Prenatal dexamethasone exposure potentiates diet-induced hepatosteatosis and decreases plasma IGF-I in a sex-specific fashion

Effects of prenatal dexamethasone exposure on adult C57BL/6J mouse metabolism and oxidative stress

Prenatal glucocorticoid exposure has been shown to alter hypothalamic-pituitary-adrenal axis function resulting in altered fetal development that can persist through adulthood. Fetal exposure to excess dexamethasone, a synthetic glucocorticoid, has been shown to alter adult behaviour and metabolism. This study investigated the effects prenatal dexamethasone exposure had on adult offspring cardiac and liver metabolism and oxidative stress. Pregnant C57BL/6 mice received a dose of 0.4 mg/kg dexamethasone on gestational days 15-17. Once pups were approximately 7 months old, glucose uptake was determined using positron emission tomography and insulin resistance (IR) was determined by homeostatic model assessment (HOMA) IR calculation. Oxidative stress was assessed by measuring 4-hydroxynonenal protein adduct formation and total reactive oxygen species. Female dexamethasone group had significantly increased glucose uptake when insulin stimulated compared to vehicle-treated mice. HOMA IR revealed no evidence of IR in either male or female offspring. There was also no change in oxidative stress markers in either cardiac or liver tissues of male or female offspring. These data suggest that prenatal dexamethasone exposure in male mice does not alter oxidative stress or metabolism. However, prenatal dexamethasone exposure increased glucocorticoids, cardiac glucose uptake, and pAkt signaling in female heart tissues in adult mice, suggesting there are sex differences in prenatal dexamethasone exposure.

Effects and potential mechanisms of IGF1/IGF1R in the liver fibrosis: A review

Liver fibrosis is a wound-healing response due to persistent liver damage and it may progress to cirrhosis and even liver cancer if no intervention is given. In the current cognition, liver fibrosis is reversible. So, it is of great significance to explore the related gene targets or biomarker for anti-fibrosis of liver. Insulin like growth factor 1 (IGF1) and IGF1 receptor (IGF1R) are mainly expressed in the liver tissues and play critical roles in the liver function. The present review summarized the role of IGF1/IGF1R and its signaling system in liver fibrosis and illustrated the potential mechanisms including DNA damage repair, cell senescence, lipid metabolism and oxidative stress that may be involved in this process according to the studies on the fibrosis of liver or other organs. In particular, the roles of IGF1 and IGF1R in DNA damage repair were elaborated, including membrane-localized and nucleus-localized IGF1R. In addition, for each of the potential mechanism in anti-fibrosis of liver, the signaling pathways of the IGF1/IGF1R mediated and the cell species in liver acted by IGF1 and IGF1R under different conditions were included. The data in this review will support for the study about the effect of IGF1/IGF1R on liver fibrosis induced by various factors, meanwhile, provide a basis for the study of liver fibrosis to focus on the communications between the different kinds of liver cells.

Impact of Angiotensin II Antagonism on the Sex-Selective Dysregulation of Cardiovascular Function Induced by In Utero Dexamethasone Exposure

In utero exposure to glucocorticoids in late gestation programs changes in cardiovascular function. The objective of this study was to determine the degree to which angiotensin II mediates sex-biased changes in autonomic function as well as basal and stress-responsive cardiovascular function following in utero glucocorticoid exposure. Pregnant rats were administered the synthetic glucocorticoid dexamethasone (DEX 0.4mg/kg per day, s.c.) or vehicle on gestation days 18-21. Mean arterial pressure, heart rate, and heart rate variability (HRV) were measured via radiotelemetry in freely moving, conscious adult rats. To evaluate the impact of stress, rats were placed in a restraint tube for 20 minutes. In a separate cohort of rats, restraint stress was performed before and after chronic treatment with the angiotensin type 1 receptor antagonist, losartan (30mg/kg per day, i.p). Frequency domain analysis of HRV was evaluated, and data integrated into low frequency (LF: 0.20-0.75Hz) and high frequency (HF: 0.75-2.00Hz) bands. Prenatal DEX resulted in an exaggerated pressor and heart rate response to restraint in female offspring that was attenuated by prior losartan treatment. HF power was higher in vehicle-exposed female rats, compared to DEX females. Following losartan, HF power was equivalent between female vehicle and DEX-exposed rats. In utero exposure to DEX produced female-biased alterations in stress-responsive cardiovascular function which may be indicative of a reduction in parasympathetic activity. Moreover, these findings suggest this autonomic dysregulation may be mediated in part by long-term changes in renin-angiotensin signaling.

