Bisphenol A-induced mechanistic impairment of decidualization.

Decidualization is a crucial precedent to embryo implantation, as its impairment is a major contributor to female infertility and pregnancy complications. Unraveling the molecular mechanisms involved in the impairment of decidualization has been a subject of interest in the field of reproductive medicine. Evidence from several experimental settings show that exposure to bisphenol A (BPA), an endocrine-disrupting chemical, affects the expression of several molecules that are involved in decidualization. Both low and high doses of BPA impair decidualization through the dysregulation of estrogen (ER) and progesterone (PR) receptors. Exposure to low doses of BPA leads to decreased levels and activities of several antioxidant enzymes, increased activity of endothelial nitric oxide synthase (eNOS), and increased production of nitric oxide (NO) via the upregulation of ER and PR. Consequently, oxidative stress is induced and decidualization becomes impaired. On the other hand, exposure to high doses of BPA downregulates ER and PR and impairs decidualization through two distinct pathways. One is through the upregulation of early growth response-1 (EGR1) via increased phosphorylation of extracellular signal-regulated protein kinases 1 and 2; and the other is through a reduced serum glucocorticoid-induced kinase-1 (SGK1)-mediated downregulation of epithelial sodium channel-α and the induction of oxidative stress. Thus, regardless of the dose, BPA can impair decidualization to trigger infertility and pregnancy complications. This warrants the need to adopt lifestyles that will decrease the tendency of getting exposed to BPA.

Cellular prion protein is involved in decidualization of mouse uterus.

Prion protein (PrP) is encoded by a single copy gene Prnp in many cell and tissue types. PrP is very famous for its infectious conformers (PrPSC) resulting in transmissible spongiform encephalopathies. At present, physiological functions of its cellular isoform (PrPC) remain ambiguous. Although PrPC expression has been found in uterus, whether it functions in maternal-fetal dialogue during early pregnant is unknown. In this study, we examined PrPC mRNA and protein in the uterus of peri-implantation mice, and found that they were expressed with a spatiotemporal dynamic pattern. Interestingly, PrPC was significantly increased in the decidual zones around the implanting embryos at the implantation window stage. To further demonstrate that PrPC is involved in the decidualization of mouse uterus during embryo implantation, we constructed the artificial decidualization models and the delayed implantation models. Once the pseudopregnant mice were artificially induced to decidualization, the PrPC expression then increased significantly in the decidua zone. And also, if the delayed implantation embryos were allowed to implant, PrPC protein was also simultaneously improved in stromal cells surrounding the implanting embryos. Moreover, PrPC expression can be inhibited by progesterone but upregulated by estrogen in mouse uterus. These results suggest that PrPC may play an important role in embryo implantation and decidualization.

Thyroxine treatment may be useful for subclinical hypothyroidism in patients with female infertility.

Infertile women sometimes associated with subclinical hypothyroidism (SCH). The guidelines of the American Endocrine Society, and American Association of Clinical Endocrinologists and American Thyroid Association recommend treatment with thyroxine (T4) for patients with SCH who want to have children. We examined 69 female infertile patients with SCH and the effects of levothyroxine (l-T4) therapy on pregnancy rates and pregnancy outcomes were observed. Fifty-eight (84.1%) patients successfully conceived during the T4 treatment period (Group A), although 17 patients (29.3%) had miscarriage afterward. The remaining 11 patients continued to be infertile (Group B). The median TSH value in Group A before the T4 treatment was 5.46 µIU/mL (range 3.1-13.3) and this significantly decreased to 1.25 µIU/mL (range 0.02-3.75) during the treatment (p<0.001). The estimated duration of infertility before the T4 treatment was 2.8±1.7 years and the duration until pregnancy after the treatment was significantly shorter at 0.9±0.9 years (p<0.001). Shortening of the infertile period after the T4 therapy was observed not only in patients who were treated with assisted reproductive technology (ART) but also in patients who conceived spontaneously in Group A. Administered T4 dose was 54.3±14.2 µg before pregnancy and 68.5±22.8 µg during pregnancy (p<0.001). Anti-thyroid autoantibodies were identified in 42.0% of all patients and no significant difference was observed in positivity between Group A and Group B. High successful pregnancy rate and shorter duration of infertility until pregnancy after T4 treatment strongly suggest that T4 enhanced fertility in infertile patients with SCH.

