Metabolic induction and early responses of mouse blastocyst developmental programming following maternal low protein diet affecting life-long health

Previously, we have shown that a maternal low protein diet, fed exclusively during the preimplantation period of mouse development (Emb-LPD), is sufficient to induce by the blastocyst stage a compensatory growth phenotype in late gestation and postnatally, correlating with increased risk of adult onset cardiovascular disease and behavioural dysfunction. Here, we examine mechanisms of induction of maternal Emb-LPD programming and early compensatory responses by the embryo. Emb-LPD induced changes in maternal serum metabolites at the time of blastocyst formation (E3.5), notably reduced insulin and increased glucose, together with reduced levels of free amino acids (AAs) including branched chain AAs leucine, isoleucine and valine. Emb-LPD also caused reduction in the branched chain AAs within uterine fluid at the blastocyst stage. These maternal changes coincided with an altered content of blastocyst AAs and reduced mTORC1 signalling within blastocysts evident in reduced phosphorylation of effector S6 ribosomal protein and its ratio to total S6 protein but no change in effector 4E-BP1 phosphorylated and total pools. These changes were accompanied by increased proliferation of blastocyst trophectoderm and total cells and subsequent increased spreading of trophoblast cells in blastocyst outgrowths. We propose that induction of metabolic programming following Emb-LPD is achieved through mTORC1signalling which acts as a sensor for preimplantation embryos to detect maternal nutrient levels via branched chain AAs and/or insulin availability. Moreover, this induction step associates with changes in extra-embryonic trophectoderm behaviour occurring as early compensatory responses leading to later nutrient recovery. © 2012 Fleming et al.

Adaptive responses of the embryo to maternal diet and consequences for post-implantation development

Maternal periconceptional (PC) nutrition, coupled with maternal physiological condition, can impact on reproductive performance and potential across mammalian species. Oocyte quality and embryo development are affected adversely by either nutrient restriction or excess. Moreover, the quality of maternal PC nutrition can have lasting effects through fetal development and postnatally into adulthood. Chronic disease, notably cardiovascular and metabolic disease, and abnormal behaviour have been identified in adult offspring in small and large animal models of PC nutrient restriction. These long-term effects associate with compensatory responses that begin from the time of early embryo development. This review assesses the field of PC nutrition in vivo on short- and long-term developmental consequences in rodent and ruminant models and considers the implications for human health. © IETS 2012.

Maternal periconceptional and gestational low protein diet affects mouse offspring growth, cardiovascular and adipose phenotype at 1 year of age

Human and animal studies have revealed a strong association between periconceptional environmental factors, such as poor maternal diet, and an increased propensity for cardiovascular and metabolic disease in adult offspring. Previously, we reported cardiovascular and physiological effects of maternal low protein diet (LPD) fed during discrete periods of periconceptional development on 6-month-old mouse offspring. Here, we extend the analysis in 1 year aging offspring, evaluating mechanisms regulating growth and adiposity. Isocaloric LPD (9% casein) or normal protein diet (18% casein; NPD) was fed to female MF-1 mice either exclusively during oocyte maturation (for 3.5 days prior to mating; Egg-LPD, Egg-NPD, respectively), throughout gestation (LPD, NPD) or exclusively during preimplantation development (for 3.5 days post mating; Emb-LPD). LPD and Emb-LPD female offspring were significantly lighter and heavier than NPD females respectively for up to 52 weeks. Egg-LPD, LPD and Emb-LPD offspring displayed significantly elevated systolic blood pressure at 52 weeks compared to respective controls (Egg-NPD, NPD). LPD females had significantly reduced inguinal and retroperitoneal fat pad: body weight ratios compared to NPD females. Expression of the insulin receptor (Insr) and insulin-like growth factor I receptor (Igf1r) in retroperitoneal fat was significantly elevated in Emb-LPD females (P&0.05), whilst Emb-LPD males displayed significantly decreased expression of the mitochondrial uncoupling protein 1 (Ucp1) gene compared to NPD offspring. LPD females displayed significantly increased expression of Ucp1 in interscapular brown adipose tissue when compared to NPD offspring. Our results demonstrate that aging offspring body weight, cardiovascular and adiposity homeostasis can be programmed by maternal periconceptional nutrition. These adverse outcomes further exemplify the criticality of dietary behaviour around the time of conception on long-term offspring health. © 2011 Watkins et al.

