The gestational foundation of sex differences in development and vulnerability.

Despite long-standing interest in the role of sex on human development, the functional consequences of fetal sex on early development are not well-understood. Here we explore the gestational origins of sex as a moderator of development. In accordance with the focus of this special issue, we examine evidence for a sex differential in vulnerability to prenatal and perinatal risks. Exposures evaluated include those present in the external environment (e.g., lead, pesticides), those introduced by maternal behaviors (e.g., alcohol, opioid use), and those resulting from an adverse intrauterine environment (e.g., preterm birth). We also provide current knowledge on the degree to which sex differences in fetal neurobehavioral development (i.e., cardiac and motor patterns) are present prior to birth. Also considered are contemporaneous and persistent sex of fetus effects on the pregnant woman. Converging evidence confirms that infant and early childhood developmental outcomes of male fetuses exposed to prenatal and perinatal adversities are more highly impaired than those of female fetuses. In certain circumstances, male fetuses are both more frequently exposed to early adversities and more affected by them when exposed than are female fetuses. The mechanisms through which biological sex imparts vulnerability or protection on the developing nervous system are largely unknown. We consider models that implicate variation in maturation, placental functioning, and the neuroendocrine milieu as potential contributors. Many studies use sex as a control variable, some analyze and report main effects for sex, but those that report interaction terms for sex are scarce. As a result, the true scope of sex differences in vulnerability is unknown.

Prenatal exposure to ethinylestradiol alters the morphologic patterns and increases the predisposition for prostatic lesions in male and female gerbils during ageing.

Ethinylestradiol (EE) is an endocrine disruptor (ED) which acts as an oestrogen agonist; this compound is known as an oral contraceptive. Male and female rodents exposed to EE during critical time points of development, such as in the prenatal period, show alterations in their reproductive tract during adulthood. Few studies have placed an emphasis on the effects of EE during ageing. Thus, this study had as it's objective the analysis of the morphological and immunohistochemical effects of exposure to EE in the prenatal period on ventral male prostate and female prostate of gerbils (Meriones unguiculatus) during ageing. The animals were exposed to EE (15 µg/kg/day) during the 18-22th days of prenatal life (EE/PRE group), and the analyses were performed when the male and female reached 12 months of age. Our results showed an increase in the development of prostatic intraepithelial neoplasia (PIN), which was observed in the male and female prostate of EE/PRE groups. Immunohistochemistry showed a rise in prostatic epithelial and basal cells immunoreactivity, respectively, and to AR and p63 in the male EE/PRE. There were alterations in the morphological pattern of the prostatic glands and increase in predisposition to emergence of prostatic lesions of both sexes during ageing. Despite male and female having been exposed to the same doses of EE, the "exposure to EE promoted modifications" more accentuated in the male prostate. Thus the male gland is more sensitive to the action of this synthetic oestrogen than the female prostate.

Ontogeny of the interferon system in chickens.

Newborn vertebrates may be susceptible to infection because the immature status of their immune system results in an inability to make an effective immune response. Consequently, newly hatched chicks appear to be more susceptible to infections than mature chickens. In particular, poultry susceptibility to virus infection may be related to poor expression of innate immune elements involved in antiviral responses. Therefore, in this study we assessed the relative development of the interferon (IFN) system: a protective system against virus infection. We investigated the age-related expression of the elements involved in the IFN response including IFN gene expression, their associated receptors and the pattern recognition receptors (PRR) involved in the regulation of IFNs. We observed that the IFN system is somewhat inadequately expressed in embryos and develops over time, just prior to and after hatching, and therefore chicks may be more susceptible to virus than mature birds because of an immature IFN network.

Early life nutrition and metabolic programming.

Research investigating the early programming of adult metabolic disease has in recent years provided much mechanistic insight into how the early environment impacts on long-term health. It includes studies addressing the roles of intrauterine nutrient availability, which is determined by maternal nutrition, maternal exposure to oxygen, toxic events, and infection; the placental interface; and also the early postnatal environment. This review will explore the epidemiological evidence for programming of metabolic disease and provide an overview of the various studies using animals to model metabolic phenotypic outcome. It will also discuss evidence for the proposed molecular mechanisms and the potential for intervention.

Early origin of adult renal disease.

Observational studies in humans and experimental studies in animals have clearly shown that renal failure may start early in life. 'Fetal programming' is regulated by adaptations occurring in uterus including maternal nutrition, placental blood supply, and epigenetic changes. Low birth weight predisposes to hypertension and renal insufficiency. Congenital abnormalities of the kidney and urinary tract, adverse postnatal events, wrong nutritional habits may produce renal damage that will become clinically relevant in adulthood. Prevention should start early in children at risk of renal disease.

