Morphology and physiology of rat placenta for toxicological evaluation

Enhanced toxic effects of photoaged microplastics on the trophoblast cells

Microplastics (MPs) are emerging as a novel pollutant, raising significant concerns regarding their adverse effects on human health. Furthermore, MPs are susceptible to light-induced aging in the environment, which alters their physical characteristics and potentially alters their toxic effects. While previous studies have documented the retention of MPs in the placenta, the specific impacts of MPs, particularly aged MPs, on placental function remain poorly understood. In the current study, we utilized 1µm polystyrene microplastics (PS-MPs), a widely used model for MPs, to evaluate the effects of photoaged MPs on the placenta. Following oral administration of PS-MPs beginning on embryonic day 3.5 (E3.5), we observed impaired fetal growth and damage to the placental labyrinth chorionic layer in the treated pregnant mice by embryonic day 13.5 (E13.5). The photoaged PS-MPs were generated by exposure to simulated lighting for 7 or 14 days, resulting in alterations to their physical properties. Notably, enhanced cytotoxicity in trophoblast cells was observed for photoaged PS-MPs compared to pristine PS-MPs. Mechanistically, the altered physical properties of PS-MPs, along with elevated lipid peroxidation, may contribute to the increased cytotoxicity of the photoaged MPs. Our findings provide new insights into the detrimental effects and underlying mechanisms of both MPs and, in particular, aged MPs on the placenta and embryonic development. These insights are crucial for assessing the risks posed by MPs to human pregnancy.

Consequences of the modulation of gestational resistance training intensity for placental cell composition and nutrient transporter expression

INTRODUCTION

Resistance training during pregnancy provides benefits for the mother and fetus, but little is known about the effects of resistance training on placental structure and function or the repercussions of modifying resistance training intensity on the mother-fetus-placenta triad.

METHODS

Female Wistar rats were submitted to resistance training involving a ladder climb (80 % of maximum load carried (MLC), 5-day/week for 3-weeks) before pregnancy. After confirmation of mating, the rats were randomly divided into three groups, according to resistance training intensity during pregnancy: constant-intensity training (CIT, trained at 80 % of MLC through gestation), decreasing-intensity training (DIT, 80 % of MLC during first and second weeks of gestation and 50 % of MLC in the third week), and undulating-intensity training (UIT, 50 % of MLC in the first and third weeks, and 80 % of MLC in the second week). A control group did not undergo any training. Samples were collected on gestational day 20.

RESULTS

Resistance training had no impact on maternal body weight, muscle glycogen content, adipocyte morphology, number of fetuses, number of absorptions, placental area, or fetal growth parameters. The CIT group presented lower maternal serum glucose. The UIT group presented increased presence of fetal capillaries in the labyrinth zone and increased Glut1, Glut3, and Snat1 expression in the placenta. Snat2 expression was upregulated in all resistance training groups and higher levels of Mtor expression were found in the DIT group. Il1b expression increased in the CIT group, and higher levels of Il10 expression were found in the DIT and UIT groups.

DISCUSSION

Resistance training was safe for pregnant rats. Its influence on glucose and amino acid transport was not dependent on changes in Mtor expression and did not impact fetal growth.

Distribution of polybrominated diphenyl ethers (PBDEs) in placental tissues of maternal and fetal origin in exposed Wistar rats and associations with thyroid hormone levels

In utero exposure to polybrominated diphenyl ethers (PBDEs) is linked to adverse pregnancy and fetal health outcomes, including altered thyroid hormone (TH) levels. Despite their phase-out, PBDEs are still commonly detected in newborn cord blood. While PBDEs can cross the placenta, few studies have separately assessed PBDEs or THs in the maternal and fetal placental tissues. Additionally, no studies have separately assessed THs in these tissues across mid- and late gestation, during the onset of fetal TH synthesis. To address these gaps, we conducted a study with Wistar rats and examined PBDE accumulation in the maternal and fetal placenta. Pregnant dams were exposed daily to sesame oil vehicle, a low dose, or high dose PBDE mixture. At GD15 and 20, dams were sacrificed and placental tissues were collected. Tissues were analyzed for PBDEs, T3, rT3, and T4 using mass spectrometry. BDE-47, -99, -100, and -209 were frequently detected in both the fetal and maternal placenta. At GD15, higher concentrations of BDE-99, -100, and -209 were measured in the fetal placenta; however, this trend reversed by GD20, with higher maternal placental concentrations. Placental T3 and T4 were significantly impacted by exposure, tissue, and exposure × tissue at GD15, with significant reductions in both THs following low-dose exposure in the maternal placenta. By GD20, maternal placental T3 was only significantly reduced in the high exposure groups and there was no effect on placental T4. Overall, these results highlight the rapid developmental changes that occur throughout gestation between the maternal and fetal placenta, and the differential impacts of gestational PBDE exposure on placental T3 and T4 across mid- and late gestation.

Quantifying Molecular Changes in the Preeclamptic Rat Placenta with Targeted Contrast-Enhanced Ultrasound Imaging

PURPOSE

Abnormal placental remodeling is linked to various pregnancy-related diseases, including preeclampsia (PE). This study applies a bicompartmental (BCM) model to quantify molecular expression changes in the placenta, indicative of abnormal placental remodeling, and evaluates the effectiveness of targeted contrast-enhanced ultrasound (T-CEUS) in detecting the abnormal placental vasculature. The BCM model provides high temporal resolution and differentiation of anatomical artery structures within the placenta by analyzing the distribution of contrast agents.

METHODS

A targeted contrast agent (TCA) composed of gas-filled microbubbles (MB), with a surface-conjugated peptide to target ανβ3 integrin, a biomarker for angiogenesis, was used for quantifying placental vascular development. CEUS images were acquired from timed pregnant Sprague Dawley rats with experimentally-induced reduced uterine perfusion pressure (RUPP) placental insufficiency. On gestational day (GD) 18 of a 21-day gestation, CEUS images were acquired from both Normal pregnant (NP; n = 6) and RUPP (n = 6) dams after injection of the TCA. The BCM model was used to estimate the binding dynamics of the TCA, providing a parametric map of the binding constant ( K b ) of the placenta.

RESULTS

The RUPP group showed a significant reduction in the value of K b compared to the NP group (p < 0.05). A histogram of the placental K b was compared to alternative analyses (differential target enhancement, dTE and late enhancement, LE) to demonstrate that it can differentiate between anatomical artery structures with a higher contrast-to-background ratio.

CONCLUSIONS

The BCM method differentiates molecular changes associated with the abnormal placental development associated with PE. It also reveals more intricate internal anatomical structures of the placenta in comparison to dTE and LE, suggesting that the BCM could enhance early detection and monitoring of PE.

A quantitative weight-of-evidence review of preclinical studies examining the potential developmental and reproductive toxicity of acetaminophen

We previously developed a quantitative weight-of-evidence (QWoE) framework using prespecified scoring criteria for preclinical acetaminophen data to characterize potential developmental neurotoxicity outcomes with considerations for biological relevance of the response to adverse outcomes and the strength of methods and study design. The current analysis uses this framework to characterize potential developmental and reproductive toxicity (DART) outcomes following exposure to acetaminophen. Two-hundred forty-two QWoE entries were documented from in vivo rodent studies identified in 110 publications across five categories: DART endpoints in the context of (1) periadolescent/adulthood (nonpregnancy) exposures; (2) pregnant female exposures; and, for in utero or other developmental exposures, (3) anatomical abnormalities, (4) reproductive development, and (5) other physical development. A mean outcome score and methods score were calculated for 242 QWoE entries. Data analyzed in our framework were of moderate quality showing no consistent evidence of DART in male and female rodents following exposure to acetaminophen at therapeutic and/or non-systemically toxic doses. Similar results were found for the individual context- and outcome-related endpoint analyses and as segregated by sex. Overall, this QWoE analysis on the in vivo rodent data demonstrated no consistent evidence of adverse effects following exposure to therapeutic and/or non-systemically toxic acetaminophen on development or on the structure and function of the reproductive system.