Tissue-specific selection of reference genes is required for expression studies in the mouse model of maternal protein undernutrition

Suboptimal maternal nutrition during gestation results in the establishment of long-term phenotypic changes and an increased disease risk in the offspring. To elucidate how such environmental sensitivity results in physiological outcomes, the molecular characterisation of these offspring has become the focus of many studies. However, the likely modification of key cellular processes such as metabolism in response to maternal undernutrition raises the question of whether the genes typically used as reference constants in gene expression studies are suitable controls. Using a mouse model of maternal protein undernutrition, we have investigated the stability of seven commonly used reference genes (18s, Hprt1, Pgk1, Ppib, Sdha, Tbp and Tuba1) in a variety of offspring tissues including liver, kidney, heart, retro-peritoneal and inter-scapular fat, extra-embryonic placenta and yolk sac, as well as in the preimplantation blastocyst and blastocyst-derived embryonic stem cells. We find that although the selected reference genes are all highly stable within this system, they show tissue, treatment and sex-specific variation. Furthermore, software-based selection approaches rank reference genes differently and do not always identify genes which differ between conditions. Therefore, we recommend that reference gene selection for gene expression studies should be thoroughly validated for each tissue of interest. © 2011 Elsevier Inc.

Maternal low-protein diet during mouse pre-implantation development induces vascular dysfunction and altered renin-angiotensin-system homeostasis in the offspring

Environmental perturbations during early mammalian development can affect aspects of offspring growth and cardiovascular health. We have demonstrated previously that maternal gestational dietary protein restriction in mice significantly elevated adult offspring systolic blood pressure. Therefore, the present study investigates the key mechanisms of blood pressure regulation in these mice. Following mating, female MF-1 mice were assigned to either a normal-protein diet (NPD; 18% casein) or an isocaloric low-protein diet throughout gestation (LPD; 9% casein), or fed the LPD exclusively during the pre-implantation period (3.5d) before returning to the NPD for the remainder of gestation (Emb-LPD). All offspring received standard chow. At 22 weeks, isolated mesenteric arteries from LPD and Emb-LPD males displayed significantly attenuated vasodilatation to isoprenaline (P=0.04 and P=0.025, respectively), when compared with NPD arteries. At 28 weeks, stereological analysis of glomerular number in female left kidneys revealed no significant difference between the groups. Real-time RT-PCR analysis of type 1a angiotensin II receptor, Na /K ATPase transporter subunits and glucocorticoid receptor expression in male and female left kidneys revealed no significant differences between the groups. LPD females displayed elevated serum angiotensin-converting enzyme (ACE) activity (P=0.044), whilst Emb-LPD males had elevated lung ACE activity (P=0.001), when compared with NPD offspring. These data demonstrate that elevated offspring systolic blood pressure following maternal gestational protein undernutrition is associated with impaired arterial vasodilatation in male offspring, elevated serum and lung ACE activity in female and male offspring, respectively, but kidney glomerular number in females and kidney gene expression in male and female offspring appear unaffected. © 2010 The Authors.

Adaptive responses by mouse early embryos to maternal diet protect fetal growth but predispose to adult onset disease

Poor maternal nutrition during pregnancy can alter postnatal phenotype and increase susceptibility to adult cardiovascular and metabolic diseases. However, underlying mechanisms are largely unknown. Here, we show that maternal low protein diet (LPD), fed exclusively during mouse preimplantation development, leads to offspring with increased weight from birth, sustained hypertension, and abnormal anxiety-related behavior, especially in females. These adverse outcomes were interrelated with increased perinatal weight being predictive of later adult overweight and hypertension. Embryo transfer experiments revealed that the increase in perinatal weight was induced within blastocysts responding to preimplantation LPD, independent of subsequent maternal environment during later pregnancy. We further identified the embryo-derived visceral yolk sac endoderm (VYSE) as one mediator of this response. VYSE contributes to fetal growth through endocytosis of maternal proteins, mainly via the multiligand megalin (LRP2) receptor and supply of liberated amino acids. Thus, LPD maintained throughout gestation stimulated VYSE nutrient transport capacity and megalin expression in late pregnancy, with enhanced megalin expression evident even when LPD was limited to the preimplantation period. Our results demonstrate that in a nutrient-restricted environment, the preimplantation embryo activates physiological mechanisms of developmental plasticity to stablize conceptus growth and enhance postnatal fitness. However, activation of such responses may also lead to adult excess growth and cardiovascular and behavioral diseases. © 2008 by the Society for the Study of Reproduction, Inc.

