2) concentrations in this compartment were two to five times higher than PGF(2a) concentrations. PGF(2 alpha) concentrations reached high values in uterine flushings recovered from cyclic mares during days 14-16 after ovulation, the expected time of luteolysis, but were negligible in flushings recovered from pregnant mares at this time. Beyond day 18 of gestation, PGF(2 alpha) concentrations in uterine flushings were high and strikingly similar to those recorded during cyclical luteolysis. It is concluded that the equine conceptus effects maternal recognition of pregnancy primarily by inhibiting the ability of the endometrium to release PGF(2 alpha) during days 12-16 after ovulation. However, the conceptus appears to delay, rather than prevent, the development of the uterine PGF(2 alpha) release pathway and an alternative mechanism must prevent luteolysis from being triggered during days 18-32 of gestation.

Role of growth hormone in development and maintenance of follicles and corpora lutea

Growth hormone (GH) is a pituitary hormone that affects animal growth, metabolism, lactation, and reproduction. Many of the effects of GH are mediated by insulin-like growth factor I (IGF-I) which is synthesized in liver and ovary in response to GH. Insulin-like growth factor I synergizes with gonadotrophins (LH and FSH) to stimulate growth and differentiation of ovarian cells. There are species differences in the effects of GH in reproductive biology. In most species, ovarian follicles and corpora lutea are potential sites for GH action because the GH receptor is found within granulosal cells as well as corpora lutea. However, growth hormone does not control ovarian IGF-I in all species and, in ruminants, endocrine IGF-I from liver may be the principal mediator of GH action. In cattle, administration of GH increases the number of small antral ovarian follicles but does not increase the number of large antral (dominant) follicles. Growth hormone may antagonize some aspects of dominant follicular function because dominant follicles are shorter-lived in GH-treated cattle. The corpora lutea has increased growth and steroidogenesis in response to GH. Growth hormone-induced steroidogenesis in cultured granulosal and luteal cells depends on IGF-I release after GH treatment. Bovine and ovine granulosal cells do not release IGF-I in response to GH in vitro and, therefore, are less responsive to GH. These results demonstrate that GH is required for normal reproductive function in ruminant as well as nonruminant species.

Growth and development of the corpus luteum

The mammalian corpus luteum, which plays a central role in the reproductive process because of its production of hormones such as progesterone, is an exceptionally dynamic organ. Growth and development of the corpus luteum are extremely rapid, and even when the corpus luteum is functionally mature cellular turnover remains high. Associated with this high rate of cell turnover, the mature corpus luteum receives the greatest blood supply per unit tissue of any organ, and also exhibits a relatively high metabolic rate. Central to the growth and development of the corpus luteum, therefore, is luteal vascular growth, which appears to be regulated primarily by the angiogenic growth factors, basic fibroblast growth factor and vascular endothelial growth factor. In addition, the corpus luteum is a complex tissue composed of parenchymal (small and large steroidogenic) and nonparenchymal (for example fibroblasts, vascular smooth muscle, pericytes and endothelial) cells. Recent studies evaluating the expression, location and regulation of gap junctions in the corpus luteum indicate an important role of gap junctional intercellular communication in the coordination of function among these diverse cell types during luteal growth and development. These studies will lead to an improved understanding not only of luteal function but also of tissue growth and development in general.

Relationship between different stages of the corpus luteum and the expression of the peroxisome proliferator-activated receptor gamma protein in bovine large lutein cells

Lutein cells produce progestins that support pregnancy. Steroidogenesis requires coordination of the anabolic and catabolic pathways of lipid metabolism. Peroxisome proliferator-activated receptors (PPAR) are transcription factors that are central in the regulation of lipid metabolism. Hence, they may play a role in regulation of the development and regression of the corpus luteum. The present study investigated the expression of PPAR-gamma, n during different stages of the corpus luteum. Lutein cells were isolated mechanically from non-pregnant and pregnant heifers on days 5, 12 and 20 of the oestrous cycle (n = 3 for each day). PPAR-gamma in single cells was analysed by flow cytometry. PPAR-gamma 1 and PPAR-gamma 2 isoforms were distinguished by immunoblotting. The cell cycle of the lutein cells was measured by the flow cytometric quantification of DNA in single cells, using propidium iodide staining after ethanol fixation and RNAse treatment, and by the detection of the proliferating cell nuclear antigen (PCNA). The response of the cells to PPAR-gamma agonist 15-deoxy-delta 12,14 prostaglandin J2 (15dPGJ2, 200 and 490 nmol l-1) with and without changing the cell cycle by the anti-apoptogenic drug aurintricarboxylic acid (ATA, 10 mumol l-1) was used as an in vitro model to study the relationship between the cell cycle and PPAR-gamma. The concentration of PPAR-gamma per cell from non-pregnant heifers was significantly higher on day 5 (3.40 +/- 0.30 fmol) compared with that on day 12 (1.34 +/- 0.18 fmol, P < 0.05) and day 20 (0.55 +/- 0.2 fmol, P < 0.05). In pregnant heifers, the concentration of PPAR-gamma was significantly (P < 0.01) higher than in non-pregnant heifers. A decrease in the PPAR-gamma 1 isoform relative to PPAR-gamma 2 was observed in cells on day 12 of the oestrous cycle compared with day 5. The cell cycle (S phase portion in cells on days 5, 12 and 20: 16 +/- 4%, 6 +/- 4% and 4 +/- 3%, respectively) and the portion of cells with PCNA correlated with the amount of PPAR-gamma in non-pregnant heifers. ATA promoted the S phase in cells of non-pregnant heifers (day 12) and the endogenous agonist of PPAR-gamma, 15dPGJ2, inhibited the response to ATA in a dose-dependent manner, indicating that PPAR-gamma plays a role in the arrest of the cell cycle in lutein cells to maintain their differentiated state.

Pregnancy, parturition, and lactation in hypophyseal stalk-transected beef heifers

Progesterone secretion is crucial for maintaining pregnancy to parturition in mammalian species, and in cattle the corpus luteum is the primary source of this hormone. This study determined the roles of prolactin (PRL), growth hormone (GH) and luteinizing hormone (LH) in the luteotropic process in beef heifers hypophyseal stalk-transected (HST, n=7) or sham operated (sham operated controls, SOC, n=9) during midgestation. The main finding was that endogenous PRL and GH maintained progesterone secretion in HST heifers in a similar manner to that in SOC throughout pregnancy. Serum PRL averaged 37 vs 187 and GH 2 vs 4 ng/ml in HST heifers compared with SOC, whereas LH abruptly decreased to undetectable levels after HST compared with a modest 0.4 ng/ml in SOC heifers. The second finding was that parturition and lactation occurred in HST heifers with calf delivery induced to occur at the same time as SOC. Milk production in HST animals was severely limited, and postpartum estrus obliterated compared with SOC. The suckling stimulus sustained milk ejection in HST heifers in spite of diminished PRL, GH, thyroid stimulating hormone, thyroxine and tri-iodothyronine secretion. The results suggest that PRL, GH and possibly placental lactogen are luteotropic during pregnancy in cattle.