Degradation of estrogen receptor α in activated blastocysts is associated with implantation in the delayed implantation mouse model.

Implantation of a blastocyst into a receptive uterus involves a series of highly coordinated cellular and molecular events directed by ovarian estrogen and progesterone. In particular, estrogen is essential for on-time uterine receptivity and blastocyst activation in mice. Although estrogen receptor α (ERα) is expressed in blastocysts, its targeted disruption leaves embryonic development and implantation unaffected. Therefore, the role of ERα in implanting blastocysts remains unclear. Using a delayed implantation model in mice, we showed increased expression of ERα in implantation-induced (activated) blastocysts; however, this ERα expression in activated blastocysts decreased within 6-h culture. In contrast, breast cancer 1 (Brca1) was maintained in the blastocysts during the culture. The treatment of activated blastocysts with the proteasome inhibitor MG132 demonstrated that proteolysis is associated with down-regulation of ERα expression in activated blastocysts. Embryo transfer of MG132-treated activated blastocysts into recipient mice on the morning of Day 4 of pseudopregnancy (Day 1 = vaginal plug) showed a decreased implantation rate, whereas combined treatment with MG132 and the ER antagonist, ICI 182,780, resulted in recovery of the rate of implantation. This study has revealed that down-regulation of ERα in activated blastocyst is associated with completion of blastocyst implantation after embryo transfer on the morning of Day 4 of pseudopregnancy. Our results also suggest that selective protein turnover, such as that of ERα, occurs in activated blastocysts, while expression of other proteins, including Brca1, is maintained at the same stage.

PARP1 during embryo implantation and its upregulation by oestradiol in mice.

Pregnancy requires successful implantation of an embryo, which occurs during a restricted period defined as 'receptivity of the endometrium' and is influenced by the ovarian steroids progesterone and oestradiol. The role of poly(ADP-ribose)polymerase-1 (PARP1) in apoptosis is well established. However, it is also involved in cell differentiation, proliferation and tissue remodelling. Previous studies have described the presence of PARP in the uterus, but its exact role in embryo implantation is not yet elucidated. Hence, in this study, we studied the expression of PARP1 in the uterus during embryo implantation and decidualisation, and its regulation by ovarian steroids. Our results show upregulation of the native form of PARP1 (∼116 kDa) in the cytosolic and nuclear compartments of implantation and non-implantation sites at day 5 (0500 h), followed by downregulation at day 5 (1000 h), during the embryo implantation period. The transcript level of Parp1 was also augmented during day 5 (0500 h). Inhibition of PARP1 activity by the drug EB-47 decreased the number of embryo implantation sites and blastocysts at day 5 (1000 h). Further, cleavage of native PARP1 was due to the activity of caspase-3 during the peri-implantation stage (day 5 (0500 h)), and is also required for embryo implantation, as inhibition of its activity compromised blastocyst implantation. The native (∼116 kDa) and cleaved (∼89 kDa) forms of PARP1 were both elevated during decidualisation of the uterus. Furthermore, the expression level of PARP1 in the uterus was found to be under the control of the hormone oestrogen. Our results clearly demonstrate that PARP1 participates in the process of embryo implantation.

Differential expression and regulation of Cryab in mouse uterus during preimplantation period.