Antidiabetic and antiradical effects of Garcinia kola seeds in dexamethasone-induced hyperglycemic rats

Background

In traditional medicine, the maceration of seeds of Garcinia kola (GK) is used to treat various diseases including diabetes. In traditional pharmacopoeia, GK seeds are used to strengthen the immune system and as a stimulant and aphrodisiac.

Aims

This study aimed to evaluate the antidiabetic free radical scavenging effects of the hydroalcoholic extract of GK seeds (HAEGS) in a dexamethasone-induced hyperglycemic (DexIH) rat model.

Settings and Design

This study was an interventional study.

Subjects and Methods

Here using in vivo model, we assessed some pharmacological properties of HAEGS in DexIH rat. Hypoglycemia, antihyperglycemia, spasmolytic and laxative activities were also evaluated in DexIH. In vitro study assessed antiradical activity. The HAEGS was obtained by decoction introducing 250 g with water–ethanol mixture (30:70). The plant extract was administered to the animals at doses of 50 (GK50) and 100 (GK100) mg/kg body weight. All animal experiments were in accordance with ARRIVE guidelines and were performed in accordance with the scientific procedures of UK Animals. Antiradical activity of GK was assessed in vitro by inhibition of the activity of 2,2-diphenyl-1-picrylhydrazyl.

Statistical Analysis Used

Statistical analysis was performed using GraphPad Prism 5.03 software, and P values less than 0.05 were considered statistically significant.

Results

At doses 50 and 100 mg/kg, GK significantly (P < 0.001) regulated DexIH after two weeks of treatment compared to the normoglycemic control and hyperglycemic rats. The extract at both doses significantly (P < 0.001) inhibited the spasmolytic activity in both normoglycemic and hyperglycemic rats compared to Imodium^®. In rats DexIH rats, only dose 100 mg/kg significantly (P < 0.05) increased laxative effects when compared to the negative control. In vitro antiradical activity of GK revealed vitamin C-like antiradical activity.

Conclusions

This study justifies the traditional use of GK seeds as an antidiabetic.

Maternally derived low glucocorticoid mediates adrenal developmental programming alteration in offspring induced by dexamethasone

Adverse environments during pregnancy can increase susceptibility to chronic diseases in adult offspring. The occurrence and development of fetal-originated diseases were associated with adrenal developmental programming and homeostasis alteration in offspring. Dexamethasone is widely used for preterm delivery-related pregnancy diseases, but the intrauterine programming alteration and its occurrence mechanism of prenatal dexamethasone exposure (PDE) on adrenal development in offspring have not been clarified. In this study, prenatal dexamethasone therapy could inhibit neonatal development and cause a low exposure of maternally derived glucocorticoid in clinic. Then, we established a rat model of PDE and observed a similar phenomenon. Further, the adrenal steroidogenic function was continuously inhibited in the PDE male offspring rats, accompanied by the decreased H3K27ac level of adrenal insulin-like growth factor 1 (IGF1) and its expression. Moreover, chronic stress in PDE adult offspring rats could reverse the changes of the above indicators through the high level of glucocorticoid. In combination with in vivo, in vitro and a series of interference experiments, we confirmed that the low level of endogenous glucocorticoids inhibited the adrenal IGF1 expression and steroidogenic function through the GRα/miR-370-3p/Sirt3 pathway. In summary, PDE could continuously inhibit the adrenal steroidogenic function in the male offspring, which is associated with the maternally derived low glucocorticoid-mediated the adrenal developmental programming alteration in offspring. This study provides a theoretical and experimental basis for explaining the adrenal development origin of PDE-induced adult chronic diseases.

