Toxicological pathology in the rat placenta

Impact of Fluoride Exposure on Rat Placenta: Foetal/Placental Morphometric Alterations and Decreased Placental Vascular Density

Inorganic fluoride is a geogenic and anthropogenic contaminant widely distributed in the environment and commonly identified in contaminated groundwater. There is limited information on the effect of fluoride exposure on pregnancy. The aim of this study was to evaluate possible placental alterations of fluoride exposure in a rat model simulating preconception and pregnancy exposure conditions in endemic areas. Fluoride exposure was administered orally to foetuses of dams exposed to 2.5 and 5 mg fluoride/kg/d. Foetal weight, height, foetal/placental weight ratio, placental zone thickness, levels of malondialdehyde (MDA) and vascular endothelial growth factor-A (VEGF-A) and vascular density in placental tissue were evaluated. The results showed a nonlinear relationship between these outcomes and the dose of fluoride exposure. In addition, a significant increase in the fluoride concentration in placental tissue was observed. The group that was exposed to 2.5 mg fluoride/kg/d had a greater increase in both MDA levels and VEGF-A levels than the higher dose group. A significant increase in the thickness of the placental zones and a decrease in the vascular density of the labyrinth zone area were also observed in the fluoride-exposed groups. In conclusion, the data obtained demonstrate that fluoride exposure results in morpho-structural alterations in the placenta and that non-monotonic changes in MDA, VEGF-A levels and placental foetal weight ratio were at environmentally relevant concentrations.

Prenatal aripiprazole induces alterations of rat placenta: a histological, immunohistochemical and ultrastructural study

Antipsychotic drugs (APDs) are used to treat many psychiatric illnesses as schizophrenia. Typical antipsychotic drugs (TAPDs) are being used; however, they have many side effects. Atypical antipsychotic drugs (AAPDs) are newer medications with known fewer side effects. Aripiprazole (ARI) is an AAPD, recommended by healthcare providers, even during pregnancy. It can cross the placental barrier and enter fetal circulation, so it might be possible that ARI can adversely impair normal placental development and growth, if it is given prenatally. ARI was applied orally to pregnant female rats in two doses (3& 6 mg/kg body weight). On gestation day 20, the mothers were sacrificed, and the placentas were removed and processed for general histological and electron microscopic evaluations. Immunohistochemistry was done using anti-PCNA (proliferating cell nuclear antigen), anti-Bax (for apoptosis) and anti-vascular endothelial growth factor alpha (VEGFA). Morphological evaluation revealed degenerative changes in the placenta as dark nuclei, vacuolization, and cyst formation. Ultra-structurally, there was degeneration of cellular components including organelles and nuclei. These changes were found in different cells of the basal and labyrinth zones and were dose dependent. Immunohistochemistry revealed upregulation of Bax and VEGFA and downregulation of PCNA. Prenatal administration of the AAPD, ARI to pregnant female rats resulted in histological changes in the placenta. Additionally, there was a decrease in cellular proliferation and increase in apoptosis, and vascular impairment. This indicates placental atrophy and dysgenesis and might suggest possible teratogenic effects to ARI, which needs further evaluation.

Histopathological Aspects of the Influence of Babesia microti on the Placentas of Infected Female Rats

Babesiosis is perceived mainly an animal disease; however, awareness that Babesia spp. parasites that can cause diseases in humans is increasing significantly. Babesiosis is spread by the bite of an infected tick (Ixodes spp.), but it can also be transmitted by transfusion of infected blood and from an infected mother to her child during pregnancy or childbirth. The parasites multiply in the bloodstream and destroy red blood cells. This study aimed to assess the influence of Babesia microti on the histological structure of the placenta. Histopathological material collected from pregnant rats infected with Babesia microti was used in the experiment. Microscopic images of the placentas were assessed by Mallory staining and by using methylene blue-stained semi-thin sections. In addition, FISH was used to detect parasite DNA. The presence of piroplasms in both maternal and fetal vessels was demonstrated. Babesia microti infection caused vacuolization of syncytioblasts and cytotrophoblasts, accumulation of collagen fibers in placental villi, and increased adhesion of erythrocytes to the vascular walls. These results indicate that Babesia may influence the course of pregnancy and invite further research on the mechanism of piroplasm penetration into cells.

Nanoparticles at the maternal-fetal interface

The increasing production of intentional and unintentional nanoparticles (NPs) has led to their accumulation in the environment as air and ground pollution. The heterogeneity of these particles primarily relies on the NP physicochemical properties (i.e., chemical composition, size, shape, surface chemistry, etc.). Pregnancy represents a vulnerable life stage for both the woman and the developing fetus. The ubiquitous nature of these NPs creates a concern for developmental fetal exposures. At the maternal-fetal interface lies the placenta, a temporary endocrine organ that facilitates nutrient and waste exchange as well as communication between maternal and fetal tissues. Recent evidence in human and animal models identifies that gestational exposure to NPs results in placental translocation leading to local effects and endocrine disruption. Currently, the mechanisms underlying placental translocation and cellular uptake of NPs in the placenta are poorly understood. The purpose of this review is to assess the current understanding of the physiochemical factors influencing NP translocation, cellular uptake, and endocrine disruption at the maternal-fetal interface within the available literature.

Maternal-fetal safety evaluation of an aqueous extract of Casearia sylvestris leaves in rats

BACKGROUND

This study evaluated the maternal, embryotoxic, and teratogenic effects of the aqueous extract of Casearia sylvestris (AECS), a species listed in the Unique Health System of Brazil, and widely used for treating several conditions, such as diarrhea, wounds, pain, and ulcers.

METHODS

Pregnant rats were daily treated orally with 0, 175, 350, or 700 mg/kg/body weight of AECS, from gestational day (GD) 6 to 15 (organogenesis period). On GD 20, the pregnant rats were euthanized, and the litters submitted to an assessment of fetal development.

RESULTS

No clinical signs of toxicity were observed in the dams during the treatment. In the embryo-fetal development study, a significant increase in the basal zone height of the placenta was observed in the intermediate dose group. Furthermore, there was a significant increase in the relative anogenital distance measurement of female fetuses in the lowest and intermediate dose groups. Although no visceral abnormalities were observed in the treated-fetuses, skeletal anomalies evidenced by changes in the ossification of the sternum and the presence of supernumerary ribs were found in the intermediate and high dose groups.

CONCLUSION

In conclusion, the treatment with AECS during organogenesis at this dose level had detrimental effects on the normal development of fetuses.

Effects of cyclophosphamide on rat placental development

We examined the morphological effects of cyclophosphamide (CPA) on placental development in pregnant rats. CPA was administered as a single dose to pregnant rats intraperitoneally at 0 mg/kg (the control group), 25 mg/kg on gestation day (GD) 12 (the CPA GD 12-treated group), and 25 mg/kg on GD 14 (the CPA GD 14-treated group). The fetal and placental weight decreased in the CPA-treated groups, complete fetal resorption from GD 17 onwards in the CPA GD 12-treated group, and external malformations in the CPA GD 14-treated group. Histopathologically, CPA induced apoptosis and/or cell proliferation inhibition in each part of the placenta. In the labyrinth zone, syncytiotrophoblasts were selectively reduced, resulting in a small placenta. In the basal zone, the number of spongiotrophoblasts was reduced, resulting in hypoplasia of glycogen cell islands. In addition, a small number of interstitial trophoblasts invaded the metrial gland from the basal zone on GD 15. The severity of these lesions was higher in the CPA GD 12-treated group than in the CPA GD 14-treated group. In the metrial gland, although the number of uterine natural killer cells was reduced, metrial gland development was not affected.