Source and site of action of anti-luteolytic interferon in red deer (Cervus elaphus): possible involvement of extra-ovarian oxytocin secretion in maternal recognition of pregnancy

Six conceptuses were collected from red deer hinds on day 22 after synchronization of oestrus with intravaginal progesterone-releasing devices (removal of device = day 0). Within 24 h of culture in vitro, the supernatant from five of six conceptuses showed detectable antiviral activity. Interferon alpha (IFN-alpha) receptors were identified by immunohistochemistry on the luminal surface of the endometrium, in the neurohypophysis and paraventricular hypothalamus, but not in the ovaries of the hinds from which the conceptuses were collected. Another 16 intact hinds were synchronized as above. Injection of 4 mg IFN i.m. twice a day on days 13-15 had no effect on cloprostenol-induced oxytocin secretion on day 15 and did not prevent cloprostenol-induced luteal regression. Sixteen ovariectomized hinds received a protocol of steroid treatment to mimic ovarian hormone secretion during the normal oestrous cycle. On day 16, hinds showed undulant oxytocin secretion that showed a degree of temporal association with uterine PGF2 alpha release. Treatment with 4 mg IFN-alpha I 1 twice a day on days 13-16 had no effect on this spontaneous oxytocin secretion, but reduced the magnitude of cloprostenol-induced oxytocin secretion on day 17 (P < 0.05). These results indicate that red deer conceptuses secrete an anti-luteolytic IFN to which the endometrium expresses a receptor during early pregnancy. The presence of IFN receptors in the hypothalamus and posterior pituitary and the IFN-induced suppression of extra-ovarian oxytocin secretion provides tentative evidence of an involvement of the central nervous system in maternal recognition of pregnancy in deer.

The effect of luteal "rescue" on the expression and localization of matrix metalloproteinases and their tissue inhibitors in the human corpus luteum

Luteolysis is associated with tissue remodeling probably involving the matrix metalloproteinases (MMPs) and their specific tissue inhibitors (TIMPs). This study investigated the expression and localization of the major MMPs and TIMPs in the human corpus luteum throughout the luteal phase and after luteal rescue with hCG. Corpora lutea (n = 9) were collected at hysterectomy and were dated by serial urinary LH estimation. In addition, corpora lutea (n = 3) were collected from women who had received daily doubling doses of hCG to mimic the hormonal changes of early pregnancy. MMP-1, MMP-2, MMP-9, TIMP-1, TIMP-2, and TIMP-3 were investigated by zymography, reverse zymography, Northern blotting, and in situ hybridization. There was no change in the expression of MMP-1, TIMP-1, and TIMP-2 throughout the luteal phase or after luteal rescue. Little TIMP-3 could be detected in the corpus luteum. MMP-9 activity peaked in the early and late luteal phase. The expression and activity of MMP-2 were maximal in the late luteal phase. Exposure to hCG during luteal rescue in vivo was associated with a reduction (P < 0.05) in the expression and activity of MMP-2. Messenger ribonucleic acids (mRNAs) for MMP-1, MMP-2, and TIMP-2 were localized to the connective tissue stroma and the thecal-lutein cells of the corpus luteum. In contrast, TIMP-1 mRNA was localized to the granulosa-lutein cells, and MMP-9 mRNA was expressed in scattered cells within the steroidogenic and nonsteroidogenic cell layers. In conclusion, during maternal recognition of pregnancy, hCG prevents the normal increase in MMP-2 in the late luteal phase. MMPs can function in an environment containing large amounts of TIMP-1, as they have a different cellular localization.

[Expression of transforming growth factor-alpha and myc oncoprotein in the human ovary during follicular growth, atresia and corpus luteum formation regression]

OBJECTIVE

To investigate the expression of transforming growth factor (TGF)-alpha and myc oncoprotein on human follicular development and atresia in vitro.

METHODS

Ovarian tissues were obtained from 36 women with regular menstrual cycles who underwent abdominal hysterectomy for a variety of gynecological conditions. Expression of TGF-alpha and myc protein in the ovarian tissues was examined by immunohistochemical technique.

RESULTS

In primordial follicale only the oocyte showed intense immunostaining for both TGF-alpha and myc oncoprotein. Immunostaining for TGF-alpha in granulosa cells and theca interna cells became apparent in the follicles of preantral stage. With the increase in the size of follicles the intensity of immunostaining in the oocyte decreased, whereas the staining intensity of the granulosa and theca cells increased, and persisted in the corpus luteum and further intensifying during the midluteal phase. myc protein expression in granulosa cells was apparent only in the preantral follicle stage. In the regressing corpus luteum, expression of both TGF-alpha and myc oncoprotein was restricted only in the peripheral theca lutein cells adjacent to the central core of scar issue. In atretic follicles theca interna cells exhibited prominent immunostaining for TGF-alpha and myc protein.

CONCLUSION

TGF-alpha and myc oncoprotein combination play a role as intraovarian regulators through autocrine and paracrine mechanism and may participate in remodelling the initial growth of the oocyte, follicular growth, differentiate and apoptosis.

Luteotrophic factors in hyperstimulated pseudopregnant rabbit: I--Evidence for aromatase activity in luteal tissue and luteal cells

It is well established that the rabbit corpus luteum (CL) function depends upon endogenous oestradiol, the major source of which in the rabbit ovary is considered to be the ovarian follicles. The absence of oestradiol formation by the rabbit CL has been previously reported. In a hyperstimulated pseudopregnant rabbit model used in our laboratory which developed a large number of corpora lutea in response to chorionic gonadotrophin (eCG)/hCG, we observed the survival of corpora lutea in vivo, and normal levels of plasma progesterone throughout pseudopregnancy (PP), despite the scarcity or the absence of follicles as a source of the luteotrophic hormone. Measurement of oestradiol in the plasma indicated that it was at high levels and correlated with the number of corpora lutea. This led us to investigate the luteal origin of oestradiol in this model. PP was induced in rabbits by i.m. injection of 200 IU eCG daily for 2 days followed on day 4 by i.m. injection of 200 IU hCG (day 0 of PP). Luteal tissue obtained at days 5, 9 and 12 of PP and cultured for 24 h synthesized oestradiol and testosterone in addition to progesterone. However, under the same conditions, follicles had limited capacity to secrete oestradiol. The presence of an aromatase activity in luteal tissue was confirmed when exogenous testosterone was added to the culture medium. P450aromatase (P450arom) mRNA was found in luteal tissue at days 5, 9 and 12 of PP. Small or large luteal cells, obtained by enzymatic digestion of the tissue followed by centrifugation in a Percoll density gradient, were cultured during several days with or without gonadotrophin or dibutyryl cAMP (dbcAMP). Both types of cells secreted oestradiol. In small cells and luteal tissue, aromatase activity was stimulated (1.5-2-fold) by hCG and dbcAMP. Large cells exhibited a greater capacity to aromatize testosterone than small cells, but aromatase activity was not modified by hCG or by dbcAMP. FSH had no effect on aromatase activity of either luteal cell type. This intrinsic luteal tissue aromatase capacity and the absence of premature regression of corpora lutea despite the limited support of follicular oestrogen, suggest an autocrine and luteotrophic role for this luteal oestrogen.

