The hemodynamic basis for positional- and inter-fetal dependent effects in dual arterial supply of mouse pregnancies

Maternal α-cypermethrin and permethrin exert differential effects on fetal growth, placental morphology, and fetal neurodevelopment in mice

Pyrethroid insecticides represent a broad class of chemicals used widely in agriculture and household applications. Human studies show mixed effects of maternal pyrethroid exposure on fetal growth and neurodevelopment. Assessment of shared pyrethroid metabolites as a biomarker for exposure obscures effects of specific chemicals within this broader class. To better characterize pyrethroid effects on fetal development, we investigated maternal exposure to permethrin, a type I pyrethroid, and α-cypermethrin, a type II pyrethroid, on fetal development in mice. Pregnant CD1 mice were exposed to permethrin (1.5, 15, or 50 mg/kg), α-cypermethrin (0.3, 3, or 10 mg/kg), or corn oil vehicle via oral gavage on gestational days (GDs) 6 to 16. Effects on fetal growth, placental toxicity, and neurodevelopment were evaluated at GD 16. Cypermethrin, but not permethrin, significantly reduced fetal growth and altered placental layer morphology. Placental RNAseq analysis revealed downregulation of genes involved in extracellular matrix remodeling in response to α-cypermethrin. Both pyrethroids induced shifts in fetal dorsal forebrain microglia morphology from ramified to ameboid states; however, the effects of α-cypermethrin were more pronounced. The α-cypermethrin transcriptome of fetal dorsal forebrain implicated altered glutamate receptor signaling, synaptogenesis, and c-AMP signaling. Coregulated gene modules in individual placenta and fetal dorsal forebrain pairs were correlated and overlapped in biological processes characterizing synapses, mitotic cell cycle, and chromatin organization, suggesting placenta-fetal brain shared mechanisms with α-cypermethrin exposure. In summary, maternal exposure to the type II pyrethroid α-cypermethrin, but not type I pyrethroid permethrin, significantly affected placental development, fetal growth, and neurodevelopment, and these effects were linked.

Aging-Associated Vacuolation of Multi-Ciliated Cells in the Distal Mouse Oviduct Reflects Unique Cell Identity and Luminal Microenvironment

The female reproductive organs present with the earliest aging characteristics, such as a decline in fertility and estrous cyclicity. While age-related changes in the ovary are well documented, it is unclear if any age-associated changes occur in the other female reproductive organs, such as the oviduct/Fallopian tube. At the distal end of aged oviducts in mice, we found vacuolated multi-ciliated cells (MCCs) with a severely apically displaced and deformed nucleus. This phenotype was unique to the distal oviduct epithelium-the infundibulum (INF) and ampulla (AMP). Ovariectomy did not affect the timeline of MCC vacuolation, suggesting little involvement of ovulation and hormonal regulation. MCC vacuolation was induced in hypoxia or hydroxyurea treatments in in vitro organotypic culture of all oviduct regions, not limited to the INF/AMP epithelium. This suggests a high oxygen demand in MCCs, compared to other cell types, and a uniquely stressed INF/AMP epithelial microenvironment in vivo. We found that the blood circulation of INF/AMP depended on the ovarian artery, different from the rest of the oviduct epithelium, and its circulation declined along with ovarian activities. We conclude that a decline in local blood circulation and distinct cellular identity of the INF/AMP epithelium caused age-associated MCC vacuolation, reflecting its mild, chronically stressed microenvironment.

Maternal α-cypermethrin and permethrin exert differential effects on fetal growth, placental morphology, and fetal neurodevelopment in mice

