Uteroplacental insufficiency lowers the threshold towards hypoxia-induced cerebral apoptosis in growth-retarded fetal rats

Magnesium sulfate and risk of hypoxic-ischemic encephalopathy in a high-risk cohort

BACKGROUND

Hypoxic-ischemic encephalopathy contributes to morbidity and mortality among neonates ≥36 weeks of gestation. Evidence of preventative antenatal treatment is limited. Magnesium sulfate has neuroprotective properties among preterm fetuses. Hypertensive disorders of pregnancy are a risk factor for hypoxic-ischemic encephalopathy, and magnesium sulfate is recommended for maternal seizure prophylaxis among patients with preeclampsia with severe features.

OBJECTIVE

(1) Determine trends in the incidence of hypertensive disorders of pregnancy, antenatal magnesium sulfate, and hypoxic-ischemic encephalopathy; (2) evaluate the association between hypertensive disorders of pregnancy and hypoxic-ischemic encephalopathy; and (3) evaluate if, among patients with hypertensive disorders of pregnancy, the odds of hypoxic-ischemic encephalopathy is mitigated by receipt of antenatal magnesium sulfate.

STUDY DESIGN

We analyzed a prospective cohort of live births ≥36 weeks of gestation between 2012 and 2018 within the California Perinatal Quality Care Collaborative registry, linked with the California Department of Health Care Access and Information files. We used Cochran-Armitage tests to assess trends in hypertensive disorders, encephalopathy diagnoses, and magnesium sulfate utilization and compared demographic factors between patients with or without hypertensive disorders of pregnancy or treatment with magnesium sulfate. Hierarchical logistic regression models were built to explore if hypertensive disorders of pregnancy were associated with any severity and moderate/severe hypoxic-ischemic encephalopathy. Separate hierarchical logistic regression models were built among those with hypertensive disorders of pregnancy to evaluate the association of magnesium sulfate with hypoxic-ischemic encephalopathy.

RESULTS

Among 44,314 unique infants, the diagnosis of hypoxic-ischemic encephalopathy, maternal hypertensive disorders of pregnancy, and the use of magnesium sulfate increased over time. Compared with patients with hypertensive disorders of pregnancy alone, patients with hypertensive disorders treated with magnesium sulfate represented a high-risk population. They were more likely to be publicly insured, born between 36 and 38 weeks of gestation, be small for gestational age, have lower Apgar scores, require a higher level of resuscitation at delivery, have prolonged rupture of membranes, experience preterm labor and fetal distress, and undergo operative delivery (all P<.002). Hypertensive disorders of pregnancy were associated with hypoxic-ischemic encephalopathy (adjusted odds ratio, 1.26 [95% confidence interval, 1.13-1.40]; P<.001) and specifically moderate/severe hypoxic-ischemic encephalopathy (adjusted odds ratio, 1.26 [95% confidence interval, 1.11-1.42]; P<.001). Among patients with hypertensive disorders of pregnancy, treatment with magnesium sulfate was associated with 29% reduction in the odds of neonatal hypoxic-ischemic encephalopathy (adjusted odds ratio, 0.71 [95% confidence interval, 0.52-0.97]; P=.03) and a 37% reduction in the odds of moderate/severe neonatal hypoxic-ischemic encephalopathy (adjusted odds ratio, 0.63 [95% confidence interval, 0.42-0.94]; P=.03).

CONCLUSION

Hypertensive disorders of pregnancy are associated with hypoxic-ischemic encephalopathy and, specifically, moderate/severe disease. Among people with hypertensive disorders, receipt of antenatal magnesium sulfate is associated with a significant reduction in the odds of hypoxic-ischemic encephalopathy and moderate/severe disease in a neonatal cohort admitted to neonatal intensive care unit at ≥36 weeks of gestation. The findings of this observational study cannot prove causality and are intended to generate hypotheses for future clinical trials on magnesium sulfate in term infants.

Ethanol Impairs NRF2/Antioxidant and Growth Signaling in the Intact Placenta In Vivo and in Human Trophoblasts

NRF2 is a redox-sensitive transcription factor that depending on the duration or magnitude of the stress, either translocates to the nucleus (beneficial) or is degraded in the cytosol (harmful). However, the role of NRF2-based mechanism(s) under ethanol (E)-induced developmental toxicity in the placental context remains unknown. Here, we used a rat prenatal model of maternal alcohol stress consisting of intermittent ethanol vapor (IEV) daily from GD11 to GD20 with a 6 h ON/18 h OFF in a vapor chamber and in vitro placental model consisting of HTR-8 trophoblasts exposed to 86 mM of E for either 24 h or 48 h. The role of NRF2 was evaluated through the NRF2-transactivation reporter assay, qRT-PCR, and Western blotting for NRF2 and cell growth-promoting protein, and cell proliferation assay. In utero and in vitro E decreased the nuclear NRF2 content and diminished its transactivation ability along with dysregulation of the proliferation indices, PCNA, CYCLIN-D1, and p21. This was associated with a ~50% reduction in cell proliferation in vitro in trophoblasts. Interestingly, this was found to be partially rescued by ectopic Nrf2 overexpression. These results indicate that ethanol-induced dysregulation of NRF2 coordinately regulates PCNA/CYCLIN-D1/p21 involving growth network, at least partially to set a stage for placental perturbations.

Cellular stress mechanisms of prenatal maternal stress: Heat shock factors and oxidative stress

Development of the brain prenatally is affected by maternal experience and exposure. Prenatal maternal psychological stress changes brain development and results in increased risk for neuropsychiatric disorders. In this review, multiple levels of prenatal stress mechanisms (offspring brain, placenta, and maternal physiology) are discussed and their intersection with cellular stress mechanisms explicated. Heat shock factors and oxidative stress are closely related to each other and converge with the inflammation, hormones, and cellular development that have been more deeply explored as the basis of prenatal stress risk. Increasing evidence implicates cellular stress mechanisms in neuropsychiatric disorders associated with prenatal stress including affective disorders, schizophrenia, and child-onset psychiatric disorders. Heat shock factors and oxidative stress also have links with the mechanisms involved in other kinds of prenatal stress including external exposures such as environmental toxicants and internal disruptions such as preeclampsia. Integrative understanding of developmental neurobiology with these cellular and physiological mechanisms is necessary to reduce risks and promote healthy brain development.

Intrauterine growth restriction and neonatal hypoxic ischemic brain injury causes sex-specific long-term neurobehavioral abnormalities in rats

There is a lack of knowledge of factors preventing an adequate response to moderate hypothermia after hypoxic ischemic (HI) brain injury. We hypothesized that growth restriction from reduced intrauterine perfusion would predispose neonatal rats to have a worse outcome with HI brain injury. IUGR was induced by placental insufficiency in dams at 14 days of gestation. HI was induced at postnatal day (P) 10 by permanent right carotid artery ligation followed by 90 min of hypoxia (8% oxygen). Tests for early brain injury and neurobehavioral outcomes were subsequently done. All statistical analysis was done using Two-way ANOVA; post hoc Holm-Sidak test. HI in control and IUGR groups decreased the success rate of the contralateral vibrissa-elicited forelimb test, increased response latency in movement initiation test and increased the time to finish elevated beam walk test at P40 and P60. IUGR augmented HI-induced abnormality in vibrissa-elicited forelimb test at P40 but showed higher success rate when compared to HI only group at P60. IUGR's negative effect on HI-induced changes on the elevated beam walk test was sex-specific and exaggerated in P60 males. Increased TUNEL positive cells in the cortex were noted at 72 h after in HI in control but not in IUGR groups. In conclusion, the consequences of IUGR on subsequent neonatal HI varied based on age, sex and outcomes examined, and overall, male sex and IUGR had worse effects on the long-term neurobehavioral outcomes following HI.

MiR-199a-5p regulates sirtuin1 and PI3K in the rat hippocampus with intrauterine growth restriction

In humans, malnutrition during pregnancy results in intrauterine growth restriction (IUGR) and an increased risk of neurological morbidities; altered miRNA characteristics have been suggested to contribute to IUGR neurological pathogenesis. A miRNA microarray was used to identify differentially expressed miRNA molecules in the hippocampi of rats with IUGR. Five of the molecules in question were selectively validated using real-time PCR in rats with IUGR. We then investigated the role of miR-199a-5p in hippocampal pathology. Bioinformatics analysis results suggested that TNF-α, caspase-3 and SIRT1 were potential targets of miR-199a-5p. Changes in PI3K, SIRT1 and caspase-3 protein expressions levels in the hippocampus were confirmed by Western blot analysis (all P < 0.05). Studies using the pheochromocytoma cell line PC12 cells and primary neurons demonstrated that miR-199a-5p modulated PI3K, caspase-3 and SIRT1 expression. Additionally, there was an inverse correlation between miR-199a-5p and caspase-3 expression, though dual-luciferase reporter assays showed that caspase-3 is not a target of miR-199a-5p. We conclude that IUGR affects hippocampal miRNAs characteristics. Our results also indicated that aberrantly high expression levels of miR-199a-5p may play an important role in the pathogenesis of IUGR by regulating SIRT1 and PI3K.