Heterozygous mutation in BRCA2 induces accelerated age-dependent decline in sperm quality with male subfertility in rats

Tumor suppressor BRCA2 executes homologous recombination to repair DNA double-strand breaks in collaboration with RAD51, involving exon 11 and 27. Exon 11 constitutes a region where pathogenic variants (PVs) accumulate, and mutations in this region are known to contribute to carcinogenesis. However, the impact of the heterozygous PVs of BRCA2 exon 11 on the life quality beyond cancer risk, including male fertility, remains unclear. Here, we established a rat model with a frameshift on the seventh BRC repeat in Brca2 exon 11 (Brca2+/p.T1942fs), which is homologous to human BRCA2+/p.T1974fs, using CRISPR/Cas9 system. Our analyses revealed that the heterozygous rats with the PV in the BRCA2 exon 11 showed increased DNA double-strand breaks and apoptosis in spermatogonia and spermatocytes, accelerated testicular germ cell loss, and deterioration in sperm quality according with aging, ultimately resulting in early male reproductive dysfunction. Of note, these alterations in testes and sperm, including DNA fragmentation in spermatozoa, were observed from completion of sexual maturation. The present findings suggest that it is crucial to consider not only cancer risk but also potential declines in reproductive capacity in men carrying BRCA2 exon 11 PVs. Further investigation is warranted to determine whether similar traits appear in humans.

Dose-, stage- and sex- difference of prenatal prednisone exposure on placental morphological and functional development

Prednisone, a synthetic glucocorticoid, is commonly used to treat autoimmune diseases in pregnant women. However, some studies suggest that the use of prednisone during pregnancy may lead to adverse pregnancy outcomes. In this study, we established PPE mouse models at different doses (0.25, 0.5, 1.0 mg/kg·d) and different stages (whole pregnancy, early pregnancy and middle-late pregnancy) and determined outcomes on the placenta and fetus. The results of our study indicated that at the highest dose of 1 mg/kg PPE using a GD 0-18 dosing regime, PPE caused placental morphological changes measured as a decrease in placental weight relative to controls and a decrease in the placenta junctional zone (JZ)/labyrinth zone (LZ) ratio. No changes were observed on the fetuses for number of live, stillborn, and absorbed fetuses between the experimental groups and the control group. In the placentas at some doses, there were decreases in cell proliferation markers measured at the RNA and protein level by Western blot and increased apoptosis. Measures of gene expression at the mRNA level showed altered nutrients (including glucose, amino acid, and cholesterol) transport gene expressions with the most significant change associated with the male placentas at high-dose and whole pregnancy PPE group. It was further found that PPE led to the inhibition of the insulin-like growth factor 2 (IGF2)/insulin-like growth factor 1 receptor (IGF1R) signaling pathway, which was well correlated with the indicators of cell proliferation, syncytialization and nutrient (glucose and amino acid) transport indices. In conclusion, PPE can alter placental morphology and nutrient transport function, with differences in effect related to dose, stage and gender. Differential gene expressions measured for genes of the IGF2/IGF1R signaling pathway suggested this pathway may be involved in the effects seen with PPE. This study provides a theoretical and experimental basis for enhancing the understanding of the effects of prednisone use on placenta during human pregnancy but does not currently raise concerns for human use as effects were not seen on the fetuses and while the effects on cell proliferation are informative they were inconsistent and the differential effects on female and male placentas unexplained suggesting that further work is required to elucidate if these findings have relevance for human use of PPE during pregnancy.

Impact of xylene exposure during organogenesis on foeto-placental efficiency and foetal viability: Exploring its association with oxidative stress-induced inflammation and apoptosis in utero

The potential maternal and foetal toxicity resulting from exposure to xylene at or below the allowable limit of 100 ppm during gestation is not thoroughly studied. The aim of this study was to investigate maternal and foetal outcomes following prenatal exposure to xylene during organogenesis. Pregnant Sprague Dawley (SD) rats were administered intraperitoneal (IP) corn oil (vehicle), 100, 500, and 1000 parts per million (ppm) of xylene from gestational day (GD) 6 until GD17. Clinical signs, maternal weight gain, and food consumption were recorded daily. A caesarean hysterectomy was performed on GD21 to assess the reproductive and foetal outcomes. Exposure to 1000 ppm of xylene caused a significant decrease in the maternal body weight and food consumption, and an increase in intrauterine foetal deaths. Foetal assessment revealed a significant decrease in foetal weight in both male and female foetuses of female rats treated with 500 and 1000 ppm. Male placental weight was significantly decreased in all xylene-treated groups, while 1000 ppm xylene significantly decreased female placental weight. Histologically, marked uterine inflammatory lesions, fibrosis of the liver and renal tissues, as well as increased placental glycogen content were observed. Immunohistochemistry revealed a significant increase in lipid peroxidation and apoptotic markers. Thus, the foeto-maternal toxicities of xylene have been shown to be mediated by a systemic inflammatory response that exacerbates intrauterine oxidative stress and impairs foeto-placental transfer, leading to an increase in foetal mortality.

Unveiling placental development in circadian rhythm-disrupted mice: A photo-acoustic imaging study on unstained tissue

INTRODUCTION

Circadian rhythm disruption has garnered significant attention for its adverse effects on human health, particularly in reproductive medicine and fetal well-being. Assessing pregnancy health often relies on diagnostic markers such as the labyrinth zone (LZ) proportion within the placenta. This study aimed to investigate the impact of disrupted circadian rhythms on placental health and fetal development using animal models.

METHODS AND RESULTS

Employing unstained photo-acoustic microscopy (PAM) and hematoxylin and eosin (HE)-stained images, we found them mutually reinforcing. Our images revealed the role of maternal circadian rhythm disrupted group (MCRD) on the LZ and fetus weight: a decrease in LZ area from 5.01 (4.25) mm2 HE (PAM) to 3.58 (2.62) mm2 HE (PAM) on day 16 and 6.48 (5.16) mm2 HE (PAM) to 4.61 (3.03) mm2 HE (PAM) on day 18, resulting in 0.71 times lower fetus weights. We have discriminated a decrease in the mean LZ to placenta area ratio from 64 % to 47 % on day 18 in mice with disrupted circadian rhythms with PAM.

DISCUSSION

The study highlights the negative influence of circadian rhythm disruption on placental development and fetal well-being. Reduced LZ area and fetal weights in the MCRD group suggest compromised placental function under disrupted circadian rhythms. PAM imaging proved to be an efficient technique for assessing placental development, offering advantages over traditional staining methods. These findings contribute to understanding the underlying mechanisms of circadian disruption on reproductive health and fetal development. Further research is needed to explore interventions to mitigate these effects and improve pregnancy outcomes.

Aspartame intake during pregnancy induces placental dysfunction through impaired mitochondrial function and biogenesis modulation

INTRODUCTION

Aspartame is a nonnutritive sweetener (NSS), which is widely used in foods and beverages worldwide. The safety of aspartame, a commonly used artificial sweetener, has been debated. Here, we investigated the potential effects and underlying mechanisms of aspartame consumption during pregnancy on placental dysfunction and birth outcomes.

METHODS

Female Sprague Dawley rats were exposed to a low (30 mg/kg) or high (60 mg/kg) dose of aspartame before and during pregnancy; moreover, we assessed placental histopathological structure, oxidative stress markers, and mitochondrial function. In addition, we explored how aspartame affects birth weight in a human maternal-infant cohort.

RESULTS

In animal study revealed that aspartame treatment of female rats for 14 weeks (12 week before pregnancy and 18 days of gestation) causes a significant reduction in the number and weight of fetuses, as well as damage to placental structure. These effects are linked to increased oxidative stress in the placenta, possibly damaging placental trophoblasts, impairing mitochondrial function, and initiating a compensatory mitochondrial biosynthesis mechanism. In the human pregnant cohort revealed that aspartame reduces birth weight considerably.

DISCUSSION

These findings suggested the potential risks associated with aspartame consumption during pregnancy. Therefore, the safety of aspartame, particularly in pregnant individuals, should be reconsidered; specifically, tailored, acceptable daily intake guidelines should be developed for aspartame in different populations.

