Pseudopregnancy and reproductive cycle synchronisation cannot be induced using conventional methods in the spiny mouse (Acomys cahirinus).

The menstruating spiny mouse is the first rodent identified to exhibit natural spontaneous decidualisation, cyclical endometrial shedding and regeneration. While the spiny mouse shares several primate-like characteristics in its reproductive biology, it has not been established whether pseudopregnancy can be induced or if its cycles can be synchronised as in non-human mammals. Here we describe attempts to induce pseudopregnancy and synchronisation of menstrual cycles (i.e. Whitten effect) in spiny mice. Virgin females (n=3-8 per group) underwent one of the following procedures to induce pseudopregnancy: daily vaginal lavage only (control), progesterone injection, mechanical stimulation of the cervix and sterile mating. A separate cohort was also exposed to male-soiled bedding to assess the Whitten effect. Pseudopregnancy was deemed successful if females presented with extended (>12 consecutive days) leukocytic vaginal cytology. No female from any method of induction met this criterion. In addition, the menstrual cycles of a group of six females could not be synchronised, nor immediate ovulation induced via exposure to male-soiled bedding. These responses indicate that the spiny mouse does not behave as a typical rodent. Like higher-order primates, the spiny mouse exhibits a relatively rare reproductive strategy, of failure to show pseudopregnancy or cyclical synchronisation. This is further endorsement of the use of this species as a versatile animal model for translational studies of menstruation and fertility.

Effects of pregnancy experience on ovarian senescence and longevity in Hatano rats bred for high- and low-avoidance learning.

We investigated the effects of pregnancy experience on ovarian senescence and longevity using two inbred strains of Hatano rats. These strains have been selectively bred for high- and low-avoidance animals (HAA and LAA, respectively), but the HAA line has a slower onset of ovarian senescence and a shorter lifespan compared with the LAA line. The onset of abnormal estrous cycles and survival curves were compared between nulliparous and parous rats in each line. In the HAA line, pregnancy experience did not change the onset of ovarian senescence but increased longevity. This suggests that a pituitary tumor, which is a causal factor for accelerated mortality in this line, developed slowly in parous rats. In the LAA line, pregnancy experience delayed the onset of ovarian senescence and reduced the incidence of mammary tumors but did not increase longevity because of an increased frequency of constipation with megacolon. These data suggest that the effects of pregnancy experience on ovarian senescence and longevity depend on the reproductive characteristics of the rat strains.

A Case of Concomitant Pseudocyesis and Couvade Syndrome Variant.

Per DSM-V, pseudocyesis is included under the category "other specified somatic symptom and related disorder" and is defined as a false belief of being pregnant that is associated with objective signs and reported symptoms of pregnancy. The male counterpart of pseudocyesis is Couvade syndrome, also called "sympathetic pregnancy" where a man experiences symptoms of pregnancy when his female partner is pregnant. There are extensive reports on pseudocyesis and Couvade syndrome in psychiatric literature but none with features of both, in a single case. Here we present a unique case of a fifty-eight-year-old mother who presented with symptoms of concomitant pseudocyesis and Couvade syndrome concurrently when her daughter was pregnant. This case report discusses the epidemiology, course of symptoms and common comorbidities associated with this interesting diagnosis.

GRIM-19, a gene associated with retinoid-interferon-induced mortality, affects endometrial receptivity and embryo implantation.

GRIM-19 is associated with apoptosis, abnormal proliferation, immune tolerance and malignant transformation, and it also plays an important role in early embryonic development. Although the homologous deletion of GRIM-19 causes embryonic lethality in mice, the precise role of GRIM-19 in embryo implantation has not been elucidated. Here we show that GRIM-19 plays an important role in endometrial receptivity and embryo implantation. Day 1 to Day 6 pregnant mouse uteri were collected. Immunohistochemistry studies revealed the presence of GRIM-19 on the luminal epithelium and glandular epithelium throughout the implantation period in pregnant mice. The protein and mRNA levels of GRIM-19 were markedly decreased on Day 4 of pregnancy in pregnant mice, but there was no change in GRIM-19 levels in a group of pseudopregnant mice. Overexpression of GRIM-19 decreased the adhesion rate of RL95-2-BeWo co-cultured spheroids and increased apoptosis. Furthermore, STAT3 and IL-11 mRNA and protein levels were reduced by overexpressing GRIM-19, but protein and mRNA levels of TNF-α were increased. These findings indicate the involvement of GRIM-19 in the embryo implantation process by regulating adhesion, apoptosis and immune tolerance.