Changes in PGC-1α-Dependent Mitochondrial Biogenesis Are Associated with Inflexible Hepatic Energy Metabolism in the Offspring Born to Dexamethasone-Treated Mothers

In the present study we investigated the participation of hepatic peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) in the metabolic programming of newborn rats exposed in utero to dexamethasone (DEX). On the 21st day of life, fasted offspring born to DEX-treated mothers displayed increased conversion of pyruvate into glucose with simultaneous upregulation of PEPCK (phosphoenolpyruvate carboxykinase) and G6Pase (glucose-6-phosphatase). Increased oxidative phosphorylation, higher ATP/ADP ratio and mitochondrial biogenesis and lower pyruvate levels were also found in the progeny of DEX-treated mothers. On the other hand, the 21-day-old progeny of DEX-treated mothers had increased hepatic triglycerides (TAG) and lower CPT-1 activity when subjected to short-term fasting. At the mechanistic level, rats exposed in utero to DEX exhibited increased hepatic PGC-1α protein content with lower miR-29a-c expression. Increased PGC-1α content was concurrent with increased association to HNF-4α and NRF1 and reduced PPARα expression. The data presented herein reveal that changes in the transcription machinery in neonatal liver of rats born to DEX-treated mothers leads to an inflexible metabolic response to fasting. Such programming is hallmarked by increased oxidative phosphorylation of pyruvate with impaired FFA oxidation and hepatic TAG accumulation.

Sex-dependent associations of maternal androgen levels with offspring BMI and weight trajectory from birth to early childhood

CONTEXT

In preclinical studies, high androgen levels during pregnancy are associated with low birth weight and rapid postnatal weight gain in the offspring. However, human data linking prenatal androgens with birth weight and early life weight gain in the offspring are scarce.

DESIGN

We evaluated 516 mother-child pairs enrolled in the New England birth cohorts of the Collaborative Perinatal Project (1959-1966). We assayed androgen bioactivity in maternal sera during third-trimester using a receptor-mediated luciferase expression bioassay. Age and sex-specific BMI Z-scores (BMIz), defined using established standards, were assessed at birth, 4 months, 1 year, 4 years, and 7 years. We used linear mixed models to evaluate the relation of maternal androgens with childhood BMIz overall and by sex. We examined the association of maternal androgens with fetal growth restriction. The association of weight trajectories with maternal androgens was examined using multinomial logistic regression.

RESULTS

Higher maternal androgen levels associated with lower BMIz at birth (β = - 0.39, 95% CI: - 0.73, - 0.06); this relation was sex-dependent, such that maternal androgens significantly associated with BMIz at birth in girls alone (β = - 0.72, 95% CI: - 1.40, - 0.04). The relation of maternal androgens with fetal growth restriction revealed dose threshold effects that differed by sex. There was no significant association between maternal androgens and weight trajectory overall. However, we found a significant sex interaction (p = 0.01); higher maternal androgen levels associated with accelerated catch-up growth in boys (aOR = 2.14, 95% CI: 1.14, 4.03).

CONCLUSION

Our findings provide evidence that maternal androgens may have differential effects on the programming of intrauterine growth and postnatal weight gain depending on fetal sex.

