Intrauterine Growth Retardation Rats Research Articles

Prenatal caffeine ingestion induces aberrant DNA methylation and histone acetylation of steroidogenic factor 1 and inhibits fetal adrenal steroidogenesis

Prenatal caffeine ingestion is one of the risk factors for intrauterine growth retardation (IUGR). Adrenal plays a pivotal role, mainly through steroidogenesis, in the regulation of intrauterine homeostasis and in fetal development and maturation. We have shown that prenatal caffeine ingestion can inhibit fetal adrenal corticosterone production, but the underlying mechanism is unknown. This study investigated the effects of prenatal caffeine ingestion on corticosterone and its associated synthesized enzymes (steroidogenic acute regulatory protein, StAR; 3β-hydroxysteroid dehydrogenase, 3β-HSD; cytochrome P450 cholesterol side chain cleavage, P450scc; P450c21; and P450c11) in the fetal adrenal in rats and further explored the underlying mechanism by analyzing the epigenetic modification and expression of the key transcription factor steroidogenic factor-1 (SF-1). The pregnant rats were intragastrically treated with 120mg/kg.d caffeine from gestational day 11–20. The results showed that the IUGR rate was 51.2% after caffeine treatment. The contents of corticosterone and the mRNA levels of StAR, P450scc, P450c21, and P450c11 were decreased significantly in the fetal adrenal. Furthermore, caffeine reduced both the protein and the mRNA expression of SF-1 in the fetal adrenal. The epigenetic analysis showed that caffeine treatment can significantly enhance the mRNA expression of DNA methyltransferase (Dnmt) 1, Dnmt3a, histone deacetylases (Hdac) 1, and Hdac2. The detection of DNA methylation by bisulfite-sequencing PCR uncovered a notably increased total methylation rate in the SF-1 promoter. The ChIP assay showed decreased acetylation levels of H3K9 and H3K14 in the SF-1 promoter. In conclusion, prenatal caffeine ingestion is able to induce aberrant DNA methylation and histone acetylation of the SF-1 promoter in the rat fetal adrenal. These effects may contribute to the inhibition of the expression of SF-1 and its associated steroidogenic enzymes and the production of corticosterone during fetal development.

Effect of intrauterine growth retardation on gluconeogenic enzymes in rat liver

To investigate the expression of gluconeogenic enzymes phosphoenolpyruvate carboxykinase (PEPCK) and G-6-Pase mRNA of hepatic tissue in rats with intrauterine growth retardation (IUGR) and to explore the molecular mechanism of insulin resistance in IUGR rats. Pregnant rats were randomly divided into 2 groups: a normal group and a model group. The normal group were fed with 21% protein forage and the model group with 10% low protein forage to obtain IUGR pup rats. The pup rats were introduced to the normal group and the IUGR group prospectively. At 1, 3 and 8 weeks, the body weight, blood glucose, insulin concentration and insulin resistance index of the pup rats were measured. Expression of PEPCK and G-6-Pase mRNA were detected by RT-PCR. The birth weight of the IUGR group was significantly lower than that of the normal group (P<0.001). The weight of the IUGR group was still lower than that of the normal group at 1, 3 and 8 weeks. There was no significant difference in the blood glucose, insulin level and insulin resistance index between the 2 groups (P>0.05). The hepatic expression of PEPCK and G-6-Pase mRNA in the IUGR group was significantly higher than that of the normal group at 1, 3 and 8 weeks (P<0.01). The significantly increased expression of PEPCK and G-6-Pase mRNA of hepatic tissue in IUGR rats may increase gluconeogenesis, which is probably one of the molecular mechanisms of insulin resistance and diabetes in IUGR.

