Placental growth, angiogenic gene expression, and vascular development in undernourished adolescent sheep

Supplementary feeding and infection control in pregnant adolescents-A secondary analysis of a randomized trial among malnourished women in Sierra Leone

Undernutrition during pregnancy in adolescence confers a high risk of maternal morbidity and adverse birth outcomes, particularly in low-resource settings. In a secondary analysis, we hypothesized that younger undernourished pregnant adolescents (<18 years) would benefit more than undernourished pregnant adults (>20 years) from the intervention of supplementary food and anti-infective treatments. The original trial in Sierra Leone enrolled 236 younger adolescents (<18 years), 454 older adolescents (aged 18-19 years), and 741 adults (≥20 years), all with a mid-upper arm circumference ≤23 cm. Younger adolescents had lower final fundal height as well as smaller newborns (-0.3 kg; 95% confidence interval [CI], -0.3, -0.2; p < 0.001) and shorter newborns (-1.1 cm; 95% CI, -1.5, -0.7; p < 0.001) than adults. The intervention's effect varied significantly between maternal age groups: adults benefited more than younger adolescents with respect to newborn birth weight (difference in difference, 166 g; 95% CI, 26, 306; interaction p = 0.02), birth length (difference in difference, 7.4 mm; 95% CI, 0.1, 14.8; interaction p = 0.047), and risk for low birth weight (<2.5 kg) (interaction p = 0.019). The differences in response persisted despite adjustments for maternal anthropometry, the number of prior pregnancies, and human immunodeficiency virus status. Older adolescents similarly benefited more than younger adolescents, though differences did not reach statistical significance. In conclusion, newborns born to younger adolescent mothers had worse outcomes than those born to adult mothers, and adults and their newborns benefited more from the intervention than younger adolescents.

Competition for nutrients in pregnant adolescents: consequences for maternal, conceptus and offspring endocrine systems

The competition for nutrients that arises when pregnancy coincides with continuing or incomplete growth in young adolescent girls increases the risk of preterm delivery and low birthweight with negative after-effects for mother and child extending beyond the perinatal period. Sheep paradigms involving nutritional management of weight and adiposity in young, biologically immature adolescents have allowed the consequences of differential maternal growth status to be explored. Although nutrient reserves at conception play a modest role, it is the dietary manipulation of the maternal growth trajectory thereafter which has the most negative impact on pregnancy outcome. Overnourishing adolescents to promote rapid maternal growth is particularly detrimental as placental growth, uteroplacental blood flows and fetal nutrient delivery are perturbed leading to a high incidence of fetal growth restriction and premature delivery of low birthweight lambs, whereas in undernourished adolescents further maternal growth is prevented, and depletion of the maternal body results in a small reduction in birthweight independent of placental size. Maternal and placental endocrine systems are differentially altered in both paradigms with downstream effects on fetal endocrine systems, organ development and body composition. Approaches to reverse these effects have been explored, predominantly targeting placental growth or function. After birth, growth-restricted offspring born to overnourished adolescents and fed to appetite have an altered metabolic phenotype which persists into adulthood, whereas offspring of undernourished adolescents are largely unaffected. This body of work using ovine paradigms has public health implications for nutritional advice offered to young adolescents before and during pregnancy, and their offspring thereafter.

HIV antiretroviral exposure in pregnancy induces detrimental placenta vascular changes that are rescued by progesterone supplementation

Adverse birth outcomes are common in HIV-positive pregnant women receiving combination antiretroviral therapy (cART), especially when cART is initiated in early pregnancy. The mechanisms remain poorly understood. Using a mouse model we demonstrate that protease inhibitor based-cART exposure beginning on day 1 of pregnancy was associated with a pro-angiogenic/pro-branching shift in the placenta driven by lower Flt-1 levels and higher Gcm-1 expression. Micro-CT imaging revealed an increase in the number of arterioles in cART-treated placentas, which correlated with fetal growth restriction. Delaying initiation of cART, or supplementing cART-treated mice with progesterone, prevented the pro-angiogenic/pro-branching shift and the associated placenta vascular changes. In agreement with our mouse findings, we observed an increase in the number of terminal-villi capillaries in placentas from HIV-positive cART-exposed women compared to HIV-negative controls. Capillary number was inversely correlated to maternal progesterone levels. Our study provides evidence that cART exposure during pregnancy influences placenta vascular formation that may in turn contribute to fetal growth restriction. Our findings highlight the need for closer investigation of the placenta in HIV-positive pregnancies, particularly for pregnancies exposed to cART from conception, and suggest that progesterone supplementation could be investigated as a possible intervention to improve placenta function in HIV-positive pregnant women.