Antenatal Dexamethasone Treatment Induces Sex-dependent Upregulation of NTPDase1/CD39 and Ecto-5'-nucleotidase/CD73 in the Rat Fetal Brain

Dexamethasone (DEX) is frequently used to treat women at risk of preterm delivery, but although indispensable for the completion of organ maturation in the fetus, antenatal DEX treatment may exert adverse sex-dimorphic neurodevelopmental effects. Literature findings implicated oxidative stress in adverse effects of DEX treatment. Purinergic signaling is involved in neurodevelopment and controlled by ectonucleotidases, among which in the brain the most abundant are ectonucleoside triphosphate diphosphohydrolase 1 (NTPDase1/CD39) and ecto-5'-nucleotidase (e5'NT/CD73), which jointly dephosphorylate ATP to adenosine. They are also involved in cell adhesion and migration, processes integral to brain development. Upregulation of CD39 and CD73 after DEX treatment was reported in adult rat hippocampus. We investigated the effects of maternal DEX treatment on CD39 and CD73 expression and enzymatic activity in the rat fetal brain of both sexes, in the context of oxidative status of the brain tissue. Fetuses were obtained at embryonic day (ED) 21, from Wistar rat dams treated with 0.5 mg DEX/kg/day, at ED 16, 17, and 18, and brains were processed and used for further analysis. Sex-specific increase in CD39 and CD73 expression and in the corresponding enzyme activities was induced in the brain of antenatally DEX-treated fetuses, more prominently in males. The oxidative stress induction after antenatal DEX treatment was confirmed in both sexes, although showing a slight bias in males. Due to the involvement of purinergic system in crucial neurodevelopmental processes, future investigations are needed to determine the role of these observed changes in the adverse effects of antenatal DEX treatment.

The Hypothalamic-Pituitary-Adrenal Axis: Development, Programming Actions of Hormones, and Maternal-Fetal Interactions

The hypothalamic-pituitary-adrenal axis is a complex system of neuroendocrine pathways and feedback loops that function to maintain physiological homeostasis. Abnormal development of the hypothalamic-pituitary-adrenal (HPA) axis can further result in long-term alterations in neuropeptide and neurotransmitter synthesis in the central nervous system, as well as glucocorticoid hormone synthesis in the periphery. Together, these changes can potentially lead to a disruption in neuroendocrine, behavioral, autonomic, and metabolic functions in adulthood. In this review, we will discuss the regulation of the HPA axis and its development. We will also examine the maternal-fetal hypothalamic-pituitary-adrenal axis and disruption of the normal fetal environment which becomes a major risk factor for many neurodevelopmental pathologies in adulthood, such as major depressive disorder, anxiety, schizophrenia, and others.

Prenatal dexamethasone exposure caused fetal rats liver dysplasia by inhibiting autophagy-mediated cell proliferation

As a synthetic glucocorticoid, dexamethasone has been widely used in the clinical treatment of premature birth and related pregnant diseases, but its clinical use is still controversial due to developmental toxicity. This study aimed to confirm the proliferation inhibitory effect of pregnant dexamethasone exposure (PDE) on fetal liver development and elucidate its molecular mechanism. In vitro studies, we found that dexamethasone inhibited hepatocyte proliferation through autophagy activated by glucocorticoid receptor (GR)-forkhead protein O1 (FOXO1) pathway. Subsequently, in vivo, we confirmed in a PDE rat model that male fetal liver proliferation was inhibited, and the expression of the GR-FOXO1 pathway and autophagy were increased. Taken together, PDE induces autophagy by activating the GR-FOXO1 pathway, which leads to fetal liver proliferation inhibition and dysplasia in offspring rats. This study confirmed that dexamethasone activates cell autophagy in utero through the GR-FOXO1 pathway, thereby inhibiting hepatocyte proliferation and liver development, which provides theoretical basis for understanding the developmental toxicity of dexamethasone and guiding the rational clinical use.