The aim of this study was to examine the expression and regulation of the crystallin, alpha B (Cryab) gene in mouse uterus during the peri-implantation period by in situ hybridization and real-time PCR. There was no detectable Cryab mRNA signal on days 1-4 of pregnancy. On day 5 of pregnancy when embryo implanted, a high level of Cryab mRNA signal was found in the subluminal stroma surrounding the implanting blastocyst. On days 6-8, Cryab mRNA was strongly expressed in the primary decidua. By real-time PCR, a high level of Cryab expression was detected on days 7 and 8 of pregnancy, although Cryab expression was seen from days 1 to 8. Under in vivo and in vitro artificial decidualization, Cryab expression was significantly elevated. Compared with the progesterone-primed delayed implantation uterus, a high level of Cryab mRNA expression was observed in estrogen-activated implantation uterus. In the uterine stromal cells, cAMP, estrogen, and progesterone could induce the expression of Cryab gene. In the ovariectomized mouse uterus, estrogen could also induce the expression of Cryab while progesterone inhibited its expression. Our data suggest that Cryab may play an important role during mouse embryo implantation and decidualization and that estrogen and progesterone can regulate the expression of Cryab gene.

Postcoital administration of asoprisnil inhibited embryo implantation and disturbed ultrastructure of endometrium in implantation window in mice.

Asoprisnil, a member of the selective progesterone receptor modulators, exerts high progesterone receptor selectivity, endometrial targeted advantages and significant anti-implantation effect in rats. The purpose of this study was to confirm the anti-implantation effect of asoprisil, investigate the ultrastructural changes of the peri-implantation endometrium in mice and explore the effect of asoprisnil on endometrial receptivity and its targeted contraceptive proficiency. Post-coitus mice were administered with different dosages (0.2, 0.1, 0.05 mg·g(-1)·day(-1)) of asoprisnil from day 1 of pregnancy to day 3. Then 3 animals in each group were killed on day 5 of pregnancy, and uteri were collected to examine the ultrastructural changes of endometria under a transmission electron microscope (TEM). A total of 80 animals were sacrificed on day 8 of pregnancy, and the uterine horns were examined for the presence or absence of nidation sites and the number of implantation embryos. The results showed that the implantation rate and the average number of implantation embryos in asoprisnil groups were statistically significantly decreased as compared with the vehicle control group (P<0.05). The TEM results revealed that, in vehicle control group, the tight junction between the luminal epithelia cells was short and straight, the gap was wide; the luminal epithelia cells were covered with plenty of short, clavate and neatly arranged microvilli; the endometril stromal cells were large with plenty of cytoplasm, and showed significant decidual change; there was more than one nucleus in stromal cells, and the karyotheca was integrity. In low dosage and high dosage asoprisnil groups, the tight junction was longer and more curve than in the vehicle control group; microvilli were uneven and asymmetrically distributed in luminal epithelia; the stromal cells were small and the decidual change was not significant; there were karyopyknosis and karyolysis in stromal cells; there were abnormal thick-wall vessels in the endometrium. It was suggested that asoprisnil changed the ultrastructure of the endometrium in implantation window, disturbed the endometrial receptivity and finally resulted in embryo implantation failure.

Local immune regulatory effects of Bangdeyun on the endometrium of mice with embryo implantation dysfunction during the implantation time.

This study examined the effects of Bangdeyun on the expressions of nuclear factor-kappaB (NF-kappaB), interferon-gamma (IFN-gamma) and interleukin-10 (IL-10) in the endometrium of mice with embryo implantation dysfunction (EID) during the implantation time (namely on pregnancy day 5, 6, 7 and 8) and explored the local immune regulatory effects of Bangdeyun. The gestational mice were randomly divided into normal group, model group and Bangdeyun-treated group. EID models of mice were established by using indomethacin. The endometrial expression of NF-kappaB was detected by immunohistochemistry and Western blotting. IFN-gamma and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA). The results showed that in the normal group, NF-kappaB and IFN-gamma were weakly expressed and IL-10 was strongly expressed in the endometrium during the whole implantation period. In the model group, the expressions of NF-kappaB and IFN-gamma were increased on pregnancy day 5, 6 and 7, and IL-10 expression decreased during the whole implantation time when compared with those in the normal group (P<0.01 for all). In the Bangdeyun-treated group, little amount of NF-kappaB and IFN-gamma was expressed and IL-10 expression was strong, much the way they were expressed in the normal group (P>0.05). The expressions of NF-kappaB and IFN-gamma were much lower in the Bangdeyun-treated group than those in the model group on pregnancy day 5, 6 and 7 (P<0.01 for all), while the expression of IL-10 was much higher than in the model group during the whole implantation time (P<0.01). It was suggested Bangderun may favor a shift from Th1- to Th2-type immune response, therefore inhibiting the maternal immune rejection, inducing the immune tolerance and improving the fetal implantation.