Up-regulation of Toll-like receptor 4/nuclear factor-kappaB signaling is associated with enhanced adipogenesis and insulin resistance in fetal skeletal muscle of obese sheep at late gestation.

Maternal obesity is increasing at an alarming rate. We previously showed that maternal obesity induces an inflammatory response and enhances adipogenesis in fetal skeletal muscle at midgestation. The objective of this study was to evaluate effects of maternal obesity on adipogenesis, inflammatory signaling, and insulin pathways at late gestation when ovine fetal skeletal muscle matures. Nonpregnant ewes were assigned to a control diet (Con, fed 100% of National Research Council nutrient recommendations, n = 6) or obesogenic diet (OB, fed 150% of National Research Council recommendations, n = 6) from 60 d before to 135 d after conception (term 148 d) when the fetal semitendenosus skeletal muscle was sampled. Expression of the adipogenic marker, peroxisome proliferator-activated receptor-gamma, was increased in OB compared with Con fetal semitendenosus muscle, indicating up-regulation of adipogenesis. More intramuscular adipocytes were observed in OB muscle. Phosphorylation of inhibitor-kappaB kinase-alpha/beta and nuclear factor-kappaB RelA/p65 were both increased in OB fetal muscle, indicating activation of nuclear factor-kappaB pathway. Phosphorylation of c-Jun N-terminal kinase and c-Jun (at Ser 63 and Ser 73) was also elevated. Toll-like receptor 4 expression was higher in OB than Con fetal muscle. Moreover, despite higher insulin concentrations in OB vs. Con fetal plasma (2.89 +/- 0.53 vs. 1.06 +/- 0.52 ng/ml; P < 0.05), phosphorylation of protein kinase B at Ser 473 was reduced, indicating insulin resistance. In conclusion, our data show maternal obesity-induced inflammatory signaling in late gestation fetal muscle, which correlates with increased im adipogenesis and insulin resistance, which may predispose offspring to later-life obesity and diabetes.

The role of Gas1 in embryonic development and its implications for human disease.

Growth Arrest Specific Gene 1 (Gas1) has long been regarded as a cell cycle inhibitor of the G(0) to S phase transition. How GAS1, a GPI-anchored plasma membrane protein, directs intracellular changes without an extracellular ligand or a transmembrane protein partner has been puzzling. A recent series of biochemical and molecular genetic studies assigned the mammalian Hedgehog (HH) growth factor to be a ligand for GAS1 in vitro and in vivo. HH has enjoyed considerable attention for its profound role in embryonic patterning as a classic morphogen, i.e. inducing various cell types in a concentration-dependent manner. GAS1 appears to help transform the HH concentration gradient into its morphogenic activity gradient by acting cooperatively with the HH receptor, the 12-transmembrane protein Patched 1 (PTC1). These findings provoke intriguing thoughts on how HH and GAS1 may coordinate cell proliferation and differentiation to create biological patterns. The role of HH extends to human genetic diseases, stem cell renewal, and cancer growth, and we consider the possibility of GAS1's involvement in these processes as well.

Prophylactic role for complementary and alternative medicine in perinatal programming of adult health.

BACKGROUND: The health status of an individual in adulthood is proposed to be determined by events occurring in the prenatal and early postnatal period. A common early life event proven to have long lasting effects on the developing fetus is stress, including pain. Exposure of fetal and neonatal infants to repetitive psychological (e.g., maternal stress) or physiological (e.g., pain, infection, and noise) stress during this period is proposed to alter mechanisms involved in the regulation of stress, immunological maturation, pain perception, and cognition. Such changes, which persist into adulthood, may occur via alterations in the development of the hypothalamic-pituitary-adrenal (HPA) axis. This process is typically referred to as 'perinatal programming'. Ontogenic alterations in the development of the HPA-axis have been related to a number of adult pathologies such as cardiovascular disease, type 2 diabetes, asthma, as well as psychopathologies such as anxiety and depression. OBJECTIVE: In this review, the effectiveness of complementary and alternative medicine (CAM), such as music, dietary supplements, massage and aromatherapy, in reducing perinatal stress in mothers and infants is examined. An emphasis is placed on these therapies as preventative measures which may be of value to individuals at risk of developing disease profiles associated with the consequences of adverse perinatal programming. The widening interest in perinatal programming and CAM suggests the potential for CAM to become a valuable tool in offsetting negative adult health outcomes resulting from perinatal programming associated with adverse gestational early life environments.