Molecular mechanisms governing offspring metabolic programming in rodent models of in utero stress

The results of different human epidemiological datasets provided the impetus to introduce the now commonly accepted theory coined as 'developmental programming', whereby the presence of a stressor during gestation predisposes the growing fetus to develop diseases, such as metabolic dysfunction in later postnatal life. However, in a clinical setting, human lifespan and inaccessibility to tissue for analysis are major limitations to study the molecular mechanisms governing developmental programming. Subsequently, studies using animal models have proved indispensable to the identification of key molecular pathways and epigenetic mechanisms that are dysregulated in metabolic organs of the fetus and adult programmed due to an adverse gestational environment. Rodents such as mice and rats are the most used experimental animals in the study of developmental programming. This review summarises the molecular pathways and epigenetic mechanisms influencing alterations in metabolic tissues of rodent offspring exposed to in utero stress and subsequently programmed for metabolic dysfunction. By comparing molecular mechanisms in a variety of rodent models of in utero stress, we hope to summarise common themes and pathways governing later metabolic dysfunction in the offspring whilst identifying reasons for incongruencies between models so to inform future work. With the continued use and refinement of such models of developmental programming, the scientific community may gain the knowledge required for the targeted treatment of metabolic diseases that have intrauterine origins.

Roles for androgens in mediating the sex differences of neuroendocrine and behavioral stress responses

Estradiol and testosterone are powerful steroid hormones that impact brain function in numerous ways. During development, these hormones can act to program the adult brain in a male or female direction. During adulthood, gonadal steroid hormones can activate or inhibit brain regions to modulate adult functions. Sex differences in behavioral and neuroendocrine (i.e., hypothalamic pituitary adrenal (HPA) axis) responses to stress arise as a result of these organizational and activational actions. The sex differences that are present in the HPA and behavioral responses to stress are particularly important considering their role in maintaining homeostasis. Furthermore, dysregulation of these systems can underlie the sex biases in risk for complex, stress-related diseases that are found in humans. Although many studies have explored the role of estrogen and estrogen receptors in mediating sex differences in stress-related behaviors and HPA function, much less consideration has been given to the role of androgens. While circulating androgens can act by binding and activating androgen receptors, they can also act by metabolism to estrogenic molecules to impact estrogen signaling in the brain and periphery. This review focuses on androgens as an important hormone for modulating the HPA axis and behaviors throughout life and for setting up sex differences in key stress regulatory systems that could impact risk for disease in adulthood. In particular, impacts of androgens on neuropeptide systems known to play key roles in HPA and behavioral responses to stress (corticotropin-releasing factor, vasopressin, and oxytocin) are discussed. A greater knowledge of androgen action in the brain is key to understanding the neurobiology of stress in both sexes.

Stress, Sex, and Sugar: Glucocorticoids and Sex-Steroid Crosstalk in the Sex-Specific Misprogramming of Metabolism

Early-life exposures to environmental insults can misprogram development and increase metabolic disease risk in a sex-dependent manner by mechanisms that remain poorly characterized. Modifiable factors of increasing public health relevance, such as diet, psychological stress, and endocrine-disrupting chemicals, can affect glucocorticoid receptor signaling during gestation and lead to sex-specific postnatal metabolic derangements. Evidence from humans and animal studies indicate that glucocorticoids crosstalk with sex steroids by several mechanisms in multiple tissues and can affect sex-steroid-dependent developmental processes. Nonetheless, glucocorticoid sex-steroid crosstalk has not been considered in the glucocorticoid-induced misprogramming of metabolism. Herein we review what is known about the mechanisms by which glucocorticoids crosstalk with estrogen, androgen, and progestogen action. We propose that glucocorticoid sex-steroid crosstalk is an understudied mechanism of action that requires consideration when examining the developmental misprogramming of metabolism, especially when assessing sex-specific outcomes.

The development of the hypothalamus-pituitary-adrenal axis during infancy may be affected by antenatal glucocorticoid therapy

BACKGROUND

Developmental changes in the hypothalamus-pituitary-adrenal (HPA) axis during infancy have been reported in term infants, but those in preterm infants have yet to be elucidated. If developmental changes in the HPA axis of preterm infants are modulated by any factors, it may affect their future health. Few studies have examined the lasting consequences of antenatal glucocorticoids on the development of the HPA axis.

METHODS

We measured pre- and post-palivizumab vaccination salivary cortisol values in two conforming periods of three-months intervals during infancy, and compared cortisol values and the response of cortisol secretion between groups with and without antenatal glucocorticoid (AG) therapy.