[Effect of Bushen Antai Recipe on prostaglandin I2 expression and its nuclear receptor at implantation site in mice with blastocyst implantation dysfunction].

OBJECTIVE: To observe the effect of Bushen Antai Recipe (BAR) on expression of prostaglandin I2 (PGI2) and its nuclear receptor peroxisome proliferators-activated receptor delta (PPARdelta) at implantation site in mice with blastocyst implantation dysfunction. METHODS: Pregnant mice were divided into three groups randomly, the normal group, the model group and the BAR group. The pregnant uterus of all mice was cut off on the 4th (D4), 5th (D5), 6th (D6) and 8th (D8) day of pregnancy for determining the PGI2 expression with radio immunoassay; and the mRNA and protein expression of PPARdelta with RT-PCR and immunohistochemistry at implantation site. RESULTS: PGI2 expression in the model group was obviously lower than that in the normal group (P < 0.01), and also lower than that in the BAR group (P < 0.01), while the index was insignificantly different between the normal and the BAR group. Compared with the normal group, the expression of PPARdelta in the model group was delayed temporally and spatially (P < 0.05), while that in the BAR group was not significantly different. CONCLUSION: BAR can improve the implantation in mice with blastocyst implantation dysfunction through promoting the PGI2 expression and its nuclear receptor PPARdelta at implantation site.

An inhalation reproductive toxicity study of octamethylcyclotetrasiloxane (D4) in female rats using multiple and single day exposure regimens.

Octamethylcyclotetrasiloxane (D(4)) has been shown to have effects on the female rat reproductive cycle. This study evaluated the phase of the female rat reproductive cycle affected by D(4) using a study design that allowed the complete female reproductive cycle, as well as phases of the cycle, from pre-mating through gestation, to be evaluated. Rats were exposed via whole body vapor inhalation up to 700 ppm D(4) during the overall phase (28 days prior to mating through gestation day (GD) 19), the ovarian phase (31-3 days prior to mating), the fertilization phase (3 days prior to the start of mating through gestation day 3), and the implantation phase (GD 2-GD 5) of the reproductive cycle. D(4) was associated with decreases in implantation sites and litter size in the overall and fertilization phases, but not in the ovarian or implantation phases. In order to further define the sensitive period for D(4) exposure, additional groups of rats were exposed on single days. A single 6h exposure to D(4) on the day prior to mating resulted in a significant reduction in fertility. These data indicate that there is a very narrow window, around the time of ovulation and fertilization, for D(4) to exert effects on the reproductive cycle of the female rat. Subsequent research, reported elsewhere, has elucidated the mode of action and assessed its potential relevance to humans.

[Study on regulatory effect of Bushen Antai Recipe on levels of estrogen and progesterone in blastocyst implantation dysfunction mice].