Atypical fetal development: Fetal alcohol syndrome, nutritional deprivation, teratogens, and risk for neurodevelopmental disorders and psychopathology

Accumulating evidence indicates that the fetal environment plays an important role in brain development and sets the brain on a trajectory across the life span. An abnormal fetal environment results when factors that should be present during a critical period of development are absent or when factors that should not be in the developing brain are present. While these factors may acutely disrupt brain function, the real cost to society resides in the long-term effects, which include important mental health issues. We review the effects of three factors, fetal alcohol exposure, teratogen exposure, and nutrient deficiencies, on the developing brain and the consequent risk for developmental psychopathology. Each is reviewed with respect to the evidence found in epidemiological and clinical studies in humans as well as preclinical molecular and cellular studies that explicate mechanisms of action.

Effects of dietary Bacillus amyloliquefaciens supplementation on growth performance, intestinal morphology, inflammatory response, and microbiota of intra-uterine growth retarded weanling piglets

BACKGROUND

The focus of recent research has been directed toward the probiotic potential of Bacillus amyloliquefaciens (BA) on the gut health of animals. However, little is known about BA's effects on piglets with intra-uterine growth retardation (IUGR). Therefore, this study investigated the effects of BA supplementation on the growth performance, intestinal morphology, inflammatory response, and microbiota of IUGR piglets.

METHODS

Eighteen litters of newborn piglets were selected at birth, with one normal birth weight (NBW) and two IUGR piglets in each litter (i.e., 18 NBW and 36 IUGR piglets in total). At weaning, the NBW piglet and one of the IUGR piglets were assigned to groups fed a control diet (i.e., the NBW-CON and IUGR-CON groups). The other IUGR piglet was assigned to a group fed the control diet supplemented with 2.0 g BA per kg of diet (i.e., IUGR-BA group). The piglets were thus distributed across three groups for a four-week period.

RESULTS

IUGR reduced the growth performance of the IUGR-CON piglets compared with the NBW-CON piglets. It was also associated with decreased villus sizes, increased apoptosis rates, reduced goblet cell numbers, and an imbalance between pro- and anti-inflammatory cytokines in the small intestine. Supplementation with BA improved the average daily weight gain and the feed efficiency of the IUGR-BA group compared with the IUGR-CON group (P < 0.05). The IUGR-BA group exhibited increases in the ratio of jejunal villus height to crypt depth, in ileal villus height, and in ileal goblet cell density. They also exhibited decreases in the numbers of jejunal and ileal apoptotic cells and ileal proliferative cells (P < 0.05). Supplementation with BA increased interleukin 10 content, but it decreased tumor necrosis factor alpha level in the small intestines of the IUGR-BA piglets (P < 0.05). Furthermore, compared with the IUGR-CON piglets, the IUGR-BA piglets had less Escherichia coli in their jejunal digesta, but more Lactobacillus and Bifidobacterium in their ileal digesta (P < 0.05).

CONCLUSIONS

Dietary supplementation with BA improves morphology, decreases inflammatory response, and regulates microbiota in the small intestines of IUGR piglets, which may contribute to improved growth performance during early life.

Intrauterine Growth Restriction: Hungry for an Answer

Intrauterine growth restriction (IUGR) has been defined in several ways, but in general describes a condition in which the fetus exhibits poor growth in utero. This complication of pregnancy poses a significant public health burden as well as increased morbidity and mortality for the offspring. In human IUGR, alteration in fetal glucose and insulin homeostasis occurs in an effort to conserve energy and survive at the expense of fetal growth in an environment of inadequate nutrient provision. Several animal models of IUGR have been utilized to study the effects of IUGR on fetal glucose handling, as well as the postnatal reprogramming of energy metabolite handling, which may be unmasked in adulthood as a maladaptive propensity for cardiometabolic disease. This developmental programming may be mediated in part by epigenetic modification of essential regulators of glucose homeostasis. Several pharmacological therapies and nonpharmacological lifestyle modifications have shown early promise in mitigating the risk for or severity of adult metabolic phenotypes but still require further study of unanticipated and/or untoward side effects.

Neurodevelopment in children with intrauterine growth restriction: adverse effects and interventions

Intrauterine growth restriction (IUGR) is associated with higher rates of fetal, perinatal, and neonatal morbidity and mortality. The consequences of IUGR include short-term metabolic, hematological and thermal disturbances that lead to metabolic syndrome in children and adults. Additionally, IUGR severely affects short- and long-term fetal brain development and brain function (including motor, cognitive and executive function) and neurobehavior, especially neuropsychology. This review details the adverse effects of IUGR on fetal brain development and discusses intervention strategies.

The Placenta as a Mediator of Stress Effects on Neurodevelopmental Reprogramming

Adversity experienced during gestation is a predictor of lifetime neuropsychiatric disease susceptibility. Specifically, maternal stress during pregnancy predisposes offspring to sex-biased neurodevelopmental disorders, including schizophrenia, attention deficit/hyperactivity disorder, and autism spectrum disorders. Animal models have demonstrated disease-relevant endophenotypes in prenatally stressed offspring and have provided unique insight into potential programmatic mechanisms. The placenta has a critical role in the deleterious and sex-specific effects of maternal stress and other fetal exposures on the developing brain. Stress-induced perturbations of the maternal milieu are conveyed to the embryo via the placenta, the maternal-fetal intermediary responsible for maintaining intrauterine homeostasis. Disruption of vital placental functions can have a significant impact on fetal development, including the brain, outcomes that are largely sex-specific. Here we review the novel involvement of the placenta in the transmission of the maternal adverse environment and effects on the developing brain.

Epigenetics/Programming in the HPA Axis

The hypothalamic-pituitary-adrenal axis provides physiological adaptations to various environmental stimuli in mammals. These stimuli including maternal care, diet, immune challenge, stress, and others have the potential to stably modify or program the functioning of the HPA axis when experienced early in life or at later critical stages of development. Epigenetic mechanisms mediate the biological embedding of environmental stimuli or conditions. These changes are influenced by the genotype and both, environment and genotype contribute to the development of a specific phenotype with regard to the stress response that might be more susceptible or resilient to the development of mental conditions. The effects of stress might be a result of cumulative stress or a mismatch between the environments experienced early in life versus the conditions much later. These effects including the associated epigenetic modifications are potentially reversible.

Neurological outcomes of animal models of uterine artery ligation and relevance to human intrauterine growth restriction: a systematic review

AIM

This review explores the molecular, neurological, and behavioural outcomes in animal models of uterine artery ligation. We analyse the relevance of this type of model to the pathological and functional phenotypes that are consistent with cerebral palsy and its developmental comorbidities in humans.

METHOD

A literature search of the PubMed database was conducted for research using the uterine artery ligation model published between 1990 and 2013. From the studies included, any relevant neuroanatomical and behavioural deficits were then summarized from each document and used for further analysis.

RESULTS

There were 25 papers that met the criteria included for review, and several outcomes were summarized from the results of these papers. Fetuses with growth restriction demonstrated a gradient of reduced body weight with a relative sparing of brain mass. There was a significant reduction in the size of the somatosensory cortex, hippocampus, and corpus callosum. The motor cortex appeared to be spared of identifiable deficits. Apoptotic proteins were upregulated, while those important to neuronal survival, growth, and differentiation were downregulated. Neuronal apoptosis and astrogliosis occurred diffusely throughout the brain regions. White matter injury involved oligodendrocyte precursor maturation arrest, hypomyelination, and an aberrant organization of existing myelin. Animals with growth restriction demonstrated deficits in gait, memory, object recognition, and spatial processing.

INTERPRETATION

This review concludes that neuronal death, white matter injury, motor abnormalities, and cognitive deficits are important outcomes of uterine artery ligation in animal models. Therefore, this is a clinically relevant type of model, as these findings resemble deficits in human cerebral palsy.