Fetal origins of stress-related adult disease.

During the past decade, a considerable body of evidence has emerged showing that circumstances during the fetal period may have lifelong programming effects on different body functions with a considerable impact on disease susceptibility. The purpose of this article is to provide a synopsis of these findings and their role in explaining the development of stress-related adult disease. In the context of Per Björntorp memorial symposium, stress-related disease will be interpreted broadly, including cardiovascular disease and components of the metabolic syndrome, for which the evidence of fetal origins is most abundant. It has however become evident that early-life programming has a much broader potential effect on an individual's health. For example, perinatal variables, such as low birth weight, have been associated with increased prevalence of depressive symptoms. Mechanistic studies in animals and humans have shown that lifelong programming of the hypothalamic-pituitary-adrenal axis (HPAA) function by fetal life conditions is likely to be a key factor in mediating associations with these disorders, which frequently are characterized by HPAA overactivity. Preliminary observations suggest a similar important role for early-life programming of sympathoadrenal function. Reduced HPAA activity is characteristic of a number of stress-related disorders, including posttraumatic stress disorder; chronic pain; fatigue; and atypical, melancholic depression. It is therefore highly plausible that susceptibility to these disorders originates in a similar manner during early life, although direct evidence is to a great deal lacking. Important targets for future research include distinction between the effects of different pregnancy conditions, such as maternal malnutrition, preeclampsia, and maternal infection, which may have dissimilar late-life consequences. This will be a crucial step when the associations that are currently emerging will be translated into disease prevention.

Mitotic defects in XRCC3 variants T241M and D213N and their relation to cancer susceptibility.

The XRCC3 variant T241M, but not D213N, has been reported to be associated with an increased risk of some cancers. XRCC3 is one out of five RAD51 paralogues and is involved in homologous recombination, as are the BRCA1 and BRCA2 proteins. However, in contrast to mutations in BRCA1 and BRCA2, the XRCC3(T241M) protein is proficient in homologous recombination and reverts sensitivity to mitomycin C found in XRCC3-deficient cells, whereas XRCC3(D213N) is defective in homologous recombination. Here, we report that both the XRCC3 D213N and T241M alleles are associated with an increase in centrosome number and binucleated cells. However, only the D213N allele gives an increase in spontaneous levels of apoptosis. We suggest that the inability of XRCC3 T241M to apoptotically eliminate aberrant cells with mitotic defects could increase cancer susceptibility in individuals carrying this variant. In contrast, cells carrying the XRCC3 D213N variant are able to eliminate aberrant cells by apoptosis, and consistent with this observation, this variant does not seem to be associated with cancer susceptibility.

Fetal programming of autonomic and HPA function: do people who were small babies have enhanced stress responses?

Studies in several species have demonstrated that an adverse early environment can influence the development of the autonomic nervous system and hypothalamic-pituitary-adrenal (HPA) axis. The autonomic nervous system and HPA axis are key components of the neuroendocrine response to stress and many of these animal models show altered biological responses to stress. Recent research now suggests that these processes operate in humans. An adverse early environment, as evidenced by reduced birth or infant weight, is associated with enhanced autonomic and HPA responses to experimental psychological stress. However, there appear to be marked sex differences in the mechanisms involved. Epidemiological studies demonstrate that physiological changes in these neuroendocrine systems may predispose to cardiovascular disease through their influence on risk factors such as plasma glucose and lipid concentrations and blood pressure. Thus the combination of enhanced stress susceptibility and the psychosocial stressors to which people are exposed may be an important component of the disease risk in human populations.

Microvascular rarefaction and decreased angiogenesis in rats with fetal programming of hypertension associated with exposure to a low-protein diet in utero.

In hypertension, increased peripheral vascular resistance results from vascular dysfunction with or without structural changes (vessel wall remodeling and/or microvascular rarefaction). Humans with lower birth weight exhibit evidence of vascular dysfunction. The current studies were undertaken to investigate whether in utero programming of hypertension is associated with in vivo altered response and/or abnormal vascular structure. Offspring of Wistar dams fed a normal (CTRL) or low (LP)-protein diet during gestation were studied. Mean arterial blood pressure response to ANG II was significantly increased, and depressor response to sodium nitroprusside (SNP) infusions significantly decreased in male LP adult offspring relative to CTRL. No arterial remodeling was observed in male LP compared with CTRL offspring. Capillary and arteriolar density was significantly decreased in striated muscles from LP offspring at 7 and 28 days of life but was not different in late fetal life [day 21 of gestation (E21)]. Angiogenic potential of aortic rings from LP newborn (day of birth, P0) was significantly decreased. Striated muscle expressions (Western blots) of ANG II AT(1) receptor subtype, endothelial nitric oxide synthase, angiopoietin 1 and 2, Tie 2 receptor, vascular endothelial growth factor and receptor, and platelet-derived growth factor C at E21 and P7 were unaltered by antenatal diet exposure. In conclusion, blood pressure responses to ANG II and SNP are altered, and microvascular structural changes prevail in this model of fetal programming of hypertension. The capillary rarefaction is absent in the fetus and appears in the neonatal period, in association with decreased angiogenic potential. The study suggests that intrauterine protein restriction increases susceptibility to postnatal factors resulting in microvascular rarefaction, which could represent a primary event in the genesis of hypertension.