OBJECTIVE: To investigate the effect and explore the mechanism of Bushen Antai Recipe (BAR) on pregnancy rate and number of implantation site in blastocyst implantation dysfunction (BID) mice induced by indomethacin. METHODS: Pregnant mice were divided into 3 groups randomly: the normal group, the model group and the BAR group. Tap water was given orally to the rats in the normal and model groups, and BAR to the rats in the BAR group from the first day of pregnancy for 5 or 8 days; on the 3rd and 4th day dissolvent was injected subcutaneously twice per day in the normal group, while indomethacin (4.33 mg/kg) was injected subcutaneously twice per day in the other two groups to establish implantation dysfunction model; serum estrogen (E) and progesterone (P4) levels were detected on the 5th and 8th day; the pregnancy rate and number of implanted site was observed and the receptors of E and P4 in endometrium of uterus were examined by immunohistochemistry on the 8th day. RESULTS: The pregnancy rate and number of implanted site was 27.3% and 5.3 +/- 0.7 respectively in the model group, significantly lower than those in the normal group (90.9%, 13.3 +/- 2.8), and the BAR group (72.7%, 10.7 +/- 2.2, P < 0.05). Serum E level was higher in the BAR group than that in the model group on the 5th and 8th day, and even higher than that in the normal group on the 8th day; serum P4 level was lower in the model and BAR groups than that in the normal group on the 5th day (P < 0.01), but higher in the BAR group than that in the model group on the 8th day. Immunohistochemical observation showed that expressions of E and P4 receptor increased remarkably in the BAR group than those in the model group. CONCLUSION: BAR increases the pregnancy rate and number of implanted site of indomethacrne induced BID mice through regulating E and P4 levels and enhancing the expressions of their receptors in the endometrium.

[Effects of jiantai liquid on the expression of estrogen/progesterone receptors in embryo implantation dysfunction mice endometrium].

OBJECTIVE: To explore the mechanism of Jiantai liquid on the endometrium development of embryo implantation dysfunction mice. METHOD: The model of embryo implantation dysfunction mice was induced by mifepristone and treated by Jiantai liquid. All animals were sacrificed on day 8 of pregnancy. Estradiol and progesterone concentrations in serum and endometrium tissue homogenates were measured by radioimmunoassay method, the endometial expressions of estrogen receptor (ER)and progesterone receptor (PR)assessed by immunohistochemical SP method. RESULT: There were no significantly differences in the estradiol and progesterone concentrations in serum and uterus tissue homogenates among three groups( P > 0.05). Absorbency and area rate of ER, PR in model group' s gland and stroma were higher than those in model group(P < 0.05), which was similar with the control group( P > 0.05). CONCLUSION: Jiantai liquid increase the implantation rate and improve the endometrial development by increasing the expressions of ER, PR in endometrium of embryo implantation dysfunction

Termination of prolactin surges with development of placental lactogen secretion in the pregnant rat.

It has been hypothesized that it is rat placental lactogen (rPL) which causes PRL surges to terminate at mid-pregnancy. Using a hormonally induced model of delayed implantation, the temporal relationship between the secretion of rPL and the nocturnal PRL surges was followed. Implantation was prevented by removing the ovaries, the source of estrogen, on day 3 of pregnancy. Blastocysts were maintained free-floating in the uterine lumen by sc injection of 4 mg progesterone in oil daily for 0, 5, 7, or 9 days. Implantation was induced and the subsequent pregnancy was maintained with 1 microgram estrone plus 4 mg progesterone daily. Nocturnal PRL surges (0500 h) were followed for 10 days after the first estrone injection. Control animals last exhibited PRL surges on day 10. Animals with 5, 7, or 9 days of implantation delay had their last PRL surge on days 15, 17, and 18, respectively. Levels of rPL in control animals, as measured by Nb2 lymphoma cell bioassay, were low on day 6, slightly higher on day 10, and significantly elevated on day 12. Delaying implantation delayed the increase in rPL secretion in the experimental groups. This proportionately prolonged the number of days the PRL surges were present. These data suggest that the termination of the nocturnal PRL surges requires the secretion of rPL by the developing conceptus.

Lesions to the anterior hypothalamus prevent the melatonin-induced lengthening of delayed implantation.