RESULTS

Although the strength of the response of cortisol secretion to palivizumab fell age-dependently (until late infancy) in the Non-AG group, the opposite pattern was exhibited in the AG group. The changes of the delta cortisol values between the 2 groups were significant.

CONCLUSIONS

This study suggests that the HPA axis of preterm infants whose mothers receive AG therapy may be upregulated during infancy, possibly leading to long lasting health problems.

The effects of prenatal dexamethasone exposure and fructose challenge on pituitary-adrenocortical activity and anxiety-like behavior in female offspring

Prenatal glucocorticoid overexposure could largely influence pituitary-adrenal activity and anxiety-like behavior in offspring. Our aim was to study the possible potentiating effect of moderate dose of fructose - common ingredient of today's diet - on prenatal glucocorticoid treatment-induced hypothalamo-pituitary-adrenal (HPA) axis changes. Pregnant female rats were treated with multiple dexamethasone (Dx) doses (3 x 0.5 mg/kg/b.m. Dx; 16th-18th gestational day). Half of female offspring from control and Dx treated dams were supplemented with 10% fructose solution, from weaning till adulthood. Immunohistochemistry, unbiased stereological evaluation and hormonal analysis are used to provide the morpho-functional state of pituitary and adrenal gland. Anxiety-like behavior was assessed using the light/dark box test and the elevated plus maze test. Prenatally Dx exposed females, with or without fructose consumption, had markedly reduced adrenocortical volume (p < 0.05) comparing to controls. Increased basal plasma ACTH level in these females (p < 0.05) maintained corticosterone concentration at control level produced by smaller adrenal glands. In parallel, anxiety-like behavior was shown by both tests used. In conclusion, prenatal Dx exposure cause negative psychophysiological outcome reflected in increased HPA axis activity and anxiety behavior in female offspring, while moderately increased fructose consumption failed to evoke any alteration or to potentiate effects of prenatal Dx exposure.

In Utero Dexamethasone Exposure Exacerbates Hepatic Steatosis in Rats That Consume Fructose During Adulthood

Distinct environmental insults might interact with fructose consumption and contribute to the development of metabolic disorders. To address whether in utero glucocorticoid exposure and fructose intake modulate metabolic responses, adult female Wistar rats were exposed to dexamethasone (DEX) during pregnancy, and the offspring were administered fructose at a later time. Briefly, dams received DEX during the third period of pregnancy, while control dams remained untreated. Offspring born to control and DEX-treated mothers were defined as CTL-off and DEX-off, respectively, while untreated animals were designated CTL-off-CTL and DEX-off-CTL. CLT-off and DEX-off treated with 10% fructose in the drinking water for 8 weeks are referred to as CTL-off-FRU and DEX-off-FRU. We found that fructose promoted glucose intolerance and whole-body gluconeogenesis in both CTL-off-FRU and DEX-off-FRU animals. On the other hand, hepatic lipid accumulation was significantly stimulated in DEX-off-FRU rats when compared to the CTL-off-FRU group. The DEX-off-FRU group also displayed impaired very-low-density lipoprotein (VLDL) production and reduced hepatic expression of apoB, mttp, and sec22b. DEX-off-FRU has lower hepatic levels of autophagy markers. Taken together, our results support the unprecedented notion that in utero glucocorticoid exposure exacerbates hepatic steatosis caused by fructose consumption later in life.