Impairments in Brain-Derived Neurotrophic Factor-Induced Glutamate Release in Cultured Cortical Neurons Derived from Rats with Intrauterine Growth Retardation: Possible Involvement of Suppression of TrkB/Phospholipase C-γ Activation

Low birth weight due to intrauterine growth retardation (IUGR) is suggested to be a risk factor for various psychiatric disorders such as schizophrenia. It has been reported that developmental cortical dysfunction and neurocognitive deficits are observed in individuals with IUGR, however, the underlying molecular mechanisms have yet to be elucidated. Brain-derived neurotrophic factor (BDNF) and its receptor TrkB are associated with schizophrenia and play a role in cortical development. We previously demonstrated that BDNF induced glutamate release through activation of the TrkB/phospholipase C-γ (PLC-γ) pathway in developing cultured cortical neurons, and that, using a rat model for IUGR caused by maternal administration of thromboxane A2, cortical levels of TrkB were significantly reduced in IUGR rats at birth. These studies prompted us to hypothesize that TrkB reduction in IUGR cortex led to impairment of BDNF-dependent glutamatergic neurotransmission. In the present study, we found that BDNF-induced glutamate release was strongly impaired in cultured IUGR cortical neurons where TrkB reduction was maintained. Impairment of BDNF-induced glutamate release in IUGR neurons was ameliorated by transfection of human TrkB (hTrkB). Although BDNF-stimulated phosphorylation of TrkB and of PLC-γ was decreased in IUGR neurons, the hTrkB transfection recovered the deficits in their phosphorylation. These results suggest that TrkB reduction causes impairment of BDNF-stimulated glutamatergic function via suppression of TrkB/PLC-γ activation in IUGR cortical neurons. Our findings provide molecular insights into how IUGR links to downregulation of BDNF function in the cortex, which might be involved in the development of IUGR-related diseases such as schizophrenia.

Maternal glucocorticoid elevation and associated blood metabonome changes might be involved in metabolic programming of intrauterine growth retardation in rats exposed to caffeine prenatally

Our previous studies demonstrated that prenatal caffeine exposure causes intrauterine growth retardation (IUGR), fetuses are over-exposed to high levels of maternal glucocorticoids (GC), and intrauterine metabolic programming and associated metabonome alteration that may be GC-mediated. However, whether maternal metabonomes would be altered and relevant metabolite variations might mediate the development of IUGR remained unknown. In the present studies, we examined the dose- and time-effects of caffeine on maternal metabonome, and tried to clarify the potential roles of maternal GCs and metabonome changes in the metabolic programming of caffeine-induced IUGR. Pregnant rats were treated with caffeine (0, 20, 60 or 180mg/kg·d) from gestational days (GD) 11 to 20, or 180mg/kg·d caffeine from GD9. Metabonomes of maternal plasma on GD20 in the dose–effect study and on GD11, 14 and 17 in the time–course study were analyzed by 1H nuclear magnetic resonance spectroscopy, respectively. Caffeine administration reduced maternal weight gains and elevated both maternal and fetal corticosterone (CORT) levels. A negative correlation between maternal/fetal CORT levels and fetal bodyweight was observed. The maternal metabonome alterations included attenuated metabolism of carbohydrates, enhanced lipolysis and protein breakdown, and amino acid accumulation, suggesting GC-associated metabolic effects. GC-associated metabolite variations (α/β-glucoses, high density lipoprotein-cholesterol, β-hydroxybutyrate) were observed early following caffeine administration. In conclusion, prenatal caffeine exposure induced maternal GC elevation and metabonome alteration, and maternal GC and relevant discriminatory metabolites might be involved in the metabolic programming of caffeine-induced IUGR.

Prenatal caffeine ingestion induces transgenerational neuroendocrine metabolic programming alteration in second generation rats

Our previous studies have demonstrated that prenatal caffeine ingestion induces an increased susceptibility to metabolic syndrome with alterations of glucose and lipid metabolic phenotypes in adult first generation (F1) of intrauterine growth retardation (IUGR) rats, and the underlying mechanism is originated from a hypothalamic–pituitary–adrenal (HPA) axis-associated neuroendocrine metabolic programming alteration in utero. This study aims to investigate the transgenerational effects of this programming alteration in adult second generation (F2). Pregnant Wistar rats were administered with caffeine (120mg/kg·d) from gestational day 11 until delivery. Four groups in F2 were set according to the cross-mating between control and caffeine-induced IUGR rats. F2 were subjected to a fortnight ice water swimming stimulus on postnatal month 4, and blood samples were collected before and after stress. Results showed that the majority of the activities of HPA axis and phenotypes of glucose and lipid metabolism were altered in F2. Particularly, comparing with the control group, caffeine groups had an enhanced corticosterone levels after chronic stress. Compared with before stress, the serum glucose levels were increased in some groups whereas the triglyceride levels were decreased. Furthermore, total cholesterol gain rates were enhanced but the high-density lipoprotein-cholesterol gain rates were decreased in most caffeine groups after stress. These transgenerational effects were characterized partially with gender and parental differences. Taken together, these results indicate that the reproductive and developmental toxicities and the neuroendocrine metabolic programming mechanism by prenatal caffeine ingestion have transgenerational effects in rats, which may help to explain the susceptibility to metabolic syndrome and associated diseases in F2.