Novel thromboxane A2 analog-induced IUGR mouse model

Rodents, particularly rats, are used in the majority of intrauterine growth restriction (IUGR) research. An important tool that is lacking in this field is the ability to impose IUGR on transgenic mice. We therefore developed a novel mouse model of chronic IUGR using U-46619, a thromboxane A2 (TXA2) analog, infusion. TXA2 overproduction is prevalent in human pregnancies complicated by cigarette smoking, diabetes mellitus and preeclampsia. In this model, U-46619 micro-osmotic pump infusion in the last week of C57BL/6J mouse gestation caused maternal hypertension. IUGR pups weighed 15% less, had lighter brain, lung, liver and kidney weights, but had similar nose-to-anus lengths compared with sham pups at birth. Metabolically, IUGR pups showed increased essential branched-chain amino acids. They were normoglycemic yet hypoinsulinemic. They showed decreased hepatic mRNA levels of total insulin-like growth factor-1 and its variants, but increased level of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha. IUGR offspring were growth restricted from birth (P1) through postnatal day 21 (P21). IUGR males caught up with sham males in weight by P28, whereas IUGR females caught up with sham females by P77. IUGR males surpassed sham males in weight by P238. In summary, we have a non-brain sparing IUGR mouse model that has a relative ease of surgical IUGR induction and exhibits features similar to the chronic IUGR offspring of humans and other animal models. As transgenic technology predominates in mice, this model now permits the imposition of IUGR on transgenic mice to interrogate mechanisms of fetal origins of adult disease.

Medium-chain TAG attenuate hepatic oxidative damage in intra-uterine growth-retarded weanling piglets by improving the metabolic efficiency of the glutathione redox cycle

The present study investigated the effects of medium-chain TAG (MCT) on hepatic oxidative damage in weanling piglets with intra-uterine growth retardation (IUGR). At weaning (mean 21 (SD 1·06) d of age), twenty-four IUGR piglets and twenty-four normal-birth weight (NBW) piglets were selected according to their birth weight (BW; IUGR: mean 0·95 (SD 0·04) kg; NBW: mean 1·58 (SD 0·04) kg) and weight at the time of weaning (IUGR: mean 5·26 (SD 0·15) kg; NBW: mean 6·98 (SD 0·19) kg) and fed either a soyabean oil (SO) diet (containing 5% SO) or a MCT diet (containing 1% SO and 4% MCT) for 28 d. IUGR piglets exhibited poor (P<0·05) growth performance, lower (P<0·05) metabolic efficiency of hepatic glutathione (GSH) redox cycle, and increased (P<0·05) levels of reactive oxygen species, apoptosis and necrosis in hepatocytes compared with NBW piglets. The MCT diet increased (P<0·05) the average daily gain and feed efficiency of piglets during the first 4 weeks after weaning. Furthermore, MCT diet-fed piglets had a higher (P<0·05) GSH:oxidised glutathione ratio and increased (P<0·05) activities of glucose-6-phosphate dehydrogenase (G6PD) and GSH reductase. The expression of G6PD was up-regulated (P<0·05) by the MCT diet irrespective of BW. Moreover, malondialdehyde concentrations in the liver and apoptosis and necrosis levels in hepatocytes were decreased (P<0·05) by the MCT diet irrespective of BW. These results indicate that MCT might have auxiliary therapeutic potential to attenuate hepatic oxidative damage in IUGR offspring during early life, thus leading to an improvement in the metabolic efficiency of the hepatic GSH redox cycle.

Antenatal taurine reduces cerebral cell apoptosis in fetal rats with intrauterine growth restriction

From pregnancy to parturition, Sprague-Dawley rats were daily administered a low protein diet to establish a model of intrauterine growth restriction. From the 12(th) day of pregnancy, 300 mg/kg rine was daily added to food until spontaneous delivery occurred. Brain tissues from normal neonatal rats at 6 hours after delivery, neonatal rats with intrauterine growth restriction, and neonatal rats with intrauterine growth restriction undergoing taurine supplement were obtained for further experiments. The terminal deoxyribonucleotidyl transferase (TdT)-mediated biotin-16-dUTP nick-end labeling assay revealed that the number of apoptotic cells in the brain tissue of neonatal rats with intrauterine growth restriction significantly increased. Taurine supplement in pregnant rats reduced cell apoptosis in brain tissue from neonatal rats with intrauterine growth restriction. nohistochemical staining revealed that taurine supplement increased glial cell line-derived neurotrophic factor expression and decreased caspase-3 expression in the cerebral cortex of intrauterine growth-restricted fetal rats. These results indicate that taurine supplement reduces cell apoptosis through the glial cell line-derived neurotrophic factor-caspase-3 signaling pathway, resulting in a protective effect on the intrauterine growth-restricted fetal rat brain.

A descriptive study of perinatal asphyxia at the University Hospital of Kinshasa (Democratic Republic of Congo)

BACKGROUND

Perinatal asphyxia is the third cause of neonatal death after prematurity and infection.

OBJECTIVE

The purpose of this study was to determine the incidence, the etiology and the HIE score at the first day in term and near-term newborns with perinatal asphyxia at the University Hospital of Kinshasa.

METHODS

50 term and near-term neonates with perinatal asphyxia were studied prospectively after they were admitted in neonatal intensive care from November 2009 to January 2011. For each patient admitted the perinatal data were collected. Clinical assessment was performed by the Sarnat grading and the Thompson score within twenty-four hours. Medcalc® was used for statistics.

RESULTS

50 babies were scored. The median maternal age was 31 years. In 22% of the mothers preeclampsia was diagnosed. Urogenital infection, IUGR were other prenatal diagnoses. Median Apgar score was 4 after 1 minute, 5 after 5 minutes and 6 after 10 minutes. Sarnat grade 1 was seen in 16 patients, Sarnat grade 2 in 20 patients and grade 3 in 8. Thompson score in the first 24 hours was more than 7 in 60% of the patients. A good correlation was found between the Thompson score and the Sarnat grade (r: 0,77; p < 0,0001). 14 of the 50 babies died. Both Sarnat and Thompson score correlated significantly with mortality.

CONCLUSION

The incidence of perinatal asphyxia at the University Hospital of Kinshasa remains high and the majority of patients had a severe HIE.

Evidence for therapeutic intervention in the prevention of cerebral palsy: hope from animal model research

Knowledge translation, as defined by the Canadian Institute of Health Research, is defined as the exchange, synthesis, and ethically sound application of knowledge--within a complex system of interactions among researchers and users--to accelerate the capture of the benefits of research through improved health, more effective services and products, and a strengthened healthcare system. The requirement for this to occur lies in the ability to continue to determine mechanistic actions at the molecular level, to understand how they fit at the in vitro and in vivo levels, and for disease states, to determine their safety, efficacy, and long-term potential at the preclinical animal model level. In this regard, particularly as it relates to long-term disabilities such as cerebral palsy that begin in utero, but only express their full effect in adulthood, animal models must be used to understand and rapidly evaluate mechanisms of injury and therapeutic interventions. In this review, we hope to provide the reader with a background of animal data upon which therapeutic interventions for the prevention and treatment of cerebral palsy, benefit this community, and increasingly do so in the future.

Fetal growth restriction alters hippocampal 17-beta estradiol and estrogen receptor alpha levels in the newborn male rat

Fetal growth restriction (FGR) is associated with impaired neurodevelopmental outcomes in affected newborns. The pathogenesis of FGR-associated neurodevelopmental impairment implicates abnormal hippocampal function. The steroid hormone estrogen and its receptor, estrogen receptor alpha (ERα), are involved in the normal programming of hippocampal development and structure. However, the impact of FGR on hippocampal estrogen and hippocampal ERα is not well characterized. We hypothesized that FGR will reduce hippocampal and serum levels of 17-beta estradiol and its receptor, ERα, in the newborn rat hippocampus. We further hypothesize that FGR will reduce hippocampal ERα levels in a region-specific manner. To test our hypotheses, we used the well characterized rat model of FGR induced by uteroplacental-insufficiency in the pregnant Sprague-Dawley rat. Hippocampi and serum were obtained from FGR and control day 0 rat pups and examined for hippocampal 17-beta estradiol, serum 17-beta estradiol, and ERα mRNA and protein levels. Immunohistochemistry was performed to examine region-specific ERα staining. FGR decreased hippocampal 17-beta estradiol levels in the hippocampi of male newborn rats but not females. Serum 17-beta estradiol levels were not affected by FGR in either gender. FGR decreased hippocampal ERα mRNA levels in males but not females. Hippocampal ERα protein levels by Western blotting were not affected by FGR. However, FGR decreased apparent ERα staining in the cornu ammonis (CA)1, CA3, and dentate gyrus regions in the hippocampi of male newborn rats but not females. We conclude that FGR affects the programming of hippocampal estrogen and hippocampal ERα levels in the newborn rat in a gender-specific manner.