IGF-1 reverses the osteogenic inhibitory effect of dexamethasone on BMP9-induced osteogenic differentiation in mouse embryonic fibroblasts via PI3K/AKT/COX-2 pathway

Glucocorticoid-Induced Osteoporosis (GIOP) is a prevalent clinical complication caused by large dose administration of glucocorticoids, such as Dexamethasone (Dex) and Prednisone. GIOP may lead to fractures and even Osteonecrosis of the Femoral Head (ONFH). It has been reported that glucocorticoids inhibit osteogenesis via the suppression of osteogenic differentiation in Mesenchymal Stem Cells (MSCs), but the precise mechanism underlying this suppression awaits further investigation. Meanwhile, novel and efficacious therapies are recommended to cope with GIOP. In this study, we demonstrated that Dex had the inhibitory effect on Bone Morphogenetic Protein 9 (BMP9)-induced ALP activities and matrix mineralization in Mouse Embryonic Fibroblasts (MEFs). In addition, the study confirmed that Dex decreased the expression of osteogenic markers such as Runx2 and OPN. However, the inhibitory effect of Dex on these osteogenic markers can be reversed when combined with insulin-like growth factor 1 (IGF-1). Regarding the inhibitory mechanism, we found that the level of AKT and p-AKT can be decreased by Dex and that Ly294002, the PI3K inhibitor, can block the reversal effect of IGF-1. Moreover, the knockdown or inhibition of COX-2 produced similar results to those of Ly294002. Our findings indicated that IGF-1 may reverse the osteogenic inhibitory effect of Dex via PI3K/AKT pathway, which may be associated with the up-regulation of COX-2. This study may provide new clinical management strategy for GIOP cases.

Resveratrol Treatment Ameliorates Leptin Resistance and Adiposity Programed by the Combined Effect of Maternal and Post-Weaning High-Fat Diet

SCOPE

Prenatal high-fat (HF) and postnatal HF diet are both associated with obesity and metabolic disturbances in adults. Leptin resistance induced by obesity limits its biological effects. The anti-obesity mechanism of resveratrol in visceral adiposity is investigated here.

METHODS AND RESULTS

During mating and lactation, Sprague-Dawley dams are fed either control or a HF diet. Subsequently, the offspring are fed chow or an HF diet. A fifth group that received maternal/postnatal HF diet and resveratrol after weaning (HHR) is used to study the effects of resveratrol treatment. Resveratrol treatment alleviates adiposity programed by maternal and postnatal HF diet by decreasing feed intake or inducing metabolic changes. Resveratrol treatment is also found to ameliorate the decrease in SIRT1 abundance observed in retroperitoneal adipose tissue, programed by maternal and postnatal HF diet. Moreover, resveratrol therapy decreases plasma leptin level and increases leptin receptor expression in retroperitoneal adipose tissue through DNA methylation modification.

CONCLUSION

These results suggest that resveratrol can alleviate peripheral leptin resistance programed by the combined effect of prenatal and postnatal HF diet through epigenetic regulation of genes coding leptin and its receptor. It provides insights into a novel mechanism explaining the beneficial effects of resveratrol in obesity management.

Prenatal caffeine exposure increases the susceptibility to non-alcoholic fatty liver disease in female offspring rats via activation of GR-C/EBPα-SIRT1 pathway

This study aimed to evaluate female adult offspring induced by prenatal caffeine exposure (PCE) are susceptible to non-alcoholic fatty liver disease (NAFLD) and to explore the underlying programming mechanisms. Pregnant rats were intragastrically administered caffeine (30, 60, and 120 mg/kg.d) on gestational day (GD) 9-20. The female adult offspring were randomly divided into three groups: offspring without or with chronic stress during postnatal week (PW) 10-12 and PW28 offspring. Results showed that PW28 PCE female offspring had a higher hepatic triglyceride content and Kleiner scores, accompanied by elevated serum corticosterone levels. Moreover, the expression levels of hepatic glucocorticoid receptor (GR), CCAAT enhancer binding protein α (C/EBPα), fatty acid synthetase (FASN) and the transcription factor-sterol regulatory element binding protein 1c (SREBP1c) were increased, but SIRT1 expression was decreased. The fetal rats and PW12 offspring with chronic stress exhibited similar changes as PW28 offspring, accompanied by increased levels of H3K14ac and H3K27ac in the SREBP1c and FASN gene promoters. These effects were also observed by treating L02 cells with cortisol and were partially reversed by GR or C/EBPα siRNA or treatment with the SIRT1 agonist resveratrol. Taken together, PCE-induced high glucocorticoids levels enhanced histone modifications and expression of SREBP1c and FASN via activation of the GR-C/EBPα-SIRT1 pathway in utero. This enhanced female fetal hepatic triglyceride synthesis and continued throughout postnatal and adult life, increasing the susceptibility to adult NAFLD.