Functionalized Human Umbilical Cord Mesenchymal Stem Cells and Injectable HA/Gel Hydrogel Synergy in Endometrial Repair and Fertility Recovery

Intrauterine adhesions (IUA) caused by endometrial injury are one of the main causes of female infertility. The current treatments for endometrial injury offer limited clinical benefits and cannot improve endometrial receptivity and pregnancy outcomes. Tissue engineering and regenerative medicine are considered potential solutions to address this concern and may offer effective treatment methods for the regeneration of injured human endometrium. Herein, we prepared an injectable hydrogel based on oxidized hyaluronic acid (HA-CHO) and hydrazide-grafted gelatin (Gel-ADH). The injectable hydrogel showed satisfactory biocompatibility when mixed with human umbilical cord mesenchymal stem cells (hUCMSCs). In an endometrial injury rat model, the treatment with hUCMSCs-loaded injectable hydrogel significantly enhanced the thickness of the endometrium and increased the abundance of blood vessels and glands in the injured endometrium compared to the control group. The hUCMSCs-loaded injectable hydrogel treatment significantly reduced endometrial fibrosis, decreased the expression of the pro-inflammatory factors (IL-1β and IL-6) and increased the expression of the anti-inflammatory factor (IL-10). This treatment induced endometrial VEGF expression by activating the MEK/ERK1/2 signaling pathway. Moreover, this treatment improved endometrial receptivity to the embryo and restored the embryo implantation rate similar to the sham group (48% in the sham group vs 46% in the treatment group), and this treatment achieved pregnancy and live birth in rats with endometrial injury. In addition, we also preliminarily validated the safety of this treatment in the maternal rats and fetuses. Collectively, our study showed that the hUCMSCs-loaded injectable hydrogel hold potential as an effective treatment strategy promoting rapid recovery of endometrial injury, and this hydrogel is a promising biomaterial for regenerative medicine applications. STATEMENT OF SIGNIFICANCE: : 1. Oxidized hyaluronic acid (HA-CHO)/hydrazide-grafted gelatin (Gel-ADH) hydrogel combined with human umbilical cord mesenchymal stem cells (hUCMSCs) are effective in improving the regeneration of endometrium in the endometrial injury rat model. 2. The hUCMSCs-loaded hydrogel treatment promotes the expression of endometrial VEGF through MEK/ERK1/2 signaling pathway and regulates the balance of inflammatory factors. 3. The embryo implantation and live birth rates restore to normal level in the endometrial injury rat model, and the hydrogel has no adverse effects on maternal rats, fetuses, and offspring development after the treatments.

Perfluorooctane sulfonic acid modulates expression of placental steroidogenesis-associated genes and hormone levels in pregnant rats

Perfluorooctane sulfonate (PFOS) is a widespread and persistent chemical in the environment. Reports show that PFOS is a potential endocrine disruptor; however, the possible effects of PFOS on placental endocrine function are unclear. This study aimed to investigate the endocrine-disrupting effects of PFOS on the placenta in pregnant rats and its potential mechanism. Pregnant rats from gestational days 4-20 were exposed to 0, 10, and 50 μg/mL PFOS through drinking water followed by analysis of various biochemical parameters. PFOS dose-dependently decreased fetal and placental weight in both sexes, with a specific decrease in weight of labyrinth but not junctional layer. Plasma progesterone (↑166%), aldosterone (↑201%), corticosterone (↑205%), testosterone (↑45%), luteinizing hormone (↑49%) levels were significantly increased, while estradiol (↓27%), prolactin (↓28%) and hCG (↓62%) levels were reduced in groups exposed to higher doses of PFOS. Real-time quantitative reverse transcriptase-polymerase chain reaction analysis revealed a significant increase in mRNA levels of placental steroid biosynthesis enzymes, including Cyp11A1 and 3β-HSD1 in male placenta and StAR, Cyp11A1, 17β-HSD1 and 17β-HSD3 in female placenta of PFOS dams. Cyp19A1 expression in ovaries was significantly decreased in PFOS dams. mRNA levels for placental steroid metabolism enzyme UGT1A1 increased in male but not in female placenta of PFOS dams. These results suggest that the placenta is a target tissue of PFOS and PFOS-induced dysregulation in steroid hormone production might be related to the altered expression of hormone biosynthesis and metabolism enzyme genes in the placenta. This hormone disruption might affect maternal health and fetal growth.

Exploration of Maternal and Fetal Toxicity Risks for Metronidazole-Related Teratogenicity and Hepatotoxicity through an Assessment in Albino Rats

Metronidazole is the primary antimicrobial drug for treating acute and chronic vaginal pathogens during pregnancy; however, there has been insufficient research on placental disorders, early pregnancy loss, and preterm birth. Here, the potential activity of metronidazole on pregnancy outcomes was investigated. 130 mg/kg body weight of metronidazole was orally given individually to pregnant rats on gestation days 0-7, 7-14, and 0-20. Pregnancy outcome evaluations were carried out on gestation day 20. It was demonstrated that metronidazole could induce maternal and fetal hepatotoxicity. There is a significant increase in the activities of maternal hepatic enzymes (ALT, AST, and ALP), total cholesterol, and triglycerides compared with the control. These biochemical findings were evidenced by maternal and fetal liver histopathological alterations. Furthermore, metronidazole caused a significant decrease in the number of implantation sites and fetal viability, whereas it caused an increase in fetal lethality and the number of fetal resorptions. In addition, a significant decrease in fetal weight, placental weight, and placental diameter was estimated. Macroscopical examination revealed placental discoloration and hypotrophy in the labyrinth zone and the degeneration of the basal zone. The fetal defects are related to exencephaly, visceral hernias, and tail defects. These findings suggest that the administration of metroniazole during gestation interferes with embryonic implantation and fetal organogenesis and enhances placental pathology. We can also conclude that metronidazole has potential maternal and fetal risks and is unsafe during pregnancy. Additionally, it should be strictly advised and prescribed, and further consideration should be given to the associated health risks.

Paternal obesity induces epigenetic aberrations and gene expression changes in placenta and fetus

Paternal epigenome regulates placental and fetal growth. However, the effect of paternal obesity on placenta and its subsequent effect on the fetus via sperm remains unknown. We previously discovered abnormal methylation of imprinted genes involved in placental and fetal development in the spermatozoa of obese rats. In the present study, elaborate epigenetic characterization of sperm, placenta, and fetus was performed. For 16 weeks, male rats were fed either control or a high-fat diet. Following mating studies, sperm, placenta, and fetal tissue were collected. Significant changes were observed in placental weights, morphology, and cell populations. Methylation status of imprinted genes-Igf2, Peg3, Cdkn1c, and Gnas in spermatozoa, correlated with their expression in the placenta and fetus. Placental DNA methylating enzymes and 5-methylCytosine levels increased. Furthermore, in spermatozoa, DNA methylation of a few genes involved in pathways associated with placental endocrine function-gonadotropin-releasing hormone, prolactin, estrogen, and vascular endothelial growth factor, correlated with their expression in placenta and fetus. Changes in histone-modifying enzymes were also observed in the placenta. Histone marks H3K4me3, H3K9me3, and H4ac were downregulated, while H3K27me3 and H3ac were upregulated in placentas derived from obese male rats. This study shows that obesity-related changes in sperm methylome translate into abnormal expression in the F1-placenta fathered by the obese male, presumably affecting placental and fetal development.

Sexually concordant and dimorphic transcriptional responses to maternal trichloroethylene and/or N-acetyl cysteine exposure in Wistar rat placental tissue

Numerous Superfund sites are contaminated with the volatile organic chemical trichloroethylene (TCE). In women, exposure to TCE in pregnancy is associated with reduced birth weight. Our previous study reported that TCE exposure in pregnant rats decreased fetal weight and elevated oxidative stress biomarkers in placentae, suggesting placental injury as a potential mechanism of TCE-induced adverse birth outcomes. In this study, we investigated if co-exposure with the antioxidant N-acetylcysteine (NAC) attenuates TCE exposure effects on RNA expression. Timed-pregnant Wistar rats were exposed orally to 480 mg TCE/kg/day on gestation days 6-16. Exposure of 200 mg NAC/kg/day alone or as a pre/co-exposure with TCE occurred on gestation days 5-16 to stimulate antioxidant genes prior to TCE exposure. Tissue was collected on gestation day 16. In male and female placentae, we evaluated TCE- and/or NAC-induced changes to gene expression and pathway enrichment analyses using false discovery rate (FDR) and fold-change criteria. In female placentae, exposure to TCE caused significant differential expression 129 genes while the TCE+NAC altered 125 genes, compared with controls (FDR< 0.05 + fold-change >1). In contrast, in male placentae TCE exposure differentially expressed 9 genes and TCE+NAC differentially expressed 35 genes, compared with controls (FDR< 0.05 + fold-change >1). NAC alone did not significantly alter gene expression in either sex. Differentially expressed genes observed with TCE exposure were enriched in mitochondrial biogenesis and oxidative phosphorylation pathways in females whereas immune system pathways and endoplasmic reticulum stress pathways were differentially expressed in both sexes (FDR<0.05). TCE treatment was differentially enriched for genes regulated by the transcription factors ATF6 (both sexes) and ATF4 (males only), indicating a cellular condition triggered by misfolded proteins during endoplasmic reticulum stress. This study demonstrates novel genes and pathways involved in TCE-induced placental injury and showed antioxidant co-treatment largely did not attenuate TCE exposure effects.