Suppression of matrix metalloproteinase production by hCG in cultures of human luteinized granulosa cells as a model for gonadotrophin-induced luteal rescue

Granulosa cells were isolated from follicular aspirates collected at ovum recovery for in vitro fertilization. Cells were cultured in a defined medium on artificial extracellular matrix (Matrigel) in the presence or absence of hCG as a model for corpus luteum function. Release of cells from this culture system is reduced by hCG and this effect may be mediated through an inhibition of extracellular matrix degradation. Using zymography and western blot analysis, we confirm the identity of matrix metalloproteinases-2 and -9 in culture media. Matrix metalloproteinase-9 was the predominant gelatinase in freshly prepared granulosa cells and in culture media, and also represented a major metalloproteinase component in homogenates of early and mid-luteal phase samples of corpora lutea. Quantitative analysis of matrix metalloproteinases in culture media, obtained throughout the 14 day culture period and expressed per microgram of DNA, showed that matrix metalloproteinase-2, undetectable on day 2, rose throughout the culture period and that this rise was significantly inhibited by hCG. In contrast, matrix metalloproteinase-9 was clearly detectable on day 2 and remained relatively constant throughout much of the culture (day 2 to day 12) in the presence of gonadotrophin. Significantly increased production of matrix metalloproteinase-9 (day 6 to day 12) was evident in the absence of hCG. Our results provide further evidence for the hypothesis that the rescue of the corpus luteum in early pregnancy involves the maintenance of cellular function through the stabilization of the extracellular matrix.

Effect of gonadotrophin on cell and matrix retention and expression of metalloproteinases and their inhibitor in cultured human granulosa cells modelling corpus luteum function

Granulosa cells were prepared from follicular aspirates obtained at oocyte collection for in-vitro fertilization (IVF) and maintained in culture. Substantial loss of cells from the culture surface occurred in the absence of gonadotrophin when cells were maintained on a thin layer of extracellular matrix (ECM) using a defined, serum-free medium. This cell loss was clearly and significantly reduced in the presence of human chorionic gonadotrophin (HCG) by days 4-6 of culture, and occurred in conjunction with loss of ECM. Analysis of culture medium by zymography using gelatin as substrate demonstrated the presence of metalloproteinases (MMP), MMP-9 (gelatinase B) appearing as the predominant band. Measurement of overall gelatinase activity in culture media revealed a progressive fall in gelatinase expressed on a per cell basis in media from HCG-treated cultures and this was less marked in controls. This suppression of gelatinase activity was consistent with an observed increase in production of tissue inhibitor of metalloproteinase-1 (TIMP-1) by HCG-treated cells, which was significant by days 6-8 of culture. We speculate that stabilization of the ECM may be an important aspect of HCG action in the corpus luteum.

Expression of tissue inhibitor of metalloproteinases-1 in the human corpus luteum after luteal rescue

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a specific inhibitor of a group of proteolytic enzymes known as matrix metalloproteinases. These enzymes have been widely implicated in the process of tissue remodelling. Extensive remodelling occurs in the corpus luteum during luteolysis unless human chorionic gonadotrophin (hCG) is produced by the early conceptus. This study aimed to investigate the expression and localisation of TIMP-1 in human corpora lutea during the luteal phase of the cycle and after luteal rescue with exogenous hCG to mimic the changes of early pregnancy. Human corpora lutea from the early (n = 4), mid- (n = 4) and late (n = 4) luteal phases and after luteal rescue by hCG (n = 4) were obtained at the time of hysterectomy. Expression of TIMP-1 was investigated in these tissues by Western blotting, immunohistochemistry, Northern blotting and in situ hybridisation. Luteal cells of thecal origin were distinguished from those of granulosa origin by immunostaining for 17 alpha-hydroxylase. A 30 kDa protein consistent with TIMP-1 was detected in human corpora lutea. This protein was localised to the granulosa lutein cells in all tissues examined. TIMP-1 mRNA was found in large quantities in all glands examined and this again localised to the granulosa lutein cells. The expression and localisation of TIMP-1 did not change throughout the luteal phase and was not altered by luteal rescue. The function of this uniform expression of TIMP-1 in the corpus luteum is not clear but these data suggest that the inhibition of structural luteolysis during maternal recognition of pregnancy is not mediated by regulation of TIMP-1 expression.

Local action of trophoblast interferons in suppression of the development of oxytocin and oestradiol receptors in ovine endometrium

Luteolysis in sheep is associated with uterine secretion of pulses of prostaglandin F2 alpha (PGF2 alpha) due to the action of luteal oxytocin on endometrial oxytocin receptors. For pregnancy to become established inhibition of oxytocin receptors is important as an antiluteolytic mechanism. The maternal recognition of pregnancy in cattle and sheep involves production, by the trophoblast, of a type 1 interferon (IFN-tau) that suppresses uterine development of oxytocin receptors and the generation of luteolytic episodes of PGF2 alpha. The action of IFN-tau in surgically prepared unilaterally pregnant ewes was investigated. Finn-Dorset ewes were anaesthetized on day 6 or 7 of the oestrous cycle and one uterine horn was surgically isolated at the uterine bifurcation from the body of the uterus. Ewes were mated at the subsequent oestrus either by a fertile or by a vasectomized ram and killed on day 13 or 16 after mating. On day 16, in the non-pregnant ewes, there was no measurable uterine IFN-tau but there were high concentrations of oxytocin receptors in both horns. In the pregnant ewes on day 16 after mating, the oxytocin receptor concentration was 45 +/- 11 fmol mg-1 protein in the pregnant horn and 585 +/- 131 fmol mg-1 in the non-pregnant horn. Antiviral activity was 5.8 x 10(7) +/- 5.2 x 10(7) U ml-1 in the pregnant horn and 2.9 x 10(3) +/- 1.2 x 10(3) U ml-1 in the non-pregnant horn. Thus, 16 days after mating, the pregnant horn exhibited high antiviral activity but oxytocin receptors were suppressed, while in the same endocrine environment (characteristic of pregnancy) there were low IFN-tau and high oxytocin receptor concentrations in the isolated horn equivalent to those expected at the onset of luteolysis. In situ hybridization to ovine mRNA encoding the oxytocin receptor and autoradiographic studies using the 125I-labelled oxytocin antagonist d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH2(9)]-vasotocin both showed that the large amount of oxytocin receptor message and binding sites in the endometrium of the isolated horn were localized in the luminal epithelium. Immunocytochemical studies showed that there was a suppression of oestradiol receptors in the pregnant horn but high concentrations equivalent to those at oestrus were present in the isolated horn. The content of progesterone receptors was low in the stromal tissue only in both horns, a pattern of localization similar to that seen in the late luteal phase and in early pregnancy.(ABSTRACT TRUNCATED AT 400 WORDS)

Conceptus interferon in uterine flush, endometrial concentrations of oxytocin receptors and prostaglandin F2 alpha release in vitro after transfer of conceptuses to ewes induced to ovulate at 28 days postpartum