Diet before and during Pregnancy and Offspring Health: The Importance of Animal Models and What Can Be Learned from Them

This review article outlines epidemiologic studies that support the hypothesis that maternal environment (including early nutrition) plays a seminal role in determining the offspring’s long-term health and metabolism, known as the concept of Developmental Origins of Health and Diseases (DOHaD). In this context, current concerns are particularly focused on the increased incidence of obesity and diabetes, particularly in youth and women of child-bearing age. We summarize key similarities, differences and limitations of various animal models used to study fetal programming, with a particular focus on placentation, which is critical for translating animal findings to humans. This review will assist researchers and their scientific audience in recognizing the pros and cons of various rodent and non-rodent animal models used to understand mechanisms involved in fetal programming. Knowledge gained will lead to improved translation of proposed interventional therapies before they can be implemented in humans. Although rodents are essential for fundamental exploration of biological processes, other species such as rabbits and other domestic animals offer more tissue-specific physiological (rabbit placenta) or physical (ovine maternal and lamb birth weight) resemblances to humans. We highlight the important maternal, placental, and fetal/neonatal characteristics that contribute to developmentally programmed diseases, specifically in offspring that were affected in utero by undernutrition, overnutrition or maternal diabetes. Selected interventions aimed at prevention are summarized with a specific focus on the 1000 days initiative in humans, and maternal exercise or modification of the n-3/n-6 polyunsaturated fatty acid (PUFA) balance in the diet, which are currently being successfully tested in animal models to correct or reduce adverse prenatal programming. Animal models are essential to understand mechanisms involved in fetal programming and in order to propose interventional therapies before they can be implemented in humans. Non-rodent animals are particularly important and should not be neglected, as they are often more physiologically-appropriate models to mimic the human situation.

N-carbamylglutamate and L-arginine improved maternal and placental development in underfed ewes

The objectives of this study were to determine how dietary supplementation ofN-carbamylglutamate (NCG) and rumen-protected L-arginine (RP-Arg) in nutrient-restricted pregnant Hu sheep would affect (1) maternal endocrine status; (2) maternal, fetal, and placental antioxidation capability; and (3) placental development. From day 35 to day 110 of gestation, 32 Hu ewes carrying twin fetuses were allocated randomly into four groups: 100% of NRC-recommended nutrient requirements, 50% of NRC recommendations, 50% of NRC recommendations supplemented with 20g/day RP-Arg, and 50% of NRC recommendations supplemented with 5g/day NCG product. The results showed that in maternal and fetal plasma and placentomes, the activities of total antioxidant capacity and superoxide dismutase were increased (P<0.05); however, the activity of glutathione peroxidase and the concentration of maleic dialdehyde were decreased (P<0.05) in both NCG- and RP-Arg-treated underfed ewes. The mRNA expression of vascular endothelial growth factor and Fms-like tyrosine kinase 1 was increased (P<0.05) in 50% NRC ewes than in 100% NRC ewes, and had no effect (P>0.05) in both NCG- and RP-Arg-treated underfed ewes. A supplement of RP-Arg and NCG reduced (P<0.05) the concentrations of progesterone, cortisol, and estradiol-17β; had no effect on T4/T3; and improved (P<0.05) the concentrations of leptin, insulin-like growth factor 1, tri-iodothyronine (T3), and thyroxine (T4) in serum from underfed ewes. These results indicate that dietary supplementation of NCG and RP-Arg in underfed ewes could influence maternal endocrine status, improve the maternal–fetal–placental antioxidation capability, and promote fetal and placental development during early-to-late gestation.

Decreasing maternal nutrient intake during the final third of pregnancy in previously overnourished adolescent sheep: effects on maternal nutrient partitioning and feto-placental development

When pregnant adolescent sheep are overnourished during pregnancy normal nutrient partitioning priorities to the gravid uterus are altered, leading to impaired placental development and fetal growth restriction. We hypothesized that decreasing dietary intake in overnourished dams during the final third of gestation may reverse this inappropriate nutrient partitioning in favor of the fetus. Adolescent ewes were offered control (C; n = 12) or high (H; n = 20) dietary intakes to induce normal vs. compromised placental development. Ten ewes receiving the H intake were switched to a low intake at d90 of gestation (HL). Between d90 to 130, HL dams lost weight and adiposity, and metabolic hormones and glucose at d130 were less than H and similar to C. In spite of these maternal changes, at d130 fetal bodyweight was equivalent in HL and H groups and ∼20% less than in C. A greater degree of brain sparing was evident in HL fetuses and glucose and insulin concentrations were more perturbed than in H fetuses. Relative to C, placentome weight was reduced by 46 and 32% in H and HL and the fetal:placentome weight ratio was H > HL > C. Placental vascular morphology was largely unaffected by maternal diet during late gestation but mRNA expression of five angiogenic genes was up-regulated in the fetal cotyledon of HL pregnancies, commensurate with blood vessel remodeling. Nevertheless, overfeeding to promote maternal anabolic growth during adolescent pregnancy impairs feto-placental development that cannot be rescued by reducing maternal intake during the final third of gestation.