Predictors of maternal control of feeding at 1 and 2 years of age

Objective: To establish the best predictors of maternal use of controlling feeding practices at 1 and 2 years of age. Design: A longitudinal study from birth to 2 years. Participants: Sixty-two mothers of 2-year-old children. Measures: Infant weight at birth, 6, 12 and 24 months, breastfeeding history, infant temperament and feeding difficulties at 6 and 12 months, maternal demographics at 12 and 24 months, maternal mental health at 6 and 12 months, maternal controlling feeding practices at 12 and 24 months. Results: Controlling feeding practices at 1 year were predicted by perceptions of infant temperament at 6 months, birth weight, length of breastfeeding, mental health at 6 months, and mealtime negativity at 6 months. Parental control over feeding when their child reached 2 years was predicted by the mother's tendency to use that particular strategy at 1 year in combination with the perceptions of infant temperament and feeding problems at 1 year, weight at 1 year, length of breastfeeding in infancy, and/or maternal mental health at 1 year. Conclusions: Breastfeeding appears to promote subsequent monitoring, and is associated with reduced use of pressurising and restrictive feeding practices. Infant characteristics are important predictors of control at both 1 and 2 years of age. The use of controlling feeding practices is relatively stable from 1 to 2 years. © 2007 Nature Publishing Group All rights reserved.

The development of maternal self-esteem

Although an important theoretical concept, little is known about the development of maternal self-esteem. This study explores the significance of maternal cognitions, psychopathological symptoms, and child temperament in the prediction of prenatal and postnatal maternal self-esteem. During pregnancy 162 women completed measures assessing their unhealthy core beliefs, psychopathological symptoms, and self-esteem. At 1 year postpartum 87 of these women completed measures assessing their self-esteem and their child's temperament. Overall maladaptive maternal core beliefs and psychopathological symptoms during pregnancy explained 19% of the variance in prenatal maternal self-esteem. Forty-two percent of the variance in maternal self-esteem at 1 year could be explained by a combination of prenatal maternal self-esteem, mental health symptoms, maternal core beliefs, and more unsociable infant temperament. Underlying maternal cognitive structures may be important in determining the development of maternal self-esteem. © 2007 2006 Michigan Association for Infant Mental Health.

Breast-feeding, maternal feeding practices and mealtime negativity at one year

This paper explores whether breast-feeding, mediated by lower maternal use of controlling strategies, predicts more positive mealtime interactions between mothers and their 1 year old infants. Eighty-seven women completed questionnaires regarding breast-feeding, assessing their control over child feeding and mealtime negativity at 1 year of infant age. Seventy-four of these women were also observed feeding their infants solid food at 1 year. Mediation analyses demonstrated that the experience of breast-feeding, mediated by lower reported maternal control over child feeding, predicted maternal reports of less negative mealtime interactions. The experience of breast-feeding also predicted observations of less conflict at mealtimes, mediated by observations of maternal sensitivity during feeding interactions. The implications of these findings are discussed.

Does maternal control during feeding moderate early infant weight gain?

OBJECTIVE. Our objective with this study was to examine whether observed maternal control during feeding at 6 months of age moderates the development of early infant weight gain during the first year of life. METHODS. Sixty-nine women were observed feeding their 6-month-old infants during a standard meal. Mealtimes were coded for maternal use of controlling feeding behavior. All infants were weighed at birth and at 6 and 12 months of age, and weight gain was calculated from birth to 6 months and from 6 to 12 months. Weight scores and weight gain scores were standardized for prematurity, age, and gender. RESULTS. Infant weight gain between 6 and 12 months of age was predicted by an interaction between early infant weight gain (birth to 6 months) and observed maternal control during feeding at 6 months. When maternal control was moderate or low, there was a significant interaction with weight gain from birth to 6 months in the prediction of later infant weight gain from 6 to 12 months, such that infants who showed slow early weight gain accelerated in their subsequent weight gain, and those with greater early weight gain decelerated. Conversely, when maternal control was high, infant weight gain followed the opposite pattern. CONCLUSION. Maternal control of solid feeding can moderate infant weight gain.