Long-term changes in the diurnal temporal regulation and set points of metabolic parameters associated with chronic maternal overnutrition in rabbits

Metabolic syndrome (MS) and obesity have become a worldwide epidemic with an alarming prevalence in women of reproductive age. Maternal metabolic condition is considered a risk factor for adverse birth outcomes and long-term MS. In this study, we developed a rabbit model of maternal overnutrition via the chronic intake of a high-fat and carbohydrate diet (HFCD), and we determined the effects of this diet on maternal metabolism and offspring metabolic set points and temporal metabolic regulation in adult life. Before and during pregnancy, the female rabbits that consumed the HFCD exhibited significant changes in body weight, serum levels of analytes associated with carbohydrate and lipid metabolism, levels of liver and kidney damage markers, and liver histology. Our data suggest that rabbits are a valuable model for studying the development of MS associated with the chronic intake of unbalanced diets and fetal metabolic programming. Furthermore, the offspring of overnourished dams exhibited considerable changes in 24-h serum metabolite profiles in adulthood, with notable sexual dimorphism. These data suggest that maternal nutritional conditions due to the chronic intake of an HFCD adversely impact key elements related to the development of circadian rhythmicity in offspring.NEW & NOTEWORTHY Maternal overnutrition previous and during pregnancy leads to long-term changes in the 24-h regulation and setpoint of metabolic profiles of the offspring.

Reliability of Rodent and Rabbit Models in Preeclampsia Research

In vivo studies on the pathology of gestation, including preeclampsia, often use small mammals such as rabbits or rodents, i.e., mice, rats, hamsters, and guinea pigs. The key advantage of these animals is their short reproductive cycle; in addition, similar to humans, they also develop a haemochorial placenta and present a similar transformation of maternal spiral arteries. Interestingly, pregnant dams also demonstrate a similar reaction to inflammatory factors and placentally derived antiangiogenic factors, i.e., soluble fms-like tyrosine kinase 1 (sFlt-1) or soluble endoglin-1 (sEng), as preeclamptic women: all animals present an increase in blood pressure and usually proteinuria. These constitute the classical duet that allows for the recognition of preeclampsia. However, the time of initiation of maternal vessel remodelling and the depth of trophoblast invasion differs between rabbits, rodents, and humans. Unfortunately, at present, no known animal replicates a human pregnancy exactly, and hence, the use of rabbit and rodent models is restricted to the investigation of individual aspects of human gestation only. This article compares the process of placentation in rodents, rabbits, and humans, which should be considered when planning experiments on preeclampsia; these aspects might determine the success, or failure, of the study. The report also reviews the rodent and rabbit models used to investigate certain aspects of the pathomechanism of human preeclampsia, especially those related to incorrect trophoblast invasion, placental hypoxia, inflammation, or maternal endothelial dysfunction.

Teratogenic Evaluation of 80% Ethanol Extract of Embelia schimperi Vatke Fruits on Rat Embryo and Fetuses

Introduction

Embelia schimperi Vatke (family Myrsinaceae) is a commonly consumed anthelminthic plant in Ethiopia. The plant has significant efficacy in treating intestinal worms. However, there are limited data about the safety/toxicity of the plant. Moreover, the teratogenic effect of the plant is not yet well studied despite significant number of Ethiopian mothers consuming herbal medication during their pregnancy.

Purpose

This study aimed to evaluate the teratogenic effect of the hydroalcoholic extract of E. schimperi fruit on rat embryos and fetuses.

Methods

Pregnant albino Wistar rats were treated with 80% hydroalcoholic fruit extract of E. schimperi at 250 mg/kg, 500 mg/kg, and 1000 mg/kg dosage, whilst the controls were pair-fed and ad libitum groups. Maternal food intake, maternal weight gain, number of implantations, number of prior resorptions, fetal viability, fetal weight, fetal and embryonic crown-ramp length, placental weight, placental gross morphology and histopathology of placental tissue, number of somites, embryonic system, gross/visceral morphological malformations, and ossification centers were evaluated as teratogenicity indices.

Results

The crude extract of E. schimperi did not exhibit a significant difference in most developmental indices including the development of a circulatory system, nervous system, and musculoskeletal systems among treated animals and the controls. However, histopathological evaluation of placentas from the treatment groups showed that inflammatory reactions and calcifications compared to the pair-fed and ad libitum controls.

Conclusion

Administration of the 80% hydroalcoholic extract of E. schimperi fruit during the period of organogenesis in rats did not show a significant toxic effect on embryonic and fetal developmental indices. However, it might affect the structural integrity of the placenta as it is evidenced by inflammatory reactions and calcifications of decidua basalis of rat placenta.

Transplacental transfer of acetaminophen in pregnant rats

Acetaminophen is among the most widely used analgesics; however, the proportion and mechanism of transplacental transfer of unbound acetaminophen with actual pharmacological activity remain unknown. Our hypothesis is that acetaminophen gradually penetrates the blood-placenta barrier to reach the fetus. A multiple microdialysis coupled to liquid chromatography with photodiode array detection method was developed to monitor acetaminophen levels in the maternal blood, placenta, fetus, and amniotic fluid of a pregnant rat and investigate this hypothesis. The pharmacokinetic data indicates that acetaminophen exhibits a nonlinear behavior in the maternal blood within the dosage regimen of 100 and 300 mg/kg. In addition, acetaminophen penetrates the placenta, fetus, and amniotic fluid during treatment. The transplacental transfer ratio represented by the area under the concentration curve (AUC) ratio for the conceptus (the collective term for the fetus, placenta, and amniotic fluid) and maternal blood (AUC_tissue/AUC_blood) was approximately 11-23 % after acetaminophen (100 and 300 mg/kg) administration. However, the transporter of multidrug resistance-associated protein (MRP) inhibitor MK-571 did not significantly change the transplacental transfer ratio. This basic study provides constructive information for the clinical application of acetaminophen in pregnant women.

Nicotine Exposure during Rodent Pregnancy Alters the Composition of Maternal Gut Microbiota and Abundance of Maternal and Amniotic Short Chain Fatty Acids

Tobacco smoking is the leading cause of preventable death. Numerous reports link smoking in pregnancy with serious adverse outcomes, such as miscarriage, stillbirth, prematurity, low birth weight, perinatal morbidity, and infant mortality. Corollaries of consuming nicotine in pregnancy, separate from smoking, are less explored, and the mechanisms of nicotine action on maternal–fetal communication are poorly understood. This study examined alterations in the maternal gut microbiome in response to nicotine exposure during pregnancy. We report that changes in the maternal gut microbiota milieu are an important intermediary that may mediate the prenatal nicotine exposure effects, affect gene expression, and alter fetal exposure to circulating short-chain fatty acids (SCFAs) and leptin during in utero development.

In vivo pharmacokinetic analyses of placental transfer of three drugs of different physicochemical properties in pregnant rats

Although the use of medication during pregnancy is common, information on exposure to the developing fetus and potential teratogenic effects is often lacking. This study used a rat model to examine the placental transfer of three small-molecule drugs with molecular weights ranging from approximately 300 to 800 Da with different physicochemical properties. Time-mated Sprague Dawley (Hsd:SD) rats aged 11-13 weeks were administered either glyburide, rifaximin, or fentanyl at gestational day 15. Maternal blood, placentae, and fetuses were collected at 5 min, 30 min, 1 h, 4 h, 8 h, 24 h, 48 h, and 96 h post-dose. To characterize the rate and extent of placental drug transfer, we calculated several pharmacokinetic parameters such as maximum concentration (Cmax), time to maximum concentration (Tmax), area under the concentration-time curve (AUC), half-life (t_1/2), clearance (CL), and volume of distribution (Vd) for plasma, placenta, and fetus tissues. The results indicated showed that fetal exposure was lowest for glyburide, accounting for only 2.2 % of maternal plasma exposure as measured by their corresponding AUC ratio, followed by rifaximin (37.9 %) and fentanyl (172.4 %). The fetus/placenta AUC ratios were found to be 10.7 % for glyburide, 11.8 % for rifaximin, and 39.1 % for fentanyl. These findings suggest that although the placenta acts as a protective shield for the fetus, the extent of protection varies for different drugs and depends on factors such as molecular weight, lipid solubility, transporter-mediated efflux, and binding to maternal and fetal plasma proteins.

Phthalate Exposures and Placental Health in Animal Models and Humans: A Systematic Review

Phthalates are ubiquitous compounds known to leach from the plastic products that contain them. Due to their endocrine-disrupting properties, a wide range of studies have elucidated their effects on reproduction, metabolism, neurodevelopment, and growth. Additionally, their impacts during pregnancy and on the developing fetus have been extensively studied. Most recently, there has been interest in the impacts of phthalates on the placenta, a transient major endocrine organ critical to maintenance of the uterine environment and fetal development. Phthalate-induced changes in placental structure and function may have significant impacts on the course of pregnancy and ultimately, child health. Prior reviews have described the literature on phthalates and placental health; however to date, there has been no comprehensive, systematic review on this topic. Here, we review 35 papers (24 human and 11 animal studies) and summarize phthalate exposures in relation to an extensive set of placental measures. Phthalate-related alterations were reported for placental morphology, hormone production, vascularization, histopathology, and gene/protein expression. The most consistent changes were observed in vascular and morphologic endpoints, including cell composition. These changes have implications for pregnancy complications such as preterm birth and intrauterine growth restriction as well as potential ramifications for children's health. This comprehensive review of the literature, including common sources of bias, will inform the future work in this rapidly expanding field.