The anterior hypothalamic area (AHA) has been postulated as a site of action for melatonin. We tested the hypothesis that lesions to the AHA (AHAx) would counteract the inhibitory effect of exogenous melatonin on blastocyst implantation in the spotted skunk by removing a possible site of action. Forty-seven females were treated as follows during delayed implantation. In Exp 1, five received empty Silastic capsules, five received Silastic capsules containing melatonin, six received sham AHAx plus empty capsules, none received AHAx plus empty capsules, and eight received AHAx plus capsules containing melatonin. In Exp 2, four skunks each received two empty capsules, five skunks each received two capsules containing melatonin, and five skunks received AHAx plus capsules containing melatonin. All capsules were inserted sc in the interscapular region 14-35 days after surgery in Exp 1 and 2 weeks before surgery in Exp 2. Surgery was performed between January 22 and February 12, 1988, in Exp 1 and on March 2-3, 1989, in Exp 2. The skunks were subjected to a natural photoperiod, and the duration of preimplantation was measured. In Exp 1, AHAx plus empty capsules significantly (P less than 0.05) shortened the duration of preimplantation (163 +/- 14.7 days) compared to that in sham AHAx or intact controls (193 +/- 26.1 and 188 +/- 10.6 days, respectively). Melatonin significantly (P less than 0.05) prolonged the duration of preimplantation (289 +/- 2.9 days) in intact skunks, but failed to do so in skunks with AHAx, as the preimplantation period was significantly shortened (159 +/- 6.1 days). In Exp 2, AHAx reversed the inhibitory effect of melatonin on the duration of preimplantation (191 +/- 21.5 days), as intact melatonin-treated skunks had a significantly longer preimplantation period (260 +/- 2.5 days) than skunks receiving empty capsules (191 +/- 16.4 days). The inhibitory effect of melatonin was reversible in all intact skunks, as blastocysts implanted 23 days, on the average, after cessation of treatment with melatonin. These data are consistent with the hypothesis that a portion of the AHA and/or adjacent regions play an essential role in timing blastocyst implantation in the spotted skunk. The lesions may have given this result by ablating a neural pathway controlling PRL secretion and may or may not have involved a site of action for melatonin.

Decreased antigenicity of mouse blastocysts after activation for implantation from experimental delay.

The antigenicity of mouse blastocysts in experimentally delayed implantation and after activation from delay by estradiol administration were determined by two different methods. CBA blastocysts were incubated in C57BL/6J anti-CBA serum, and the amount of antibodies bound to the blastocysts was traced by -125-I-conjugated sheep antimouse gamma-globulin (isotope antiglobulin technique) and sensitized sheep red cells (mixed haemadsorption technique). With both techniques it was possible to demonstrate that mouse blastocysts in experimental delay of implantation possess alloantigens, and that this antigen expression has decreased markedly 14 hr after activation for implantation. It is suggested that this phenomenon may be of significance for noncognition of the allogeneic conceptus during pregnancy.

Effects of lactation and season on plasma prolactin concentrations and response to bromocriptine during lactation in the Bennett's wallaby (Macropus rufogriseus rufogriseus).

Prolactin concentration was measured in plasma collected each week for 13 months from lactating and non-lactating Bennett's wallabies (Macropus rufogriseus rufogriseus). In non-lactating animals, prolactin concentrations decreased towards the end of the study but such changes did not appear to fit a seasonal pattern. Prolactin concentrations were low during early lactation and at a similar level to non-lactating animals, increased significantly during late pouch life (February-May), and then returned to non-lactating levels at a time coincident with permanent exit of the joey from the pouch. Temporary removal of joeys from their mothers in April was followed by a rapid decline in prolactin concentrations which remained low for 24 h until the joey was returned to its mother, whereupon prolactin concentrations increased significantly within 2 h. The effect of a single injection of bromocriptine (5 mg/kg) on lactation, embryonic diapause and plasma prolactin concentrations was examined at two stages of lactation. In November (lactational diapause), bromocriptine had no effect on prolactin concentrations but two out of four suckling joeys died on days 13 and 14 after treatment, and three out of four females gave birth on days 27, 27 and 28. Bromocriptine treatment in April (seasonal diapause) was followed by a significant reduction in prolactin concentrations and reduced growth rate of joeys belonging to treated females. New births were not observed. In view of the effect of bromocriptine on plasma prolactin concentrations in late lactation and the demonstration that domperidone (a dopamine antagonist) significantly increases plasma prolactin concentrations, it would seem that dopamine can act as a prolactin inhibitory hormone in this as in other mammalian species.