Adverse metabolic phenotype in low-birth-weight lambs and its modification by postnatal nutrition

Both high and low maternal dietary intakes adversely affect fetal nutrient supply in adolescent sheep pregnancies. Aims were: (a) to assess the impact of prenatal nutrition on pregnancy outcome, offspring growth and offspring glucose metabolism and (b) to determine whether the offspring metabolic phenotype could then be altered by modifying postnatal nutrition. Dams carrying a single fetus were offered either an optimal control (C) intake to maintain adiposity throughout pregnancy, undernourished to maintain weight at conception but deplete maternal reserves (UN), or overnourished to promote rapid maternal growth and adiposity (ON). Placental weight and gestation length were reduced in ON dams and lamb birth weights were C>UN>ON (P < 0·001). All offspring were fed ad libitum from weaning to 6 months of age. ON offspring exhibited rapid catch-up growth and had increased fasting glucose and relative glucose intolerance compared with C offspring (P < 0·05). Irrespective of prenatal diet and sex, birth weight correlated negatively with these indices of glucose metabolism. From 7 to 12 months offspring either had continued ad libitum diet (ADLIB; to induce an obesogenic state) or a decreased ration appropriate for normal growth (NORM). At 12 months, the negative relationship between birth weight and indices of glucose metabolism persisted in ADLIB females (for example, fasting glucose, r − 0·632; P < 0·03) but was absent in NORM females and in both male groups. Therefore, low-birth-weight offspring from differentially achieved prenatal malnutrition exhibit an early adverse metabolic phenotype, and this can apparently be ameliorated by postnatal nutrition in females but not in males.

Postnatal hypothalamic - pituitary - adrenal function in sheep is influenced by age and sex, but not by prenatal growth restriction

The relationship between impaired fetal nutrient supply and postnatal hypothalamic–pituitary–adrenal (HPA) function was examined in ovine models of prenatal growth restriction (GR) caused by small placental size (SP) or by maternal undernutrition (UN). Adrenocorticotrophin (ACTH) and cortisol responses following corticotrophin-releasing hormone (CRH) plus arginine vasopressin (AVP) challenge were examined at 9, 18 and 24 months in growth-restricted (GR-SP) and normal birthweight (control) females (Experiment 1), and at 6 months in growth-restricted (GR-SP, GR-UN) and normal weight males and females (Experiment 2). In Experiment 1, GR-SP offspring were born early, were 40% lighter at birth and had higher fractional weight gains to weaning than control offspring. Baseline ACTH and cortisol were independent of GR and cortisol decreased with age. GR did not affect the HPA response to CRH + AVP challenge at any stage, but ACTH increased with age. In Experiment 2, birthweight was greater in control offspring than in GR-UN offspring, which had a higher birthweight again compared with GR-SP offspring. Only the latter group was born early and exhibited rapid catch-up growth to weaning. Neither nutritional route to GR altered HPA function at 6 months. Males grew faster than females and HPA responses after stimulation were lower in males. Together, the results of these studies demonstrate that postnatal HPA function in sheep is influenced by age and sex, but not by GR.

Maternal selenium supplementation and timing of nutrient restriction in pregnant sheep: effects on maternal endocrine status and placental characteristics

To determine the effects of maternal Se intake and plane of nutrition during midgestation, late gestation, or both on hormone and metabolite concentrations in the dam and on placental characteristics, pregnant ewe lambs (n = 64) were assigned to 1 of 8 treatments arranged in a 2 x 2 x 2 factorial array: Se level [initiated at breeding; adequate (3.05 microg/kg of BW) or high (70.4 microg/kg of BW)] and nutritional level [100% (control) or 60% (restricted) of NRC recommendations] fed at different times of gestation [d 50 to 90 (midgestation) or d 91 to 130 (late gestation)]. The control ewes had a greater (P = 0.01) percentage change in BW from d 50 than restricted ewes during both mid- and late gestation. Although blood urea N was not affected by either Se or nutritional level, restricted ewes had greater (P = 0.01) concentrations of circulating Se on d 66, 78, 106, 120, and 130 of gestation compared with control ewes. Both Se and timing of the nutritional level affected circulating progesterone; however, only nutritional level affected thyroxine and triiodothyronine concentrations in the dam. Nutrient restriction during late gestation decreased (P <or= 0.01) fetal BW and fetal fluid weight compared with the control ewes (3.75 vs. 4.13 +/- 0.10 kg and 1.61 vs. 2.11 +/- 0.11 kg). Although neither Se nor nutritional level affected (P >or= 0.1) placental, caruncular, or cotyledonary weights, cotyledonary cellular proliferation was decreased (P < 0.05) in ewes receiving a high concentration of Se compared with those receiving adequate Se. In addition, either Se or nutritional level affected vascular endothelial growth factor (VEGFA), VEGFA-receptor 1, VEGFA-receptor 2, and NO synthase mRNA abundance in the cotyledonary tissue. In the caruncular tissue, either Se or nutritional level affected VEGFA-receptor 1, placental growth factor, and NO synthase mRNA abundance. Selenium supplementation and the duration or timing of nutrient restriction appear to influence the endocrine and metabolic status of the ewe, which may influence nutrient transport and placental function.