Newborn lamb coronary artery reactivity is programmed by early gestation dexamethasone before the onset of systemic hypertension.

Exposure of the early gestation ovine fetus to exogenous glucocorticoids induces organ-specific alterations in postnatal cardiovascular physiology. To determine whether early gestation corticosteroid exposure alters coronary reactivity before the development of systemic hypertension, dexamethasone (0.28 mg x kg(-1) x day(-1)) was administered to pregnant ewes by intravenous infusion over 48 h beginning at 27 days gestation (term, 145 days). Vascular responsiveness was assessed in endothelium-intact coronary arteries isolated from 1-wk-old steroid-exposed and age-matched control lambs (N = 6). Calcium imaging was performed in fura 2-loaded primary cultures of vascular smooth muscle cells (VSMC) from the harvested coronary arteries. Early gestation steroid exposure did not significantly alter mean arterial blood pressure or coronary reactivity to KCl, thromboxane A(2) mimetic U-46619, or ANG II. Steroid exposure significantly increased coronary artery vasoconstriction to acetylcholine and endothelin-1. Vasodilatation to adenosine, but not nitroprusside or forskolin, was significantly attenuated following early gestation steroid exposure. Endothelin-1 or U-46619 stimulation resulted in a comparable increase in intracellular calcium concentration ([Ca(2+)](i)) in coronary VSMC isolated from either dexamethasone-treated or control animals. However, the ANG II- or KCl-mediated increase in [Ca(2+)](i) in control VSMC was significantly attenuated in VSMC harvested from dexamethasone-treated lambs. Coronary expression of muscle voltage-gated l-type calcium channel alpha-1 subunit protein was not significantly altered by steroid exposure, whereas endothelial nitric oxide synthase expression was attenuated. These findings demonstrate that early gestation glucocorticoid exposure elicits primary alterations in coronary responsiveness before the development of systemic hypertension. Glucocorticoid-induced alterations in coronary physiology may provide a mechanistic link between an adverse intrauterine environment and later cardiovascular disease.

Environmental influences during development and their later consequences for health and disease: implications for the interpretation of empirical studies.

Early experience has a particularly great effect on most organisms. Normal development may be disrupted by early environmental influences; individuals that survive have to cope with the damaging consequences. Additionally, the responses required to cope with environmental challenges in early life may have long-term effects on the adult organism. A further set of processes, those of developmental plasticity, may induce a phenotype that is adapted to the adult environment predicted by the conditions of early life. A mismatch between prediction and subsequent reality can cause severe health problems in those human societies where economic circumstances and nutrition are rapidly improving. Understanding the underlying mechanisms of plasticity is, therefore, clinically important. However, to conduct research in this area, developmental plasticity must be disentangled from disruption and the adverse long-term effects of coping. The paper reviews these concepts and explores ways in which such distinctions may be made in practice.

The fetal, neonatal, and infant environments-the long-term consequences for disease risk.

The developmental origins of health and disease can be understood by reference to the fundamentals of developmental plasticity. It is essential to distinguish between those environmental effects acting during development that are disruptive from those that have adaptive value. The latter are likely to underpin programming and the developmental origins of adult disease. It is suggested that greater disease risk is created by a mismatch between the environment predicted during the plastic phase of development and the actual environment experienced in the postplastic phase. This plastic phase extends from conception to after birth at least for some systems. It is not necessary to invoke a particular mechanism in the neonatal or infant period. There is increasing evidence that prematurity can be associated with long-term consequences, and this is to be anticipated from conceptual considerations. Different preventative strategies may be relevant in different populations.

Prenatal cocaine exposure increases heart susceptibility to ischaemia-reperfusion injury in adult male but not female rats.