Uteroplacental insufficiency alters rat hippocampal cellular phenotype in conjunction with ErbB receptor expression

INTRODUCTION

Uteroplacental insufficiency (UPI) produces significant neurodevelopmental deficits affecting the hippocampus of intrauterine growth-restricted (IUGR) offspring. IUGR males have worse deficits as compared with IUGR females. The exact mechanisms underlying these deficits are unclear. Alterations in hippocampal cellular composition along with altered expression of neural stem cell (NSC) differentiation molecules may underlie these deficits. We hypothesized that IUGR hippocampi would be endowed with altered neuronal, astrocytic, and immature oligodendrocytic proportions at birth, with males showing greater cellular deficits. We further hypothesized that UPI would perturb rat hippocampal expression of ErbB receptors (ErbB-Rs) and neuregulin 1 (NRG1) at birth and at weaning to account for the short- and long-term IUGR neurological sequelae.

METHODS

A well-established rat model of bilateral uterine artery ligation at embryonic day 19.5 was used to induce IUGR.

RESULTS

As compared with gender-matched controls, IUGR offspring have altered hippocampal neuronal, astrocytic, and immature oligodendrocytic composition in a subregion- and gender-specific manner at birth. In addition, IUGR hippocampi have altered receptor type- and gender-specific ErbB-R expression at birth and at weaning.

DISCUSSION

These cellular and molecular alterations may account for the neurodevelopmental complications of IUGR and for the male susceptibility to worse neurologic outcomes.

Intracerebral lipopolysaccharide induces neuroinflammatory change and augmented brain injury in growth-restricted neonatal rats

INTRODUCTION

Intrauterine growth restriction (IUGR) alters fetal development and is associated with neurodevelopmental abnormalities. We hypothesized that growth restriction from reduced intrauterine perfusion would predispose neonatal rats to subsequent inflammatory brain injury.

METHODS

In this study, IUGR was achieved by induced placental insufficiency in pregnant rats at 14 days of gestation. IUGR offspring and sham-operated control pups were subsequently injected with intracerebral lipopolysaccharide (LPS) as a model of periventricular leukomalacia (PVL).

RESULTS

LPS similarly elevates proinflammatory cytokines in the brains of both IUGR and control rat pups. However, the chemokines cytokine-induced neutrophil chemoattractant-1 (CINC-1) and macrophage chemoattractant protein-1 (MCP-1), as well as microglia activation, were significantly higher in LPS-treated IUGR rat pups as compared with LPS-treated controls. In addition to the unique brain inflammatory response, IUGR rat pups demonstrated increased brain damage with an increased number of apoptotic cells, larger lateral ventricular size, and more severe impairment of myelination.

DISCUSSION

This study provides evidence that placental insufficiency may sensitize the innate immune system in the immature brain and reveals a possible link between brain inflammation and injury.

Differential effect of intrauterine hypoxia on caspase 3 and DNA fragmentation in fetal guinea pig hearts and brains

The aim of this study is to quantify the effect of intrauterine hypoxia (HPX) and the role of nitric oxide (NO) on the apoptotic enzyme, caspase 3, and DNA fragmentation in fetal heart and brain. Hypoxia and NO are important regulators of apoptosis, although this has been little studied in the fetal organs. We investigated the effect of intrauterine HPX on apoptosis and the role of NO in both fetal hearts and brains. Pregnant guinea pigs were exposed to room temperature (N = 14) or 10.5% O₂ (N = 12) for 14 days prior to term (term = 65 days) and administered water or L-N6-(1-iminoethyl)-lysine (LNIL), an inducible nitric oxide synthase (iNOS) inhibitor, for 10 days. Fetal hearts and brains were excised from anesthetized near-term fetuses for study. Chronic HPX decreased pro- and active caspase 3, caspase 3 activity, and DNA fragmentation levels in fetal hearts compared with normoxic controls. L-N6-(1-iminoethyl)-lysine prevented the HPX-induced decrease in caspase 3 activity but did not alter DNA fragmentation levels. In contrast, chronic HPX increased both apoptotic indices in fetal brains, which were inhibited by LNIL. Thus, the effect of HPX on apoptosis differs between fetal organs, and NO may play an important role in modulating these effects.

Postnatal pancreatic islet β cell function and insulin sensitivity at different stages of lifetime in rats born with intrauterine growth retardation

Epidemiological studies have linked intrauterine growth retardation (IUGR) to the metabolic diseases, consisting of insulin resistance, type 2 diabetes, obesity and coronary artery disease, during adult life. To determine the internal relationship between IUGR and islet β cell function and insulin sensitivity, we established the IUGR model by maternal nutrition restriction during mid- to late-gestation. Glucose tolerance test and insulin tolerance test(ITT) in vivo and glucose stimulated insulin secretion(GSIS) test in vitro were performed at different stages in IUGR and normal groups. Body weight, pancreas weight and pancreas/body weight of IUGR rats were much lower than those in normal group before 3 weeks of age. While the growth of IUGR rats accelerated after 3 weeks, pancreas weight and pancreas/body weight remained lower till 15 weeks of age. In the newborns, the fasting glucose and insulin levels of IUGR rats were both lower than those of controls, whereas glucose levels at 120 and 180 min after glucose load were significantly higher in IUGR group. Between 3 and 15 weeks of age, both the fasting glucose and insulin levels were elevated and the glucose tolerance was impaired with time in IUGR rats. At age 15 weeks, the area under curve of insulin(AUCi) after glucose load in IUGR rats elevated markedly. Meanwhile, the stimulating index of islets in IUGR group during GSIS test at age 15 weeks was significantly lower than that of controls. ITT showed no significant difference in two groups before 7 weeks of age. However, in 15-week-old IUGR rats, there was a markedly blunted glycemic response to insulin load compared with normal group. These findings demonstrate that IUGR rats had both impaired pancreatic development and deteriorated glucose tolerance and insulin sensitivity, which would be the internal causes why they were prone to develop type 2 diabetes.

Organ-specific defects in insulin-like growth factor and insulin receptor signaling in late gestational asymmetric intrauterine growth restriction in Cited1 mutant mice

Late gestational placental insufficiency resulting in asymmetric intrauterine organ growth restriction (IUGR) is associated with an increased incidence of diabetes, cardiovascular and renal disease in adults. The molecular mechanisms mediating these defects are poorly understood. To explore this, we investigated the mechanisms leading to IUGR in Cited1 knockout mice, a genetic model of late gestational placental insufficiency. We show that loss of placental Cited1 leads to asymmetric IUGR with decreased liver, lung, and kidney sizes and preservation of fetal brain weight. IGF and insulin signaling regulate embryonic organ growth. IGF-I and IGF-II protein and mRNA expression are reduced in livers, lungs, and kidneys of embryonic d 18.5 embryos with IUGR. Decreased IGF-I is associated with reduced activating phosphorylation of the type 1 IGF receptor (pIGF-IR) in the kidney, whereas reduced IGF-II is associated with decreased phosphorylation of the insulin receptor (pIR) in the lung. In contrast, decreased pIR is associated with reduced IGF-I but not IGF-II in the liver. However, pancreatic β-cell mass and serum insulin levels are also decreased in mice with IUGR, suggesting that hepatic IR signaling may be regulated by alterations in fetal insulin production. These findings contrast with observations in IUGR fetal brains in which there is no change in IGF-IR/IR phosphorylation, and IGF-I and IGF-II expression is actually increased. In conclusion, IUGR disrupts normal fetal IGF and insulin production and is associated with organ-specific defects in IGF-IR and IR signaling that may regulate asymmetric IUGR in late gestational placental insufficiency.