Transuterine relocation of pregnant uterine horn segment in an exploratory rat model with implications for tubal ectopic pregnancy

Ectopic pregnancy affects ~ 2% of pregnancies annually in the United States, with no current treatments allowing for the continuation of the pregnancy. Thus, this study sought to initiate an investigation into the potential design of a surgical technique, in an animal model, that could serve as a foundation for future research into the potential of relocating an ectopic embryo into the uterus at the human level. Female Long-Evans rats were randomly assigned to one of two groups: Embryo Relocation (ER; n = 12; underwent embryo relocation surgery) and Normal Pregnancy (NP; n = 12; carried a normal pregnancy; no surgery). Eight rats/group were allowed to carry their pregnancy to term and deliver, while four had their uteri collected at the end of gestation. Briefly, for the ER group, a uterine horn containing 1-2 embryos was translocated to the contralateral horn, which had been incised and cleared of its contents, prior to being wrapped around the relocated horn. Rat weight, food consumption and vaginal impedance of the mothers were measured throughout the experiment. Ultrasounds were performed and fetal heart rates measured on day 20-21 of gestation. Additionally, rat weight of all offspring was measured at adulthood. Our findings indicate that, in the ER group, 15/15 (100%) of the relocated embryos had detectable heart rates at the end of gestation (within the normal range), 14/15 (93%) were delivered vaginally, and 12/14 (86%) survived until adulthood. A significant decrease in rat weight and food consumption was observed only on the day following surgery. Fertility, as measured by vaginal impedance, was minimally impacted by surgery. Moreover, there was no significant difference between groups in average body weight of offspring at adulthood. Histological analysis indicated a thicker placenta in the ER group, attributable to the fetal part of the placenta, potentially indicating compensatory mechanisms. Our findings reflect a successful transuterine embryo relocation followed by vaginal birth and survival of offspring to adulthood, in a rat model. Such findings lay the foundation for future preclinical research in higher animals, with potential implications on a procedure relevant to human ectopic embryo relocation.

Ethanol consumption during gestation promotes placental alterations in IGF-1 deficient mouse placentas

Background

During pregnancy, the placenta is an extremely important organ as it secretes its own hormones, e.g. insulin-like growth factor 1 (IGF-1), to ensure proper intrauterine fetal growth and development. Ethanol, an addictive and widely used drug, has numerous adverse effects during pregnancy, including fetal growth restriction (FGR). To date, the molecular mechanisms by which ethanol triggers its toxic effects during pregnancy, particularly in the placenta, are not entirely known. For this reason, a murine model of partial IGF-1 deficiency was used to determine ethanol alterations in placental morphology and aspartyl/asparaginyl β-hydroxylase (AAH) expression.

Methods

Wild type (WT, Igf1 +/+) and heterozygous (HZ, Igf1 +/-) female mice were given 10% ethanol in water during 14 days as an acclimation period and throughout pregnancy. WT and HZ female mice given water were used as controls. At gestational day 19, pregnant dams were sacrificed, placentas were collected and genotyped for subsequent studies.

Results

IGF-1 deficiency and ethanol consumption during pregnancy altered placental morphology, and decreased placental efficiency and AAH expression in placentas from all genotypes. No differences were found in Igf1, Igf2, Igf1r and Igf2r mRNA expression in placentas from all groups.

Conclusions

IGF-1 deficiency and ethanol consumption throughout gestation altered placental development, suggesting the crucial role of IGF-1 in the establishment of an adequate intrauterine environment that allows fetal growth. However, more studies are needed to study the precise mechanism to stablish the relation between both insults.

Effects of letrozole on rat placental development

We examined the morphological effects of letrozole on placental development in pregnant rats. Letrozole was orally administered at a repeat dose to pregnant rats at 0 mg/kg (control group) and 0.04 mg/kg (letrozole group) from gestation day (GD) 6 to GD 20. In the letrozole group, fetal mortality and placental weight increased from GD 15 onwards and GD 13 onwards, respectively. Fetal weights increased on GDs 15 and 17 but decreased on GD 21. Histopathologically, letrozole treatment induced multiple cysts lined with undifferentiated syncytiotrophoblasts in the trophoblastic septa on GD 13. These cysts then develop into dilated maternal sinusoids with congestive hyperemia, resulting in an enlarged placenta. In the metrial gland, there was a dilated lumen of the spiral artery and interstitial edema throughout the experimental period, resulting in thickened metrial gland. These changes are considered to be due to maternal blood circulation stagnation in the metrial gland, which is associated with dilated maternal sinusoids in the labyrinth zone. Thus, although letrozole induces an enlarged placenta due to congestive hyperemia of the labyrinth zone and transient increases in fetal weight, these placentas are thought to decline in function as the pregnancy progresses, leading to intrauterine growth restriction at the end of pregnancy.

Protective effect of leukotriene receptor antagonist, montelukast, against cyclophosphamide-induced placental toxicity via modulation of NLRP3/IL-1β signaling pathway in rats

BACKGROUNDS & AIM

Placental insufficiency is a serious complication that affects pregnancy and fetal growth. Cyclophosphamide (CYC) is considered one of the chemotherapeutic agents. Unfortunately, CYC not only affects tumor cells but also affects healthy cells causing multiple injuries including the placenta. The present study aimed to evaluate the effect of cysteinyl leukotriene receptor antagonist; montelukast (MK), on CYC-induced placental injury in rats.

MATERIALS AND METHODS

Forty-eight female Wister rats were randomly divided into 8 experimental groups. Group 1: control pregnant group; Group 2: MK 5 mg-treated pregnant rats; Group 3: MK 10 mg-treated pregnant rats; Group 4: MK 20 mg-treated pregnant rats; Group 5: pregnant rats received CYC (20 mg/kg, i.p); Group 6: pregnant rats received MK 5 mg and CYC; Group 7: pregnant rats received MK 10 mg and CYC; Group 8: pregnant rats received MK 20 mg and CYC. Placental malondialdehyde (MDA), reduced glutathione (GSH), total antioxidant capacity (TAC), placental growth factor (PlGF), and Nod-like receptor p3 (NLRP3) inflammasome were measured. Histological changes, interleukin-1β (IL-1β), and cleaved caspase-3 immuno-expressions were also evaluated.

RESULTS

CYC showed a significant decrease in placental GSH, TAC, and PlGF with a significant increase in placental MDA, NLRP3, and immuno-expression of IL-1β and caspase-3. MK showed significant improvement in all oxidative stress (MDA, GSH and TAC), inflammatory (NLRP3 and IL-1β), and apoptotic (caspase-3) parameters.

CONCLUSION

According to the findings, MK was proved to have a possible protective role in CYC-induced placental injury via modulation of NLRP3/IL-1β signaling pathway with anti-oxidant, anti-inflammatory, and anti-apoptotic effects.

Impact of Ionizing Radiation Exposure on Placental Function and Implications for Fetal Programming

Accidental exposure to high-dose radiation while pregnant has shown significant negative effects on the developing fetus. One fetal organ which has been studied is the placenta. The placenta performs all essential functions for fetal development, including nutrition, respiration, waste excretion, endocrine communication, and immunological functions. Improper placental development can lead to complications during pregnancy, as well as the occurrence of intrauterine growth-restricted (IUGR) offspring. IUGR is one of the leading indicators of fetal programming, classified as an improper uterine environment leading to the predisposition of diseases within the offspring. With numerous studies examining fetal programming, there remains a significant gap in understanding the placenta's role in irradiation-induced fetal programming. This review aims to synthesize current knowledge on how irradiation affects placental function to guide future research directions. This review provides a comprehensive overview of placental biology, including its development, structure, and function, and summarizes the placenta's role in fetal programming, with a focus on the impact of radiation on placental biology. Taken together, this review demonstrates that fetal radiation exposure causes placental degradation and immune function dysregulation. Given the placenta's crucial role in fetal development, understanding its impact on irradiation-induced IUGR is essential.