The present study tested the hypothesis that prenatal cocaine exposure differentially regulates heart susceptibility to ischaemia-reperfusion (I/R) injury in adult offspring male and female rats. Pregnant rats were administered intraperitoneally either saline or cocaine (15 mg kg(-1)) twice daily from day 15 to day 21 of gestational age. There were no differences in maternal weight gain and birth weight between the two groups. Hearts were isolated from 2-month-old male and female offspring and were subjected to I/R (25 min/60 min) in a Langendorff preparation. Preischaemic values of left ventricular (LV) function were the same between the saline control and cocaine-treated hearts for both male and female rats. Prenatal cocaine exposure significantly increased I/R-induced myocardial apoptosis and infarct size, and significantly attenuated the postischaemic recovery of LV function in adult male offspring. In contrast, cocaine did not affect I/R-induced injury and postischaemic recovery of LV function in the female hearts. There was a significant decrease in PKCepsilon and phospho-PKCepsilon levels in LV in the male, but not female, offspring exposed to cocaine before birth. These results suggest that prenatal cocaine exposure causes a sex-specific increase in heart susceptibility to I/R injury in adult male offspring, and the decreased PKCepsilon gene expression in the male heart may play an important role.

Critical periods in human growth and their relationship to diseases of aging.

It has long been recognized that there are "critical periods" during mammalian development when exposure to specific environmental stimuli are required in order to elicit the normal development of particular anatomical structures or their normal functioning. The responses of the organism to these stimuli depend on a specific level of anatomical maturation and a state of rapid anatomical and/or functional change. This discussion of critical periods in growth is not confined to the classic definition of a narrow time frame of development during which a particular environmental threshold or limit must exist for normal growth and function to ensue. Using both auxological and epidemiological approaches, we suggest a lifespan perspective which encompasses accumulating and interacting risks that are manifest from prenatal life onward. By understanding the process of growth development, and by scrutinizing the growth process, early variations that lead to later disease can be identified. Here we review a significant amount of the evidence that links exposure during growth to later morbidity and mortality. The fetus appears to respond to insults during the prenatal period through the process of "programming," which has short-term survival advantages but may have a long-term disadvantage in that it is associated with cardiovascular disease, hypertension, type II diabetes, and later obesity. Low birth weight combined with rapid postnatal growth during infancy also appears to be associated, for instance, with later childhood and adult sequelae in terms of glucose tolerance and obesity. Independent of birth weight, the timing of adiposity rebound during mid-childhood also predicts later obesity. The timing, magnitude, and duration of adolescent growth and maturationare associated with critical body composition changes, including the normal acquisition of body fat and bone mineralization. In particular, the acquisition of appropriate peak bone mass is critical in determining the later risk of osteoporosis. A putative causal mechanism linking early growth variation to later chronic disease risk through telomeric attrition is discussed. The obligatory loss of telomeric DNA with each cell division serves as a mitotic clock and marks the rate of growth and repair processes in the cell. Although much more work is required, existing studies support the notion that telomere shortening is not only a clock of cellular division, but also marks relative growth rate, as well as contributing to common degenerative processes of aging through its impact on cellular senescence.

Effects of the Ay gene on susceptibility to hydrocortisone fetotoxicity and teratogenicity in mice.

Effects of the Ay gene, a coat color gene, on susceptibility to hydrocortisone fetotoxicity and teratogenicity were investigated by using the congenic strain of C57BL/6-Ay (Ay/a) which had been maintained by repeated back-crosses of the Ay gene to the C57BL/6 (a/a) background. Matings were conducted as follows (female x male): group I, a/a; group II, a/a x Ay/a; and group III, Ay/a x a/a. Pregnant females were subcutaneously given daily doses of 0, 12.5, 25, or 50 mg/kg of hydrocortisone on days 10-13 of pregnancy. On day 18 of pregnancy, fetuses were sexed, weighed, and examined for external abnormalities. In group I, the mean fetal weight was significantly decreased at a dose of 25 mg/kg or more. The incidences of cleft palate were 3.2 and 22.7% at 25 and 50 mg/kg, respectively. In group II, in which half of the fetuses were expected to carry the Ay gene, the mean fetal weight was decreased significantly at 12.5 mg/kg or more. The incidence of cleft palate in group II at 50 mg/kg was 44.2%, which was significantly higher than that in group I. In group III, in which maternal mice as well as half of their fetuses carried the Ay gene, a decrease in the mean fetal weight was greater than in group II. In addition, the mean percentage of fetal resorptions was significantly increased at 50 mg/kg. The incidence of cleft palate in group III was significantly increased at 25 mg/kg (10.5%) when compared with those in groups I and II. These results indicate that the Ay gene may be associated with susceptibility to hydrocortisone fetotoxicity and teratogenicity in mice.