Intrauterine growth restriction alters hippocampal expression and chromatin structure of Cyp19a1 variants

We evaluated the impact of uteroplacental insufficiency (UPI), and subsequent intrauterine growth restriction (IUGR), on serum testosterone and hippocampal expression of Cyp19a1 variants and aromatase in rats. Additionally, we determined UPI induced histone modification of the promoter regions of Cyp19a1 variants using chromatin immunoprecipitation. Cyp19a1 is the gene encoding the protein aromatase, that catalyzes the biosynthesis of estrogens from androgens and is necessary for masculinization of the brain. IUGR was induced via bilateral uterine artery. UPI increased serum testosterone in day of life 0 (D(0)) and day of life 21 (D(21)) IUGR males to 224% and 299% of control values, respectively. While there was no significant impact of UPI on testosterone in D(0) females, testosterone in D(21) IUGR females was 187% of controls. Cyp19a1 variant 1.f and variant II are expressed in the rat hippocampus at D(0) and D(21). UPI significantly reduced expression of Cyp19a1 variant 1.f in D(0) males, with no impact in females. Similarly at D(0), UPI reduced expression of aromatase, the protein encoded by Cyp19a1, in males. Dimethylation of H3K4 was increased in the promoter region of variant 1.f (P1.f) and trimethylation of H3K4 was decreased in the promoter region of variant II (PII). At D(21), dimethylation of H3K4 is significantly reduced in PII of IUGR males. We conclude that UPI increases serum testosterone and reduces Cyp19a1 variant 1.f expression in the hippocampus of D(0) IUGR males. Additionally, UPI alters the chromatin structure of CYP19a1 at both D(0) and D(21).

Placental insufficiency associated with loss of Cited1 causes renal medullary dysplasia

A number of studies have shown that placental insufficiency affects embryonic patterning of the kidney and leads to a decreased number of functioning nephrons in adulthood; however, there is circumstantial evidence that placental insufficiency may also affect renal medullary growth, which could account for cases of unexplained renal medullary dysplasia and for abnormalities in renal function among infants who had experienced intrauterine growth retardation. We observed that mice with late gestational placental insufficiency associated with genetic loss of Cited1 expression in the placenta had renal medullary dysplasia. This was not caused by lower urinary tract obstruction or by defects in branching of the ureteric bud during early nephrogenesis but was associated with decreased tissue oxygenation and increased apoptosis in the expanding renal medulla. Loss of placental Cited1 was required for Cited1 mutants to develop renal dysplasia, and this was not dependent on alterations in embryonic Cited1 expression. Taken together, these findings suggest that renal medullary dysplasia in Cited1 mutant mice is a direct consequence of decreased tissue oxygenation resulting from placental insufficiency.

Growth retardation of fetal rats exposed to nicotine in utero: possible involvement of CYP1A1, CYP2E1, and P-glycoprotein

To elucidate the possible metabolic mechanism of intrauterine growth retardation induced by nicotine, this study determines the effects of prenatal nicotine exposure on fetal development and cytochrome P4501A1 (CYP1A1), CYP2E1, and P-glycoprotein (Pgp) expression in maternal liver and placenta. Pregnant rats were given 1.0 mg/kg nicotine subcutaneously twice a day from gestational day (GD) 8 to GD 15, 18, or 21. In nicotine-treated groups, fetal developmental parameters including body weight were significantly lower. The activities of CYP1A1 and CYP2E1 in maternal liver microsomes in nicotine-treated groups increased significantly with progressing gestation when compared with the corresponding control, but returned to the level similar to the control in late pregnancy. Nicotine-treated groups induced pathological changes and increased malondialdehyde (MDA) content in the placenta when compared with the control. The gene expressions of CYP1A1 and CYP2E1 in the placenta increased significantly in nicotine-treated groups on GD 15 and GD 18, but returned to the level similar to the corresponding control on GD 21. In nicotine group, there was a decrease of mdr1a expression on GD 15, GD 18, and GD 21, with the most significant decrease on GD 15. In contrast, no significant difference was found in mdr1b mRNA expression between the nicotine-treated animals and the corresponding control. In comparison with the corresponding control, the placental Pgp protein significantly decreased on GD 15 and GD 18. Our results showed that prenatal nicotine exposure resulted in inhibition of fetal growth significantly. The induction of CYP2E1 and CYP1A1 gene expression by nicotine in the maternal liver and placenta may be involved with the observed increase in oxidative stress and lipid peroxidation. The inhibition of the placental Pgp expression by nicotine may also contribute to an increased susceptibility of the fetus to environmental toxins.

Quantitative immunohistochemical analysis of nitric oxide synthases and apoptosis regulator proteins in the fetal rat brain following maternal uterine artery ligation

The purpose of this study was to determine the relation between nitric oxide synthases (calcium-independent iNOS and calcium-dependent eNOS) and apoptosis regulator proteins (anti-apoptotic Bcl-2, pro-apoptotic p53) of fetal rat brain in experimental intrauterine growth retardation (IUGR) model via quantitative immunohistochemistry. Cortical zone of parietal cerebral cortex and ventricular zone of third ventricle were studied following bilateral uterine artery ligation on gestational day 18. Significant increase in iNOS immunoreactivity was determined in parietal cerebral cortex and ventricular zones as eNOS immunoreactivity increased in ventricular zone of IUGR group. Bcl-2 expression was significantly decreased in ventricular zone; whereas cortical zone of IUGR group expressed p53 immunoreactivity.

Expression and function of the LIM homeobox containing genes Lhx3 and Lhx4 in the mouse placenta

The LIM homeobox containing genes of the LIM-3 group, Lhx3 and Lhx4, are critical for normal development. Both genes are involved in the formation of the pituitary and the motoneuron system and loss of either gene causes perinatal lethality. Previous studies had shown that Lhx3 is overexpressed in hyperplastic placentas of mouse interspecies hybrids. To determine the role of LHX3 in the mouse placenta, we performed expression and function analyses. Our results show that Lhx3 exhibits specific spatial and temporal expression in the mouse placenta. However, deletion of Lhx3 does not produce a placental phenotype. To test whether this is due to functional substitution by Lhx4, we performed a phenotype analysis of Lhx3-/-; Lhx4-/- double-mutant placentas. A subset of Lhx3-/-; Lhx4-/- placentas exhibited abnormal structure of the labyrinth. However, absence of both LIM-3 genes did not interfere with placental transport nor consistently with expression of target genes such as Gnrhr. Thus, LHX3 and LHX4 appear to be dispensable for placental development and function.

Differential gene expression of somatotrophic and growth factors in response to in vivo hypoxia in human placenta

OBJECTIVE

Hypoxia-inducible transcription factors (HIFs) have been characterized as the most important regulators of O(2)-dependent gene transcription. We investigated expression of HIF-dependent growth factors and HIF-independent somatotrophic factors in term placenta in response to hypoxic ischemia.

STUDY DESIGN

Our cross-sectional in vivo analysis included term placentas of gestations complicated by the following: (1) birth asphyxia (n = 22); (2) chronic hypoxic ischemia (n = 22); and (3) controls (n = 28). Gene expression of leptin, insulin-like growth factor (IGF)-1, IGF-2, ghrelin, and human placental growth hormone (hPGH) were measured by TaqMan reverse transcriptase-polymerase chain reaction.

RESULTS

Acute and chronic hypoxia significantly increased leptin messenger ribonucleic acid (mRNA) levels, compared with controls (P < .001). Augmented IGF-2 mRNA levels were present in chronic hypoxia (P < .001) but not in birth asphyxia. IGF-1, ghrelin, and hPGH mRNA levels did not change in relation to hypoxia.

CONCLUSION

IGF-2 and leptin are suggested to be involved in adaptive response to hypoxic ischemia in term placenta with differential transcriptional regulation related to the duration of hypoxia.

Increased cerebral lactate during hypoxia may be neuroprotective in newborn piglets with intrauterine growth restriction

Intrauterine growth restriction (IUGR) can increase susceptibility to perinatal hypoxic brain injury for reasons that are unknown. Previous studies of the neonatal IUGR brain have suggested that the cerebral mitochondrial capacity is reduced but the glycolytic capacity increased relative to normal weight (NW) neonates. In view of these two factors, we hypothesized that the generation of brain lactate during a mild hypoxic insult would be greater in neonatal IUGR piglets compared to NW piglets. Brain lactate/N-acetylaspartate (NAA) ratios and apparent diffusion coefficients (ADCs) were determined by proton magnetic resonance spectroscopy and imaging of the brain before, during and after hypoxia in seven neonatal piglets with asymmetric IUGR and six NW piglets. During hypoxia, IUGR piglets had significantly higher brain lactate/NAA ratios than NW piglets (P=0.046). The lactate response in the IUGR piglets correlated inversely with apoptosis in the thalamus and frontal cortex of the brain measured 4 h post hypoxia (Pearson's r=0.86, P<0.05). Apoptosis in IUGR piglets with high brain lactate was similar to that in the NW piglets whereas IUGR piglets with low brain lactate had significantly higher apoptosis than NW piglets (P=0.019). ADCs in the high lactate IUGR piglets were significantly lower during hypoxia than in all the other piglets. This signifies increased diffusion of water into brain cells during hypoxia, possibly in response to increased intracellular osmolality caused by high intracellular lactate concentrations. These findings support previous studies showing increased susceptibility to hypoxic brain injury in IUGR neonates but suggest that increased glycolysis during hypoxia confers neuroprotection in some IUGR piglets.