Pyrethroid insecticides represent a broad class of chemicals used widely in agriculture and household applications. Human studies show mixed effects of maternal pyrethroid exposure on fetal growth and neurodevelopment. Assessment of shared pyrethroid metabolites as a biomarker for exposure obscures effects of specific chemicals within this broader class. To better characterize pyrethroid effects on fetal development, we investigated maternal exposure to permethrin, a type I pyrethroid, and α-cypermethrin, a type II pyrethroid, on fetal development in mice. Pregnant CD1 mice were exposed to permethrin (1.5, 15, or 50 mg/kg), α-cypermethrin (0.3, 3, or 10 mg/kg), or corn oil vehicle via oral gavage on gestational days (GD) 6-16. Effects on fetal growth, placental toxicity, and neurodevelopment were evaluated at GD 16. Cypermethrin, but not permethrin, significantly reduced fetal growth and altered placental layer morphology. Placental RNAseq analysis revealed downregulation of genes involved in extracellular matrix remodeling in response to α-cypermethrin. Both pyrethroids induced shifts in fetal dorsal forebrain microglia morphology from ramified to ameboid states; however, effects of α-cypermethrin were more pronounced. The α-cypermethrin transcriptome of fetal dorsal forebrain implicated altered glutamate receptor signaling, synaptogenesis, and c-AMP signaling. Coregulated gene modules in individual placenta and fetal dorsal forebrain pairs were correlated and overlapped in biological processes characterizing synapses, mitotic cell cycle, and chromatin organization, suggesting placenta-fetal brain shared mechanisms with α-cypermethrin exposure. In summary, maternal type II pyrethroid α-cypermethrin exposure but not type I pyrethroid permethrin significantly affected placental development, fetal growth, and neurodevelopment, and these effects were linked.

Placenta-tropic VEGF mRNA lipid nanoparticles ameliorate murine pre-eclampsia

Pre-eclampsia is a placental disorder that affects 3-5% of all pregnancies and is a leading cause of maternal and fetal morbidity worldwide1,2. With no drug available to slow disease progression, engineering ionizable lipid nanoparticles (LNPs) for extrahepatic messenger RNA (mRNA) delivery to the placenta is an attractive therapeutic option for pre-eclampsia. Here we use high-throughput screening to evaluate a library of 98 LNP formulations in vivo and identify a placenta-tropic LNP (LNP 55) that mediates more than 100-fold greater mRNA delivery to the placenta in pregnant mice than a formulation based on the Food and Drug Administration-approved Onpattro LNP (DLin-MC3-DMA)3. We propose an endogenous targeting mechanism based on β2-glycoprotein I adsorption that enables LNP delivery to the placenta. In both inflammation- and hypoxia-induced models of pre-eclampsia, a single administration of LNP 55 encapsulating vascular endothelial growth factor (VEGF) mRNA resolves maternal hypertension until the end of gestation. In addition, with our VEGF mRNA LNP 55 therapeutic, we demonstrate improvements in fetal health and partially restore placental vasculature, the local and systemic immune landscape and serum levels of soluble Fms-like tyrosine kinase-1, a clinical biomarker of pre-eclampsia1. Together, these results demonstrate the potential of this mRNA LNP platform for treating placental disorders such as pre-eclampsia.

Modeling normal mouse uterine contraction and placental perfusion with non-invasive longitudinal dynamic contrast enhancement MRI

BACKGROUND

The placenta is a transient organ critical for fetal development. Disruptions of normal placental functions can impact health throughout an individual's entire life. Although being recognized by the NIH Human Placenta Project as an important organ, the placenta remains understudied, partly because of a lack of non-invasive tools for longitudinally evaluation for key aspects of placental functionalities.

OBJECTIVE

Our goal is to create a non-invasive preclinical imaging pipeline that can longitudinally probe murine placental health in vivo. We use advanced imaging processing schemes to establish functional biomarkers for non-invasive longitudinal evaluation of placental development.

METHODOLOGY

We implement dynamic contrast enhancement magnetic resonance imaging (DCE-MRI) and analysis pipeline to quantify uterine contraction and placental perfusion dynamics. We use optic flow and time-frequency analysis to quantify and characterize contraction-related placental motion. Our novel imaging and analysis pipeline uses subcutaneous administration of gadolinium for steepest slope-based perfusion evaluation, enabling non-invasive longitudinal monitoring.

RESULTS

We demonstrate that the placenta exhibits spatially asymmetric contractile motion that develops from E14.5 to E17.5. Additionally, we see that placental perfusion, perfusion delivery rate, and substrate delivery all increase from E14.5 to E17.5, with the High Perfusion Chamber (HPC) leading the placental changes that occur from E14.5 to E17.5.

DISCUSSION

We advance the placental perfusion chamber paradigm with a novel, physiologically based threshold model for chamber localization and demonstrate spatially varying placental chambers using multiple functional metrics that assess mouse placental development and remodeling throughout gestation.