We examined the key events underlying maternal recognition of pregnancy and the prevention of luteolysis in early postpartum ewes by synchronously transferring single expanded blastocysts recovered from control ewes on day 11 of pregnancy into the uterus of either postpartum recipients that had been induced to ovulate 28 days after lambing (n = 12) or control recipients (n = 11). Conceptus development uterine flush interferon (oTP-1) concentrations, endometrial oxytocin receptor concentrations and endometrial prostaglandin F2 alpha (PGF2 alpha) release in vitro were determined 5 days later (corresponding to day 16 of the ovarian cycle). By this stage, both conceptus mass and oTP-1 content of total uterine flush in the eight postpartum recipients that remained pregnant were significantly lower (P < 0.01) than in the eight pregnant control ewes (524 +/- 116.6 versus 959 +/- 80.6 mg and 968 +/- 16.9 versus 1512 +/- 106.2 ng oTP-1 for postpartum and control recipients, respectively). These effects were independent of ovulation rate and daily peripheral progesterone concentrations after blastocyst transfer, which were similar between groups. Endometrial oxytocin receptor density was variable in both groups when they were killed, and was generally higher in pregnant postpartum than in control recipients, and was significantly different (P < 0.05) when the values for the transfer but not the contralateral uterine horns were compared. Similarly, basal and oxytocin-stimulated endometrial PGF2 alpha release during a 4 h incubation were higher (P < 0.01) in pregnant postpartum versus control recipients.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure to maintain luteal function: a possible cause of early embryonic loss in a cow

The effect of early pregnancy failure on the release of prostaglandin F2 alpha (PGF2 alpha) in response to oxytocin (Ot) was examined in an abnormal breeder (AB) heifer that was not able to maintain a pregnancy beyond 21 days. This animal was used in three experiments: 1) She received one intravenous injection of 100 IU Ot 17 days after the onset of oestrus (Day 0). Frequent blood samples were taken for the measurement of 15-keto-13,14-dihydro-PGF2 alpha (PGFM) by radioimmunoassay. Daily samples for progesterone (P4) determinations were taken to monitor luteal function. This was then repeated using the same animal at either day 17 or 18 or 19 (day 17-19) of pregnancy. 2) Embryos from superovulated normal breeder (NB) donors were transferred at day 7 to the AB heifer as well as to NB control animals. 3) Seven day old embryos from the superovulated AB heifer were transferred to NB recipient animals. At day 17-19 of pregnancy all the recipient heifers (experiments 2 and 3) were subjected to the same protocol as in experiment 1. The results showed that the ability of Ot to stimulate PGF2 alpha release was reduced in the NB recipients bearing viable embryos when compared to cyclic animals. However, for the AB heifer, Ot stimulated PGF2 alpha release to the same extent whether the animal was cyclic or pregnant. Furthermore, the AB animal did not have the extended luteal function associated with removal of viable embryos on day 17-19. The data suggest that the embryonic loss might have been caused by failure of the embryos to prevent the luteolytic release of PGF2 alpha.

Evaluation of the preovulatory rise of follicle stimulating hormone and progesterone in normally ovulating women of reproductive age

Sixteen normally ovulating women of reproductive age were evaluated to determine the extent of the preovulatory FSH and progesterone rise in association with the LH surge. Highly significant differences were demonstrated between the baseline and peak preovulatory levels of both FSH and progesterone (P less than .0005). These significant peak ovulatory differences of FSH and progesterone were associated with a 2.5-fold rise (mean difference of 9.06 mIU/mL) of FSH and a 3.0-fold rise (mean difference of 1.94 ng/mL) of progesterone. These small, yet very significant, preovulatory increments of FSH and progesterone are important in the ovulatory process and the formation of an adequate corpus luteum.

Effect of hysterectomy on the short life-cycle corpus luteum produced after GnRH-induced ovulation in the anoestrous ewe

Anoestrous Romney Marsh ewes were treated with small-dose (250 ng) multiple injections of GnRH. Ewes in Groups 1 and 3 were hysterectomized 2 weeks before treatment, while those in Groups 2 and 4 were intact controls. Groups 1 and 2 were primed with progesterone (+P) and treated with 2 h injections of GnRH (250 ng) for 36 h, while Groups 3 and 4 were not pretreated (-P) but were given 2 h injections of GnRH (250 ng) for 18 h. Both treatment regimens were terminated with a bolus injection of GnRH (125 micrograms), given to synchronize the timing of the LH surge and subsequent luteal progesterone production. The plasma progesterone profiles of 5/5 animals in Group 2 (+P controls) and 2/5 animals in Group 4 (-P controls) were indicative of normal luteal function, while the remaining 3/5 animals in Group 4 produced plasma progesterone profiles typical of abnormal luteal function. However, in all the hysterectomized animals (Groups 1 and 3) peripheral plasma progesterone concentrations rose to reach a mean peak value of 1.3 ng/ml plasma on Day 8 which was maintained in all animals irrespective of progesterone pretreatment. The absence of a fall in progesterone concentrations precluded the identification of any animal in Group 4 showing abnormal luteal function. It was also noted that, after hysterectomy, although the corpus luteum was maintained, it was with reduced secretory capacity. The prevention of the expected proportion (70%) of -P animals from displaying a decline in plasma progesterone concentration after hysterectomy provides firm evidence that the uterus is involved in the premature regression of the short-cycle corpus luteum.

Is oxytocin of conceptus origin involved in inhibition of luteal regression in early pregnancy in ewes?

This study describes the presence in and production by the ovine conceptus of an oxytocin-like peptide during the early stages of development. Oxytocin was measured by radioimmunoassay in ovine conceptuses from days 14 to 30 of pregnancy. Tissue concentrations of oxytocin increased from day 14 (24.8 +/- 5 pg/100 mg) until day 19 (122.9 +/- 52 pg/100 mg) and then decreased (3 +/- 1 pg/100 mg). Oxytocin was released into culture medium by day-15 ovine conceptuses at a rate of 262 +/- 55 pg/24 h. Reverse-phase high-performance liquid chromatography (HPLC) analysis of peptides extracted from a pool of ovine conceptuses was conducted using chromatographic conditions developed to separate oxytocin from other nonapeptides. Radioimmunoassay of HPLC fractions for oxytocin revealed an immunoactive conceptus peptide in a single fraction at the same retention time as chromatographed authentic oxytocin. Radioimmunoassay and chromatographic data therefore suggest that this oxytocin-like peptide is similar, if not identical, to authentic oxytocin. Concentrations of oxytocin in conceptus tissue were maximal during the period of inhibition of luteal regression (days 14-19). It is proposed that conceptus oxytocin is involved in the maintenance of luteal function in early pregnancy.