Role of oxidative stress in intrauterine growth restriction

AIMS

The objectives of this study were to determine the role of oxidative stress in intrauterine growth restriction (IUGR) and to investigate the possible molecular mechanism(s) leading to oxidant stress in IUGR.

METHODS

Parameters of the oxidative and antioxidant system were evaluated in maternal plasma, umbilical cord blood, and placental tissue of pregnant women with IUGR fetuses. The same samples were obtained from women with normal pregnancies and were evaluated.

RESULTS

The results of this study indicate that while the levels of malondialdehyde (MDA) and xanthine oxidase (XO) were higher in maternal plasma, umbilical cord plasma, and placental tissues of the patients with IUGR when compared to the control group [MDA: 142.8 +/- 18.0 vs. 86.4 +/- 22.5 nmol/ml, 151.6 +/- 25.8 vs. 93.3 +/- 7.4 nmol/ml, and 0.72 +/- 0.19 vs. 0.42 +/- 0.09 nmol/mg protein, respectively (for all p < 0.0005); XO: 1.251 +/- 0.674 vs. 0.20 +/- 0.019 mIU/ml (p < 0.0005), 1.97 +/- 0.73 vs. 0.237 +/- 0.143 mIU/ml (p < 0.0005), and 0.023 +/- 0.0012 vs. 0.012 +/- 0.004 mIU/ml (p < 0.025), respectively], the levels of antioxidant potential were identified to be lower in maternal plasma, umbilical cord plasma, and placental tissues of the patients with IUGR: 63.3 +/- 11.9 vs. 198.0 +/- 31.9 U/ml (p < 0.0005), 32.6 +/- 3.7 vs. 206.5 +/- 27.1 U/ml (p < 0.0005), and 0.56 +/- 0.23 vs. 1.16 +/- 0.29 U/ml (p < 0.0005), respectively. On the other hand, the activities of adenosine deaminase of the IUGR patients were higher than those of the control group in maternal plasma (204.8 +/- 103.5 vs. 115.6 +/- 31.8 U/l, p < 0.01) and umbilical cord blood samples (584.2 +/- 285.2 vs. 147.9 +/- 44.8 U/l, p < 0.0005) which may suggest that oxidative stress has a role in IUGR. Moreover, an increased superoxide dismutase activity in maternal plasma (128.2 +/- 37.4 vs. 88.8 +/- 16.6 U/ml, p < 0.005) and cord blood (162.1 +/- 37.0 vs. 116.6 +/- 20.7 U/ml, p < 0.005) and an increased glutathione peroxidase activity in maternal plasma (1.83 +/- 0.26 vs. 1.47 +/- 0.31 IU/ml, p < 0.01) and placental tissue (0.007 +/- 0.0015 vs. 0.003 +/- 0.0012 IU/ml, p < 0.0005) were detected, while decreased catalase activities in cord blood (23,717 +/- 3,538 vs. 16,397 +/- 2,771 IU/ml, p < 0.0005) and placental tissue (47.2 +/- 17.2 vs. 70.7 +/- 11.3 IU/ml, p < 0.005) were identified in IUGR groups.

CONCLUSIONS

In the light of the results of this study, it can be stated that the oxidative stress increases in patients with IUGR. Providing high-risk patients with an antioxidant may be useful in the prevention or treatment of IUGR, although it is a condition with no certain treatment outcome.

Comparison of the effects of maternal protein malnutrition and intrauterine growth restriction on redox state of central nervous system in offspring rats

Both maternal protein malnutrition and intrauterine growth restriction (IUGR) have deleterious effects on brain development, but a comparison of these effects has not been previously reported. The objectives of this study were to investigate and compare the effects of both factors on the oxidative status of the central nervous system (CNS), including the spinal cord, in offspring rats. We evaluated various parameters of oxidative status and antioxidant enzyme activities of superoxide dismutase and catalase (CAT) in different regions of the CNS from 60-day-old rats subjected to prenatal and postnatal protein restrictions [middle protein restriction 12%, severe protein restriction (SPR) 4%] or IUGR produced by uterine artery ligation. Furthermore, we compared these study groups to each other and to control rats fed an isocaloric 24% protein diet. Results were analyzed using one-way ANOVA followed by Tukey's post hoc test. Both protein restrictions and IUGR altered various parameters of oxidative status. In all evaluated structures, protein restrictions resulted in increases in thiobarbituric acid-reactive substances level and index of lipid peroxidation (P<0.001), and in decreases in antioxidant enzyme activities (P<0.005). IUGR also increased lipid peroxidation levels in the blood samples (P<0.04) and protein oxidative damage in the cerebellum and cerebral cortex (P<0.005); however, no effects were detected on the spinal cord. The greatest decrease in CAT activity was in the cerebellum of rats fed with SPR diet (P<0.001). This study suggests that not only severe but also middle protein malnutrition have deleterious effects on CNS structures, including the spinal cord. Protein restriction has a greater effect on the redox state of the CNS than IUGR.

Uteroplacental insufficiency decreases p53 serine-15 phosphorylation in term IUGR rat lungs

Intrauterine growth restriction (IUGR) increases the incidence of chronic lung disease (CLD). The molecular mechanisms responsible for IUGR-induced acute lung injury that predispose the IUGR infant to CLD are unknown. p53, a transcription factor, plays a pivotal role in determining cellular response to stress by affecting apoptosis, cell cycle regulation, and angiogenesis, processes required for thinning of lung mesenchyme. Because thickened lung mesenchyme is characteristic of CLD, we hypothesized that IUGR-induced changes in lung growth are associated with alterations in p53 expression and/or modification. We induced IUGR through bilateral uterine artery ligation of pregnant rats. Uteroplacental insufficiency significantly decreased serine-15-phosphorylated (serine-15P) p53, an active form of p53, in IUGR rat lung. Moreover, we found that decreased phosphorylation of lung p53 serine-15 localized to thickened distal air space mesenchyme. We also found that IUGR significantly decreased mRNA for targets downstream of p53, specifically, proapoptotic Bax and Apaf, as well as Gadd45, involved in growth arrest, and Tsp-1, involved in angiogenesis. Furthermore, we found that IUGR significantly increased mRNA for Bcl-2, an antiapoptotic gene downregulated by p53. We conclude that in IUGR rats, uteroplacental insufficiency induces decreased lung mesenchymal p53 serine-15P in association with distal lung mesenchymal thickening. We speculate that decreased p53 serine-15P in IUGR rat lungs alters lung phenotype, making the IUGR lung more susceptible to subsequent injury.

Growth retardation alters the epigenetic characteristics of hepatic dual specificity phosphatase 5

Uteroplacental insufficiency leads to intrauterine growth retardation (IUGR) and adult onset insulin resistance in both humans and rats. IUGR rat liver is characterized by persistent changes in histone 3 lysine 9 and lysine 14 acetylation, which may induce postnatal changes in gene expression. We hypothesized that it would be possible to identify hepatic genes whose epigenetic characteristics and mRNA levels are altered due to IUGR using chromatin immunoprecipitation (ChIP) coupled with random primed differential display polymerase chain reaction (PCR). One of the isolated sequences identified contained exon 2 of the dual specificity phosphatase-5 gene (DUSP5). IUGR affected hepatic DUSP5 mRNA levels and exon 2 DNA methylation into adulthood in the rat. DUSP5 dephosphorylates Erk1 and Erk2 within the MAPK signaling cascade, which in turn affects serine 612 phosphorylation of insulin receptor substrate-1 (p612 IRS-1). In adult rat liver, IUGR increased Erk1/Erk2 phosphorylation and p612 IRS-1 phosphorylation. Increased serine phosphorylation of hepatic IRS-1 may contribute to the insulin resistance that characterizes these animals. We conclude that intrauterine growth retardation induced by uteroplacental insufficiency 1) affects the hepatic epigenetic characteristics and mRNA of the DUSP-5 and 2) increases hepatic insulin receptor substrate-1 phosphorylation at serine 612 in adult rats.