Confirmed dioestrus in pseudopregnant mice using vaginal exfoliative cytology improves embryo transfer implantation rate.

Embryo transfer is a commonly performed surgical technique. In mice, protocols typically specify pairing recipient females with vasectomized males to induce a receptive uterine environment for embryo implantation. However, this induced receptive state is not always maintained until implantation occurs. The use of a well-characterized correlation between oestrous state and exfoliative vaginal cytology was therefore evaluated to assess uterine receptivity immediately before embryo transfer. Eight- to 12-week-old virgin female CD1 mice (n = 22) were paired overnight with vasectomized males and successfully mated, indicated by the presence of a vaginal plug. These dams underwent embryo transfer 3 days later with embryos obtained from superovulated 4-week-old F1 (C57BL/6 × CBA) females. Non-invasive vaginal lavage was conducted immediately before transfer. Dams were killed 6 days after transfer and the uterus collected for histological analysis. Embryo implantation rate in mice was 96% when cytological analysis of the lavage samples signified dioestrus (n = 6), whereas the implantation rate was <15% (n = 16) when cytology signified other stages of oestrous. This simple, quick, non-invasive measure of receptivity was accurate and easily adopted and, when applied prospectively, will avoid unnecessary surgery and subsequent culling of non-suitable recipients, while maximizing the implantation potential of each recipient female.

[Modulation of rat myometrium contractile activity by peptidoglycan of Staphylococcus aureus cell wall].

Peptidoglycan of Staphylococcus aureus cell wall impact on the both estrogen-treated and pseudopragnant rat myometrium contractile activity dynamics was studied. The results of experiments shown that rat myomatrium sensitivity to peptidoglican depends on the hormonal background. Peptidoglycan modified the myometrium contractile activity of both estrogen-treated and pseudopragnant rats. In estrogen-treated rat myometrium peptidoglycan reduces frequency and duration of contractions (elongated the uterine cycle) while in the pseudopregnant rat myometrium it increased the amplitude as well as the duration and the freqwency (deshortened the uterine cycle). During the experiments we found that peptidoglycan has stronger uterotonic effect than prostaglandin F2α. In this connection we conclude that the changes ofmyometral contractile activity after peptidoglycan action may have negative effects for fertility and course of pregnancy.

Endocrinology and physiology of pseudocyesis.

This literature review on pseudocyesis or false pregnancy aims to find epidemiological, psychiatric/psychologic, gynecological and endocrine traits associated with this condition in order to propose neuroendocrine/endocrine mechanisms leading to the emergence of pseudocyetic traits. Ten women from 5 selected studies were analyzed after applying stringent criteria to discriminate between cases of true pseudocyesis (pseudocyesis vera) versus delusional, simulated or erroneous pseudocyesis. The analysis of the reviewed studies evidenced that pseudocyesis shares many endocrine traits with both polycystic ovarian syndrome and major depressive disorder, although the endocrine traits are more akin to polycystic ovarian syndrome than to major depressive disorder. Data support the notion that pseudocyetic women may have increased sympathetic nervous system activity, dysfunction of central nervous system catecholaminergic pathways and decreased steroid feedback inhibition of gonadotropin-releasing hormone. Although other neuroendocrine/endocrine pathways may be involved, the neuroendocrine/endocrine mechanisms proposed in this review may lead to the development of pseudocyetic traits including hypomenorrhea or amenorrhea, galactorrhea, diurnal and/or nocturnal hyperprolactinemia, abdominal distension and apparent fetal movements and labor pains at the expected date of delivery.