CONCLUSION

Our pipeline enables the non-invasive, longitudinal assessment of multiple placenta functions from a single imaging session. Our pipeline serves as a key toolbox for advancing research in mouse models of placental disease and disorder.

Modeling Normal Mouse Uterine Contraction and Placental Perfusion with Non-invasive Longitudinal Dynamic Contrast Enhancement MRI

The placenta is a transient organ critical for fetal development. Disruptions of normal placental functions can impact health throughout an individual's entire life. Although being recognized by the NIH Human Placenta Project as an important organ, the placenta remains understudied, partly because of a lack of non-invasive tools for longitudinally evaluation for key aspects of placental functionalities. Non-invasive imaging that can longitudinally probe murine placental health in vivo are critical to understanding placental development throughout pregnancy. We developed advanced imaging processing schemes to establish functional biomarkers for non-invasive longitudinal evaluation of placental development. We developed a dynamic contrast enhancement magnetic resonance imaging (DCE-MRI) pipeline combined with advanced image process methods to model uterine contraction and placental perfusion dynamics. Our novel imaging pipeline uses subcutaneous administration of gadolinium for steepest-slope based perfusion evaluation. This enables non-invasive longitudinal monitoring. Additionally, we advance the placental perfusion chamber paradigm with a novel physiologically-based threshold model for chamber localization and demonstrate spatially varying placental chambers using multiple functional metrics that assess mouse placental development and continuing remodeling throughout gestation. Lastly, using optic flow to quantify placental motions arisen from uterine contractions in conjunction with time-frequency analysis, we demonstrated that the placenta exhibited asymmetric contractile motion.

Maternal chronic caffeine intake impairs fertility, placental vascularization and fetal development in mice

Caffeine is commonly consumed by pregnant women to avoid fatigue or as a habit. However, it is not clearly determined its side effects to the conceptuses. This study evaluated placental morphofunctional alterations after maternal chronic caffeine intake and the effects on fetal growth. Female Swiss mice received, via gavage, caffeine doses (either 60, 120 or 240 mg/kg/day) seven days before mating until gestational days-(GD) 11.5 or 17.5. Fetal biometrical parameters were assessed, and placentae were either submitted to histomorphometrical or molecular evaluation of angiogenesis (placental growth factor-1[PlGF-1]), apoptosis (Caspase-3) and proliferation (Ki-67) markers (evaluated in Swiss dams) and to intravital microscopy (evaluated in C57BL/6 dams). Caffeine exposed fetuses exhibited intrauterine growth restriction in a sex-dependent manner, with greater commitment of female fetuses (P < 0.05). In addition, placentae from dams that received 120 mg/kg/day showed less irrigation by maternal blood and greater development of fetal vasculature, characterized by higher number of larger vessels (P < 0.05). Although no effects on apoptosis (Caspase-3) and angiogenesis (PlGF-1) were observed, dams treated with 60 mg/kg/day showed greater placental cell proliferation (Ki-67 staining) at GD 11.5 (P < 0.05). The group treated with 240 mg/kg/day exhibited only one pregnant dam for each gestational age, suggesting that this high caffeine consumption may compromise fertility. Taken together, even in the doses currently ingested by many pregnant women, caffeine has detrimental effects on placental vasculature and fetal development in mice. Therefore, our results strongly suggest that caffeine consumption in human pregnancies greater than the recommended doses should be avoided.

Establishment of a murine model of congenital toxoplasmosis and validation of a qPCR assay to assess the parasite load in maternal and fetal tissues

Toxoplasma gondii is the causative agent of toxoplasmosis, a disease that affects warm-blooded animals and one third of the human population worldwide. Pregnant women who have never been exposed to the parasite constitute an important risk group, as infection during pregnancy often leads to congenital toxoplasmosis, the most severe form of the disease. Current therapy for toxoplasmosis is the same as it was 50 years ago and has little or no effect when vertical transmission occurs. Therefore, it is urgent to develop new strategies to prevent mother-to-fetus transmission. The implementation of experimental animal models of congenital toxoplasmosis that reproduces the transmission rates and clinical signs in humans opens an avenue of possibilities to interfere in the progression of the disease. In addition, knowing the parasite load in maternal and fetal tissues after infection, which may be related to organ abnormalities and disease outcome, is another important step in designing a promising intervention strategy. Therefore, we implemented here a murine model of congenital toxoplasmosis with outbred Swiss Webster mice infected intravenously with tachyzoites of the ME49 strain of T. gondii that mimics the frequency of transmission of the parasite, as well as important clinical signs of human congenital toxoplasmosis, such as macrocephaly, in addition to providing a highly sensitive quantitative real-time PCR assay to assess parasite load in mouse tissues. As the disease is not restricted to humans, also affecting several domestic animals, including companion animals and livestock, they can also benefit from the model presented in this study.