Effect of Chemotherapy Cytarabine and Acute Myeloid Leukemia on the Development of Spermatogenesis at the Adult Age of Immature Treated Mice

Acute myeloid leukemia (AML) accounts for around 20% of diagnosed childhood leukemia. Cytarabine (CYT) is involved in the AML treatment regimen. AML and CYT showed impairment in spermatogenesis in human and rodents in adulthood. We successfully developed an AML disease model in sexually immature mice. Monocytes and granulocytes were examined in all groups: untreated control, AML alone, CYT alone and AML+CYT (in combination). There was a significant increase in the counts of monocytes and granulocytes in the AML-treated immature mice (AML) compared to the control, and AML cells were demonstrated in the blood vessels of the testes. AML alone and CYT alone impaired the development of spermatogenesis at the adult age of the AML-treated immature mice. The damage was clear in the structure/histology of their seminiferous tubules, and an increase in the apoptotic cells of the seminiferous tubules was demonstrated. Our results demonstrated a significant decrease in the meiotic/post-meiotic cells compared to the control. However, CYT alone (but not AML) significantly increased the count of spermatogonial cells (premeiotic cells) that positively stained with SALL4 and PLZF per tubule compared to the control. Furthermore, AML significantly increased the count of proliferating spermatogonial cells that positively stained with PCNA in the seminiferous tubules compared to the control, whereas CYT significantly decreased the count compared to the control. Our result showed that AML and CYT affected the microenvironment/niche of the germ cells. AML significantly decreased the levels growth factors, such as SCF, GDNF and MCSF) compared to control, whereas CYT significantly increased the levels of MCSF and GDNF compared to control. In addition, AML significantly increased the RNA expression levels of testicular IL-6 (a proinflammatory cytokine), whereas CYT significantly decreased testicular IL-6 levels compared to the control group. Furthermore, AML alone and CYT alone significantly decreased RNA expression levels of testicular IL-10 (anti-inflammatory cytokine) compared to the control group. Our results demonstrate that pediatric AML disease with or without CYT treatment impairs spermatogenesis at adult age (the impairment was more pronounced in AML+CYT) compared to control. Thus, we suggest that special care should be considered for children with AML who are treated with a CYT regimen regarding their future fertility at adult age.

Progesterone partially recovers placental glucose transporters in dexamethasone-induced intrauterine growth restriction

RESEARCH QUESTION

How does progesterone improve fetal outcome and change the expression of placental glucose transporters (GLUT) in dexamethasone-induced intrauterine growth restriction (IUGR)?

DESIGN

A total of 64 rats were divided randomly into four different treatment groups based on daily i.p. injections of either saline or dexamethasone in the presence or absence of progesterone. Injections started on the 15th day of gestation (15dg) and lasted until the day of sacrifice at 19dg or 21dg. Maternal plasma progesterone concentrations were measured by enzyme-linked immunosorbent assay. The gene and protein expression of placental GLUT1 and GLUT3 were evaluated in the placental labyrinth and basal zones by real-time polymerase chain reaction and Western blotting, respectively. The localization of GLUT1 and GLUT3 was evaluated by immunohistochemistry.

RESULTS

Dexamethasone induced significant decreases in maternal serum progesterone concentrations (P = 0.029) and placental (P < 0.001) and fetal body (P = 0.009) weights. Dexamethasone also reduced the expression of GLUT1 in the labyrinth zone (P = 0.028) and GLUT3 in both the labyrinth (P = 0.002) and basal zones (P = 0.026). Coadministration of dexamethasone and progesterone prevented the reduction in fetal body weight, placental weight and placental GLUT expression compared with that seen in dexamethasone-treated groups.

CONCLUSION

These results suggest that progesterone prevents the significant reduction in fetal and placental weights in dexamethasone-induced IUGR, possibly through improving the expression of placental GLUT.

Placental nutrient transporters adapt during persistent maternal hypoglycaemia in rats

Maternal malnutrition is associated with decreased nutrient transfer to the foetus, which may lead to foetal growth restriction, predisposing children to a variety of diseases. However, regulation of placental nutrient transfer during decreased nutrient availability is not fully understood. In the present study, the aim was to investigate changes in levels of placental nutrient transporters accompanying maternal hypoglycaemia following different durations and stages of gestation in rats. Maternal hypoglycaemia was induced by insulin-infusion throughout gestation until gestation day (GD)20 or until end of organogenesis (GD17), with sacrifice on GD17 or GD20. Protein levels of placental glucose transporters GLUT1 (45/55 kDa isotypes) and GLUT3, amino acid transporters SNAT1 and SNAT2, and insulin receptor (InsR) were assessed. On GD17, GLUT1-45, GLUT3, and SNAT1 levels were increased and InsR levels decreased versus controls. On GD20, following hypoglycaemia throughout gestation, GLUT3 levels were increased, GLUT1-55 showed the same trend. After cessation of hypoglycaemia at end of organogenesis, GLUT1-55, GLUT3, and InsR levels were increased versus controls, whereas SNAT1 levels were decreased. The increases in levels of placental nutrient transporters seen during maternal hypoglycaemia and hyperinsulinemia likely reflect an adaptive response to optimise foetal nutrient supply and development during limited availability of glucose.

Trichloroethylene modifies energy metabolites in the amniotic fluid of Wistar rats

Exposure to trichloroethylene (TCE), an industrial solvent, is associated with several adverse pregnancy outcomes in humans and decreased fetal weight in rats. However, effects of TCE on energy metabolites in amniotic fluid, which have associations with pregnancy outcomes, has not been published previously. In the current exploratory study, timed-pregnant Wistar rats were exposed to 480 mg TCE/kg/day via vanilla wafer or to vehicle (wafer) alone from gestational day (GD) 6-16. Amniotic fluid collected on GD 16 was analyzed for metabolites important in energy metabolism using short chain fatty acid and tricarboxylic acid plus platforms (N = 4 samples/sex/treatment). TCE decreased concentrations of the following metabolites in amniotic fluid for both fetal sexes: 6-phosphogluconate, guanosine diphosphate, adenosine diphosphate, adenosine triphosphate, and flavin adenine dinucleotide. TCE decreased fructose 1,6-bisphosphate and guanosine triphosphate concentrations in amniotic fluid of male but not female fetuses. Moreover, TCE decreased uridine diphosphate-D-glucuronate concentrations, and increased arginine and phosphocreatine concentrations, in amniotic fluid of female fetuses only. No metabolites were increased in amniotic fluid of male fetuses. Pathway analysis suggested that TCE altered folate biosynthesis and pentose phosphate pathway in both sexes. Using metabolite ratios to investigate changes within specific pathways, some ratio alterations, including those in arginine metabolism and phenylalanine metabolism, were detected in females only. Ratio analysis also suggested enzymes, including gluconokinase, as potential TCE targets. Together, results from this exploratory study suggest that TCE differentially modified energy metabolites in amniotic fluid based on sex. These findings may inform future studies of TCE reproductive toxicity.

The effect of progesterone administration on the expression of metastasis tumor antigens (MTA1 and MTA3) in placentas of normal and dexamethasone-treated rats

BACKGROUND

Dexamethasone (DEX) induces intrauterine growth restriction (IUGR) in pregnant rats. IUGR can occur due to apoptosis of trophoblasts, which is believed to be inhibited by progesterone (P4). A group of genes called MTAs play a role in proliferation and apoptosis. MTA1 upregulates trophoblasts proliferation and differentiation, while MTA3 downregulates proliferation and induces apoptosis. Hence, we hypothesized that during IUGR, placental MTA1 decreases and MTA3 increases and this is reversed by P4 treatment.

METHODS

Pregnant Sprague-Dawley rats were divided into 4 groups based on daily intraperitoneal injections: control (C, saline), DEX (DEX, 0.2 mg/kg/day), DEX and P4 (DEX + P4, DEX: 0.2 mg/kg/day, P4: 5 mg/kg/day) and P4-treated (P4, 5 mg/kg/day) groups. Injections were started on 15 dg until the day of dissection (19 or 21 dg). Gene and protein expressions of MTA1 and MTA3 were studied in the labyrinth (LZ) and basal (BZ) zones using real-time PCR and Western blotting, respectively.

RESULTS

DEX treatment induced 18% reduction in fetal body weight (p < 0.001) and 30% reduction in placental weight (p < 0.01). Maternal P4 level was also significantly lower in DEX treated groups (p < 0.05). MTA1 expression was decreased in the LZ (gene, p < 0.001) and BZ (protein p < 0.01), while MTA3 protein expression was upregulated in the LZ with DEX treatment (p < 0.001). These changes were reversed with P4 treatment.

CONCLUSION

The findings of the present study indicate that DEX induces IUGR through changing the expression of placental MTA1 and MTA3 antigens and P4 improved pregnancy outcome by preventing the changes in MTAs expression.