Ultrasound based radiomics model for assessment of placental function in pregnancies with preeclampsia

The goal of our research is to elucidate and better assess placental function in rats with preeclampsia through an innovative application of ultrasound-based radiomics. Using a rat model induced with L-NAME, we carefully investigated placental dysfunction via microstructural analysis and immunoprotein level assessment. Employing the Boruta feature selection method on ultrasound images facilitated the identification of crucial features, consequently enabling the development of a robust model for classifying placental dysfunction. Our study included 12 pregnant rats, and thorough placental evaluations were conducted on 160 fetal rats. Distinct alterations in placental microstructure and angiogenic factor expression were evident in rats with preeclampsia. Leveraging high-throughput mining of quantitative image features, we extracted 558 radiomic features, which were subsequently used to construct an impressive evaluation model with an area under the receiver operating curve (AUC) of 0.95. This model also exhibited a remarkable sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 88.7%, 91.5%, 90.2%, 90.4%, and 90.0%, respectively. Our findings highlight the ability of ultrasound-based radiomics to detect abnormal placental features, demonstrating its potential for evaluating both normative and impaired placental function with high precision and reliability.

Sex Differences in Impacts of Early Gestational and Peri-Adolescent Ozone Exposure on Lung Development in Rats: Implications for Later Life Disease in Humans

Air pollution exposure during pregnancy may affect fetal growth. Fetal growth restriction (FGR) is associated with reduced lung function in children that can persist into adulthood. Using an established model of asymmetrical FGR in Long-Evans rats, this study investigated sex differences in effects of early life ozone exposure on lung development and maturation. Adverse health effects for i) gestational exposure (with impacts on primary alveolarization), ii) peri-adolescent exposure (with impacts on secondary alveolarization), and iii) cumulative exposure across both periods were evaluated. Notably, female offspring were most affected by gestational ozone exposure, likely because of impaired angiogenesis and corresponding decreases in primary alveolarization. Females had diminished lung capacity, fewer mature alveoli, and medial hypertrophy of small and large pulmonary arteries. Males, especially FGR-prone offspring, were more affected by peri-adolescent ozone exposure. Males had increased ductal areas, likely due to disrupted secondary alveolarization. Altered lung development may increase risk of developing diseases, such as pulmonary arterial hypertension or chronic obstructive pulmonary disease. Pulmonary arterial hypertension disproportionately affects women. In the United States, chronic obstructive pulmonary disease prevalence is increasing, especially in women; and prevalence for both men and women is highest in urbanized areas. This investigation underlines the importance of evaluating results separately by sex, and provides biologic plausibility for later consequences of early-life exposure to ozone, a ubiquitous urban air pollutant.

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.

Exposure to fine particulate matter 2.5 from wood combustion smoke causes vascular changes in placenta and reduce fetal size

During gestation, maternal blood flow to the umbilical cord and placenta increases, facilitating efficient nutrient absorption, waste elimination, and effective gas exchange for the developing fetus. However, the effects of exposure to wood smoke during this period on these processes are unknown. We hypothesize that exposure to PM2.5, primarily sourced from wood combustion for home heating, affects placental vascular morphophysiology and fetal size. We used exposure chambers that received either filtered or unfiltered air. Female rats were exposed to PM2.5 during pre-gestational and/or gestational stages. Twenty-one days post-fertilization, placentas were collected via cesarean section. In these placentas, oxygen diffusion capacity was measured, and the expression of angiogenic factors was analyzed using qPCR and immunohistochemistry. In groups exposed to PM2.5 during pre-gestational and/or gestational stages, a decrease in fetal weight, crown-rump length, theoretical and specific diffusion capacity, and an increase in HIF-1α expression were observed. In groups exposed exclusively to PM2.5 during the pre-gestational stage, there was an increase in the expression of placental genes Flt-1, Kdr, and PIGF. Additionally, in the placental labyrinth region, the expression of angiogenic factors was elevated. Changes in angiogenesis and angiogenic factors reflect adaptations to hypoxia, impacting fetal growth and oxygen supply. In conclusion, this study demonstrates that exposure to PM2.5, emitted from wood smoke, in both pre-gestational and gestational stages, affects fetal development and placental health. This underscores the importance of addressing air pollution in areas with high levels of wood smoke, which poses a significant health risk to pregnant women and their fetuses.

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.

Entry of cannabidiol into the fetal, postnatal and adult rat brain

Cannabidiol is a major component of cannabis but without known psychoactive properties. A wide range of properties have been attributed to it, such as anti-inflammatory, analgesic, anti-cancer, anti-seizure and anxiolytic. However, being a fairly new compound in its purified form, little is known about cannabidiol brain entry, especially during development. Sprague Dawley rats at four developmental ages: embryonic day E19, postnatal day P4 and P12 and non-pregnant adult females were administered intraperitoneal cannabidiol at 10 mg/kg with [3H] labelled cannabidiol. To investigate the extent of placental transfer, the drug was injected intravenously into E19 pregnant dams. Levels of [3H]-cannabidiol in blood plasma, cerebrospinal fluid and brain were estimated by liquid scintillation counting. Plasma protein binding of cannabidiol was identified by polyacrylamide gel electrophoresis and its bound and unbound fractions measured by ultrafiltration. Using available RNA-sequencing datasets of E19 rat brain, choroid plexus and placenta, as well as P5 and adult brain and choroid plexus, expression of 13 main cannabidiol receptors was analysed. Results showed that cannabidiol rapidly entered both the developing and adult brains. Entry into CSF was more limited. Its transfer across the placenta was substantially restricted as only about 50% of maternal blood plasma cannabidiol concentration was detected in fetal plasma. Albumin was the main, but not exclusive, cannabidiol binding protein at all ages. Several transcripts for cannabidiol receptors were expressed in age- and tissue-specific manner indicating that cannabidiol may have different functional effects in the fetal compared to adult brain.

Animal models of postpartum hemorrhage

Postpartum hemorrhage (PPH)-heavy bleeding following childbirth-is a leading cause of morbidity and mortality worldwide. PPH can affect individuals regardless of risks factors and its incidence has been increasing in high-income countries including the United States. The high incidence and severity of this childbirth complication has propelled research into advanced treatments and alternative solutions for patients facing PPH; however, the development of novel treatments is limited by the absence of a common, well-established and well-validated animal model of PPH. A variety of animals have been used for in vivo studies of novel therapeutic materials; however, each of these animals differs considerably from the anatomy and physiology of a postpartum woman, and the methods used for achieving a postpartum hemorrhagic condition vary widely. Here we critically evaluate the various animal models of PPH presented in the literature and propose additional and alternative methods for modeling PPH in in vivo studies. We highlight how current animal models successfully or unsuccessfully mimic the anatomy and physiology of a postpartum woman and how this may impact treatment development. We aim to equip researchers with the necessary background information to select appropriate animal models for their research related to PPH solutions, while supporting the goals of refinement, reduction and replacement (3Rs) in preclinical animal studies.

Developmental expression of catecholamine system in the human placenta and rat fetoplacental unit

Catecholamines norepinephrine and dopamine have been implicated in numerous physiological processes within the central nervous system. Emerging evidence has highlighted the importance of tightly regulated monoamine levels for placental functions and fetal development. However, the complexities of synthesis, release, and regulation of catecholamines in the fetoplacental unit have not been fully unraveled. In this study, we investigated the expression of enzymes and transporters involved in synthesis, degradation, and transport of norepinephrine and dopamine in the human placenta and rat fetoplacental unit. Quantitative PCR and Western blot analyses were performed in early-to-late gestation in humans (first trimester vs. term placenta) and mid-to-late gestation in rats (placenta and fetal brain, intestines, liver, lungs, and heart). In addition, we analyzed the gene expression patterns in isolated primary trophoblast cells from the human placenta and placenta-derived cell lines (HRP-1, BeWo, JEG-3). In both human and rat placentas, the study identifies the presence of only PNMT, COMT, and NET at the mRNA and protein levels, with the expression of PNMT and NET showing gestational age dependency. On the other hand, rat fetal tissues consistently express the catecholamine pathway genes, revealing distinct developmental expression patterns. Lastly, we report significant transcriptional profile variations in different placental cell models, emphasizing the importance of careful model selection for catecholamine metabolism/transport studies. Collectively, integrating findings from humans and rats enhances our understanding of the dynamic regulatory mechanisms that underlie catecholamine dynamics during pregnancy. We identified similar patterns in both species across gestation, suggesting conserved molecular mechanisms and potentially shedding light on shared biological processes influencing placental development.