Gold nanoparticle biodistribution in pregnant mice following intravenous administration varies with gestational age

The use of nanoparticles (NPs) to deliver therapeutics to reproductive organs is an emerging approach to safely and effectively treat mothers and babies facing pregnancy complications. This study investigates the biodistribution of two different sized gold-based NPs in pregnant mice following systemic delivery as a function of gestational age. Poly(ethylene glycol)-coated 15 nm gold nanoparticles or 150 nm diameter silica core/gold nanoshells were intravenously administered to pregnant mice at gestational days (E)9.5 or 14.5. NP distribution was analyzed twenty-four hours later by inductively coupled plasma-mass spectrometry and silver staining of histological specimens. More NPs accumulated in placentas than embryos and delivery to these tissues was greater at E9.5 than E14.5. Neither NP type affected fetal weight or placental weight, indicating minimal short-term toxicity in early to mid-stage pregnancy. These findings warrant continued development of NPs as tools to deliver therapeutics to reproductive tissues safely.

Uterine Vascular Control Preconception and During Pregnancy

Successful pregnancy and reproduction are dependent on adequate uterine blood flow, placental perfusion, and vascular responsivity to fetal demands. The ability to support pregnancy centers on systemic adaptation and endometrial preparation through decidualization, embryonic implantation, trophoblast invasion, arterial/arteriolar reactivity, and vascular remodeling. These adaptations occur through responsiveness to endocrine signaling and local uteroplacental mediators. The purpose of this article is to highlight the current knowledge associated with vascular remodeling and responsivity during uterine preparation for and during pregnancy. We focus on maternal cardiovascular systemic and uterine modifications, endometrial decidualization, implantation and invasion, uterine and spiral artery remodeling, local uterine regulatory mechanisms, placentation, and pathological consequences of vascular dysfunction during pregnancy. © 2021 American Physiological Society. Compr Physiol 11:1-23, 2021.

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.

A descriptive angiographic study of the uterine arteries during pregnancy, the postpartum period and CEH/pyometra in bitches

The aim of this descriptive study was to monitor the changes in uterine arteries during pregnancy, postpartum period and pyometra in bitches using angiography. Fifteen uteri of mixed breed bitches on days 24, 30, 33, 40, 43, 47, 50 and 56 of pregnancy and weeks 1, 2, 3, 4 and 7-8 of postpartum and two CEH/pyometra bitches were examined after ovariohysterectomy. The results showed that with the onset of normal pregnancy and in about 30 ± 1 days of gestation, anastomoses begin to form between the left and right middle uterine arteries, developing during the next days and continuing until 4 weeks postpartum. On 4th week after parturition, when physiologic changes occur and the uterus returns to non-pregnant conditions, these anastomoses begin to degenerate, and they completely disappear approximately on the 7th-8th week after parturition. Similarly, in CEH/pyometra bitches, anastomoses were formed between left and right median uterine arteries. These findings can be considered as a part of the physiological changes of the uterus and its vessels during pregnancy and postpartum periods and could affect the results and interpretation of relevant findings.