Integrating in vitro chemical transplacental passage into a generic PBK model: A QIVIVE approach

With the increasing application of cell culture models as primary tools for predicting chemical safety, the quantitative extrapolation of the effective dose from in vitro to in vivo (QIVIVE) is of increasing importance. For developmental toxicity this requires scaling the in vitro observed dose-response characteristics to in vivo fetal exposure, while integrating maternal in vivo kinetics during pregnancy, in particular transplacental transfer. Here the transfer of substances across the placental barrier, has been studied using the in vitro BeWo cell assay and six embryotoxic compounds of different kinetic complexity. The BeWo assay results were incorporated in an existing generic Physiologically Based Kinetic (PBK) model which for this purpose was extended with rat pregnancy. Finally, as a "proof of principle", the BeWo PBK model was used to perform a QIVIVE based on developmental toxicity as observed in various different in vitro toxicity assays. The BeWo results illustrated different transport profiles of the chemicals across the BeWo monolayer, allocating the substances into two distinct groups: the 'quickly-transported' and the 'slowly-transported'. BeWo PBK exposure simulations during gestation were compared to experimentally measured maternal blood and fetal concentrations and a reverse dosimetry approach was applied to translate in vitro observed embryotoxicity into equivalent in vivo dose-response curves. This approach allowed for a direct comparison of the in vitro dose-response characteristics as observed in the Whole Embryo Culture (WEC), and the Embryonic Stem Cell test (cardiac:ESTc and neural:ESTn) with in vivo rat developmental toxicity data. Overall, the in vitro to in vivo comparisons suggest a promising future for the application of such QIVIVE methodologies for screening and prioritization purposes of developmental toxicants. Nevertheless, the clear need for further improvements is acknowledged for a wider application of the approach in chemical safety assessment.

Extended Prophylactic Effect of N-tert-Butyl-α-phenylnitron against Oxidative/Nitrosative Damage Caused by the DNA-Hypomethylating Drug 5-Azacytidine in the Rat Placenta

Antioxidant N-tert-Butyl-α-phenylnitron (PBN) partly protected embryos from the negative effects of a DNA demethylating drug 5-azacytidine during pregnancy. Our aim was to investigate PBN's impact on the placenta. Fischer rat dams were treated on gestation days (GD) 12 and 13 by PBN (40 mg/kg), followed by 5azaC (5 mg/kg) after one hour. Global methylation was assessed by pyrosequencing. Numerical density was calculated from immunohistochemical expression in single cells for proliferating (PCNA), oxidative (oxoguanosine) and nitrosative (nitrotyrosine) activity. Results were compared with the PBN-treated and control rats. PBN-pretreatment significantly increased placental weight at GD15 and GD20, diminished by 5azaC, and diminished apoptosis in GD 20 placentas caused by 5azaC. Oxoguanosine expression in placentas of 5azaC-treated dams was especially high in the placental labyrinth on GD 15, while PBN-pretreatment lowered its expression on GD 15 and GD 20 in both the labyrinth and basal layer. 5azaC enhanced nitrotyrosine level in the labyrinth of both gestational stages, while PBN-pretreatment lowered it. We conclude that PBN exerted its prophylactic activity against DNA hypomethylating agent 5azaC in the placenta through free radical scavenging, especially in the labyrinthine part of the placenta until the last day of pregnancy.

Physiological characterization of an arginine vasopressin rat model of preeclampsia

Rodent models have contributed greatly to our understanding of preeclampsia (PE) progression in humans, however to-date no model has been able to effectively replicate the clinical presentation of the disease. This study aimed to provide a thorough physiological characterization of the arginine vasopressin (AVP)-induced rat model of PE to determine its applicability in studying the pathophysiology of PE. Female Sprague Dawley rats (n = 24) were separated into four groups (n = 6 per group) viz., pregnant AVP, pregnant saline, non-pregnant AVP, and non-pregnant saline. All animals received a continuous dose of either AVP (150 ng/h) or saline via subcutaneous mini osmotic pumps for 18 days. Full physiological characterization of the model included measuring systolic and diastolic blood pressure, and collecting urine and blood samples for biochemical analysis. AVP infusion significantly increased blood pressure and urinary protein levels in the pregnant rats (p < 0.05). Biochemical markers measured, differed significantly in the AVP-treated vs the pregnant saline groups (p < 0.05). Placental and individual pup weight decreased significantly in the pregnant AVP vs pregnant saline group (p < 0.05). The physiological and hematological data confirm the usefulness of this rat model in the study of PE, since AVP-induced vasoconstriction increases peripheral resistance and successfully mimics the pathological changes associated with PE development in humans.Abbreviations: PE: preeclampsia; AVP: arginine vasopressin; ISSHP: International Society for the Study of Hypertension in Pregnancy; ACOG: American College of Obstetricians and Gynecologists; RUPP: reduced uterine perfusion pressure; sFlt-1: soluble fms-like tyrosine kinase; VEGF: vascular endothelial growth factor; PlGF: placental growth factor; AVP: arginine vasopressin; PAVP: pregnant AVP-treated; PS: pregnant saline; GD: gestational day; ALT: alanine transaminase; NAVP: non-pregnant AVP-treated; NS: non-pregnant saline; AST: aspartate aminotransferase; HDL: high-density lipoprotein; RBC: red blood cell; RAAS: renin-angiotensin aldosterone system; HELLP: hemolysis, elevated liver enzymes, low platelet.

Toxic Effect of Khat in Rat Embryos and Fetuses

Khat (Catha edulis Forsk) is a plant consumed by many people in Eastern Africa, including Ethiopia, and Southern Arabia to be stimulated. There are several human and animal studies on khat that provide information about its toxic effects. However, the potential toxic effects of khat on embryos and fetuses have not been elucidated. The aim of the present study was to investigate the embryotoxic and fetotoxic effects of khat exposure during the earliest period of gestation in rats. Pregnant Wistar albino rats were treated with khat extract at 250, 500, and 750 mg/kg doses from day 6 through day 12 of gestation. The treatment was delivered by gavage. Embryos and fetuses were recovered on gestational day 12 or day 20, respectively, and were quantitatively and qualitatively assessed for developmental anomalies. Placentae from the treatment and control groups were investigated for histopathological effects. Results of the present study showed that khat exposure during pregnancy had dose-dependent toxic effects in rat embryos and fetuses. Prenatal growth retardation such as reduced fetal weight and crown-rump length was observed in near-term fetuses, especially, in animals treated with the highest dose of khat (p < 0.05). Growth retardation and developmental anomalies were also observed in day 12 embryos of khat-treated rats. Maternal weight gain of the khat-treated group was also significantly lower than the control group. Cytolysis, decidual hypoplasia, and atrophy were observed in the placenta of the khat-treated rats. Findings of the present study revealed, for the first time, that exposure of pregnant rat to crude extract of khat causes embryotoxic and fetotoxic effects.

Efficacy of vitamin E in protection against methotrexate induced placental injury in albino rats

Methotrexate (MXT) is a chemotherapeutic drug that has been used in a wide range of clinical practices. Unfortunately, the administration of MXT during pregnancy may induce abortion, fetal deformities, and intrauterine growth retardation. Vitamin E is an antioxidant agent that can ameliorate free radical damage. The current work aimed to shed more light on the possible protective effect of vitamin E against MXT induced placental toxicity and to determine the possible mechanisms; biochemically, histologically, and immunohistochemically. Four groups were used: control pregnant, Vitamin E (VIT E) pregnant, Methotrexate (MXT) pregnant, and Vitamin E Methotrexate (VIT E-MXT) pregnant. The placental tissues were processed for light, immunohistochemical, and electron microscopic study. Other samples were obtained for biochemical study; the placental oxidant/antioxidant status was evaluated. The results showed that MXT caused various placental morphological changes in the form of distorted chorionic projection with an accumulation of hemosiderin granules in the trophoblastic cells. Maternal blood vessels showed a homogenous acidophilic material Edema of the extra-embryonic fetal membranes was noticed. A significant decreased in placental weight as well as increase in the oxidative and inflammatory markers were detected. Increased COX2 and decreased eNOS expressions were observed in the MXT group if compared to the control group. VIT E significantly restored the normal histological and immunohistochemical appearance, placental weight, and oxidant/antioxidant balance. It could be concluded the biochemical, morphological, and morphometric findings suggested that vitamin E coadministration is promising in attenuating the placental toxic effect of methotrexate. In this study, VIT E decreased the inflammatory and oxidative stress effect of methotrexate on the placental tissue by enhancing the level of eNOS.