Maternal cognitions, psychopathologic symptoms, and infant temperament as predictors of early infant feeding problems:a longitudinal study

Objective: The current study examined the contribution of prenatal and postnatal maternal core beliefs, self-esteem, psychopathologic symptoms, and postnatal infant temperament to the prediction of infant feeding difficulties. Method: Ninety-nine women completed questionnaires assessing their core beliefs, psychopathology, and self-esteem during pregnancy and at 6 months postpartum. At 6 months, mothers also rated their infant's temperament and feeding, and were observed feeding their infants. Results: Maternal reports of child feeding difficulties were predicted by higher levels of emotional deprivation and entitlement core beliefs and lower levels of self-sacrifice and enmeshment core beliefs during pregnancy. Postnatal social isolation core beliefs, lower maternal self-esteem, and more difficult infant temperament added significantly to the variance explained by prenatal factors. Maternal core beliefs, self-esteem, psychopathology, and infant temperament failed to significantly predict independent observations of child food refusal. Conclusion: Maternal cognitions are implicated in the development of maternal reports of feeding difficulty.

Is maternal psychopathology related to obesigenic feeding practices at 1 year?

Objective: To investigate the relationship between maternal psychopathological symptomatology during pregnancy and at 6 and 12 months postnatally and maternal use of controlling and restrictive feeding practices at 1 year. Research Methods and Procedures: Eighty-seven women completed a measure of psychological distress during pregnancy and at 6 and 12 months postpartum, and at 12 months postnatally these women reported their usage of controlling and restrictive feeding practices and were observed feeding their infants. Results: General psychological distress, particularly anxious psychopathology, during pregnancy and at 6 and 12 months postnatally was significantly associated with maternal use of restrictive feeding practices at 1 year, even when controlling for length of breast-feeding and the infants' weights at 1 year. Contrary to expectations, depression and eating psychopathology as measured by the SCOFF eating disorder measure during pregnancy or at 6 or 12 months postnatally were not associated with the use of controlling or restrictive feeding practices at 1 year. Discussion: These findings indicate that anxious maternal psychopathology may partially explain the development of maternal use of restriction when feeding. Copyright © 2005 NAASO.

Maternal core beliefs and children's feeding problems

Background: Although maternal mental health problems have been implicated in the exacerbation of childhood feeding difficulties, little research has assessed the contribution of broader maternal cognitions to these problems. The current study examined gender differences in the relationships between mothers' core beliefs and children's feeding problems. Methods: One hundred and three mothers of girls and 93 mothers of boys (age range, 7-64 months) completed the Young Schema Questionnaire and the Child Feeding Assessment Questionnaire. Results: While controlling for child age, a clear link between maternal core beliefs and perceived feeding difficulties emerged for mothers of girls. In particular, abandonment, failure to achieve, dependence and incompetence, enmeshment and defectiveness, and shame beliefs were associated with increased reports of feeding problems in girls. In contrast, emotional deprivation and subjugation beliefs were associated with maternal reports of food fussiness and food refusal in boys. Conclusions: There appears to be a clear role for maternal core beliefs in the reporting of feeding difficulties in children, and the specificity of these links differs depending on the gender of the child. Further research is required to establish the direction of causality and the specificity of these relationships. © 2005 by Wiley Periodicals, Inc.

Maternal nutrition modifies trophoblast giant cell phenotype and fetal growth in mice

Mammalian placentation is dependent upon the action of trophoblast cells at the time of implantation. Appropriate fetal growth, regulated by maternal nutrition and nutrient transport across the placenta, is a critical factor for adult offspring long-term health. We have demonstrated that a mouse maternal low-protein diet (LPD) fed exclusively during preimplantation development (Emb-LPD) increases offspring growth but programmes adult cardiovascular and metabolic disease. In this study, we investigate the impact of maternal nutrition on post-implantation trophoblast phenotype and fetal growth. Ectoplacental cone explants were isolated at day 8 of gestation from female mice fed either normal protein diet (NPD: 18% casein), LPD (9% casein) or Emb-LPD and cultured in vitro. We observed enhanced spreading and cell division within proliferative and secondary trophoblast giant cells (TGCs) emerging from explants isolated from LPD-fed females when compared with NPD and Emb-LPD explants after 24 and 48 h. Moreover, both LPD and Emb-LPD explants showed substantial expansion of TGC area during 24-48 h, not observed in NPD. No difference in invasive capacity was observed between treatments using Matrigel transwell migration assays. At day 17 of gestation, LPD- and Emb-LPD-fed conceptuses displayed smaller placentas and larger fetuses respectively, resulting in increased fetal:placental ratios in both groups compared with NPD conceptuses. Analysis of placental and yolk sac nutrient signalling within the mammalian target of rapamycin complex 1 pathway revealed similar levels of total and phosphorylated downstream targets across groups. These data demonstrate that early post-implantation embryos modify trophoblast phenotype to regulate fetal growth under conditions of poor maternal nutrition.