Regulation of maternal-fetal metabolic communication

Pregnancy may be the most nutritionally sensitive stage in the life cycle, and improved metabolic health during gestation and early postnatal life can reduce the risk of chronic disease in adulthood. Successful pregnancy requires coordinated metabolic, hormonal, and immunological communication. In this review, maternal-fetal metabolic communication is defined as the bidirectional communication of nutritional status and metabolic demand by various modes including circulating metabolites, endocrine molecules, and other secreted factors. Emphasis is placed on metabolites as a means of maternal-fetal communication by synthesizing findings from studies in humans, non-human primates, domestic animals, rabbits, and rodents. In this review, fetal, placental, and maternal metabolic adaptations are discussed in turn. (1) Fetal macronutrient needs are summarized in terms of the physiological adaptations in place to ensure their proper allocation. (2) Placental metabolite transport and maternal physiological adaptations during gestation, including changes in energy budget, are also discussed. (3) Maternal nutrient limitation and metabolic disorders of pregnancy serve as case studies of the dynamic nature of maternal-fetal metabolic communication. The review concludes with a summary of recent research efforts to identify metabolites, endocrine molecules, and other secreted factors that mediate this communication, with particular emphasis on serum/plasma metabolomics in humans, non-human primates, and rodents. A better understanding of maternal-fetal metabolic communication in health and disease may reveal novel biomarkers and therapeutic targets for metabolic disorders of pregnancy.

Murine transcription factor Math6 is a regulator of placenta development

The murine basic helix-loop-helix transcription (bHLH) factor mouse atonal homolog 6 (Math6) is expressed in numerous organs and supposed to be involved in several developmental processes. However, so far neither all aspects nor the molecular mechanisms of Math6 function have been explored exhaustively. To analyze the in vivo function of Math6 in detail, we generated a constitutive knockout (KO) mouse (Math6^−/−) and performed an initial histological and molecular biological investigation of its main phenotype. Pregnant Math6^−/− females suffer from a disturbed early placental development leading to the death of the majority of embryos independent of the embryonic Math6 genotype. A few placentas and fetuses survive the severe uterine hemorrhagic events at late mid-gestation (E13.5) and subsequently develop regularly. However, these fetuses could not be born due to obstructions within the gravid uterus, which hinder the birth process. Characterization of the endogenous spatiotemporal Math6 expression during placenta development reveals that Math6 is essential for an ordered decidualization and an important regulator of the maternal-fetal endocrine crosstalk regulating endometrial trophoblast invasion and differentiation. The strongly disturbed vascularization observed in the maternal placenta appears as an additional consequence of the altered endocrine status and as the main cause for the general hemorrhagic crisis.

Venoarterial communication mediates arterial wall shear stress-induced maternal uterine vascular remodeling during pregnancy

Although expansive remodeling of the maternal uterine circulation during pregnancy is essential for maintaining uteroplacental perfusion and normal fetal growth, the underlying physiological mechanisms are not well understood. Using a rat model, surgical approaches were used to alter uterine hemodynamics and wall shear stress (WSS) to evaluate the effects of WSS and venoarterial communication (e.g., transfer of placentally derived growth signals from postplacental veins to preplacental arteries) on gestational uterine vascular remodeling. Changes in WSS secondary to ligation of the cervical but not the ovarian end of the main uterine artery and vein provoked significant expansive remodeling at the opposite end of both vessels, but only in pregnant animals. The ≈50% increase in lumen diameter (relative to the contralateral horn) was associated with an upregulation of total endothelial nitric oxide (NO) synthase expression and was abolished by in vivo NO synthase inhibition with N-nitro-l-arginine methyl ester. Complete removal of a venous segment adjacent to the uterine artery to eliminate local venous influences significantly attenuated the WSS-induced remodeling by about one-half ( P < 0.05). These findings indicate that, during pregnancy, 1) increased WSS stimulates uterine artery growth via NO signaling and 2) the presence of an adjacent vein is required for arterial remodeling to fully occur. NEW & NOTEWORTHY This study provides the first in vivo evidence for the importance of venous influences on arterial growth within the uteroplacental circulation.

Antenatal pomegranate juice rescues hypoxia-induced fetal growth restriction in pregnant mice while reducing placental cell stress and apoptosis

INTRODUCTION

There is a need for prophylaxis to reduce placental-associated intrauterine growth restriction (IUGR). Pomegranate juice (PJ) is replete with phytochemicals having biological effects at non-pharmacological concentrations. We test the hypothesis that exposure of pregnant mice to hypoxia late in gestation induces cellular stress in the placenta, which can be ameliorated by antecedent maternal consumption of PJ.

MATERIALS AND METHODS

We exposed pregnant mice to 12% or 21% oxygen, with food ad libitum or restricted, and with consumption of PJ or glucose between 12.5 and 18.5 days post conception (dpc). We examined the outcomes of the nine groups (n = 10) at 18.5 dpc, quantifying fetal and placental weights and placental labyrinthine and junctional zone depths and areas. We assayed cellular stress by expression of Hsp90 and apoptosis by TUNEL staining and expression of cleaved caspase 3.