The effects of hypothyroidism and hyperthyroidism on placental Hofbauer cells of pregnant rats

We investigated the effects of maternal thyroid disorders on Hofbauer cells of both the placenta and the fetus in pregnant rats. We divided 21 rats into three groups: control group, induced hypothyroidism (hypo) group and induced hyperthyroidism (hyper) group. Hypothyroidism was induced using propylthiouracil and hyperthyroidism was induced using L-thyroxine. We measured maternal weight, maternal free thyroxine, fetal weight, fetal viability and placental morphology. At the end of the experiment, fetuses of the hypo and hyper groups were less developed than those of the control group. In the hypo and hyper groups, the thickness of the labyrinth zone was decreased, but thickness of the basal zone and decidua basalis was increased. The number of Hofbauer cells was increased in both the hypo and hyper groups. Vascular endothelial growth factor expression was increased in both the hypo and hyper groups compared to controls. Our findings indicate that maternal thyroid disorders exert a negative effect on fetal growth and placental development.

Rift Valley Fever: a Threat to Pregnant Women Hiding in Plain Sight?

The potential for emerging mosquito-borne viruses to cause fetal infection in pregnant women was overlooked until the Zika fever outbreak several years ago. Rift Valley fever virus (RVFV) is an emerging arbovirus with a long history of fetal infection and death in pregnant livestock. The effect of RVFV infection on pregnant women is not well understood. This Gem examines the effects that this important emerging pathogen has during pregnancy, its potential impact on pregnant women, and the current research efforts designed to understand and mitigate adverse effects of RVFV infection during pregnancy.

Effects of ethanol and nicotine co-administration on follicular atresia and placental histo-morphology in the first-generation mice pups during intrauterine development and lactation periods

This study is evaluating the effects of ethanol and nicotine exposure during pregnancy and lactation on placenta histology and follicular atresia in the first-generation (f1) mice pups. The experimental groups were 5 groups of NMRI pregnant mice, including: control, vehicle (received normal saline) ethanol (3 g/kg/day, 20 % v/v intraperitoneally), nicotine (1 mg/kg/day, subcutaneously), and ethanol plus nicotine which received both. Pregnant animals in each group were then divided into two groups, one group for examining the placenta that was treated for 18 days and the other group for the ovary of one-day-old (PND1) and fifty-six-day-old (PND56) female offspring who were treated for 42 days (during intrauterine development and lactation). After the autopsy procedure, histopathological and morphometrical observations were done. Data revealed that the exposed mice had a significant change in the placenta morphometry and histology as well as a marked increase in the number of ovarian TUNEL positive cells on postnatal days 1 and 56. Therefore, maternal exposure to alcohol and nicotine during developmental and lactation periods could lead to changes in the placenta properties as well as an increase in the apoptotic ovarian follicles in f1 mice pups.

Considering intrauterine location in a model of fetal growth restriction after maternal titanium dioxide nanoparticle inhalation

Fetal growth restriction (FGR) is a condition with several underlying etiologies including gestational disease (e.g., preeclampsia, gestational diabetes) and xenobiotic exposure (e.g., environmental contaminants, pharmaceuticals, recreational drugs). Rodent models allow study of FGR pathogenesis. However, given the multiparous rodent pregnancy, fetal growth variability within uterine horns may arise. To ascertain whether intrauterine position is a determinant of fetal growth, we redesigned fetal weight analysis to include litter size and maternal weight. Our FGR model is produced by exposing pregnant Sprague Dawley rats to aerosolized titanium dioxide nanoparticles at 9.44 ± 0.26 mg/m3 on gestational day (GD) 4, GD 12 or GD 17 or 9.53 ± 1.01 mg/m3 between GD 4-GD 19. In this study fetal weight data was reorganized by intrauterine location [i.e., right/left uterine horn and ovarian/middle/vaginal position] and normalized by maternal weight and number of feti per uterine horn. A significant difference in fetal weight in the middle location in controls (0.061g ± 0.001 vs. 0.055g ± 0.002), GD 4 (0.033g ± 0.003 vs. 0.049g ± 0.004), and GD 17 (0.047g ± 0.002 vs. 0.038g ± 0.002) exposed animals was identified. Additionally, GD 4 exposure produced significantly smaller feti in the right uterine horn at the ovarian end (0.052g ± 0.003 vs. 0.029g ± 0.003) and middle of the right uterine horn (0.060g ± 0.001 vs. 0.033g ± 0.003). GD 17 exposure produced significantly smaller feti in the left uterine horn middle location (0.055g ± 0.002 vs. 0.033 ± 0.002). Placental weights were unaffected, and placental efficiency was reduced in the right uterine horn middle location after GD 17 exposure (5.74g ± 0.16 vs. 5.09g ± 0.14). These findings identified: 1) differences in fetal weight of controls between the right and left horns in the middle position, and 2) differential effects of single whole-body pulmonary exposure to titanium dioxide nanoparticles on fetal weight by position and window of maternal exposure. In conclusion, these results indicate that consideration for intrauterine position, maternal weight, and number of feti per horn provides a more sensitive assessment of FGR from rodent reproductive and developmental studies.

N-Acetyl-L-cysteine and aminooxyacetic acid differentially modulate trichloroethylene reproductive toxicity via metabolism in Wistar rats

Exposure to the industrial solvent trichloroethylene (TCE) has been associated with adverse pregnancy outcomes in humans and decreased fetal weight in rats. TCE kidney toxicity can occur through formation of reactive metabolites via its glutathione (GSH) conjugation metabolic pathway, largely unstudied in the context of pregnancy. To investigate the contribution of the GSH conjugation pathway and oxidative stress to TCE toxicity during pregnancy, we exposed rats orally to 480 mg TCE/kg/day from gestational day (GD) 6 to GD 16 with and without N-acetyl-L-cysteine (NAC) at 200 mg/kg/day or aminooxyacetic acid (AOAA) at 20 mg/kg/day as pre/co-treatments from GD 5-16. NAC is a reactive oxygen species scavenger that modifies the GSH conjugation pathway, and AOAA is an inhibitor of cysteine conjugate β-lyase (CCBL) in the GSH conjugation pathway. TCE decreased fetal weight, and this was prevented by AOAA but not NAC pre/co-treatment to TCE. Although AOAA inhibited CCBL activity in maternal kidney, it did not inhibit CCBL activity in maternal liver and placenta, suggesting that AOAA prevention of TCE-induced decreased fetal weight was due to CCBL activity inhibition in the kidneys but not liver or placenta. Unexpectedly, NAC pre/co-treatment with TCE, relative to TCE treatment alone, altered placental morphology consistent with delayed developmental phenotype. Immunohistochemical staining revealed that the decidua basale, relative to basal and labyrinth zones, expressed the highest abundance of CCBL1, flavin-containing monooxygenase 3, and cleaved caspase-3. Together, the findings show the differential effects of NAC and AOAA on TCE-induced pregnancy outcomes are likely attributable to TCE metabolism modulation.

Cinnamaldehyde mitigates placental vascular dysfunction of gestational diabetes and protects from the associated fetal hypoxia by modulating placental angiogenesis, metabolic activity and oxidative stress

Gestational diabetes mellitus (GDM) is a major pregnancy-related disorder with an increasing prevalence worldwide. GDM is associated with altered placental vascular functions and has severe consequences for fetal growth. There is no commonly accepted medication for GDM due to safety considerations. Actions of the currently limited therapeutic options focus exclusively on lowering the blood glucose level without paying attention to the altered placental vascular reactivity and remodelling. We used the fat-sucrose diet/streptozotocin (FSD/STZ) rat model of GDM to explore the efficacy of cinnamaldehyde (Ci; 20 mg/kg/day), a promising antidiabetic agent for GDM, and glyburide/metformin-HCl (Gly/Met; 0.6 + 100 mg/kg/day), as a reference drug for treatment of GDM, on the placenta structure and function at term pregnancy after their oral intake one week before mating onward. Through genome-wide transcriptome, biochemical, metabolome, metal analysis and histopathology we obtained an integrated understanding of their effects. GDM resulted in maternal and fetal hyperglycemia, fetal hyperinsulinemia and placental dysfunction with subsequent fetal anemia, hepatic iron deficiency and high serum erythropoietin level, reflecting fetal hypoxia. Differentially-regulated genes were overrepresented for pathways of angiogenesis, metabolic transporters and oxidative stress. Despite Ci and Gly/Met effectively alleviated the maternal and fetal glycemia, only Ci offered substantial protection from GDM-associated placental vasculopathy and prevented the fetal hypoxia. This was explained by Ci's impact on the molecular regulation of placental angiogenesis, metabolic activity and redox signaling. In conclusion, Ci provides a dual impact for the treatment of GDM at both maternal and fetal levels through its antidiabetic effect and the direct placental vasoprotective action. Lack of Gly/Met effectiveness to restore it's impaired functionality demonstrates the vital role of the placenta in developing efficient medications for GDM.