Effects of paracetamol/acetaminophen on the expression of solute carriers (SLCs) in late-gestation fetal rat brain, choroid plexus and the placenta

Solute carriers (SLCs) regulate transfer of a wide range of molecules across cell membranes using facilitative or secondary active transport. In pregnancy, these transporters, expressed at the placental barrier, are important for delivery of nutrients to the fetus, whilst also limiting entry of potentially harmful substances, such as drugs. In the present study, RNA-sequencing analysis was used to investigate expression of SLCs in the fetal (embryonic day 19) rat brain, choroid plexus and placenta in untreated control animals and following maternal paracetamol treatment. In the treated group, paracetamol (15 mg/kg) was administered to dams twice daily for 5 days (from embryonic day 15 to 19). In untreated animals, overall expression of SLCs was highest in the placenta. In the paracetamol treatment group, expression of several SLCs was significantly different compared with control animals, with ion, amino acid, neurotransmitter and sugar transporters most affected. The number of SLC transcripts that changed significantly following treatment was the highest in the choroid plexus and lowest in the brain. All SLC transcripts that changed in the placenta following paracetamol treatment were downregulated. These results suggest that administration of paracetamol during pregnancy could potentially disrupt fetal nutrient homeostasis and affect brain development, resulting in major consequences for the neonate and extending into childhood.

Long-lasting developmental effects in rat offspring after maternal exposure to acetamiprid in the drinking water during gestation

Neonicotinoids (NNTs) are a class of insecticides proposed to be safe for pest control in urban, suburban, and agricultural applications. However, little is known about their developmental effects after repeated low-dose exposures during gestation. Here, we tested a dose considered subthreshold for maternal toxicity in rats (6 mg/kg/day) by assessing several morphological, biochemical, and neurobehavioral features in preterm fetuses and developing pups after maternal administration of the NTT acetamiprid (ACP) dissolved in the drinking water during gestational days (GD) 2-19. The exploratory evaluation included monitoring maternal body weight gain, fetal viability, body weight and sex ratio, cephalic length, neonatal body weight and sex ratio, metabolic enzymes in the placenta, maternal blood and fetal liver, and anogenital distance and surface righting response during infancy. We also used the circling training test to study the integrity of the associative-spatial-motor response in adolescence. Results showed no consistent findings indicating maternal, reproductive or developmental toxicity. However, we found ACP effects on maternal body weight gain, placental butyrylcholinesterase activity, and neurobehavioral responses, suggestive of a mild toxic action. Thus, our study showed a trend for developmental susceptibility at a dose so far considered subtoxic. Although the ACP concentration in environmental samples of surface water and groundwater has been mostly reported to be much lower than that used in our study, our results suggest that the ACP point of departure used in current guidelines aimed to prevent developmental effects may need to be verified by complementary sensitive multiple-endpoint testing in the offspring.

Oxytocin-induced birth causes sex-specific behavioral and brain connectivity changes in developing rat offspring

Despite six decades of the use of exogenous oxytocin for management of labor, little is known about its effects on the developing brain. Motivated by controversial reports suggesting a link between oxytocin use during labor and autism spectrum disorders (ASDs), we employed our recently validated rat model for labor induction with oxytocin to address this important concern. Using a combination of molecular biological, behavioral, and neuroimaging assays, we show that induced birth with oxytocin leads to sex-specific disruption of oxytocinergic signaling in the developing brain, decreased communicative ability of pups, reduced empathy-like behaviors especially in male offspring, and widespread sex-dependent changes in functional cortical connectivity. Contrary to our hypothesis, social behavior, typically impaired in ASDs, was largely preserved. Collectively, our foundational studies provide nuanced insights into the neurodevelopmental impact of birth induction with oxytocin and set the stage for mechanistic investigations in animal models and prospective longitudinal clinical studies.

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.

Evaluation of a microphysiological human placental barrier model for studying placental drug transfer

Understanding drug transport across the placental barrier is important for assessing the potential fetal drug toxicity and birth defect risks. Current in vivo and in vitro models have structural and functional limitations in evaluating placental drug transfer and toxicity. Microphysiological systems (MPSs) offer more accurate and relevant physiological models of human tissues and organs on a miniature scale for drug development and toxicology testing. MPSs for the placental barrier have been recently explored to study placental drug transfer. We utilized a multilayered hydrogel membrane-based microphysiological model composed of human placental epithelial and endothelial cells to replicate the key structure and function of the human placental barrier. A macroscale human placental barrier model was created using a transwell to compare the results with the microphysiological model. Placental barrier models were characterized by assessing monolayer formation, intercellular junctions, barrier permeability, and their structural integrity. Three small-molecule drugs (glyburide, rifaximin, and caffeine) that are prescribed or taken during pregnancy were studied for their placental transfer. The results showed that all three drugs crossed the placental barrier, with transfer rates in the following order: glyburide (molecular weight, MW = 494 Da) < rifaximin (MW = 785.9 Da) < caffeine (MW = 194.19 Da). Using non-compartmental analysis, we estimated human pharmacokinetic characteristics based on in vitro data from both MPS and transwell models. While further research is needed, our findings suggest that MPS holds potential as an in vitro tool for studying placental drug transfer and predicting fetal exposure, offering insights into pharmacokinetics.

An investigation of the distributions of ferroptosis and necroptosis mediators in the maternal-fetal interface at different days of rat pregnancy

Ferroptosis and necroptosis are recognized as playing major roles in the regulation of various physiological processes. However, the physiological role of the cell death mediated by these two pathways in the developmental process has not yet been clearly established. This study investigated ferroptosis and necroptosis signalling pathways in maternal-fetal tissue in the different gestational days (GD) of rat pregnancy using immunohistochemical and western blot methods in order to fill this gap. Twenty-four female Wistar albino rats were mated and divided into three groups. Maternal-fetal tissue samples were collected on GD 5, 12 and 19 of pregnancy. Expression and total protein levels of the markers glutathione peroxidase-4, soluble transporter family 7 member 11, transferrin receptor, receptor-interacting serine/threonine-protein kinase 1, receptor-interacting serine/threonine-protein kinase 3 and mixed lineage kinase domain-like protein were investigated on both the maternal and fetal surfaces of the placenta using immunohistochemical and western blot methods. The results showed varying levels of protein expression of both ferroptosis and necroptosis mediators in the GD 5, 12 and 19 of pregnancy. Immunohistochemical analyses revealed that these mediators were located on both the maternal (decidua and metrial gland) and fetal surfaces (labyrinth zone, yolk sac and basal zone) and that their expression levels changed in the different GD. The findings revealed the existence of important ferroptosis and necroptosis pathway mediators in rat maternal-fetal tissue. These results may provide a molecular framework for a better understanding of the communication between the placenta, decidua and fetus during the developmental process.

Histopathology of fused triplet placenta in rat

A fused triplet placenta was observed in a Wistar Hannover rat on gestation day 15. Each placenta (referred to as PL-A, PL-B, and PL-C) of this fused placenta was attached to one fetus each, but their fetal weights were lower than that of the fetus attached to the only normal placenta (referred to as PL-N) in this dam. Histopathologically, thinning of the trophoblastic septa and dilatation of the maternal sinusoid in the labyrinth zone were observed in PL-B and PL-C, but not in PL-A or PL-N. The points of placental fusion were at the junctional zone derived from each side of the placenta without connective tissues, and the septum was composed of trophoblastic giant cells. Although PL-A had a solitary metrial gland, PL-B and PL-C shared one metrial gland with one spiral artery terminus branching towards each labyrinth zone.