RESULTS

Maternal exposure to 12% oxygen or food restriction in 21% oxygen, induced IUGR, compared to control. The labyrinth to junctional zone ratio was lower in hypoxic ad libitum, compared to normoxic food-restricted, placentas. Antenatal PJ prior to and during hypoxic exposure significantly improved fetal growth, reduced Hsp90 expression, and limited apoptosis in the labyrinth, while enhancing junctional zone apoptosis.

DISCUSSION

Maternal exposure to hypoxia induces IUGR, cell stress, and apoptosis in mouse placentas. The labyrinth and junctional zone of the mouse placenta are differentially sensitive to FiO₂ and to PJ. PJ offers benefits in the prophylaxis of IUGR in the mouse, but PJ effects on the junctional zone require further study.

Hypothalamic miR-219 regulates individual metabolic differences in response to diet-induced weight cycling

Consumption of a low calorie diet is the most common approach to lose weight. While generally effective at first, it is frequently followed by a relapse where the pre-diet weight is regained, and often exceeded. This pattern of repeated weight loss/regain is referred to as weight cycling and the resulting metabolic response varies greatly between individuals.

Objective

We attempted to address the issue of individual differences in the response to weight cycling in male mice.

Methods

We first exposed adult wild type mice to repeated cycles of high/low fat food. Next, using a lentiviral approach, we knocked-down or over-expressed miR-219 in the ventromedial hypothalamus (VMH) of an additional mouse cohort and performed a full metabolic assessment.

Results

Exposure of wild type males to weight cycling resulted in the division of the cohort into subsets of resistant versus metabolic-syndrome-prone (MS) animals, which differed in their metabolic profile and hypothalamic miR-219 levels. Lentiviral knock-down of miR-219 in the VMH led to exacerbation of metabolic syndrome. In contrast, over-expression of miR-219 resulted in moderation of the metabolic syndrome phenotype.

Conclusions

Our results suggest a role for miR-219 in the mediation of the metabolic phenotype resulting from repeated weight cycling.

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Repeated cycles of high fat diet induce different responses in adult males.

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Low miR-219 in ventromedial hypothalamus are linked to metabolic-syndrome proneness.

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Lentiviral knockdown of miR-219 induces metabolic-syndrome-prone phenotype.

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Lentiviral overexpression of miR-219 provides moderate protection from metabolic-syndrome.

Survival and growth of C57BL/6J mice lacking the BK channel, Kcnma1: lower adult body weight occurs together with higher body fat

Big conductance potassium (BK) channels contribute to K⁺ flow and electrical behavior in many cell types. Mice made null for the gene (Kcnma1) producing the BK channel (BK^KO) exhibit numerous deficits in physiological functions. Breeding mice lacking a single allele of Kcnma1 (C57BL/6J background) had litter sizes of approximately eight pups. For the period of maternal care (P0–P21), pup deaths peaked at P1 with a second less severe interval of death peaking near P13. Early deaths were twice as likely during a 20‐month period of building construction compared with the quiescent period after cessation of construction. Births during construction were not consistent with Mendelian predictions indicating the likelihood of a specific disadvantage induced by this environmental stressor. Later BK^KO pup deaths (~P13) also were more numerous than Mendelian expectations. After weaning, weight gain was slower for BK^KO mice compared with wild‐type littermates: 5 g less for male BK^KO mice and 4 g less for female BK^KO mice. Body composition determined by quantitative magnetic resonance indicated a higher fat proportion for wild‐type female mice compared with males, as well as a higher hydration ratio. Both male and female BK^KO mice showed higher fat proportions than wild‐type, with female BK^KO mice exhibiting greater variation. Together, these results indicate that BK^KO mice suffered disadvantages that lead to prenatal and perinatal death. A metabolic difference likely related to glucose handling led to the smaller body size and distinct composition for BK^KO mice, suggesting a diversion of energy supplies from growth to fat storage.