Association of imprinting status of IGF2 with the pathophysiology of intrauterine growth retardation in rats

Insulin like growth factor 2 (IGF2) is a crucial imprinting gene which prompting placenta development and fetal growth. It demonstrates parent-of-origin-specific allelic expression that is epigenetically regulated by differential methylation of IGF2/H19 DMR. We aim to explore if abnormal IGF2 imprinting status that regulated by altered DNA methylation of IGF2/H19 DMR affects IGF2 expression leading to the occurrence of IUGR. First we established an IUGR model of rat at two different stages(19-d gestational age and 1-day-old) by maternal nutrition restriction, and the rat tissues in the control group and the IUGR group were collected which were divided into four subgroups(N=6~8, each subgroup): Subgroup 1 and Subgroup 2 was the placenta and liver tissue of fetuses with 19-d gestational age, respectively, Subgroup 3 and Subgroup 4 was the liver tissue and skeletal muscle tissue in the posterior limbs of 1-day-old rats, respectively. Then the mRNA and protein levels of IGF2 were tested in the four subgroups of the two groups. In each subgroup, pyrosequencing was used to test the DNA methylation level of imprinting control region IGF2/H19 DMR. We observed that the expression levels of IGF2 in the Subgroup1, Subgroup 2, Subgroup 3 were decreased significantly compared with the control group, but there were no obvious differences in the Subgroup 4 of the two groups. The pyrosequencing showed no significant differences in methylation levels of the CpG dinucleotides in IGF2/H19 DMR between the two groups. What’s more, the methylation ratio didn't change versus age, and maintained the same from fetus till adult, and it also stayed the same among different tissue types except for placenta which had a lower methylation fraction than the other tissues. We concluded that the expression of IGF2 was down-regulated in the IUGR rats, which could play an important role in the pathogenesis of IUGR. However, the down regulation was not always the result of the aberrant imprinting status of the imprinting control region H19 DMR, as there wasn't a clear association between the two. IGF2 could be down regulated through other pathways, such as histone modification, or altered imprinting of another control region, to mediate the development of IUGR.

Decreased Kv1.5 expression in intrauterine growth retardation rats with exaggerated pulmonary hypertension

Chronic hypoxia pulmonary hypertension (CH-PHT) in adulthood is likely to be of fetal origin following intrauterine growth retardation (IUGR). Oxygen (O₂)-sensitive voltage-gated potassium channels (Kv channels) in resistance pulmonary artery smooth muscle cells (PASMCs) play an important role in scaling pulmonary artery (PA) pressure. Expression and functional changes of Kv channels are determined, in part, by embryonic development. We hypothesized that O₂-sensitive Kv channels play an important role in exaggerated CH-PHT following IUGR. We established a rat model of IUGR by restricting maternal food during the entire pregnancy and exposed IUGR rats and their age-matched controls aged 12 wk to hypoxia for 2 wk. We found that hypoxia exposure significantly induced increased PA pressure and thicker smooth muscle layer in the IUGR group relative to controls. We compared the constriction of the resistance PA to inhibitors of K⁺ channels, 4-aminopyridine (4-AP), tetraethylammonium, and BaCl₂. Despite the thickness of the smooth muscle layer, the constriction to 4-AP was significantly reduced in the IUGR group exposed to hypoxia. Consistent with these changes in pulmonary vascular reactivity, 2 wk of hypoxia induced weaker 4-AP-sensitive Kv currents in a single IUGR PASMC. Moreover, after 2 wk of hypoxia, Kv1.5 expression in resistance PAs decreased significantly in the IUGR group. Overexpression of Kv1.5 in cultured PASMCs could offset hypoxia-induced cell proliferation and hypoxia-inhibited Kv currents in the IUGR group. These results suggest that the inhibited expression of Kv1.5 in PASMCs contribute to the development of exaggerated CH-PHT in IUGR rats during adulthood.