Effect of flushing of blastocysts on days 10-13 on the life-span of the corpora lutea in the pig

Blastocysts were flushed out of both uterine horns of gilts on Days 10, 11, 12 or 13. In mated non-pregnant gilts flushing had no effect on progesterone profile or cycle length (20.8 +/- 0.4 versus 20.6 +/- 0.6 days in the preflush cycle, N = 6, mean +/- s.e.m.). Flushing the blastocysts out of the uterine horns on Day 10 resulted in a cycle with a normal progesterone profile and a normal length (21.2 +/- 0.4 days, N = 5). Flushing on Days 11, 12 or 13 resulted in a normal cycle or in maintenance of the CL for 3-13 days as indicated by elevated progesterone concentrations and an increased interoestrous interval of, respectively, 22.0 +/- 1.2 versus 19.8 +/- 0.6 days (Day 11; N = 6), 24.8 +/- 1.4 versus 21.0 +/- 0.6 days (Day 12; N = 5; P less than 0.05) and 26.3 +/- 2.3 versus 20.5 +/- 0.4 days (Day 13; N = 6; P less than 0.05). There was a positive relationship between the change in interoestrous interval and the interval between the first observed standing oestrus and flushing of the blastocysts (rs = 0.350; n = 22; P less than 0.1). There was a large variation in the diameter of the blastocysts flushed on the same day. Only in those gilts in which the blastocysts were greater than or equal to 8 mm or filamentous were the CL maintained for 3 or more days. These results indicate that a first signal for maternal recognition of pregnancy is generated on Day 12 and that blastocysts greater than or equal to 8 mm are required for prolongation of CL function for 3 or more days. Since CL function is only extended for a maximum of 13 days (mean 7.4 +/- 1.0), a second signal seems necessary to maintain the CL for the whole period of pregnancy.

Modification of prostaglandin F-2 alpha synthesis and release in the ewe during the initial establishment of pregnancy

Pregnant (N = 10) and non-pregnant (N = 10) ewes were bled every 2 h from Days 12 to 17 after oestrus (oestrus = Day 0). Plasma concentrations of progesterone, 15-keto-13,14-dihydro-PGF-2 alpha and 11-ketotetranor-PGF metabolites were determined in all samples. The number of PGF-2 alpha pulses in non-pregnant ewes was 8.2 +/- 0.4 (mean +/- s.e.m.) with an interpulse interval of 10.7 +/- 0.7 h. Two or 3 pulses of low frequency (interpulse interval = 13.4 +/- 1.6 h) occurred in most non-pregnant ewes before the onset of luteolysis; the interpulse interval then decreased to 7.9 +/- 0.4 h for the 6.0 +/- 0.3 pulses temporally associated with luteolysis. In contrast, the number of PGF-2 alpha pulses in pregnant ewes was lower (2.5 +/- 0.7, 0-8) and the interpulse intervals longer (18.9 +/- 6.1 h). Most pulses occurred on Days 14 and 15 in the pregnant and non-pregnant ewes. The mean concentrations of both PGF-2 alpha metabolites in non-pregnant ewes were highest on Day 15 while basal levels of both metabolites remained constant at all times. In pregnant ewes, the mean concentrations of both metabolites were highest on Day 14; basal concentrations of both metabolites were also highest on Day 14. The mean concentrations of 15-keto-13,14-dihydro-PGF-2 alpha were higher in pregnant than in non-pregnant ewes on Days 13 and 14 (P less than 0.05) and higher in non-pregnant than pregnant ewes on Day 15 (P less than 0.05). The basal concentrations of the 15-keto metabolite were higher in pregnant than non-pregnant ewes at Days 13, 14, 15, 16 and 17 (P less than 0.05). Both the mean and the basal concentrations of 11-ketotetranor-PGF metabolites were higher in pregnant than in non-pregnant ewes on Day 14 (P less than 0.05). It is concluded that uterine production of PGF-2 alpha peaks at Days 14-15 after oestrus in pregnant and non-pregnant ewes. Patterns of release differ, however, in that non-pregnant ewes have a pulsatile PGF-2 alpha pattern superimposed on a constant baseline, while pregnant ewes have an increasing basal secretory pattern which is more nearly continuous, i.e. not pulsatile in form. Modification of pulsatile PGF-2 alpha synthesis and release is therefore a key aspect of prolongation of luteal function at the beginning of pregnancy in the ewe.

Characterization of plasma membrane lipids and luteinizing hormone receptors of ovine corpora lutea during luteolysis and early pregnancy

Lipid composition of plasma membranes from luteal cells was examined to determine whether changes in this organelle occur during regression and maintenance of the corpus luteum in nonpregnant (NP) and pregnant (P) ewes, respectively. Forty ewes were assigned to be killed on Day 13 or 15 of the estrous cycle (D13-NP and D15-NP) or pregnancy (D13-P and D15-P). Purification of luteal plasma membranes on discontinuous sucrose gradients yielded two fractions, designated F1 and F2, that exhibited the greatest enrichment of 5'-nucleotidase activity (five- and fourfold, respectively) over that of the homogenate. These fractions also yielded the lowest contamination by endoplasmic reticulum as represented by nicotinamide adenine dinucleotide phosphate (NADPH) cytochrome C reductase activity and mitochondrial membranes as indicated by succinate dehydrogenase activity. Predominant phospholipids identified in membranes obtained from all groups were phosphatidylcholine (PC, 48.9 +/- 0.6% of total phospholipid), phosphatidylethanolamine (PE, 33.3 +/- 0.4%), sphingomyelin (SPH, 9.7 +/- 0.3%), phosphatidylserine (PS, 3.5 +/- 0.2%), and phosphatidylinositol (PI, 4.0 +/- 0.5%). No changes in microgram phospholipid/mg membrane protein were observed for any luteal phospholipid on D13 and 15 of the estrous cycle or pregnancy. No significant changes in the relative percentages of major fatty acids present in PC (palmitic [16:0], oleic [18:1]), PE (stearic [18:0], 18:1 and arachidonic [20:4]), or PS (18:0, 18:1, docosatetraenoic [22:4]), nor in the ratios of unsaturated (U) to saturated (S) fatty acids in these phospholipids were observed. Significant differences in unsaturated fatty acids of chain length greater than 20 carbons present in minor quantities in PC, PE, and PS were detected between NP and P ewes as well as between days within reproductive stage. The profile of major fatty acids present in PI revealed decreases in 18:0 and 20:4 in D15-NP and increases in 22:4 and docosapentaenoic acid (22:5) in luteal membranes of both D13- and D15-NP ewes relative to the levels of these fatty acids in PI of corresponding groups of pregnant ewes. There was a general trend for 20:4 levels of PC and PI in membranes of D15-NP ewes to be inversely related to those of D15-P ewes. Collectively, these changes were reflected by an increased U:S fatty acid ratio in luteal membrane PI during the estrous cycle. Specific binding of [125I] iodo-human chorionic gonadotropin to luteal plasma membranes from NP and P ewes on D13 and 15 (6/group) revealed similar affinities and concentrations of unoccupied luteinizing hormone (LH) receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Steroidogenic capacity and ultrastructural morphology of cultured ovine luteal cells

Corpora lutea were surgically collected from superovulated ewes 36 h post-injection of human chorionic gonadotropin (hCG) (Day 2), dissociated (0.2% collagenase), plated, and maintained in culture Days 2-10 in Medium 199 supplemented with 5% calf serum. Accumulation of progesterone in the cultures did not decrease (p greater than 0.05) from Day 3 (17.5 +/- 5.1 nmol/10(6) cells) to Day 10 (4.8 +/- 1.7 nmol/10(6) cells). Calf serum (5%) in the medium supported greater (p less than 0.05) progesterone production than fetal calf serum (5%) or medium without added serum. Steroidogenic cells did not increase (Days 2-10) in numbers, but increased (p less than 0.01) in mean cell diameter (Day 2, 11.7 +/- 0.4 micron; Day 10, 24.5 +/- 1.6 micron). Steroidogenic capacity on Day 10 of cells cultured Days 2-10 (in vitro) was not different (p greater than 0.05) from that of cells collected from the ovary on Day 10 (in vivo); however, steroidogenic cells recovered from plates had greater (p less than 0.01) mean cell diameters (24.5 +/- 1.6 micron, in vitro, compared to 15.2 +/- 1.0 micron, in vivo). Transmission electron microscopy revealed that cultured cells (Days 5, 10) possessed less smooth endoplasmic reticulum but more lipid droplet inclusions, ribosomes, and rough endoplasmic reticulum than cells obtained in situ (Day 10). Electron-dense secretory granules were rarely seen. Although subcellular morphology of ovine luteal cells in culture was altered, these changes did not appear to significantly affect the ability of these cells to produce progesterone.