Mammary gland proliferation in female rats: effects of the estrous cycle, pseudo-pregnancy and age.

Assessment of mammary gland proliferation in rats is an important endpoint in preclinical safety studies of pharmaceutical compounds. However, existing data on mammary gland proliferation in rats during the estrous cycle is conflicting, and it is unknown whether mammary gland proliferation differs between young and mature female virgin rats. Additionally, it is unclear which of the commonly applied markers of proliferating cells that is optimal for assessment of rat mammary gland proliferation. In this study the caudal thoracic, the abdominal and the cranial inguinal (i.e., the 3rd the 4th and the 5th) mammary gland were collected from 29 young and 26 mature non-treated, virgin female Sprague Dawley rats. Estrous cycle stage was determined from repeated vaginal smears and histological examination of the reproductive organs. Proliferation of mammary epithelium was assessed by immunohistochemistry using three markers: PCNA, Ki67, and BrdU. Proliferation of the mammary epithelium occurred mainly in the terminal end buds in the young animals. Epithelial proliferation was significantly increased during metestrus compared to the other phases. Mammary gland proliferation in pseudo-pregnant females was increased compared to proestrus, estrus and diestrus, but not metestrus. Except during estrus no difference in mammary gland proliferation was observed between young and mature female rats, and no significant differences was observed between different mammary glands. The percentages of PCNA-, Ki67- and BrdU-positive epithelial cells were significantly correlated. In conclusion, the variation in normal proliferation between estrous cycle stages and animals with an irregular estrous cycle should be considered in toxico-pathological studies of mammary gland proliferation.

Retinoic acid metabolizing enzyme CYP26A1 is implicated in rat embryo implantation.

BACKGROUND: The retinoic acid metabolizing enzyme Cyp26a1 plays a pivotal role in vertebrate embryo development. Cyp26a1 was characterized previously as a differentially expressed gene in peri-implantation rat uteri via suppressive subtracted hybridization analysis. However, the role of Cyp26a1 in rat embryo implantation remained elusive. METHODS: The expression of Cyp26a1 in the uteri of early pregnancy, pseudopregnancy and artificial decidualization was detected by northern blotting, real time-PCR, in situ hybridization, western blotting and immunofluorescent staining. The effect of Cyp26a1 on apoptosis of endometrial stromal cells (ESCs) isolated from rat uteri was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and Hoechst staining. Apoptosis-related proteins in ESCs were detected by western blotting. RESULTS: Cyp26a1 showed distinctive expression patterns in embryos and uteri during the peri-implantation period, with a remarkable increase (P < 0.01 versus Days 4-5) in mRNA and protein in the implantation phase (Days 5.5-6.5 of pregnancy). CYP26A1 was specifically localized in glandular epithelium, luminal epithelium and decidua basalis. The level of CYP26A1 protein was significantly increased in uteri of artificial decidualization (P < 0.01 versus control). Forced Cyp26a1 overexpression significantly reduced the sensitivity of ESCs to etoposide-induced apoptosis, with reductions in p53 (P < 0.01) and Fas (P < 0.05) proteins versus control, while in contrast, FasL (P < 0.01) and proliferating cell nuclear antigen (P < 0.05) proteins increased. CONCLUSIONS: Cyp26a1 is spatiotemporally expressed in the uterus during embryo implantation and decidualization. Overexpression of Cyp26a1 attenuates the process of uterine stromal cell apoptosis, probably via down-regulating the expression of p53 and FasL.

Temporal and spatial regulation of let-7a in the uterus during embryo implantation in the rat.