Identifying placental epigenetic alterations in an intrauterine growth retardation (IUGR) rat model induced by gestational protein deficiency

Identifying placental epigenetic alterations in an intrauterine growth retardation (IUGR) rat model induced by gestational protein deficiency

Expressions of cannabinoid receptor 1 and L1 cell adhesion molecule in brain of rats with intrauterine growth retardation

Objective To study the mechanism of brain development delay in rats with intrauterine growth retardation(IUGR) through establishing IUGR animal model by low protein diet during pregnancy and examining the expressions of cannabinoid receptor1(CB1) and L1 cell adhesion molecule (NCAM-L1)in IUGR and normal rats. Methods Thirty-two pregnant rats were randomly fed with normal diet or lower protein diet during pregnancy (16 rats in each group). The offspring rats were divided into IUGR group and control group by birth weight, and sacrificed on day 0, 7, 14, 21 after birth, brain weight was recorded.The expressions of CB1 and NCAM-L1 in the brain were examined by immunohistochemistry staining.Image-Pro Plus 5.1 image processing software was used for semi-quantitative analysis.The integrated optical density of the CB1 and NCAM-L1 of the positive cells was calculated. Results The expressions of CB1 and NCAM-L1 in offspring rats brain were basically in the same area, the changes in both was in accord with the brain weight change.The expression of CB1 in the brain of the pup rats in the IUGR group was significantly lower than that in the control group 0, 7, 14, 21 days after birth, by contrast, the expression of NCAM-L1 was significantly higher(all P<0.05), and the expressions of CB1 and NCAM-L1 were negatively correlated between both groups(P=0.032, 0.010). Conclusions CB1 and NCAM-L1 were involved in the process of rat brain development.The effect of CB1 on rat brain development may be achieved by NCAM-L1. Key words: Intrauterine growth retardation; Cannabinoid receptor 1; L1 cell adhesion molecule; Rat

Epigenetics of hypoxic pulmonary arterial hypertension following intrauterine growth retardation rat: epigenetics in PAH following IUGR

BackgroundAccumulating evidence reveals that intrauterine growth retardation (IUGR) can cause varying degrees of pulmonary arterial hypertension (PAH) later in life. Moreover, epigenetics plays an important role in the fetal origin of adult disease. The goal of this study was to investigate the role of epigenetics in the development of PAH following IUGR.MethodsThe IUGR rats were established by maternal undernutrition during pregnancy. Pulmonary vascular endothelial cells (PVEC) were isolated from the rat lungs by magnetic-activated cell sorting (MACS). We investigated epigenetic regulation of the endothelin-1 (ET-1) gene in PVEC of 1-day and 6-week IUGR rats, and response of IUGR rats to hypoxia.ResultsThe maternal nutrient restriction increased the histone acetylation and hypoxia inducible factor-1α (HIF-1α) binding levels in the ET-1 gene promoter of PVEC in IUGR newborn rats, and continued up to 6 weeks after birth. These epigenetic changes could result in an IUGR rat being highly sensitive to hypoxia later in life, causing more significant PAH or pulmonary vascular remodeling.ConclusionsThese findings suggest that epigenetics is closely associated with the development of hypoxic PAH following IUGR, further providing a new insight for improved prevention and treatment of IUGR-related PAH.

Effects of SOCS 1/3 gene silencing on the expression of C/EBPα and PPARγ during differentiation and maturation of rat preadipocytes

Suppressor of cytokine signaling-1 and -3 (SOCS-1 and SOCS-3) are two important negative regulators in the insulin-signaling pathway, and their overexpression may aggravate insulin resistance. Subjects with insulin resistance are often obese and have increased expressions of SOCS-1 and SOCS-3. We speculated that SOCS-1 and SOCS-3 may be involved in abnormal deposition of adipose tissues during insulin resistance. A catch-up growth intrauterine growth retardation (CG-IUGR) rat model with insulin resistance was established; mRNA and protein expression of SOCS-1, SOCS-3, the CCAAT/enhancer binding protein (C/EBPα), and peroxisome proliferator-activated receptor (PPARγ) in adipose tissue were measured by real-time PCR and western blot; plasmids carrying small hairpin RNAs (shRNAs) targeting the SOCS-1 and SOCS-3 genes were constructed and transfected into preadipocytes, which were then induced to mature. At 72 h after differentiation was induced, the expressions of C/EBPα and PPARγ, two important molecules promoting the differentiation of preadipocytes, were detected. Expressions of SOCS-1, SOCS-3, C/EBPα, and PPARγ were markedly increased in adipose tissues of CG-IUGR rats, whereas the expressions of C/EBPα and PPARγ were significantly reduced after gene silencing of SOCS-1 or SOCS-3 in adipocytes. Overexpression of SOCS-1 and SOCS-3 may enhance the expression of C/EBPα and PPARγ, resulting in abnormal deposition of adipose tissues during insulin resistance.