Neuroendocrine processes in the establishment of pregnancy and pseudopregnancy in rats

Rats, like mice, hamsters and other small rodents, have a short, incomplete estrous cycle. They lack a spontaneous luteal phase, and the corpora lutea (CL) of the estrous cycle are short-lived and nonfunctional. The activation of the luteal phase in these incompletely cycling females depends on the neuroendocrine reflex provided by the male at the time of mating. In this article we review our research on the cervix-brain-pituitary-ovary interaction at the endocrine, neuroendocrine, neurotransmitter and behavioural levels, dealing with the chain of events initiated by the male and necessary for the establishment of the progestational state.

Prolactin as an inhibitor of granulosa cell luteinization: implications for hyperprolactinemia-associated luteal phase dysfunction

Chronic and transient hyperprolactinemia have been associated with luteal phase dysfunction in both spontaneously cycling women and those subjected to ovarian hyperstimulation by exogenous gonadotropins. It is the objective of the in vitro and in vivo studies reported herein to examine the possibility that prolactin (PRL), a known constituent of ovarian follicular fluid, may account, at least in part, for the luteinization inhibitory (LI) activity exerted by follicular fluid (FF) under both physiologic and pathophysiologic circumstances. In vitro treatment with human PRL (100 ng/ml) reduced by 57% the specific binding of luteinizing hormone (LH) to follicle-stimulating hormone(FSH)-primed cultured rat granulosa cells, an effect associated with a 2.6-fold diminution of human chorionic gonadotropin (hCG; 10 ng/ml)-stimulated progesterone biosynthesis. Importantly, the ability of PRL to exert a direct inhibitory effect on FSH-supported LH binding was fully reproduced under in vivo conditions. Inasmuch as the acquisition of LH receptors and progesterone (P) biosynthetic capacity are acceptable as criteria of granulosa cell luteinization, the authors' findings indicate that PRL, acting at concentrations achievable in vivo within the ovarian FF, may account, if only in part, for physiologically encountered LI-like activity. Moreover, subject to limitations imposed by the rat model employed, consideration also must be given to the possibility that hyperprolactinemia-associated luteal phase dysfunction may not only reflect the suppressive effect(s) of PRL at the central level of the reproductive axis, but may also be due, at least in part, to the consequences of inappropriately elevated PRL at the level of the follicular microenvironment.

Persistent progesterone production associated with autoimmune oophoritis. A case report

A woman with autoimmune oophoritis was found to have luteal phase progesterone levels throughout a six-month period of amenorrhea. The common presentation of amenorrhea or metrorrhagia, despite the presence of a corpus luteum, in women with autoimmune oophoritis might result from this chronic progesterone production. A clinical picture consistent with a persistent corpus luteum may be a very early sign of autoimmune oophoritis.

Identification of bovine trophoblast protein-1, a secretory protein immunologically related to ovine trophoblast protein-1

This paper demonstrates that a group of proteins, representing a major secretory component of cattle conceptuses, is immunologically related to ovine trophoblast protein-1 (oTP-1), a principal product of culture Day 13 to 21 sheep conceptuses. Conceptuses from cows (Day 17-18) and ewes (Day 16-17) were cultured for 24 h in the presence of L-[3H]leucine. By using a rabbit antiserum to oTP-1 and Ouchterlony double-immunodiffusion analysis it was shown that material in the bovine conceptus culture medium was serologically related, but not identical, to oTP-1. A solid-phase radiobinding assay indicated that the cross-reacting bovine secretory component had an affinity for anti-oTP-1 antibody similar to that of oTP-1. Anti-oTP-1 antiserum specifically immunoprecipitated a group of 6-8 polypeptides from culture medium of cow conceptuses which, when analysed by two-dimensional gel electrophoresis, fell into two major molecular weight classes (22,000 and 24,000) with isoelectric points between 6.5 and 6.7. These immunoprecipitated polypeptides, defined as bTP-1, constituted the major secretory products of Day 16-25 cow conceptuses. They were larger and more basic than oTP-1 polypeptides (Mr about 18,000; pI 5.4-5.7). Anti-oTP-1 antiserum also recognized the major translation product of Day 17 bovine conceptus mRNA, a polypeptide significantly smaller (Mr approximately 18,000) than the secreted protein. It is suggested that oTP-1 and the homologous bovine protein may play similar roles in the phenomenon of maternal recognition of pregnancy in the two species.

Luteal phase insufficiency: clinical aspects

The author analyzes different controversial clinical aspects of luteal phase insufficiency (LPI) on the basis of his own data. Conceptual and diagnostic concerns include: (1) the lack of predictive value of midluteal plasma progesterone determination regarding the progestational transformation of the endometrium, and (2) the need for a minimum of two, and even three, endometrial biopsies for diagnosis of LPI. From an etiologic point of view, follicular phase determinants of LPI are emphasized. Primary therapeutic approaches of LPI and the effectiveness and significance of such therapy on fertility are discussed.

Measurement of glucuronometabolites of 17 beta-estradiol and progesterone in diluted overnight urine. An approach to the study of luteal insufficiency

The determination of the concentrations of estrone-3-glucuronide, pregnanediol-3-glucuronide and luteinizing hormone has been performed in early morning urine samples of 14 normal menstruating women using a timed and measured volume urine collection procedure. In order to investigate the variability of the urinary hormonal concentrations due to day-to-day differences in diuresis, the absolute hormonal concentrations have been corrected either for the urinary creatinine excretion or for the volume of urine voided during the night. The results demonstrate that both correction factors are able to reduce substantially the coefficient of variation values in comparison to the absolute hormonal concentrations. The urinary test of ovarian function has been performed in 11 infertile women affected by luteal insufficiency using the same procedure, and the hormonal profiles showed some alterations in both estrone-3-glucuronide and pregnanediol-3-glucuronide concentrations in comparison to the hormonal profiles of the normal subjects. Such alterations were significant in the single subject when integrated values of the hormonal data in defined time intervals were investigated.