Functional MRI of the placenta--From rodents to humans

The placenta performs a wide range of physiological functions; insufficiencies in these functions may result in a variety of severe prenatal and postnatal syndromes with long-term negative impacts on human adult health. Recent advances in magnetic resonance imaging (MRI) studies of placental function, in both animal models and humans, have contributed significantly to our understanding of placental structure, blood flow, oxygenation status, and metabolic profile, and have provided important insights into pregnancy complications.

Maternal uterine vascular remodeling during pregnancy

Remodeling of the maternal uterine vasculature during pregnancy is a unique cardiovascular process that occurs in the adult and results in significant structural and functional changes in large and small arteries and veins, and in the creation of the placenta--a new fetomaternal vascular organ. This expansive, hypertrophic process results in increases in both lumen circumference and length, and is effected through a combination of tissue and cellular hypertrophy, endothelial and vascular smooth muscle hyperplasia, and matrix remodeling. This review summarizes what is currently known about the time course and extent of the remodeling process, and how local vs. systemic factors influence its genesis. The main focus is on upstream maternal vessels rather than spiral artery changes, although the latter are considered from the overall hemodynamic perspective. We also consider some of the underlying mechanisms and provide a hypothetical scenario that integrates our current knowledge. Abrogation of this adaptive vascular process is associated with several human gestational pathologies such as preeclampsia and intrauterine growth restriction (IUGR), which not only raise the risk of infant mortality and morbidity but are also a significant source of maternal mortality and susceptibility to cardiovascular and other diseases for both mother and neonate later in life.

Leukocyte driven-decidual angiogenesis in early pregnancy

Successful pregnancy and long-term, post-natal maternal and offspring cardiac, vascular and metabolic health require key maternal cardiovascular adaptations over gestation. Within the pregnant decidualizing uterus, coordinated vascular, immunological and stromal cell changes occur. Considerable attention has been given to the roles of uterine natural killer (uNK) cells in initiating decidual spiral arterial remodeling, a process normally completed by mid-gestation in mice and in humans. However, leukocyte roles in much earlier, region specific, decidual vascular remodeling are now being defined. Interest in immune cell-promoted vascular remodeling is driven by vascular aberrations that are reported in human gestational complications such as infertility, recurrent spontaneous abortion, preeclampsia (PE) and fetal growth restriction. Appropriate maternal cardiovascular responses during pregnancy protect mothers and their children from later cardiovascular disease risk elevation. One of the earliest uterine responses to pregnancy in species with hemochorial placentation is stromal cell decidualization, which creates unique niches for angiogenesis and leukocyte recruitment. In early decidua basalis, the aspect of the implantation site that will cradle the developing placenta and provide the major blood vessels to support mature placental functions, leukocytes are greatly enriched and display specialized properties. UNK cells, the most abundant leukocyte subset in early decidua basalis, have angiogenic abilities and are essential for normal early decidual angiogenesis. The regulation of uNK cells and their roles in determining maternal and progeny cardiovascular health over pregnancy and postpartum are discussed.

Quantitative T2 changes and susceptibility-weighted magnetic resonance imaging in murine pregnancy

OBJECTIVE

To evaluate gestational age-dependent changes in the T2 relaxation time in normal murine placentas in vivo. The role of susceptibility-weighted imaging (SWI) in visualization of the murine fetal anatomy was also elucidated.

METHODS

Timed-pregnant CD-1 mice at gestational day (GD) 12 and GD17 underwent magnetic resonance imaging. Multi-echo spin echo and SWI data were acquired. The placental T2 values on GD12 and GD17 were quantified. To account for the influence of systemic maternal physiological factors on placental perfusion, maternal muscle was used as a reference for T2 normalization. A linear mixed-effects model was used to fit the normalized T2 values, and the significance of the coefficients was tested. Fetal SWI images were processed and reviewed for venous vasculature and skeletal structures.

RESULTS

The average placental T2 value decreased significantly on GD17 (40.17 ± 4.10 ms) compared to the value on GD12 (55.78 ± 8.13 ms). The difference in normalized T2 values also remained significant (p = 0.001). Using SWI, major fetal venous structures like the cardinal vein, the subcardinal vein, and the portal vein were visualized on GD12. In addition, fetal skeletal structures could also be discerned on GD17.

CONCLUSION

The T2 value of a normal murine placenta decreases with advancing gestation. SWI provided clear visualization of the fetal venous vasculature and bony structures. © 2014 S. Karger AG, Basel.