Sex-Specific Placental Responses in Fetal Development

Sex-Specific Metabolic Outcomes in Offspring of Female Rats Born Small or Exposed to Stress During Pregnancy

Low birth weight increases adult metabolic disease risk in both the first (F1) and second (F2) generation. Physiological stress during pregnancy in F1 females that were born small induces F2 fetal growth restriction, but the long-term metabolic health of these F2 offspring is unknown. Uteroplacental insufficiency (restricted) or sham (control) surgery was performed in F0 rats. F1 females (control, restricted) were allocated to unstressed or stressed pregnancies. F2 offspring exposed to maternal stress in utero had reduced birth weight. At 6 months, F2 stressed males had elevated fasting glucose. In contrast, F2 restricted males had reduced pancreatic β-cell mass. Interestingly, these metabolic deficits were not present at 12 month. F2 males had increased adrenal mRNA expression of steroidogenic acute regulatory protein and IGF-1 receptor when their mothers were born small or exposed to stress during pregnancy. Stressed control F2 males had increased expression of adrenal genes that regulate androgen signaling at 6 months, whereas expression increased in restricted male and female offspring at 12 months. F2 females from stressed mothers had lower area under the glucose curve during glucose tolerance testing at 12 months compared with unstressed females but were otherwise unaffected. If F1 mothers were either born small or exposed to stress during her pregnancy, F2 offspring had impaired physiological outcomes in a sex- and age-specific manner. Importantly, stress during pregnancy did not exacerbate disease risk in F2 offspring of mothers born small, suggesting that they independently program disease in offspring through different mechanisms.

Sexual dimorphism of the cerebellar vermis in schizophrenia

Converging lines of evidence implicate structural and functional abnormalities in the cerebellum in schizophrenia (SCZ). The cerebellar vermis is of particular interest given its association with clinical symptoms and cognitive deficits in SCZ and its known connections with cortical regions such as the prefrontal cortex. Prior neuroimaging studies have shown structural and functional abnormalities in the vermis in SCZ. In this study, we examined the cerebellar vermis in 50 individuals with SCZ and 54 healthy controls (HC) using a quantitative volumetric approach. All participants underwent high-resolution structural magnetic resonance imaging (MRI). The vermis was manually traced for each participant, and vermis volumes were computed using semiautomated methods. Volumes for total vermis and vermis subregions (anterior and posterior vermis) were analyzed in the SCZ and HC groups. Significant diagnosis-by-sex interaction effects were found in total vermis and vermis subregion analyses. These effects appeared to be driven by significantly decreased posterior vermis volumes in males with SCZ. Exploratory analyses did not reveal significant effects of clinical variables (FEP status, illness duration, and BPRS total score and subscores) on vermis volumes. The findings herein highlight the presence of neural sex differences in SCZ and the need for considering sex-related factors in studying the disorder.

Programming of maternal and offspring disease: impact of growth restriction, fetal sex and transmission across generations

Babies born small are at an increased risk of developing myriad adult diseases. While growth restriction increases disease risk in all individuals, often a second hit is required to unmask 'programmed' impairments in physiology. Programmed disease outcomes are demonstrated more commonly in male offspring compared with females, with these sex-specific outcomes partly attributed to different placenta-regulated growth strategies of the male and female fetus. Pregnancy is known to be a major risk factor for unmasking a number of conditions and can be considered a 'second hit' for women who were born small. As such, female offspring often develop impairments of physiology for the first time during pregnancy that present as pregnancy complications. Numerous maternal stressors can further increase the risk of developing a maternal complication during pregnancy. Importantly, these maternal complications can have long-term consequences for both the mother after pregnancy and the developing fetus. Conditions such as preeclampsia, gestational diabetes and hypertension as well as thyroid, liver and kidney diseases are all conditions that can complicate pregnancy and have long-term consequences for maternal and offspring health. Babies born to mothers who develop these conditions are often at a greater risk of developing disease in adulthood. This has implications as a mechanism for transmission of disease across generations. In this review, we discuss the evidence surrounding long-term intergenerational implications of being born small and/or experiencing stress during pregnancy on programming outcomes.

Environmental factors, epigenetics, and developmental origin of reproductive disorders

Sex-specific differentiation, development, and function of the reproductive system are largely dependent on steroid hormones. For this reason, developmental exposure to estrogenic and anti-androgenic endocrine disrupting chemicals (EDCs) is associated with reproductive dysfunction in adulthood. Human data in support of "Developmental Origins of Health and Disease" (DOHaD) comes from multigenerational studies on offspring of diethylstilbestrol-exposed mothers/grandmothers. Animal data indicate that ovarian reserve, female cycling, adult uterine abnormalities, sperm quality, prostate disease, and mating behavior are susceptible to DOHaD effects induced by EDCs such as bisphenol A, genistein, diethylstilbestrol, p,p'-dichlorodiphenyl-dichloroethylene, phthalates, and polyaromatic hydrocarbons. Mechanisms underlying these EDC effects include direct mimicry of sex steroids or morphogens and interference with epigenomic sculpting during cell and tissue differentiation. Exposure to EDCs is associated with abnormal DNA methylation and other epigenetic modifications, as well as altered expression of genes important for development and function of reproductive tissues. Here we review the literature exploring the connections between developmental exposure to EDCs and adult reproductive dysfunction, and the mechanisms underlying these effects.