Ovarian follicular development during early pregnancy in cattle

On the day of oestrus (Day 0), 23 cows were assigned randomly to 4 groups in a 2 X 2 factorial experiment. Main effects were cow status [pregnant (P) versus non-pregnant (NP; not mated)] and day (Day 17 versus Day 34) when cows were slaughtered and ovaries collected; i.e. Groups NP-17 (N = 6), NP-34 (N = 5), P-17 (N = 6) and P-34 (N = 6). To mimic CL maintenance associated with presence of a conceptus in Group P-34, cows assigned to Group NP-34 were hysterectomized between Days 4 and 6 after oestrus. Pregnancy in Groups P-17 and P-34 (recovery of conceptus) and CL maintenance between day of surgery and Day 34 in Group NP-34 were confirmed. In Group NP-17, all cows except one were slaughtered before luteolysis. CL-bearing ovaries were serially sectioned (10 microns) and follicles (greater than 0.15 mm) were counted and measured using routine histological techniques. For each size class of follicles, the percentages of follicles were similar (P greater than 0.1) on Days 17 and 34. The percentage of non-atretic follicles (less than 4 pycnotic bodies) was lower (P less than 0.002) in pregnant than non-pregnant groups in the smallest class of antral follicles (0.16-0.28 mm) but was higher (P less than 0.03) in larger classes (0.68-3.67 mm) for pregnant groups. Percentages of atretic follicles were 3.7 and 4.9 (P greater than 0.1) for follicles of 0.16-0.67 mm, 91.1 and 78.9 for follicles of 0.68-3.67 mm (P less than 0.04) and 5.1 and 16.1 (P less than 0.05) for follicles of 3.67-78.56 mm in pregnant and non-pregnant groups respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Bilateral maintenance of rabbit corpora lutea by the feto-placental unit

The present study was undertaken to determine whether the rabbit feto-placental unit maintains corpora lutea systematically and/or locally and the interrelationships between conceptus number, luteal weight, luteal progesterone concentrations and serum progesterone levels. Thirty-three does were divided into the following treatment groups: (I) bilaterally pregnant, two ovaries; (II) unilaterally pregnant, two ovaries; (III) bilaterally pregnant, one ovary; (IV) unilaterally pregnant, one ovary, contralateral and (V) unilaterally pregnant, one ovary, ipsilateral. Blood samples were obtained from all rabbits on days 6, 9, 12, 15, 18 and 21 post coitum. Does were killed on day 21, and the percentage of viable fetuses, fetal weights, and luteal weights recorded. Blood samples and corpora lutea were analysed for progesterone. Serum progesterone levels were similar for all groups until day 9 post coitum. Levels in groups III, IV and V declined significantly between days 9 and 12 following removal of one ovary at day 9. Fetal viability, fetal weights and luteal progesterone concentrations did not differ among any of the groups. Luteal weights did not differ among groups I, III, IV and V, but luteal weights of animals in group II were lower than those of group I (P less than 0.05). Ratios of viable fetuses to number of corpora lutea ranged from 1:11-10:5. No differences were observed in serum progesterone, luteal weights or luteal progesterone concentrations among animals with two conceptuses and those with seven or more, but serum progesterone levels in does with only one conceptus were lower than those in does with more (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Interrelationships between uterus and conceptus to maintain corpus luteum function in early pregnancy: sheep, cattle, pigs and horses

Processes associated with "Maternal Recognition of Pregnancy" are reviewed extensively from the ovine, bovine, porcine and equine species. Comparisons among these species indicate that CL maintenance is achieved primarily by a predominant antiluteolytic-anti PGF effect, and there is strong evidence for antiluteolytic-luteoprotective and luteotropic controls that complement this basic system. The nature of the chemical signals (steroids, prostaglandins and proteins) to regulate these processes among the species are described. Common to all of the species reviewed is a change in vascular dynamics to and from the uterus and ovary during early pregnancy. The dialogue between endometrial epithelium and trophectoderm of the developing conceptus is described. The consequence of these various physiological and biochemical responses of early pregnancy is maintenance of the CL to provide a sustained embryotrophic environment. Either in the absence of or death of a conceptus, an efficient and acute system is operational to terminate this progestational environment via regression of the CL through uterine production of PGF.

Prostaglandin concentrations in uterine fluid of cows with pyometra

Uterine fluid was obtained from eight clinical cases of pyometra with retained corpus luteum and nine additional samples of fluid were collected from animals slaughtered at an abattoir. These samples, along with uterine flushes from normal cows in their luteal phase were analyzed for prostaglandin of the F (PGF) and E (PGE) groups. Blood samples were also obtained from the clinical cases for analysis of 13,14-dihydro-15-keto PGF (PGFM) the major metabolite of PGF. Pyometrial exudate from clinical cases of abattoir samples had high concentrations of PGF (17.9 ng/mL) and PGE (33.2 ng/mL) and the total amount of PGF and PGE in the uterus was calculated to be several hundred times as great as in normal cows. Furthermore, clinical cases had elevated PGFM in their blood compared to that of controls, which suggests that at least some of the PGF was being absorbed from the uterus. These results are discussed in light of our current understanding of the maternal recognition of pregnancy in cattle.

Effect of partial stepwise luteectomy in pregnant gilts on maternal and fetal concentrations of progesterone

The number of corpora lutea (CL) in gilts was reduced to 8, 5, and 3 on Days 30, 40, and 50 of gestation, respectively. In a second group of gilts the number of CL was reduced to 5 by luteectomy by Day 50. Luteectomy did not affect concentrations of progesterone (P) in maternal uterine or fetal umbilical vessels sampled at Day 80. Concentration of P was higher in umbilical than uterine plasma in all treatments (P less than 0.01). The uterine arterial-venous (A/V) difference in concentrations of P was positive and the umbilical A/V difference was negative in all groups. The uterine and umbilical A/V differences at Day 80 decreased as the number of CL decreased. Fetal survival was reduced in luteectomized gilts. These results indicate that gradual reduction of numbers of CL does not result in placental secretion of P into the maternal circulation but does alter the uptake of P by the uterus and umbilical circulation.

Assessment of the cause of infertility

The different causes of infertility and evaluation of the infertile couple are reviewed in this paper. Forty to 50 percent of cases are due to male factors, and special emphasis is placed in describing techniques to diagnosis this type of infertility. Five to ten percent of infertile couples have infertility of unknown etiology even after a complete, appropriate evaluation. Special instruction in how to diagnose and treat these types of patients is described. A step by step evaluation of peritoneal factors, ovulation factors, and male and cervical mucus interaction is presented for the clinicians' use.

Unexplained infertility: a review

When investigations fail to reveal a cause for infertility, treatment must then be based on possible, but unproven, causes, and since there is a high spontaneous pregnancy rate in unexplained infertility the effect of any treatment is difficult to assess. Such treatment has included correction of anatomical variants such as uterine retroversion and the use of hormonal manipulation during the follicular and luteal phases of the menstrual cycle. Ovum entrapment, occult spontaneous abortion and faults in sperm fertilizing capacity have all been implicated, and it is likely that immunological factors play a substantial role in unexplained infertility. Evidence does not support the use of bromocriptine in the absence of hyperprolactinaemia. Successful treatment by intrauterine insemination is unlikely if there are circulating anti-sperm antibodies in the partner. Improving cervical mucus by treatment with oestrogens and clearing infections with antibiotics may have a modest place but it is very difficult to show that these treatments have more than a placebo effect. Endometriosis is often missed and the possibility of it having developed after initial investigation warrants repeat laparoscopy after 2 years. Three approaches are currently acceptable in the management of the couple with unexplained infertility: await spontaneous pregnancy, the empirical use of clomiphene and in-vitro fertilization.