Maternal hypertension induced by NO blockade does not program adult metabolic diseases in growth-restricted rat fetuses

ObjectivePreeclampsia is a frequent and potentially lethal placental insufficiency pathology causing maternal hypertension and proteinuria, as well as a high rate of intrauterine growth retardation (IUGR) in offspring. Reduced nitric oxide (NO) production may play a role in the mechanisms of this disease. As exposure to adverse early life environment and IUGR has been proposed to increase cardiometabolic diseases risk, we investigated in rats the effects of maternal NO blockade on growth and metabolic phenotype of offspring. Material and MethodsOsmotic pumps were implanted in pregnant rats at E17 and diffused saline or L-NAME (50mg/day), a nitric oxide synthesis inhibitor. At birth, IUGR male newborns without limb defects were selected. Body growth, feeding behavior and glucose tolerance were evaluated in offspring. Organs weights, plasma level of several metabolic hormones and genes expressions were determined in fasted 9month-old rats. ResultsL-NAME mothers had elevated blood pressure at E20. Male offspring from L-NAME mothers had a markedly reduced birth weight and developed postnatal catch-up growth during lactation. Some L-NAME newborns presented some limb defects but were not selected in this study (1/3 of all pups). Improved glucose tolerance and hyperphagia after fasting were found in 3-month-old L-NAME rat but not thereafter. In 9-month-old L-NAME rats, a moderate increase of food intake during the light phase and, after fasting, an augmentation of plasma insulin and a reduction of brown adipose tissue (BAT) deposit were found associated with an increased expression of UCP-1 mRNA in this tissue. ConclusionsDespite IUGR and postnatal catch up growth, male rats exposed to L-NAME did not develop metabolic diseases when limb defects were not induced by L-NAME. We postulate that maternal hypertension during late gestation is not a major ‘programming’ metabolic factor for offspring.

Maternal protein restriction in rats leads to reduced PGC-1α expression via altered DNA methylation in skeletal muscle

Intrauterine growth retardation (IUGR) is thought to program insulin resistance, type 2 diabetes and other metabolic diseases in later life. Skeletal muscle is an important tissue involved in regulating the metabolism. We therefore hypothesized that the regulation of glucose- and lipid-related genes in skeletal muscle may contribute to metabolic changes in rats with IUGR. In this study, IUGR rats were bred from pregnant rats fed a protein-restricted (PR) diet. Insulin resistance (IR)-related metabolic parameters and the expression of key regulatory IR genes such as peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α) and glucose transporter 4 (GLUT4) were measured in skeletal muscle from 18-month-old female IUGR rats. The methylation status of promoters of PGC-1α and GLUT4 were assessed in the same tissues. During the aging process, IUGR rats exhibited catch-up growth and obesity. In old age, they showed impaired glucose tolerance demonstrated by high glucose and insulin AUC (area under the curve) values. The expression of glucose transporter 4 (GLUT4) and PGC-1α in skeletal muscle was significantly reduced in IUGR rats. Mean CpG island methylation in the PGC-1α promoter sequence was significantly increased. These results suggest that a PR diet during gestation may induce epigenetic changes, such as DNA methylation, in the promoters of specific genes. The changes may affect gene expression and account for the metabolic alterations in female rats with IUGR.