Dolutegravir in pregnant mice is associated with increased rates of fetal defects at therapeutic but not at supratherapeutic levels

Background

Dolutegravir (DTG) is a preferred regimen for all people with HIV including pregnant women, but its effects on the fetus are not fully understood. Periconceptional exposure to DTG has been associated with increased rates of neural tube defects (NTDs), although it is unknown whether this is a causal relationship. This has led to uncertainty around the use of DTG in women of reproductive potential.

Methods

Pregnant C57BL/6J mice were randomly allocated to control (water), 1x-DTG (2.5 mg/kg-peak plasma concentration ~3000 ng/ml – therapeutic level), or 5x-DTG (12.5 mg/kg-peak plasma concentration ~12,000 ng/ml – supratherapeutic level), once daily from gestational day 0.5 until sacrifice. DTG was administered with 50 mg/kg tenofovir+33.3 mg/kg emtricitabine. Fetal phenotypes were determined, and maternal and fetal folate levels were quantified by mass-spectrometry.

Findings

352 litters (91 control, 150 1x-DTG, 111 5x-DTG) yielding 2776 fetuses (747 control, 1174 1x-DTG, 855 5x-DTG) were assessed. Litter size and viability rates were similar between groups. Fetal and placenta weights were lower in the 1x-DTG vs. control. Placental weight was higher in the 5x-DTG vs. control. Five NTDs were observed, all in the 1x-DTG group. Fetal defects, including microphthalmia, severe edema, and vascular/bleeding defects were more frequent in the 1x-DTG group. In contrast, defect rates in the 5x-DTG were similar to control. Fetal folate levels were similar between control and 1x-DTG, but were significantly higher in the 5x-DTG group.

Interpretation

Our findings support a causal relationship of DTG at therapeutic doses with increased risk for fetal defects, including NTDs at a rate that is similar that reported in the Tsepamo study for women exposed to DTG-based ART from conception. The non-monotonic dose-response relationship between DTG and fetal anomalies could explain the previous lack of fetal toxicity findings from pre-clinical DTG studies. The fetal folate levels suggest that DTG is unlikely to be an inhibitor of folate uptake.

Funding

This project has been funded with Federal funds from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, under Contract No. HHSN275201800001I.

Cotton Rat Placenta Anatomy and Fc Receptor Expression and Their Roles in Maternal Antibody Transfer

Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and viral pneumonia in infants and young children worldwide. Currently no vaccine is available to prevent RSV infection, but virus-neutralizing monoclonal antibodies can be given prophylactically, emphasizing the protective potential of antibodies. One concept of RSV vaccinology is mothers' immunization to induce high antibody titers, leading to passive transfer of high levels of maternal antibody to the fetus through the placenta and to the neonate through colostrum. Cotton rats are an excellent small animal model for RSV infection and have been used to test maternal immunization. To mechanistically understand antibody transfer in the cotton rat model, we characterized the cotton rat placenta and Fc receptor localization. Placentas from cotton rats at midgestation (approximately day 14) and at late gestation (approximately day 25) and neonatal (younger than 1 wk) gastrointestinal tracts were collected for light microscopy, immunohistochemistry, and transmission electron microscopy. The cotton rat placenta is hemotrichorial and has 5 distinct layers: decidua, junctional zone, labyrinth, chorionic plate, and yolk sac. Consistent with the transfer of maternal antibodies, the majority of the Fc receptors are present in the yolk sac endoderm and fetal capillary endothelium of the chorionic plate, involving 10% of the cells within the labyrinth. In addition, Fc receptors are present on duodenal and jejunal enterocytes in cotton rats, similar to humans, mice, and rats. These findings provide the structural basis for the pre- and postnatal transfer of maternal antibodies described in cotton rats.

The effects of a technical mixture of naphthenic acids on placental trophoblast cell function

There is considerable concern that naphthenic acids (NA) related to oil extraction can negatively impact reproduction in mammals, yet the mechanisms are unknown. Since placental dysfunction is central to many adverse pregnancy outcomes, the goal of this study was to determine the effects of NA exposure on placental trophoblast cell function. HTR-8/SVneo cells were exposed to a commercial technical NA mixture for 24 hours to assess transcriptional regulation of placentation-related pathways and functional assessment of migration, invasion, and angiogenesis. Pathway analysis suggests that NA treatment resulted in increased epithelial-to-mesenchymal transition. However, there was reduced migration and invasive potential. NA treatment increased angiogenesis-related pathways with a concomitant increase in tube formation. Since decreased trophoblast invasion/migration and aberrant angiogenesis have been associated with placental dysfunction, these findings suggest that it is biologically plausible that exposure to NA may result in altered placental development and/or function.

Leptin Distribution in Rat Foetal and Extraembryonic Tissues in Late Gestation: A Physiological View of Amniotic Fluid Leptin

Prenatal leptin is key to regulating foetal growth and early metabolic programming. The presence of intact leptin in rat foetal (at late gestation) and neonatal (immediately after birth) stomach content and mucosa has been previously described, suggesting that it may act as a regulatory nutrient for the neonate rats, be internalised by the stomach, and play a physiological role early in life, which requires to be further investigated, including its origin. We aimed to study the ontogeny of the presence of leptin in the foetal stomach and key extraembryonic tissues in rats at late gestation (days 18-21). Leptin concentration was determined by enzyme-linked immunosorbent assay, and placental leptin immunolocalisation was analysed by immunohistochemistry. Leptin showed a sudden appearance in the amniotic fluid (AF) at day 20 of gestation, gastric content (swallowed AF), stomach, and umbilical cord, significantly increasing at day 21. Leptin levels in these fluids and tissues were positively correlated. In the placenta, leptin was detectable at all the studied days, but its localisation changed from widespread throughout the placenta at day 18 to well-defined in the labyrinth zone from day 19 onwards. The results support a possible internalisation of AF leptin by the immature stomach of near-term foetuses and suggest that changes in placental leptin localisation might help to explain the sudden appearance of leptin in AF at gestational day 20, with potential physiological significance regarding short-term feeding control and metabolic programming in the developing offspring.

Utero-placental vascular remodeling during late gestation in Sprague-Dawley rats

BACKGROUND

Remodeling of the uterine spiral arteries and blood vessels within the placenta allows delivery of nutrients to the growing utero-fetal-placental unit. While abnormal remodeling of these vessels is thought to play an important role in syndromes including intrauterine growth restriction and preeclampsia, there are a lack of studies that have quantified vascular remodeling in normal pregnant rats. Thus, the purpose of this study was to quantify time-dependent remodeling of the utero-placental vasculature during late gestation in normal pregnant rats.

METHODS

Timed-pregnant Sprague-Dawley rats were used. Gestational days of 14 and 19 were chosen because this when a large amount of fetal and placental growth occurs. A combined method of perfusion-casting and 3D micro-computed tomography were utilized to construct ex-vivo utero-placental vasculature images.

RESULTS

Significant spiral artery remodeling occurred between days 14 and 19. Vessel density shifted away from a distribution of smaller to larger diameters by day 19. Total spiral artery area and average diameter were increased by day 19. Moreover, branching and tortuosity of the spiral arteries were greater by day 19. In rodents, spiral arteries feed into the central canal vessels that funnel to sites of exchange. Canal vessel area and diameter were increased by day 19.

CONCLUSIONS

Our study supports a quantitative method to examine the placental vasculature showing that significant vascular remodeling occurs during late gestation in the utero-placental-fetal unit of the normal pregnant rat. This method may serve as a tool to investigate fundamental pathophysiological mechanisms underlying placental-related diseases in rat models.

PBDEs Concentrate in the Fetal Portion of the Placenta: Implications for Thyroid Hormone Dysregulation

During pregnancy, the supply of thyroid hormone (TH) to the fetus is critically important for fetal growth, neural development, metabolism, and maintenance of pregnancy. Additionally, in cases where maternal and placental TH regulation is significantly altered, there is an increased risk of several adverse pregnancy outcomes. It is unclear what may be disrupting placental TH regulation; however, studies suggest that environmental contaminants, such as polybrominated diphenyl ethers (PBDEs), could be playing a role. In this study, Wistar rats were gestationally exposed to a mixture of PBDEs for 10 days. THs and PBDEs were quantified in paired maternal serum, dissected placenta, and fetuses, and mRNA expression of transporters in the placenta was assessed. Significantly higher concentrations of PBDEs were observed in the fetal portion of the placenta compared with the maternal side, suggesting that PBDEs are actively transported across the interface. PBDEs were also quantified in 10 recently collected human maternal and fetal placental tissues; trends paralleled observations in the rat model. We also observed an effect of PBDEs on T3 levels in dam serum, as well as suggestive changes in the T3 levels of the placenta and fetus that varied by fetal sex. mRNA expression in the placenta also significantly varied by fetal sex and dose. These observations suggest the placenta is a significant modifier of fetal exposures, and that PBDEs are impacting TH regulation in a sex-specific manner during this critical window of development.