Mammalian embryonic implantation requires reciprocal interactions between implantation-competent blastocysts and a receptive uterus. Some microRNAs might play a key role during embryo implantation in the mouse, but the let-7a expression profiles in the rat uterus during peri-implantation are unknown. In the study, the expression of let-7a in the uterus during early pregnancy, pseudopregnancy, artificial decidualization and activation of delayed implantation was detected by Northern blotting and in situ hybridization. The effect of steroid hormones on let-7a expression was also detected by Northern blotting and in situ hybridization. Here, we found that the expression level of let-7a was higher on gestation day 6-7 (g.d. 6-7) in rats than on g.d.4-5 and g.d.8-9. Let-7a was specifically localized in glandular and luminal epithelia and decidua. The expression of let-7a was not significantly different in the pseudopregnant uterus and increased significantly in the uteri of rats subjected to artificial decidualization and activation of delayed implantation. Treatment with estradiol-17beta or progesterone significantly increased let-7a expression. Thus, let-7a expression was significantly induced by the process of embryo invasion, and this increased expression level was mainly induced by active blastocysts and decidualization during the window of implantation, implying that let-7a may participate in endometrial decidualization. Steroid hormones, estradiol-17beta or progesterone stimulated let-7a expression.

Transforming growth factor beta isoforms regulation of Akt activity and XIAP levels in rat endometrium during estrous cycle, in a model of pseudopregnancy and in cultured decidual cells.

BACKGROUND: During the estrous cycle, the rat uterine endometrium undergoes many changes such as cell proliferation and apoptosis. If implantation occurs, stromal cells differentiate into decidual cells and near the end of pregnancy, a second wave of apoptosis occurs. This process called decidual regression, is tightly regulated as is it crucial for successful pregnancy. We have previously shown that TGF-beta1, TGF-beta2 and TGF-beta3 are expressed in the endometrium during decidual basalis regression, but although we had demonstrated that TGF- beta1 was involved in the regulation of apoptosis in decidual cells, the ability of TGF- beta2 and TGF-beta3 isoforms to trigger apoptotic mechanisms in these cells remains unknown. Moreover, we hypothesized that the TGF-betas were also present and regulated in the non-pregnant endometrium during the estrous cycle. The aim of the present study was to determine and compare the specific effect of each TGF-beta isoform in the regulation of apoptosis in sensitized endometrial stromal cells in vitro, and to investigate the regulation of TGF-beta isoforms in the endometrium during the estrous cycle in vivo. METHODS: Rats with regular estrous cycle (4 days) were killed at different days of estrous cycle (diestrus, proestrus, estrus and metestrus). Pseudopregnancy was induced with sex steroids in ovariectomized rats and rats were killed at different days (days 1-9). Uteri were collected and either fixed for immunohistochemical staining (IHC) or processed for RT-PCR and Western analyses. For the in vitro part of the study, rats were ovariectomized and decidualization was induced using sex steroids. Endometrial stromal decidual cells were purified, cultured and treated with different concentrations of TGF-beta isoforms. RESULTS: Our results showed that all three TGF-beta isoforms are present, but are localized differently in the endometrium during the estrous cycle and their expression is regulated differently during pseudopregnancy. In cultured stromal cells, we found that TGF-beta3 isoform induced Smad2 phosphorylation, indicating that the Smad pathway is activated by TGF-beta3 in these cells. Furthermore, TGF-beta2 and TGF-beta3 induced a dose-dependant increase of apoptosis in cultured stromal cells, as demonstrated by Hoechst nuclear staining. Noteworthy, TGF-beta2 and TGF-beta3 reduced the level of the anti-apoptotic XIAP protein, as well as the level of phosphorylated/active Akt, a well known survival protein, in a dose-dependent manner. CONCLUSION: Those results suggest that TGF-beta might play an important role in the remodelling endometrium during the estrous cycle and in the regulation of apoptosis in rat decidual cells, in which inhibition of Akt survival pathway might be an important mechanism involved in the regulation of apoptosis.

Group IVA phospholipase A(2) activity may mediate prostaglandin F(2alpha)-induced luteal regression in pseudopregnant rats.