Downregulating SOCS3 with siRNA ameliorates insulin signaling and glucose metabolism in hepatocytes of IUGR rats with catch-up growth

Individuals with intrauterine growth retardation (IUGR) who demonstrate a catch-up in body weight are prone to insulin resistance. High expressions of suppressor of cytokine signaling 3 (SOCS3) are thought to aggravate insulin resistance. We hypothesized that downregulating SOCS3 expression via small interfering RNA (siRNA) might have beneficial effects on insulin-resistant hepatocytes of catch-up growth IUGR rats (CG-IUGRs). An IUGR rat model was employed via maternal nutritional restriction. After evaluating metabolic states of CG-IUGR offspring, effective SOCS3-specific siRNA (siSOCS3) was transfected into cultured hepatocytes using liposomes. mRNA levels of SOCS3, insulin receptor substrates (IRSs), phosphatidylinositol 3-kinase (PI3K), and Akt2, key gluconeogenesis genes, were assessed via real-time PCR. Protein expression and phosphorylation changes were evaluated via western blot. CG-IUGR hepatocytes showed increases in SOCS3 and gluconeogenic gene expressions, and decreases in IRS1 and PI3K expressions as compared with controls. After transfecting CG-IUGR hepatocytes with siSOCS3, protein levels of IRS1, PI3K, and phosphorylated Akt2 were higher as compared with those of untransfected CG-IUGR cells. Transcriptional suppression effects of gluconeogenesis genes were more obvious in siSOCS3-treated cells after insulin stimulation. Additional insights were provided to understand mechanisms of insulin resistance in CG-IUGR rats. Downregulating SOCS3 might improve insulin signaling transduction and ameliorate hepatic glucose metabolism in insulin-resistant CG-IUGR rats in vitro.

A hypothalamic–pituitary–adrenal axis-associated neuroendocrine metabolic programmed alteration in offspring rats of IUGR induced by prenatal caffeine ingestion

Caffeine is a definite factor of intrauterine growth retardation (IUGR). Previously, we have confirmed that prenatal caffeine ingestion inhibits the development of hypothalamic–pituitary–adrenal (HPA) axis, and alters the glucose and lipid metabolism in IUGR fetal rats. In this study, we aimed to verify a programmed alteration of neuroendocrine metabolism in prenatal caffeine ingested-offspring rats. The results showed that prenatal caffeine (120mg/kg.day) ingestion caused low body weight and high IUGR rate of pups; the concentrations of blood adrenocorticotropic hormone (ACTH) and corticosterone in caffeine group were significantly increased in the early postnatal period followed by falling in late stage; the level of blood glucose was unchanged, while blood total cholesterol (TCH) and triglyceride (TG) were markedly enhanced in adult. After chronic stress, the concentrations and the gain rates of blood ACTH and corticosterone were obviously increased, meanwhile, the blood glucose increased while the TCH and TG decreased in caffeine group. Further, the hippocampal mineralocorticoid receptor (MR) expression in caffeine group was initially decreased and subsequently increased after birth. After chronic stress, the 11β-hydroxysteroid dehydrogenase-1, glucocorticoid receptor (GR), MR as well as the MR/GR ratio were all significantly decreased. These results suggested that prenatal caffeine ingestion induced the dysfunction of HPA axis and associated neuroendocrine metabolic programmed alteration in IUGR offspring rats, which might be related with the functional injury of hippocampus. These observations provide a valuable experimental basis for explaining the susceptibility of IUGR offspring to metabolic syndrome and associated diseases.

Delayed Myelination in an Intrauterine Growth Retardation Model Is Mediated by Oxidative Stress Upregulating Bone Morphogenetic Protein 4

Intrauterine growth retardation (IUGR) is associated with neurological deficits including cerebral palsy and cognitive and behavioral disabilities. The pathogenesis involves oxidative stress that leads to periventricular white matter injury with a paucity of mature oligodendrocytes and hypomyelination. The molecular mechanisms underlying this damage remain poorly understood. We used a rat model of IUGR created by bilateral ligation of the uterine artery at embryonic Day 19 that results in fetal growth retardation and oxidative stress in the developing brain. The IUGR rat pups showed significant delays in oligodendrocyte differentiation and myelination that resolved by 8 weeks. Bone morphogenetic protein 4 (BMP4), which inhibits oligodendrocyte maturation, was elevated in IUGR brains at postnatal time points and returned to near normal by adulthood. Despite the apparent recovery, behavioral deficiencies were found in 8-week-old female animals, suggesting that the early transient myelination defects have permanent effects. In support of these in vivo data, oligodendrocyte precursor cells cultured from postnatal IUGR rats retained increased BMP4 expression and impaired differentiation that was reversed with the BMP inhibitor noggin. Oxidants in oligodendrocyte cultures increased BMP expression, which decreased differentiation; however, abrogating BMP signaling with noggin in vitro and in BMP-deficient mice prevented these effects. Together, these findings suggest that IUGR results in delayed myelination through the generation of oxidative stress that leads to BMP4 upregulation.