Maternal recognition of pregnancy--a review of the literature

A review of the literature concerning the endocrinological changes around early pregnancy in the domestic animals is presented. During this period the presence of the blastocyst must be recognized by the mother ("Maternal Recognition of Pregnancy") leading to a rescue and maintenance of the corpus luteum function. Several hormones are involved in these processes and the initial hormonal changes are dependent on a viable blastocyst. The key event is its control of the prostaglandin synthetizing system.

Maternal recognition of pregnancy in cattle

Nature and potential functions of chemical signals involved in the process of pregnancy recognition in cattle are discussed. The array of prostaglandins, steroid metabolites, and proteins produced by the conceptus and endometrium are described and collated with histological and physiological responses of the uterus and ovary that lead toward maintenance of the corpus luteum. Advances during the last 10 yr partially have identified the conceptus-endometrial-ovarian signal sequence that is associated with maternal recognition of pregnancy in cattle. Final evaluation of the control system should permit investigators to improve embryo survival and augment further the impact of embryo manipulation to improve genetic merit of the cattle population.

Maintenance of the corpus luteum of early pregnancy in the ewe. III. Differences between pregnant and nonpregnant ewes in luteal responsiveness to prostaglandin F2 alpha

The effects of pregnancy and number of corpora lutea on luteal regression induced with prostaglandin F2 alpha (PGF2 alpha) were examined in 93 ewes. Bred and nonpregnant ewes were assigned randomly to receive a single im injection of PGF2 alpha: 0, 2, 4, 6, 8 or 10 mg/58 kg body weight. Injections were given on d 13 postestrus. The concentration of progesterone in serum 24 h after PGF2 alpha injection was affected by dose (P less than .001). The effect of pregnancy and the interaction of pregnancy with number of corpora lutea on levels of progesterone in serum were significant (P less than .05); therefore, data were partitioned according to pregnancy status and analyzed separately. There was an effect of number of corpora lutea on serum concentration of progesterone in pregnant (P less than .01) but not nonpregnant ewes (P greater than .10). Similar relationships among groups were observed for the concentration of progesterone in luteal tissue. In nonpregnant ewes the minimum dose of PGF2 alpha to produce a significant suppression of progesterone in serum (P less than .05) was 4 mg/58 kg body weight. In pregnant ewes with one or two corpora lutea, the minimum effective doses were 6 and 10 mg/58 kg body weight, respectively. The concentration of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) in serum was related to the dose of PGF2 alpha injected. There were no differences in the concentration of PGFM in serum between pregnant and nonpregnant ewes either before or after injection. Corpora lutea of early pregnancy appear to be resistant to the luteolytic effect of PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Rate of blood flow and growth of the corpora lutea of pregnancy and of previous cycles throughout pregnancy in the rat

The rate and distribution of ovarian blood flow was measured with radioactive microspheres in nulliparous rats at Days 4, 7, 10, 13, 16 and 22 of gestation; term is Day 23. Ovaries were dissected into large corpora lutea (or CL of pregnancy), small CL, assumed to be those of previous cycles, and the ovarian stroma which included follicles and additional small CL. Total ovarian blood flow was similar over Days 4-10, but then increased progressively to reach 916 +/- 69 microliter/min at Day 22. The main cause of this increase was a 786% rise in blood flow to the large CL over Days 10-22. Weight of the CL of previous cycles increased by 289% over Days 10-16 and their rate of blood flow and histological appearance were similar to those of the large CL. These results indicate that neither reduced blood flow nor vascular degeneration, as determined by light microscopic examination, initiates the reported fall in progesterone secretion near term. At least some of the CL of previous cycles are maintained and indeed grow during gestation and have a blood circulation and histological appearance characteristic of steroidogenic tissue.

Dissociation of copulation from ovulation in pregnant rabbits

Experiments were designed to determine why copulation in the pregnant rabbit does not terminate pregnancy while treatment with ovulatory doses of luteinizing hormone (LH) human chorionic gonadotropin (hCG) or luteinizing hormone-releasing hormone (LHRH) is known to do so. Pregnant rabbits (Day 8) were mated or were injected with hCG (25 IU/doe) or LHRH (1, 10 micrograms/kg). Serial blood samples were collected over the next 72 h and analyzed for content of LH, follicle-stimulating hormone (FSH) and progesterone. At sacrifice, uteri and ovaries from these animals were examined for viability of the embryos and for signs of recent ovulation. Injection of hCG or LHRH into pregnant animals led to ovulation and to patterns of LH, FSH and progesterone secretion like those which precede ovulation in estrous rabbits. However, mating the pregnant does did not lead to ovulation or to any changes in the circulating hormones. To investigate whether the elevated levels of progesterone during pregnancy were responsible for the dissociation of coitus from ovulation, nonpregnant rabbits were injected with progesterone (2 mg/kg) and then mated or injected with hCG or LHRH. In virtually every respect, the numbers of ovulations and the patterns of hormone secretion in the progesterone-treated, nonpregnant rabbits mimicked those observed in the 8-day pregnant animals; injection of hCG or LHRH caused ovulation and hormonal surges while hCG caused ovulation only. Mating did not lead to ovulation or any change in blood levels of LH, FSH or progesterone. Taken together, the results show that the elevated circulating levels of progesterone, characteristic of pregnancy, are probably responsible for the dissociation of copulation from gonadotropin release in pregnant rabbits.

Luteolytic influence of intrauterine dead embryos in the early pregnant rat

The present investigation was an endeavour to study if annihilation of embryos in the uterus of the rat before the establishment of placental luteotropic functions has any influence on corpus luteal function, and, if there is any, whether it is local or systemic. The responsibility of pregnancy maintenance was imposed on a single ovary by performing unilateral ovariectomy after implantation (on Day 5 postcoitum). The implantation sites in one uterine horn, either ipsilateral or contralateral to the remaining ovary, were selectively destroyed by injecting 0.1 ml of sterile normal saline to that particular horn only, and the peripheral progesterone level and viability of the embryos in the untreated horn, which depended on the functions of the remaining ovary, were examined. Selective killing of embryos in the uterine horn of the ovariectomized side did not exert any influence on the fetal viability in the untreated horn ( nonovariectomized side) and the peripheral progesterone level also remained statistically unaffected. On the contrary, induction of fetal resorptions in the uterine horn of the intact side produced a significant fall in the peripheral level of progesterone and induced resorption of embryos of the ovariectomized side also. The latter could significantly be prevented by simultaneous administration of exogenous progesterone, indicating luteolysis as the major, if not sole, factor responsible for fetal resorption in the untreated horn. The luteolytic effect was attributed neither to saline itself, nor to the distension of the uterine horn caused by saline injection. Luteolytic factors from the dead embryo-bearing horn which act locally on the adjacent ovary only, are discussed.