Effect of the Aqueous Extract of Chrysobalanus icaco Leaves on Maternal Reproductive Outcomes and Fetal Development in Wistar Rats

Toxicological studies on medicinal plants are essential to ensure their safety and effectiveness in treating various diseases. Despite the species Chrysobalanus icaco L. being popularly used in the treatment of several diseases due to the pharmacological properties of its bioactive compounds, there are few studies in the literature regarding its toxicity regarding reproduction. Therefore, the purpose of this study was to assess the potential embryotoxic and teratogenic effects of the aqueous extract of C. icaco leaves (AECi) on Wistar rats. Animals were given AECi at doses of 100, 200, and 400 mg/kg during the pre-implantation and organogenesis periods. Data were analyzed using ANOVA followed by Tukey's test and Kruskal-Wallis. Pregnant rats treated during the pre-implantation period showed no signs of reproductive toxicity. Rats that received AECi at 100, 200, and 400 mg/kg during organogenesis did not exhibit any signs of maternal systemic toxicity or significant differences in gestational and embryotoxic parameters. Some skeletal changes were observed in the treated groups. Therefore, it can be suggested that AECi at doses of 100, 200, and 400 mg/kg is safe for treated animals and does not induce reproductive toxicity under the experimental conditions applied, but it also caused low systemic toxicity.

Dietary Folic Acid Supplementation Attenuates Maternal High-Fat Diet-Induced Fetal Intrauterine Growth Retarded via Ameliorating Placental Inflammation and Oxidative Stress in Rats

The placenta is particularly susceptible to inflammation and oxidative stress, leading to placental vascular dysfunction and placental insufficiency, which is associated with fetal intrauterine growth restriction (IUGR). It is unknown whether folic acid (FA) supplementation can alleviate high-fat diet-induced IUGR in rats by improving placental function. In this study, pregnant rats were randomized into one of four diet-based groups: (1) control diet (CON), (2) control diet supplemented with FA, (3) high-fat diet (HFD), and (4) high-fat diet supplemented with FA (HFD + FA). Dams were sacrificed at gestation day 18.5 (GD18.5). The results indicated that dietary FA supplementation normalized a maternal HFD-induced decrease in fetal weight. The decrease in placental efficiency, labyrinth zone (LZ) area, blood sinusoid area, vascular density, and the levels of angiogenesis factors induced by a maternal HFD were alleviated by the addition of FA, suggesting that FA supplementation can alleviate placental vascular dysplasia. Furthermore, FA supplementation increased the protein expressions of SIRT1, inhibited NF-κB transcriptional activation, attenuated the levels of NF-κB/downstream pro-inflammatory cytokines, induced Nrf2 activation, and increased downstream target protein expression. In conclusion, we found that dietary FA supplementation during pregnancy could improve maternal HFD-induced IUGR by alleviating placental inflammation and oxidative stress, which may be associated with the regulation of SIRT1 and its mediated NF-κB and Nrf2 signaling pathways.

RISING STARS: Approaches to modeling placental function in preeclampsia in vitro and in vivo

Modeling preeclampsia remains difficult due to the nature of the disease and the unique characteristics of the human placenta. Members of the Hominidae superfamily have a villous hemochorial placenta that is different in structure from those of other therian mammals, including the mouse hemochorial placenta, making this common animal model less ideal for studying this disease. Human placental tissues delivered from pregnancies complicated by preeclampsia are excellent for assessing the damage the disease causes but cannot answer how or when the disease begins. Symptoms of preeclampsia manifest halfway through pregnancy or later, making it currently impossible to identify preeclampsia in human tissues obtained from an early stage of pregnancy. Many animal and cell culture models recapitulate various aspects of preeclampsia, though none can on its own completely capture the complexity of human preeclampsia. It is particularly difficult to uncover the cause of the disease using models in which the disease is induced in the lab. However, the many ways by which preeclampsia-like features can be induced in a variety of laboratory animals are consistent with the idea that preeclampsia is a two-stage disease, in which a variety of initial insults may lead to placental ischemia, and ultimately systemic symptoms. The recent development of stem cell-based models, organoids, and various coculture systems have brought in vitro systems with human cells ever closer to recapitulating in vivo events that lead to placental ischemia.

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.

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.

Effects of melamine and cyanuric acid on placental and fetal development in rats

Melamine or cyanuric acid alone has low toxicity, but combined exposure to melamine and cyanuric acid was reported to cause unexpected toxicological effects. This study investigated the potential effects and toxic mechanism of combined exposure to melamine and cyanuric acid on placental and fetal development in rats. Exposure to melamine and cyanuric acid caused maternal toxicity manifested by increased abnormal symptoms and decreased body weight gain. Developmental toxic effects included a decrease in placental and fetal weights with increased fetal deaths and post-implantation loss. Melamine and cyanuric acid induced oxidative stress in the developing placenta and fetus. The placentas from rats treated with melamine and cyanuric acid showed shortening of the placental layers with histological changes, decreased cell proliferation, increased apoptotic changes, and decreased insulin-like growth factor (IGF)/IGF-binding proteins (IGFBPs) and placental lactogen (PL) expression levels. Fetuses from melamine- and cyanuric acid-treated dams showed increased apoptotic changes and suppressed cellular proliferation in their livers and vertebrae. Consequently, combined exposure to melamine and cyanuric acid resulted in high levels of oxidative stress and impaired placental development associated with impairment of the IGF/IGFBP and PL systems, resulting in increased apoptotic changes and reduced fetal cell proliferation.

Placental adaptations supporting fetal growth during normal and adverse gestational environments

NEW FINDINGS

What is the topic of this review? How the placenta, which transports nutrients and oxygen to the fetus, may alter its support of fetal growth developmentally and with adverse gestational conditions. What advances does it highlight? Placental formation and function alter with the needs of the fetus for substrates for growth during normal gestation and when there is enhanced competition for substrates in species with multiple gestations or adverse gestational environments, and this is mediated by imprinted genes, signalling pathways, mitochondria and fetal sexomes.

ABSTRACT

The placenta is vital for mammalian development and a key determinant of life-long health. It is the interface between the mother and fetus and is responsible for transporting the nutrients and oxygen a fetus needs to develop and grow. Alterations in placental formation and function, therefore, have consequences for fetal growth and birthweight, which in turn determine perinatal survival and risk of non-communicable diseases for the offspring in later postnatal life. However, the placenta is not a static organ. As this review summarizes, research from multiple species has demonstrated that placental formation and function alter developmentally to the needs of the fetus for substrates for growth during normal gestation, as well as when there is greater competition for substrates in polytocous species and monotocous species with multiple gestations. The placenta also adapts in response to the gestational environment, integrating information about the ability of the mother to provide nutrients and oxygen with the needs of the fetus in that prevailing environment. In particular, placental structure (e.g. vascularity, surface area, blood flow, diffusion distance) and transport capacity (e.g. nutrient transporter levels and activity) respond to suboptimal gestational environments, namely malnutrition, obesity, hypoxia and maternal ageing. Mechanisms mediating developmentally and environmentally induced homeostatic responses of the placenta that help support normal fetal growth include imprinted genes, signalling pathways, subcellular constituents and fetal sexomes. Identification of these placental strategies may inform the development of therapies for complicated human pregnancies and advance understanding of the pathways underlying poor fetal outcomes and their consequences for health and disease risk.

A Systematic Review of the Placental Translocation of Micro- and Nanoplastics

PURPOSE OF REVIEW

Despite increasing awareness of the ubiquity of microplastics (MPs) in our environments, little is known about their risk of developmental toxicity. Even less is known about the environmental distribution and associated toxicity of nanoplastics (NPs). Here, we review the current literature on the capacity for MPs and NPs to be transported across the placental barrier and the potential to exert toxicity on the developing fetus.

RECENT FINDINGS

This review includes 11 research articles covering in vitro, in vivo, and ex vivo models, and observational studies. The current literature confirms the placental translocation of MPs and NPs, depending on physicochemical properties such as size, charge, and chemical modification as well as protein corona formation. Specific transport mechanisms for translocation remain unclear. There is emerging evidence of placental and fetal toxicity due to plastic particles based on animal and in vitro studies. Nine out of eleven studies examined in this review found that plastic particles were capable of placental translocation. In the future, more studies are needed to confirm and quantify the existence of MPs and NPs in human placentas. Additionally, translocation of different plastic particle types and heterogenous mixtures across the placenta, exposure at different periods of gestation, and associations with adverse birth and other developmental outcomes should also be investigated.