Intrauterine growth restriction due to uteroplacental vascular insufficiency leads to increased hypoxia-induced cerebral apoptosis in newborn piglets

Uteroplacental vascular insufficiency in humans is a common cause of intrauterine growth restriction (IUGR) and is associated with an increased incidence of perinatal asphyxia and neurodevelopmental disorders compared to normal weight newborns. Experimental models that provide an opportunity to analyze the pathogenesis of these relationships are limited. Here, we used neonatal pigs from large litters in which there were piglets of normal birth weight (for controls) and of low birth weight (for uteroplacental vascular insufficiency). Hypoxia was induced in paired littermates by reducing the fraction of inspired oxygen to 4% for 25 min. Brain tissue was collected 4 h post-hypoxia. Cerebral levels of apoptosis were quantified morphologically and verified with caspase-3 activity and TUNEL. Expression of Bcl-2, Bcl-XL and Bax proteins was investigated using immunohistochemistry. Cellular positivity for Bcl-2 was consistently higher in the non-apoptotic white matter of the hypoxic IUGR animals compared with their littermates and reached significance at P < 0.05 in several pairs of littermates. Alterations in Bax showed a trend towards higher expression in the hypoxic IUGR littermates but rarely reached significance. The IUGR piglets showed a significantly greater amount of apoptosis in response to the hypoxia than the normal weight piglets, suggesting an increased vulnerability to apoptosis in the IUGR piglets.

Uteroplacental insufficiency affects epigenetic determinants of chromatin structure in brains of neonatal and juvenile IUGR rats

Intrauterine growth retardation (IUGR) increases the risk of neuroendocrine reprogramming. In the rat, IUGR leads to persistent changes in cerebral mRNA levels. This suggests lasting alterations in IUGR cerebral transcriptional regulation, which may result from changes in chromatin structure. Candidate nutritional triggers for these changes include altered cerebral zinc and one-carbon metabolite levels. We hypothesized that IUGR affects cerebral chromatin structure in neonatal and postnatal rat brains. Rats were rendered IUGR by bilateral uterine artery ligation; controls (Con) underwent sham surgery. At day of life 0 (d0), we measured cerebral DNA methylation, histone acetylation, expression of chromatin-affecting enzymes, and cerebral levels of one-carbon metabolites and zinc. At day of life 21 (d21), we measured cerebral DNA methylation and histone acetylation, as well as the caloric content of Con and IUGR rat breast milk. At d0, IUGR significantly decreased genome-wide and CpG island methylation, as well as increased histone 3 lysine 9 (H3/K9) and histone 3 lysine 14 (H3/K14) acetylation in the hippocampus and periventricular white matter, respectively. IUGR also decreased expression of the chromatin-affecting enzymes DNA methyltransferase 1 (DNMT1), methyl-CpG binding protein 2 (MeCP2), and histone deacetylase (HDAC)1 in association with increased cerebral levels of zinc. In d21 female IUGR rats, cerebral CpG DNA methylation remained lower, whereas H3/K9 and H3/K14 hyperacetylation persisted in hippocampus and white matter, respectively. In d21 male rats, IUGR decreased acetylation of H3/K9 and H3/K14 in these respective regions compared with controls. Despite these differences, caloric, fat, and protein content were similar in breast milk from Con and IUGR dams. We conclude that IUGR results in postnatal changes in cerebral chromatin structure and that these changes are sex specific.

GLUT4 expression and subcellular localization in the intrauterine growth-restricted adult rat female offspring

Intrauterine growth restriction (IUGR) leads to obesity, glucose intolerance, and type 2 diabetes mellitus in the adult. To determine the mechanism(s) behind this "metabolic imprinting" phenomenon, we examined the effect of total calorie restriction during mid- to late gestation modified by postnatal ad libitum access to nutrients (CM/SP) or nutrient restriction (SM/SP) vs. postnatal nutrient restriction alone (SM/CP) on skeletal muscle and white adipose tissue (WAT) insulin-responsive glucose transporter isoform (GLUT4) expression and insulin-responsive translocation. A decline in skeletal muscle GLUT4 expression and protein concentrations was noted only in the SM/SP and SM/CP groups. In contrast, WAT demonstrated no change in GLUT4 expression and protein concentrations in all experimental groups. The altered in utero hormonal/metabolic milieu was associated with a compensatory adaptation that persisted in the adult and consisted of an increase in the skeletal muscle basal plasma membrane-associated GLUT4 concentrations. This perturbation led to no further exogenous insulin-induced GLUT4 translocation, thereby disabling the insulin responsiveness of the skeletal muscle but retaining it in WAT. These changes, which present at birth, collectively maximize basal glucose transport to the compromised skeletal muscle with a relative resistance to exogenous/postprandial insulin. Preservation of insulin responsiveness in WAT may serve as a sink that absorbs postprandial nutrients that can no longer efficiently access skeletal muscle. We speculate that, in utero, GLUT4 aberrations may predict type 2 diabetes mellitus, whereas postnatal nutrient intake may predict obesity, thereby explaining the heterogeneous phenotype of the IUGR adult offspring.

Reduced birth defects caused by maternal immune stimulation in methylnitrosourea-exposed mice: association with placental improvement

BACKGROUND

Methylnitrosourea (MNU) is a potent carcinogen and teratogen that is associated with central nervous system, craniofacial, skeletal, ocular, and appendicular birth defects following transplacental exposure at critical time points during development, and preliminary studies have suggested that nonspecific maternal immunostimulation may offer protection against development of these birth defects.

METHODS

Our study examined morphologic alterations in fetal limb and digital development and placental integrity following maternal exposure to MNU on GD 9 in CD-1 mice, and characterized the improvement in placental integrity and abrogation of fetal defects following maternal immune stimulation with interferon-gamma (IFN-gamma) on GD 7.

RESULTS

Fetal limbs were significantly shortened (p < 0.0001) and incidence of limb and digital defects (syndactyly, polydactyly, oligodactyly, clubbing, and webbing) was dramatically increased following mid-gestational maternal MNU exposure. Maternal immune stimulation with IFN-gamma on GD 7 lessened incidence of fetal limb shortening and maldevelopment on GD 12 and 14. Further, disruption of placental spongiotrophoblast integrity, increased cell death in placental trophoblasts with increased intercellular spaces in the spongiotrophoblast layer and minimal inflammation, and increased loss of fetal labyrinthine endothelial cells from MNU-exposed dams suggested that MNU-induced placental breakdown may contribute to fetal limb and digital maldevelopment. MNU + IFN-gamma was associated with diminished cell death within all layers of the placenta, especially in the labyrinthine layer.

CONCLUSIONS

These data verify improved distal limb development in MNU-exposed mice as a result of maternal IFN-gamma administration, and suggest a link between placental integrity and proper fetal development.

Pontosubicular apoptosis (“necrosis”) in human neonates with intrauterine growth retardation and placental infarction

In a previous study of 37 autopsied stillbirths with non-dysmorphic intrauterine growth retardation (IUGR), 26 cases were associated with placental infarction, a morphologic marker of uteroplacental insufficiency. Nine of the 26 cases with both IUGR and placental infarction, where archival tissue was available, had grey matter ischaemic lesions that were subsequently identified as "pontosubicular necrosis". This lesion is now regarded as a localized form of apoptosis. A further eight third trimester stillbirth cases with both IUGR and placental infarction were ascertained prospectively. Sixteen of these 17 cases showed pontosubicular apoptosis, identified morphologically and verified using activated caspase-3 and TUNEL. Five of the 17 cases showed apoptosis in the frontal or temporal cortex as well. In this current study, pontosubicular apoptosis was strongly associated with IUGR and placental infarction in third trimester stillborns, suggesting that uteroplacental insufficiency leading to chronic fetal hypoxaemia may cause cerebral apoptosis.

Uteroplacental insufficiency induces site-specific changes in histone H3 covalent modifications and affects DNA-histone H3 positioning in day 0 IUGR rat liver

Uteroplacental insufficiency and subsequent intrauterine growth retardation (IUGR) increase the risk of adult onset insulin resistance and dyslipidemia in humans and rats. IUGR rats are further characterized by postnatal alterations in hepatic PPAR-γ coactivator (PGC-1) and carnitine-palmitoyl-transferase I (CPTI) expression, as well as overall hyperacetylation of histone H3. However, it is unknown whether the histone H3 hyperacetylation is site specific or relates to the changes in gene expression previously described in IUGR rats. We therefore hypothesized that uteroplacental insufficiency causes site-specific modifications in hepatic H3 acetylation and affects the association of acetylated histone H3 with PGC-1 and CPTI promoter sequences. Uteroplacental insufficiency was used to produce asymmetrical IUGR rats. IUGR significantly increased acetylation of H3 lysine-9 (H3/K9), lysine-14 (H3/K14), and lysine-18 (H3/K18) at day 0 of life, and these changes occurred in association with decreased nuclear protein levels of histone deacetylase 1 (HDAC1) and HDAC activity. Chromatin immunoprecipitation using acetyl-H3/K9 antibody and day 0 chromatin revealed that uteroplacental insufficiency affected the association between acetylated H3/K9 and the promoters of PGC-1 and CPTI, respectively, in IUGR liver. At day 21 of life, the neonatal pattern of H3 hyperacetylation persisted only in the IUGR males. We conclude that uteroplacental insufficiency increases H3 acetylation in a site-specific manner in IUGR liver and that these changes persist in male IUGR animals. The altered association of the PGC-1 and CPTI promoters with acetylated H3/K9 correlates with previous reports of IUGR altering the expression of these genes. We speculate that in utero alterations of chromatin structure contribute to fetal programming.