Sex and Gender Differences in Risk, Pathophysiology and Complications of Type 2 Diabetes Mellitus

The steep rise of type 2 diabetes mellitus (T2DM) and associated complications go along with mounting evidence of clinically important sex and gender differences. T2DM is more frequently diagnosed at lower age and body mass index in men; however, the most prominent risk factor, which is obesity, is more common in women. Generally, large sex-ratio differences across countries are observed. Diversities in biology, culture, lifestyle, environment, and socioeconomic status impact differences between males and females in predisposition, development, and clinical presentation. Genetic effects and epigenetic mechanisms, nutritional factors and sedentary lifestyle affect risk and complications differently in both sexes. Furthermore, sex hormones have a great impact on energy metabolism, body composition, vascular function, and inflammatory responses. Thus, endocrine imbalances relate to unfavorable cardiometabolic traits, observable in women with androgen excess or men with hypogonadism. Both biological and psychosocial factors are responsible for sex and gender differences in diabetes risk and outcome. Overall, psychosocial stress appears to have greater impact on women rather than on men. In addition, women have greater increases of cardiovascular risk, myocardial infarction, and stroke mortality than men, compared with nondiabetic subjects. However, when dialysis therapy is initiated, mortality is comparable in both males and females. Diabetes appears to attenuate the protective effect of the female sex in the development of cardiac diseases and nephropathy. Endocrine and behavioral factors are involved in gender inequalities and affect the outcome. More research regarding sex-dimorphic pathophysiological mechanisms of T2DM and its complications could contribute to more personalized diabetes care in the future and would thus promote more awareness in terms of sex- and gender-specific risk factors.

Developmental programming, adiposity, and reproduction in ruminants

Although sheep have been widely adopted as an animal model for examining the timing of nutritional interventions through pregnancy on the short- and long-term outcomes, only modest programming effects have been seen. This is due in part to the mismatch in numbers of twins and singletons between study groups as well as unequal numbers of males and females. Placental growth differs between singleton and twin pregnancies which can result in different body composition in the offspring. One tissue that is especially affected is adipose tissue which in the sheep fetus is primarily located around the kidneys and heart plus the sternal/neck region. Its main role is the rapid generation of heat due to activation of the brown adipose tissue-specific uncoupling protein 1 at birth. The fetal adipose tissue response to suboptimal maternal food intake at defined stages of development differs between the perirenal abdominal and pericardial depots, with the latter being more sensitive. Fetal adipose tissue growth may be mediated in part by changes in leptin status of the mother which are paralleled in the fetus. Then, over the first month of life plasma leptin is higher in females than males despite similar adiposity, when fat is the fastest growing tissue with the sternal/neck depot retaining uncoupling protein 1, whereas other depots do not. Future studies should take into account the respective effects of fetal number and sex to provide more detailed insights into the mechanisms by which adipose and related tissues can be programmed in utero.

Life-Long Implications of Developmental Exposure to Environmental Stressors: New Perspectives

The Developmental Origins of Health and Disease (DOHaD) paradigm is one of the most rapidly expanding areas of biomedical research. Environmental stressors that can impact on DOHaD encompass a variety of environmental and occupational hazards as well as deficiency and oversupply of nutrients and energy. They can disrupt early developmental processes and lead to increased susceptibility to disease/dysfunctions later in life. Presentations at the fourth Conference on Prenatal Programming and Toxicity in Boston, in October 2014, provided important insights and led to new recommendations for research and public health action. The conference highlighted vulnerable exposure windows that can occur as early as the preconception period and epigenetics as a major mechanism than can lead to disadvantageous "reprogramming" of the genome, thereby potentially resulting in transgenerational effects. Stem cells can also be targets of environmental stressors, thus paving another way for effects that may last a lifetime. Current testing paradigms do not allow proper characterization of risk factors and their interactions. Thus, relevant exposure levels and combinations for testing must be identified from human exposure situations and outcome assessments. Testing of potential underpinning mechanisms and biomarker development require laboratory animal models and in vitro approaches. Only few large-scale birth cohorts exist, and collaboration between birth cohorts on a global scale should be facilitated. DOHaD-based research has a crucial role in establishing factors leading to detrimental outcomes and developing early preventative/remediation strategies to combat these risks.