Role of p53‐dependent placental apoptosis in the reproductive and developmental toxicities of caffeine in rodents

The aim of the present study was to evaluate the role of placental apoptosis in mediating the reproductive and developmental toxicity of caffeine in rodents. Female Kunming mice were treated with caffeine (60, 120 and 240mg/kg per day) before and during pregnancy. The conception rate, maternal bodyweight gain, placental weight and indices of fetal developmental, including the rate of intrauterine growth retardation (IUGR; i.e. the actual number of fetuses exhibiting IUGR as a percentage of the total number of fetuses), were determined on gestational day (GD) 18. Female Wistar rats were treated with caffeine (20, 60 and 180mg/kg per day) from GD11 to GD20. The IUGR rate, maternal plasma angiotensin (Ang) II and prolactin concentrations, placental pathology, expression of angiotensin AT(1) and AT(2) receptors and apoptosis-related proteins were measured on GD20. In mice, caffeine treatment dose-dependently reduced the total conception rate, delayed conception and decreased maternal bodyweight gain, placental weight, fetal bodyweight and fetal body and tail lengths, whereas the IUGR rate was increased. In rats, caffeine treatment dose-dependently decreased placental weight and fetal bodyweight and increased the IUGR rate. Abnormal placental structures and decreased maternal plasma prolactin concentrations were observed following 180mg/kg per day caffeine treatment, which resulted in increases in renin-angiotensin system (RAS) activity, including maternal plasma AngII concentrations and placental AT(1B) and AT(2) receptor expression, and Bax and p53 expression, but decreases in placental Bcl-2 expression. On the basis of the results of the present study, it appears that caffeine ingestion has detrimental effects on the reproductive system and fetal development in rodents that are associated with chronic activation of the maternal and placental RAS, and induction of p53-dependent placental apoptosis.

Perinatal undernutrition alters intestinal alkaline phosphatase and its main transcription factors KLF4 and Cdx1 in adult offspring fed a high-fat diet

Nutrient restriction during gestation and/or suckling is associated with an increased risk of developing inflammation, obesity and metabolic diseases in adulthood. However, the underlying mechanisms, including the role of the small intestine, are unclear. We hypothesized that intestinal adaptation to the diet in adulthood is modulated by perinatal nutrition. This hypothesis was tested using a split-plot design experiment with 20 controls and 20 intrauterine growth-retarded (IUGR) rats aged 240 days and randomly assigned to be fed a standard chow or a high-fat (HF) diet for 10 days. Jejunal tissue was collected at necropsy and analyzed for anatomy, digestive enzymes, goblet cells and mRNA levels. Cecal contents and blood serum were analyzed for alkaline phosphatase (AP). IUGR rats failed to adapt to HF by increasing AP activity in jejunal tissue and cecal content as observed in controls. mRNA levels of transcription factors KLF4 and Cdx1 were blunted in jejunal epithelial cell of IUGR rats fed HF. mRNA levels of TNF-α were lower in IUGR rats. They also displayed exacerbated aminopeptidase N response and reduced jejunal goblet cell density. Villus and crypt architecture and epithelial cell proliferation increased with HF in both control and IUGR rats. Serum AP tended to be lower, and serum levamisole inhibition-resistant AP fraction was lower, in IUGR than controls with HF. Serum fatty acids and triglycerides were higher in IUGR rats and higher with HF. In conclusion, the adult intestine adapts to an HF diet differentially depending on early nutrition, jejunal AP and transcription factors being blunted in IUGR individuals fed HF.

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.

Reduction in BDNF-induced neurotransmitter release in cultured cortical neurons from intrauterine growth retardation rats

Reduction in BDNF-induced neurotransmitter release in cultured cortical neurons from intrauterine growth retardation rats