Ingested Polystyrene Nanospheres Translocate to Placenta and Fetal Tissues in Pregnant Rats: Potential Health Implications

Recent studies in experimental animals found that oral exposure to micro- and nano-plastics (MNPs) during pregnancy had multiple adverse effects on outcomes and progeny, although no study has yet identified the translocation of ingested MNPs to the placenta or fetal tissues, which might account for those effects. We therefore assessed the placental and fetal translocation of ingested nanoscale polystyrene MNPs in pregnant rats. Sprague Dawley rats (N = 5) were gavaged on gestational day 19 with 10 mL/kg of 250 µg/mL 25 nm carboxylated polystyrene spheres (PS25C) and sacrificed after 24 h. Hyperspectral imaging of harvested placental and fetal tissues identified abundant PS25C within the placenta and in all fetal tissues examined, including liver, kidney, heart, lung and brain, where they appeared in 10-25 µm clusters. These findings demonstrate that ingested nanoscale polystyrene MNPs can breach the intestinal barrier and subsequently the maternal-fetal barrier of the placenta to access the fetal circulation and all fetal tissues. Further studies are needed to assess the mechanisms of MNP translocation across the intestinal and placental barriers, the effects of MNP polymer, size and other physicochemical properties on translocation, as well as the potential adverse effects of MNP translocation on the developing fetus.

Imbalance of Angiogenic and Growth Factors in Placenta in Maternal Hyperhomocysteinemia

Numerous studies have shown that various adverse factors of different nature and action mechanisms have similar negative influence on placental angiogenesis, resulting in insufficiency of placental blood supply. One of the risk factors for pregnancy complications with placental etiology is an increased level of homocysteine in the blood of pregnant women. However, the effect of hyperhomocysteinemia (HHcy) on the development of the placenta and, in particular, on the formation of its vascular network is at present poorly understood. The aim of this work was to study the effect of maternal HHcy on the expression of angiogenic and growth factors (VEGF-A, MMP-2, VEGF-B, BDNF, NGF), as well as their receptors (VEGFR-2, TrkB, p75NTR), in the rat placenta. The effects of HHcy were studied in the morphologically and functionally different maternal and fetal parts of the placenta on the 14th and 20th day of pregnancy. The maternal HHcy caused increase in the levels of oxidative stress and apoptosis markers accompanied by an imbalance of the studied angiogenic and growth factors in the maternal and/or fetal part of the placenta. The influence of maternal HHcy in most cases manifested in a decrease in the protein content (VEGF-A), enzymatic activity (MMP-2), gene expression (VEGFB, NGF, TRKB), and accumulation of precursor form (proBDNF) of the investigated factors. In some cases, the effects of HHcy differed depending on the placental part and stage of development. The influence of maternal HHcy on signaling pathways and processes controlled by the studied angiogenic and growth factors could lead to incomplete development of the placental vasculature and decrease in the placental transport, resulting in fetal growth restriction and impaired fetal brain development.

Perfused rat term placenta as a preclinical model to investigate placental dopamine and norepinephrine transport

The placenta represents a non-neuronal organ capable of transporting and metabolizing monoamines. Since these bioactive molecules participate in numerous processes essential for placental and fetal physiology, any imbalance in their levels during pregnancy may affect brain development, projecting a higher risk of behavioral disorders in childhood or adulthood. Notably, the monoamine system in the placenta is a target of various psychoactive drugs and can be disrupted in several pregnancy pathologies. As research in pregnant women poses significant ethical restrictions, animal models are widely employed to study monoamine homeostasis as a mechanism involved in fetal programming. However, detailed knowledge of monoamine transport in the rat placenta is still lacking. Moreover, relatability to the human placental monoamine system is not examined. The present study provides insights into the transplacental monoamine dynamics between maternal and fetal circulation. We show that norepinephrine maternal-to-fetal transport is <4% due to high metabolism within the trophoblast. In contrast, dopamine maternal-to-fetal transport exceeds 25%, likely through passive transport across the membrane. In addition, we show high clearance of norepinephrine and dopamine from the fetal circulation mediated by the organic cation transporter 3 (OCT3). Altogether, we present transcriptional and functional evidence that the in situ rat placenta perfusion represents a suitable model for (patho)physiological investigation of dopamine and norepinephrine homeostasis in the fetoplacental unit. With the rapid advancements in drug discovery and environmental toxicity, the use of rat placenta as a preclinical model could facilitate screening of possible xenobiotic effects on monoamine homeostasis in the placenta.

SERPINA5 may promote the development of preeclampsia by disruption of the uPA/uPAR pathway

Preeclampsia (PE) is the leading cause of maternal and fetal morbidity or mortality but lacks reliable methods for early diagnosis. In a previous study, serum SERPINA5 levels were higher in women with PE before the clinical manifestation of the disease. This study aimed to evaluate the efficacy of SERPINA5 in predicting PE and investigate its role in trophoblast cell biology. A multicenter, 2-stage observational case-control study was performed to develop and validate an early predictive PE model based on SERPINA5, maternal characteristics, and inflammatory factors. To further understand the relationship between SERPINA5 and PE, SERPINA5 was overexpressed or knocked down in extravillous trophoblast cells (EVT) and a pregnant rat model. After development and initial validation, a model that combined SERPINA5 and inflammatory factors had a high predictive ability for PE before 20 weeks gestation with an AUC of 0.90 (95% CI 0.83-0.96). It also demonstrated that SERPINA5 inhibited primary EVT cell invasion by disrupting the urokinase-type plasminogen activator/urokinase-type plasminogen activator receptor (uPA/uPAR) pathway, in turn, is involved in the development of PE. In vivo experiments also proved that overexpression of SERPINA5 induced a PE-like syndrome (hypertension and proteinuria) in pregnant rats. Therefore, serum SERPINA5 is a promising early biomarker of PE, suggesting that it may be involved in placental development through its action on the uPA/uPAR system prior to the clinical manifestation of PE.

Maternal nutrient restriction and dietary melatonin alter neurotransmitter pathways in placental and fetal tissues

INTRODUCTION

Recent research indicates an important role in the placental fetal brain axis, with a paucity of information reported in large animals. Melatonin supplementation has been investigated as a potential therapeutic to negate fetal growth restriction. We hypothesized that maternal nutrient restriction and melatonin supplementation would alter neurotransmitter pathways in fetal blood, cotyledonary and hypothalamus tissue.

METHODS

On day 160 of gestation, Brangus heifers (n = 29 in fall study; n = 25 in summer study) were assigned to one of four treatments: adequately fed (ADQ-CON; 100% NRC recommendation), nutrient restricted (RES-CON; 60% NRC recommendation), and ADQ or RES supplemented with 20 mg/d of melatonin (ADQ-MEL; RES-MEL). Placentomes, fetal blood, and hypothalamic tissue were collected at day 240 of gestation. Neurotransmitters were analyzed in fetal blood and fetal and placental tissues. Transcript abundance of genes in the serotonin pathway and catecholamine pathway were determined in fetal hypothalamus and placental cotyledon.

RESULTS

Serotonin was increased (P < 0.05) by 12.5-fold in the blood of fetuses from RES dams versus ADQ in the fall study. Additionally, melatonin supplementation increased (P < 0.05) neurotransmitter metabolites and transcript abundance of the monoamine oxidase A (MAOA) enzyme in the cotyledon. In the summer study, plasma dopamine and placental dopamine receptors were decreased (P < 0.05) in RES dams versus ADQ.

DISCUSSION

In conclusion, these data indicate novel evidence of the presence of neurotransmitters and their synthesis and metabolism in the bovine conceptus, which could have greater implications in establishing postnatal behavior.