We investigated role(s) of luteal group IVA phospholipase A(2) (GIVA PLA(2)) in prostaglandin (PG) F(2alpha)-induced regression in pseudopregnant rats. Prostaglandin F(2alpha) (PGF(2alpha)) treatment of day 6 pseudopregnant rats stimulated luteal PLA(2) activity, which was sensitive to inhibitors and associated with increased GIVA PLA(2) immunoreactivity. Intra-bursal treatment with the enzyme inhibitor (AACOCF3) prior to PGF(2alpha) failed to prevent the initial decline in progesterone but induced subsequently a persistent rise that was significantly higher than that of vehicle-treated group. TUNEL-positive signals in luteal cells of control group were reduced by AACOCF3 treatment. TUNEL-positive reaction induced in luteal cells in vitro by combined cytokines and agonistic anti-Fas were both reduced by AACOCF3 and another inhibitor pyrrophenone. Overall data show that luteal GIVA PLA(2) activity and expression increased following PGF(2alpha) administration and that acute chemical inhibition of this activity could reverse, at least partly, PGF(2alpha)-induced functional regression and prevent apoptosis induced by PGF(2alpha)in vivo and by cytokines in vitro.

Paracrine signals from the mouse conceptus are not required for the normal progression of decidualization.

The purpose of this study was to determine whether the conceptus directs the formation of a tight- and adherens-dependent permeability barrier formed by the primary decidual zone and normal progression of decidual cell differentiation during embryo implantation. Four artificial models of decidualization were used, some apparently more physiological than others. The results show that both the formation of the permeability barrier and decidual cell differentiation of three of the artificial models were quite different from that of pregnant uteri. One artificial model of decidualization, namely pseudopregnant animals receiving concanavalin A-coated Sepharose bead transfers on d 2.5 of pseudopregnancy, better recapitulated the decidual changes that occur in the pregnant uterus undergoing decidualization. This included the formation of a primary decidual zone-like permeability barrier and decidual growth. This model also exhibited similar temporal changes of the expression of genes involved in decidualization that are markers of decidual cell differentiation. Overall, the results of this study indicate that some models of inducing decidualization artificially produce responses that are more similar to those occurring in the pregnant uterus, whereas others are quite different. More importantly, the results suggest that concanavalin A-coated Sepharose beads can provide an equivalent stimulus as the trophectoderm to cause the formation of the primary decidual zone permeability barrier.

Progesterone withdrawal promotes remodeling processes in the nonpregnant mouse cervix.

Prepartum cervical ripening is associated with remodeling of collagen structure and with inflammation. Progesterone withdrawal is critical for parturition, but the effects of progesterone decline on cervical morphology are unknown. The present study tested the hypothesis that progesterone withdrawal promotes processes associated with remodeling of the cervix. Adult, virgin, female C57BL/6 mice received silastic capsules with oil vehicle or estradiol plus progesterone to parallel concentrations in circulation during pregnancy. After 17 days of estradiol and progesterone treatment, the progesterone implant was removed from one group. Mice in each group were killed 15, 18, or 19 days after placement of capsules. Sections of cervix were stained for collagen, and the densities of macrophages, neutrophils, and area with nerve fibers were assessed. Treatment with gonadal steroids promoted hypertrophy of the cervix, as well as reduced collagen and increased area with nerve fibers compared with vehicle-treated controls. Removal of the progesterone capsule did not affect hypertrophy or innervation, but it did reduce collagen. By contrast, significantly more macrophages and neutrophils were present in the cervix on Days 18 and 19 (i.e., by 24 and 48 h after withdrawal of the progesterone capsule); the immune cell census was equivalent to that in vehicle controls. Findings indicate that gonadal steroids, comparable to those during pregnancy, promote hypertrophy and suppress immigration of immune cells in the cervix. Therefore, in a nonpregnant murine model for parturition, progesterone withdrawal is suggested to recruit immune cells and processes that remodel the cervix.

Effects of cholesterol and cAMP on progesterone production in cultured luteal cells isolated from pseudopregnant cat ovaries.