The effect of propolis administration on fetal development

Propolis is one of the bee products that widely used in health therapy. However, there has no study evaluating the developmental toxicity of propolis. This study was aimed to analyze the effect of propolis administration during pregnancy on fetal development. The pregnant mice were divided into five groups including control group (Tween 80 1%), low-dose (380 mg/kg b.wt.) and high-dose (1400 mg/kg b.wt.) of water extract of propolis from Banten (WEB), and low-dose (380 mg/kg b.wt.) and high-dose (1400 mg/kg b.wt.) of ethanol extract of propolis from South Sulawesi (EES). Propolis was administered for 18 days of gestation and then sacrificed to analyze the fetal development by examining external and skeletal abnormalities. The histopathological examination of placenta was also conducted. The result showed both low-dose groups did not inhibit fetal development. However, the high-dose of EES significantly reduced the weight, crown-rump of fetuses and increased the number of resorption (p < 0.05). Fetal weight was the only significantly reduced parameter of fetal growth in the highdose group of WEB (p < 0.05). The histopathological examination of placenta showed a reduction of labyrinth development in both high-dose groups. Dose of 380 mg/kg dose of Indonesian propolis is relatively safe for consumption during pregnancy.

Importance of gestational hypoglycaemia for foetal malformations and skeletal development in rats

The aim was to investigate embryo-foetal effects of continuous maternal insulin-induced hypoglycaemia extending throughout gestation or until gestation day (GD)17 (typical last day of dosing during pre-clinical evaluation) providing comparator data for safety assessment of longer-acting insulin analogues in non-diabetic rats. Pregnant rats received human insulin (HI)-infusion during gestation until either GD20 or GD17 (HI-GD20; HI-GD17). On GD20, foetal abnormalities and skeletal ossification/mineralisation were evaluated. HI-infusion induced continuous hypoglycaemia. Foetal skeletal and eye malformations (e.g. bent ribs, microphthalmia) were common in both groups. Foetal size and skeletal ossification/mineralisation decreased, particularly with infusion throughout gestation. Concluding, insulin-induced hypoglycaemia during gestation in non-diabetic rats is damaging to embryo-foetal growth and skeletal development, particularly after GD17. Three days without HI-infusion after GD17 allows for some developmental catch-up. Eye development is sensitive to HI-infusion before GD17. These results should serve as a benchmark during pre-clinical safety assessment of longer-acting insulin analogues tested in rats.

Toxic effects of maternal exposure to silver nanoparticles on mice fetal development during pregnancy

BACKGROUND

Silver nanoparticles (SNPs) are being increasingly used in medical and industrial products. The aim of the present study was to evaluate the toxic effect of maternal exposure to SNP (1 mg/kg/day, 70 nm) on fetal development during the first and second weeks of pregnancy.

METHODS

Twenty-four pregnant mice were divided into four groups. SNP was administered by oral gavage on gestational days (GD) 1-7, GD8-14, or GD1-14. Phosphate buffered saline was administered by oral gavage to a control group. On GD15, the uteri were excised, and fetal bodies and placentas were weighed. Head and placental circumferences and fetal crown-rump length were measured, and fetuses were evaluated for external malformation. TUNEL assay was performed to assess apoptosis in the fetal midbrain. Hematoxylin-eosin staining was carried out to determine changes in fetal histomorphology. Fetal liver cells were used for karyotype analysis.

RESULTS

Significant decreases in fetal body weight, and crown-rump length were observed in SNP-treated groups. Exencephaly, small head, scoliosis, lordosis, short thorax and trunk, also fused digits were detected in SNPs-treated groups. Fibrosis, necrosis, and apoptotic cells in fetal midbrains increased significantly in the GD8-14 and GD1-14 groups compared to the control group. Chromosomal features were not different in fetuses between groups.

CONCLUSIONS

Exposure to 1 mg/kg/day SNP during pregnancy in mice adversely affected on fetal development. The results do suggest a potential risk for humans that needs to be followed up with more definitive investigations.

Subcutaneous maternal resveratrol treatment increases uterine artery blood flow in the pregnant ewe and increases fetal but not cardiac growth

KEY POINTS

Substrate restriction during critical developmental windows of gestation programmes offspring for a predisposition towards cardiovascular disease in adult life. This study aimed to determine the effect of maternal resveratrol (RSV) treatment in an animal model in which chronic fetal catheterisation is possible and the timing of organ maturation reflects that of the human. Maternal RSV treatment increased uterine artery blood flow, fetal oxygenation and fetal weight. RSV was not detectable in the fetal circulation, indicating that it may not cross the sheep placenta. This study highlights RSV as a possible intervention to restore fetal substrate supply in pregnancies affected by placental insufficiency.

ABSTRACT

Suboptimal in utero environments with reduced substrate supply during critical developmental windows of gestation predispose offspring to non-communicable diseases such as cardiovascular disease (CVD). Improving fetal substrate supply in these pregnancies may ameliorate the predisposition these offspring have toward adult-onset CVD. This study aimed to determine the effect of maternal resveratrol (RSV) supplementation on uterine artery blood flow and the direct effects of RSV on the fetal heart in a chronically catheterised sheep model of human pregnancy. Maternal RSV treatment significantly increased uterine artery blood flow as measured by phase contrast magnetic resonance imaging, mean gestational fetal P a O 2 and S a O 2 as well as fetal weight. RSV was not detectable in the fetal circulation, and mRNA and protein expression of the histone/protein deacetylase SIRT1 did not differ between treatment groups. No effect of maternal RSV supplementation on AKT/mTOR or CAMKII signalling in the fetal left ventricle was observed. Maternal RSV supplementation is capable of increasing fetal oxygenation and growth in an animal model in which cardiac development parallels that of the human.

Longitudinal characterization of local perfusion of the rat placenta using contrast-enhanced ultrasound imaging

The placenta performs many physiological functions critical for development. Insufficient placental perfusion, due to improper vascular remodelling, has been linked to many pregnancy-related diseases. To study longitudinal in vivo placental perfusion, we have implemented a pixel-wise time-intensity curve (TIC) analysis of contrast-enhanced ultrasound (CEUS) images. CEUS images were acquired of pregnant Sprague Dawley rats after bolus injections of gas-filled microbubble contrast agents. Conventionally, perfusion can be quantified using a TIC of contrast enhancement in an averaged region of interest. However, the placenta has a complex structure and flow profile, which is insufficiently described using the conventional technique. In this work, we apply curve fitting in each pixel of the CEUS image series in order to quantify haemodynamic parameters in the placenta and surrounding tissue. The methods quantified an increase in mean placental blood volume and relative blood flow from gestational day (GD) 14 to GD18, while the mean transit time of the microbubbles decreased, demonstrating an overall rise in placental perfusion during gestation. The variance of all three parameters increased during gestation, showing that regional differences in perfusion are observable using the pixel-wise TIC approach. Additionally, the high-resolution parametric images show distinct regions of high blood flow developing during late gestation. The developed methods could be applied to assess placental vascular remodelling during the treatment of the pathologies of pregnancy.

Histopathological changes in placenta and liver of pregnant rats administered with aqueous extract of Dioscorea hispida var. daemona (Roxb) Prain & Burkill

Dioscorea hispida var. daemona (Roxb) Prain & Burkill (DH), also known a tropical yam or intoxicating yam is a bitter wild tuber which is consumed as a staple food and traditionally used as a remedy in Malaysia. However, DH is also notorious for its intoxicating effects and there is currently a dearth of study of possible effects of DH on liver and placental tissues and hence its safe consumption warrants in-depth investigation. This study was therefore designed to investigate into the effect of DH on liver and placenta of pregnant rat via histopathological examination. Thirty pregnant Sprague-Dawley rats were randomly divided into five groups consisting of a control (distilled water) and four DH aqueous extract groups (250, 500, 1000 and 2000 mg/kg body weight). The extracts were administered via oral gavage daily throughout the study and animals were sacrificed on day 21. Paraffin-embedded, hematoxylin and eosin stained sections of placenta and liver were examined. Significant changes (p < 0.05) were observed on relative liver and placental weights of animals treated with 2000 mg/kg body weight DH extract. The placental numbers were decreased with the increased of DH extract concentration. Liver histological examination in all treated groups showed that tissues underwent degeneration characterized by hepatocyte swelling, cytoplasmic vacuolation, cytolysis, margination and clumping of nucleus chromatin. Changes of the basal and labyrinth zone were observed in placental tissues in all treated groups. Glycogen cells were reduced with fibrin deposition in the basal zone, while irregular vessel formation was demonstrated in the labyrinth zone. UHPLC-ESI-MS analysis showed the presence four steroidal saponins DH. In conclusion, DH aqueous extract exert hepatotoxicity and adverse effects on the placenta of rats. However, the underlying mechanism and phytochemicals inducing the observed toxicity require further investigation.