Nonresponsiveness of cerebral p53-MDM2 functional circuit in newborn rat pups rendered IUGR via uteroplacental insufficiency

Severe uteroplacental insufficiency causes cerebral apoptosis in the fetus. Moderate uteroplacental insufficiency causes intrauterine growth retardation (IUGR) and increases the risk of postnatal neurological morbidity. In the rat, uteroplacental insufficiency and IUGR affect cerebral gene expression of Bcl-2 and predispose the newborn IUGR rat toward cerebral apoptosis when challenged with perinatal hypoxia. Expression of Bcl-2, as well as the proapoptotic protein Bax, is regulated by p53. p53 also induces MDM2 transcription, which functions to limit further p53-induced apoptosis. The predisposition of the IUGR fetus toward cerebral apoptosis suggests that the p53-MDM2 "functional" circuit may be perturbed in the newborn IUGR rat brain. We hypothesized that MDM2 cerebral expression does not increase in response to increased p53 expression or increased levels of phospho-p53 (Ser15), an activated form of p53. To prove this hypothesis, we induced IUGR through bilateral uterine ligation of the pregnant rat. Uteroplacental insufficiency significantly increased p53 mRNA, total p53 protein, and phospho-p53 (Ser15) protein levels in the brain at term. Increased expression of phospho-p53 (Ser15) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells were localized to the CA1 region of the hippocampus, the subcortical and periventricular white matter, and the amygdala of the IUGR rat brain. In contrast, uteroplacental insufficiency decreased cerebral MDM2 mRNA and phospho-MDM2 (Ser166) protein levels in the IUGR rat pups. We conclude that the cerebral MDM2 response to increased p53 expression is not present in the newborn IUGR rat pup, and we speculate that this contributes to the predisposition of the IUGR fetus toward perinatal and long-term neurodevelopmental morbidities.

Uteroplacental insufficiency decreases small intestine growth and alters apoptotic homeostasis in term intrauterine growth retarded rats

Human and animal studies demonstrate that uteroplacental insufficiency and subsequent intrauterine growth retardation (IUGR) decrease intestinal growth and lead to both an increased incidence of feeding intolerance and necrotizing enterocolitis. Our objective was to determine the effects of uteroplacental insufficiency upon small intestine growth, histology, gene expression of the apoptosis related proteins Bcl-2, Bax and p53, and caspase-3 activity. For this purpose, we induced uteroplacental insufficiency through bilateral uterine artery ligation on day 19 of gestation in fully anesthetized pregnant Sprague-Dawley rats and harvested pups at term 2 days latter. Pups from sham surgeries served as controls. Uteroplacental insufficiency reduced cell count per crypt and decreased small intestinal weight. In association with these changes, IUGR intestinal Bcl-2 mRNA levels were decreased significantly, and Bax and p53 mRNA were significantly increased in distal ileum. Immunohistochemistry for Bcl-2, Bax, and p53 revealed similar findings. In association with the decreased Bcl-2 and the increased Bax gene expression, increased caspase-3 activity characterized the IUGR distal ileum. We conclude that uteroplacental insufficiency affects intestinal growth and morphology in association with altered gene expression of apoptosis related proteins. We speculate that the morphological change and associated altered apoptotic homeostasis contribute to the increased morbidity of infants affected by uteroplacental insufficiency.

Uteroplacental insufficiency increases apoptosis and alters p53 gene methylation in the full-term IUGR rat kidney

Uteroplacental insufficiency causes intrauterine growth retardation (IUGR), which is associated with adult onset diseases such as hypertension. Previous studies demonstrate that growth retardation in humans and rats decreases glomeruli number; however, the molecular mechanisms responsible for this reduction are unknown. Apoptosis plays a key role in renal organogenesis. We therefore hypothesized that the in utero deprivation associated with uteroplacental insufficiency decreases glomeruli, increases apoptosis, and alters the mRNA levels of key apoptosis-related proteins in full-term IUGR kidneys. To prove this hypothesis, we induced asymmetric IUGR through bilateral uterine artery ligation of the pregnant rat. We found that uteroplacental insufficiency significantly reduced glomeruli number while increasing TUNEL staining and caspase-3 activity in the IUGR kidney. A significant decrease in Bcl-2 mRNA and a significant increase in Bax and p53 mRNA further characterized the IUGR kidney. Because altered p53 CpG methylation affects p53 expression, we analyzed p53 promoter CpG methylation using methylation-sensitive restriction enzymes and real-time PCR. Uteroplacental insufficiency specifically decreased CpG methylation of the renal p53 BstU I site promoter without affecting the Hha I or the Aci I sites. Uteroplacental insufficiency also induced a relative hypomethylation from exon 5 to exon 8, which was associated with deceased mRNA levels of DNMT1. We conclude that uteroplacental insufficiency alters p53 DNA CpG methylation, affects mRNA levels of key apoptosis-related proteins, increases renal apoptosis, and reduces glomeruli number in the IUGR kidney. We speculate that these changes represent mechanisms that contribute to the fetal origins of adult disease.

IGF alters jejunal glucose transporter expression and serum glucose levels in immature rats

Milk-borne insulin-like growth factors (IGFs) enhance nutrient absorption in the immature intestine, which is characterized by low levels of glucose oxidation. We therefore hypothesized that feeding a rat milk substitute (RMS) devoid of growth factors to rat pups would lower serum glucose levels relative to dam-fed control rats and that supplementation of RMS with physiological doses of either IGF-I or IGF-II would normalize serum glucose levels via increased jejunal glucose transporter 2 (GLUT2) and high-affinity Na(+)-glucose cotransporter (SGLT1) expression. We found lower serum glucose concentrations in RMS-fed pups; in contrast, serum glucose levels in the IGF-supplemented pups were similar to those of dam-fed controls. RT-PCR and laser scanning confocal microscopy similarly demonstrated that IGF supplementation increased expression of jejunal glucose transporters. Further experiments demonstrated that IGF supplementation altered mRNA levels of key mitochondrial enzymes without altering jejunal lactase activity. We conclude that IGF-I and IGF-II supplementation increases serum glucose levels in the immature rat pup fed artificial formula and alters gene expression of the jejunal glucose transporters.

Prolonged mild fetal hypoxia up-regulates type I nitric oxide synthase expression in discrete areas of the late-gestation fetal sheep brain

OBJECTIVE

Our purpose was to study the effects of prolonged mild hypoxemia on type I nitric oxide synthase (NOS) messenger RNA, protein, and enzymatic activity in the fetal sheep brain.

STUDY DESIGN

Pregnant sheep were randomly allocated to receive maternal nitrogen (n = 8) or compressed air (controls, n = 5) to reduce fetal brachial artery PO(2) by 25% for 5 days. Type I NOS mRNA (determined by ribonuclease protection assay) protein (determined by Western blot) and enzymatic activity (determined by citrulline assay) were measured in the hippocampus, striatum, cerebellum, and frontal cortex. Data are presented as mean +/- SEM and were compared by means of one-way analysis of variance or two-sample t test.

RESULTS

The reduction in maternal inspired oxygen concentration decreased fetal PO(2) by 26% and oxygen content by 25% without an associated change in PCO(2) or pH. Fetal hypoxemia increased type I NOS mRNA by threefold in the striatum and by 2-fold in the frontal cortex and cerebellum, but it did not change mRNA expression in the hippocampus (P <.05). Type I NOS protein and catalytic activity increased only in the striatum (P <.05).

CONCLUSION

Prolonged mild hypoxemia has a differential effect on type I NOS mRNA in fetal sheep brain areas. Type I NOS protein and catalytic activity significantly increased only in the striatum. Our data suggest that fetal type I NOS gene expression is regulated at transcriptional, post-transcriptional, and translational levels.