The present study was designed to incubate luteal cells isolated from pseudopregnant cats and to investigate the effects of cholesterol and cAMP on luteal progesterone production. Corpora lutea were collected from the cats on days 10 and 15 of pseudopregnancy. Luteal cells were isolated from the ovaries by collagenase digestion. Steroidogenic luteal cells were stained for 3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity. Cells (2 x 10(4)) staining positive for 3beta-HSD were cultured for up to 7 days. The cells were treated with 22(R)-hydroxycholesterol (22R-HC) and dibutyryl cyclic AMP (dbcAMP) on days 1, 3 and 7. Treatment of cells with 22R-HC resulted in a dose-dependent increase (p<0.001) in progesterone production. When 22R-HC was used at a concentration of 10 microg/ml, it resulted in 2.7- and 5.1-fold increases in progesterone production on days 3 and 5, respectively. When the dose was doubled (20 microg/ml), treated cells produced four times more progesterone on days 3 and 7, and three times more on day 5. By day 7, progesterone production increased up to 9.1 times more than the control. Incubation of cells with both concentrations of dbcAMP (0.1 mM and 1 mM) resulted in significant stimulations of progesterone on days 5 and 7 (p<0.001). However, on day 3, only higher doses of dbcAMP (1 mM) resulted in significant stimulation (p<0.05). Progesterone production was increased up to 2- and 2.9-fold of the control when cells were treated with lower concentration of dbcAMP (0.1 mM) on days 5 and 7, respectively. Incubation of cells with 1 mM concentrations of dbcAMP induced a 3.2-fold increase on day 5 and a 5-fold increase on day 7. In conclusion, a successful incubation was performed for long-life culturing of luteal cells collected from pseudopregnant cats. The method works well and allows for optimal growth and development of cells in the culture. The present study also demonstrated that incubating cat luteal cells with 22R-HC and dbcAMP induces a significant increase in luteal progesterone synthesis.

Expression of the novel gene embryo implantation factor 2 (EMO2) in the mouse uterus at the implantation sites.

OBJECTIVE: The aim of this study was to identify a novel implantation-related molecule and to examine EMO2 expression in the mouse uterus during the peri-implantation period. DESIGN: Experimental study. SETTING: Research laboratory. ANIMAL(S): Adult ICR mice aged 6-8 weeks. INTERVENTION(S): Adult female mice were mated with fertile males to achieve pregnancy. Implantation was delayed by ovariectomizing pregnant mice on day 4 and administering P during days 5-7; implantation was then initiated by administering E(2). Pseudopregnant mice were obtained by mating females with vasectomized males. MAIN OUTCOME MEASURE(S): The tissue distribution of EMO2 mRNA was detected by reverse transcriptase-polymerase chain reaction, and the uterine expression pattern of the EMO2 protein was determined by immunohistochemistry. RESULT(S): The full cDNA sequence of EMO2 was registered in GenBank (AY372183). EMO2 mRNA expression was observed in all mouse tissues tested. The expression of the EMO2 protein was predominately localized in decidual cells at the implantation site during days 5-6 of pregnancy, and its expression was induced by the active blastocyst and artificially induced decidualization. CONCLUSION(S): Our data indicate that EMO2 may play a key role in the mouse embryo implantation process.

Expression and localization of the serine proteases high-temperature requirement factor A1, serine protease 23, and serine protease 35 in the mouse ovary.

Proteolytic degradation of extracellular matrix components has been suggested to play an essential role in the occurrence of ovulation. Recent studies in our laboratory have indicated that the plasminogen activator and matrix metalloproteinase systems, which were previously believed to be crucial for ovulation, are not required in this process. In this study we have used a microarray approach to identify new proteases that are involved in ovulation. We found three serine proteases that were relatively highly expressed during ovulation: high-temperature requirement factor A1 (HtrA1), which was not regulated much during ovulation; serine protease 23 (PRSS23), which was down-regulated by gonadotropins; and serine protease 35 (PRSS35), which was up-regulated by gonadotropins. We have further investigated the expression patterns of these proteases during gonadotropin-induced ovulation in immature mice and in the corpus luteum (CL) of pseudopregnant mice. We found that HtrA1 was highly expressed in granulosa cells throughout follicular development and ovulation, as well as in the forming and regressing CL. PRSS23 was highly expressed in atretic follicles, and it was expressed in the ovarian stroma and theca tissues just before ovulation. PRSS35 was expressed in the theca layers of developing follicles. It was also highly induced in granulosa cells of preovulatory follicles. PRSS35 was also expressed in the forming and regressing CL. These data suggest that HtrA1 and PRSS35 may be involved in ovulation and CL formation and regression, and that PRSS23 may play a role in follicular atresia.