Maternal immune activation as an epidemiological risk factor for neurodevelopmental disorders: Considerations of timing, severity, individual differences, and sex in human and rodent studies

Epidemiological evidence suggests that one's risk of being diagnosed with a neurodevelopmental disorder (NDD)-such as autism, ADHD, or schizophrenia-increases significantly if their mother had a viral or bacterial infection during the first or second trimester of pregnancy. Despite this well-known data, little is known about how developing neural systems are perturbed by events such as early-life immune activation. One theory is that the maternal immune response disrupts neural processes important for typical fetal and postnatal development, which can subsequently result in specific and overlapping behavioral phenotypes in offspring, characteristic of NDDs. As such, rodent models of maternal immune activation (MIA) have been useful in elucidating neural mechanisms that may become dysregulated by MIA. This review will start with an up-to-date and in-depth, critical summary of epidemiological data in humans, examining the association between different types of MIA and NDD outcomes in offspring. Thereafter, we will summarize common rodent models of MIA and discuss their relevance to the human epidemiological data. Finally, we will highlight other factors that may interact with or impact MIA and its associated risk for NDDs, and emphasize the importance for researchers to consider these when designing future human and rodent studies. These points to consider include: the sex of the offspring, the developmental timing of the immune challenge, and other factors that may contribute to individual variability in neural and behavioral responses to MIA, such as genetics, parental age, the gut microbiome, prenatal stress, and placental buffering.

Maternal Dexamethasone Exposure Induces Sex-Specific Changes in Histomorphology and Redox Homeostasis of Rat Placenta

As the mediator between the mother and fetus, the placenta allows the most appropriate environment and optimal fetal growth. The placenta of one sex sometimes has a greater ability over the other to respond to and protect against possible maternal insults. Here, we characterized sex differences in the placenta’s morphological features and antioxidant status following dexamethasone (Dx) exposure. Pregnant rats were exposed to Dx or saline. The placenta was histologically and stereologically analyzed. The activity of the antioxidant enzymes, lipid peroxides (TBARS), superoxide anion and nitric oxide (NO) was measured. The decrease in placental zone volumes was more pronounced (p < 0.05) in female placentas. The volume density of PCNA-immunopositive nuclei was reduced (p < 0.05) in both sexes. The reduced (p < 0.05) antioxidant enzyme activities, enhanced TBARS and NO concentration indicate that Dx exposure triggered oxidative stress in the placenta of both fetal sexes, albeit stronger in the placenta of female fetuses. In conclusion, maternal Dx treatment reduced the size and volume of placental zones, altered placental histomorphology, decreased cell proliferation and triggered oxidative stress; however, the placentas of female fetuses exerted more significant responses to the treatment effects. The reduced placental size most probably reduced the transport of nutrients and oxygen, thus resulting in the reduced weight of fetuses, similar in both sexes. The lesser ability of the male placenta to detect and react to maternal exposure to environmental challenges may lead to long-standing health effects.

Congenital Rift Valley fever in Sprague Dawley rats is associated with diffuse infection and pathology of the placenta

Rift Valley fever (RVF) is a disease of animals and humans associated with abortions in ruminants and late-gestation miscarriages in women. Here, we use a rat model of congenital RVF to identify tropisms, pathologies, and immune responses in the placenta during vertical transmission. Infection of late-gestation pregnant rats resulted in vertical transmission to the placenta and widespread infection throughout the decidua, basal zone, and labyrinth zone. Some pups from infected dams appeared normal while others had gross signs of teratogenicity including death. Histopathological lesions were detected in placenta from pups regardless of teratogenicity, while teratogenic pups had widespread hemorrhage throughout multiple placenta layers. Teratogenic events were associated with significant increases in placental pro-inflammatory cytokines, type I interferons, and chemokines. RVFV displays a high degree of tropism for all placental tissue layers and the degree of hemorrhage and inflammatory mediator production is highest in placenta from pups with adverse outcomes. Given the potential for RVFV to emerge in new locations and the recent evidence of emerging viruses, like Zika and SARS-CoV-2, to undergo vertical transmission, this study provides essential understanding regarding the mechanisms by which RVFV crosses the placenta barrier.

Rift Valley fever virus (RVFV) infections cause human health and economical burdens given its ability to induce high rates of abortions in ruminants and possible contributions towards late-term miscarriages in women. In this study, we have identified important structures in the placenta targeted by this emerging bunyavirus. Inflammation was associated with more severe fetal outcomes such as death and fetal deformities. The striking similarities between the pathologies of the placenta in the rat model of congenital RVF and those observed in naturally infected ruminants highlight the utility of this rodent model. These findings may be further translated towards understanding the mechanisms involved in vertical transmission of RVFV in humans.

Selective modulation of placental and fetal MDR transporters by chronic in utero exposure to NRTIs in Sprague-Dawley rats: Importance for fetoprotection

Multidrug resistance (MDR) transporters present in placenta and fetal tissues reduce intracellular accumulation of their substrates. Consequently, induction of protein expression may further reduce toxic effects of specific xenobiotics. This work aimed to study whether sustained drug treatments in utero could modulate MDR transporters P-gp, BCRP, and MRP2 and thus impact their fetoprotective action. Pregnant Sprague-Dawley rats were daily treated by gavage with zidovudine (AZT, 60 mg/kg) or lamivudine (3TC, 30 mg/kg) from gestation day (GD) 11 to 20. On GD 21, DNA damage and MDR protein abundance were assessed by comet assay and western blotting, respectively. Moreover, a single IV dose of AZT or 3TC was administered on GD 21 and drug concentrations were measured in maternal blood and fetal liver by HPLC-UV. Chronic exposure to 3TC caused significantly higher DNA damage than AZT in fetal liver cells, whereas no differences were observed in maternal blood cells. Increased levels of BCRP protein were found in the placenta and fetal liver after AZT, but not 3TC, chronic in utero exposure. Contrarily, no modifications in the protein abundance of P-gp or MRP2 were found after sustained exposure to these drugs. The area under the curve of AZT in fetal liver was significantly lower in the AZT-pretreated rats than in the VEH or 3TC groups. Moreover, pre-administration of the BCRP inhibitor gefitinib (20 mg/kg, IP) increased AZT levels to the values observed in the VEH-treated group in this tissue. On the other hand, the disposition of 3TC in maternal blood or fetal liver was not modified after chronic treatment in either group. In conclusion, chronic exposure to AZT selectively induces BCRP expression in the placenta and fetal liver decreasing its own accumulation which may account for the lower DNA damage observed for AZT compared to 3TC in fetal liver cells.

Intrauterine Growth Restriction (IUGR) as a potential target for transamniotic stem cell therapy

BACKGROUND

We sought to determine whether intrauterine growth restriction (IUGR) could be a target for mesenchymal stem cell (MSC)-based transamniotic stem cell therapy (TRASCET).

METHODS

Pregnant dams subjected to hypoxia (10.5% O₂) cycles had their fetuses divided into four groups: untreated (n = 24) and three groups receiving volume-matched intra-amniotic injections of either saline (sham; n = 16), or suspensions of luciferase-labeled, syngeneic amniotic fluid-derived MSCs that were either native (TRASCET-unprimed; n = 29), or primed by exposure to IFNγ and IL-1β (TRASCET-primed; n = 31). Normal fetuses served as additional controls (n = 22). Multiple analyses were performed at term.

RESULTS

Compared to normal, fetal weights were significantly decreased in all hypoxia groups (p = 0.002 to <0.001), except for TRASCET-primed. Placental efficiency (fetal/placental weight) was significantly decreased in all hypoxia groups (p = 0.002 to <0.001), but normalized in both TRASCET groups. A significant increase in metrial expression of IFNγ in both the untreated and sham groups (p = 0.04 to 0.02) was reversed only in the TRASCET-primed group. Luciferase DNA was present in both TRASCET groups' placentas.

CONCLUSIONS

Transamniotic stem cell therapy with primed mesenchymal stem cells reverses some of the effects of intrauterine growth restriction in a rat model. Further study into this novel approach for the treatment of this disease is warranted.

LEVEL OF EVIDENCE

N/A (Animal and Laboratory Study).