3'-deoxyadenosine and implantation of delayed blastocysts in mice.

Pregnant mice were ovariectomized 3 days after mating and pregnancy was maintained by progesterone treatment. Different regimens of intraperitoneal injections of 3'-deoxyadenosine were applied 3 days after ovariectomy. Repetition of the injections at 3 h intervals induced a significant rate of implantation by delayed blastocysts. Other types of treatment with 3-deoxyadenosine as well as adenosine injections were found to be ineffective. Paradoxically, 3'-deoxyadenosine treatment had an adverse effect on the overall pregnancy rate found at autopsy.

Maintenance of unimplanted fertilized ova in spayed rats: effects of cortisone acetate therapy during the period of embryonic diapause.

Rat dams were ovariectomized on day 3 of pregnancy and treated with corn oil (0.25 ml/day), progesterone (4 mg/day), cortisone acetate (2 or 10 mg/day), cortisone acetate (10 mg/day) plus progesterone (4 mg/day) or progesterone (4 mg/day) plus oestrone (1 microgram/day) from days 2 to 8 or 14, followed by 6 to 11 days of treatment with progesterone (4 mg/day) plus oestrone (1 microgram/day). Implantation of ova at the normal time was realized in the animals treated from day 2 with progesterone plus oestrone. Implantation of ova was only realized subsequent to progesterone plus oestrone in the dams treated with progesterone alone, cortisone acetate alone, or progesterone plus cortisone acetate, except for one animal in the latter group. Implantation of ova was not usually realized even after progesterone plus oestrone treatment in the dams treated with corn oil. Even though cortisone acetate maintained unimplanted ova in spayed rats in much the same manner as does progesterone, it was not equivalent to progesterone in efficacy or action.

A study of carbohydrate metabolism in 'delayed' and 'activated' mouse blastocyst and uterus.

Several regulatory enzymes of carbohydrate metabolism were studied in blastocysts and uteri of mice in which implantation had been delayed and of oestrogen-activated mice, and compared with those of normal mice just before implantation on day 4 of pregnancy. A significant increase in the activities of phosphofructokinase and pyruvate kinase was observed but the level of lactate dehydrogenase declined in delayed blastocysts. Carbohydrate metabolism in the uterus remained essentially unchanged during the delay period. A study of uterine mitotic patterns showed a steady increase in stromal mitosis after administration of oestradiol to animals in which implantation had been delayed.

The effects of ovarian steroids in controlling rat uterine prostaglandin F2-alpha during the peri-implantation period.

Rats with delayed implantation, induced by ovariectomy or hypophysectomy, as well as those with normal pregnancy were used to examine the changes in uterine prostaglandin F2 alpha (PGF2 alpha) associated with implantation. In normal pregnant rats, while maximal uterine production of PGF2 alpha was found at 09:00, maximal catabolic enzyme activity (CEA) was seen at 17:00 of day 4. Uterine content of PGF2 alpha was high at 17:00 of day 4, but decreased by 80% within the next 24 h. There was no change in PGF2 alpha production during the first 6 h after injection of estradiol to hypophysectomized animals. There was, however, a dramatic decrease in production within the next 6 h. In contrast, CEA was not different in animals treated with estrogen than in those receiving only progesterone. In ovariectomized animals, uterine PGF2 alpha production also was lowered by estrogen but in these animals CEA was significantly elevated 18 h after injection of estradiol. Estrogen caused a greater increase in PGF2 alpha content in the hypophysectomized, compared to the ovariectomized, rats. The results are consistent with the view that ovarian steroids play an important role in controlling the changes in uterine PGF2 alpha around the time of implantation in rat.