Adult hippocampal cell proliferation is suppressed with estrogen withdrawal after a hormone-simulated pregnancy.

Estradiol withdrawal after pregnancy is hypothesized to precipitate depressive symptoms in vulnerable women. A hormone-simulated pregnancy was induced in female rats and the effects of a 'postpartum' drop in estradiol on hippocampal cell proliferation were examined. All groups were ovariectomized or given sham surgery prior to treatment. Rats were randomly assigned to 'postpartum', 'postpartum'+EB (estradiol benzoate), 'postpartum'+DPN (diarylpropionitrile; an ERbeta agonist), 'postpartum'+IMI (imipramine; a tricyclic antidepressant), sham, ovariectomized (OVX), sham+IMI or OVX+IMI groups. All 'postpartum' groups received hormone injections (estradiol and progesterone) over 23 days to simulate pregnancy, while IMI groups also received daily imipramine injections. After day 23, 'postpartum' rats were withdrawn from the hormone-simulated pregnancy (mimicking the postpartum drop in gonadal hormones), while other 'postpartum' treatment groups received daily injections of DPN, EB or IMI. On day 3 'postpartum' all rats were injected with bromodeoxyuridine (BrdU; a DNA synthesis marker) and perfused 24 h later to assess cell proliferation and cell death in the dentate gyrus. 'Postpartum' hormone withdrawal decreased hippocampal cell proliferation in the 'postpartum' and 'postpartum'+EB groups only. Chronic imipramine significantly increased hippocampal cell proliferation in sham+IMI, but not OVX+IMI rats suggesting that imipramine's effects to increase hippocampal cell proliferation in female rats is related to reproductive status. Cell death (pyknotic cells) was decreased only in the 'postpartum' group. Together, these results suggest an important, though complex, role for gonadal hormones in the cellular changes accompanying this model of postpartum depression.

Implantation-associated gene-1 (Iag-1): a novel gene involved in the early process of embryonic implantation in rat.

BACKGROUND: In order to study the novel genes related to rat embryonic implantation, a novel implantation-associated gene, Iag-1, was identified and characterized from rat uterus of early pregnancy. Iag-1 was initially derived from suppressive subtracted hybridization of a cDNA library of rat uterus, which was used to analyse differentially expressed genes between the preimplantation and implantation period. METHODS: The full-length cDNA sequence of Iag-1 was cloned from rat uterus on D5.5 of pregnancy by 5'- and 3'-RACE. The expression of Iag-1 in the uterus of early pregnancy, pseudopregnancy, artificial decidualization and activation of delayed implantation was detected by northern blotting, in situ hybridization, western blotting and immunofluorescence. Endometrial stromal cells (ESCs) were isolated from rat uterus. The effect of Iag-1 on ESCs proliferation and apoptosis were determined by MTT assay, TUNEL and Hoechst staining. Apoptosis-related proteins in ESCs were detected by western blotting. RESULTS: Differential patterns of Iag-1 expression were detected in rat embryo and in the uterus during the peri-implantation period. Iag-1 was specifically localized in glandular epithelium and luminal epithelium. In contrast, the expression of Iag-1 was not significantly altered in uterus of pseudopregnancy and artificial decidualization, but was significantly increased in the uterus after activation of delayed implantation. Stable expression of introduced Iag-1 inhibited the proliferation of in vitro-cultured ESCs. Significant apoptosis was also detected in the ESCs overexpressing Iag-1, along with the enhancement of p53 and Bax protein expression. CONCLUSIONS: Overexpression of Iag-1 can inhibit ESCs proliferation and induce ESCs apoptosis, and p53 and Bax may play an important role in the process of Iag-1-induced apoptosis.