Sex differences in major depression and comorbidity of cardiometabolic disorders: impact of prenatal stress and immune exposures

Major depressive disorder topped ischemic heart disease as the number one cause of disability worldwide in 2012, and women have twice the risk of men. Further, the comorbidity of depression and cardiometabolic disorders will be one of the primary causes of disability worldwide by 2020, with women at twice the risk. Thus, understanding the sex-dependent comorbidities has public health consequences worldwide. We propose here that sex differences in MDD-cardiometabolic comorbidity originate, in part, from pathogenic processes initiated in fetal development that involve sex differences in shared pathophysiology between the brain, the vascular system, the CNS control of the heart and associated hormonal, immune, and metabolic physiology. Pathways implicate neurotrophic and angiogenic growth factors, gonadal hormone receptors, and neurotransmitters such as gamma amino butyric acid (GABA) on neuronal and vascular development of HPA axis regions, such as the paraventricular nucleus (PVN), in addition to blood pressure, in part through the renin-angiotensin system, and insulin and glucose metabolism. We show that the same prenatal exposures have consequences for sex differences across multiple organ systems that, in part, share common pathophysiology. Thus, we believe that applying a sex differences lens to understanding shared biologic substrates underlying these comorbidities will provide novel insights into the development of sex-dependent therapeutics. Further, taking a lifespan perspective beginning in fetal development provides the opportunity to target abnormalities early in the natural history of these disorders in a sex-dependent way.

Adverse effect of dexamethasone on development of the fetal rat ovary

Dexamethasone (Dx) is often used in obstetric practice to promote fetal lung maturation and to prevent respiratory distress syndrome when the risk of preterm delivery persists. This therapy enables survival of the newborn, but also is associated with deleterious effects on the offspring, such as reproductive disorders. The aim of this study was to determine specifically whether prenatal exposure to Dx disturbs the physiological balance between proliferation and apoptosis of germinative cells (GC) in the ovary of 19- and 21-day-old fetuses and thus induces developmental programming of the female reproductive system. Pregnant Wistar rats (n = 10/group), separated into control (vehicle) and Dx-treated (0.5 mg/kg body mass) groups, received injections on gestational days 16, 17, and 18. Exposure to Dx lowered the volume of the fetal ovary by 30% (P < 0.05) in 21-day-old fetuses, as well as the total number of GC in the ovary by 21% (P < 0.05). When compared to the controls, in Dx-exposed fetuses, the total number of PCNA-positive GC was 27% lower at 19 days and 71% lower at 21 days old (P < 0.05), while total numbers of caspase-3-positive GC were 2.3-fold and 34% higher, respectively (P < 0.05). Our results demonstrate that prenatal exposure to Dx diminished proliferation but increased the rate of germinative cell apoptosis, with consequently reduced total germinative cell number and ovary volume. Impairment of fetal oogenesis and fewer GC in the fetal ovary compromise the oogonial stock and thus may constitute a risk of female fertility.

Course-, dose-, and stage-dependent toxic effects of prenatal dexamethasone exposure on long bone development in fetal mice

Dexamethasone is routinely used for treating those mothers at risk for preterm delivery. However, overexposure to exogenous glucocorticoids induces bone loss in offspring, and the "critical window" and safe dose of this treatment are largely unknown. In this study, we found that femoral length, and the length of the primary ossification center were significantly reduced in fetal mice after repeated prenatal dexamethasone exposure (PDE). Compared with single-course exposure on gestational day (GD)15, newborn mice with repeated PDE (3 times, from GD15 to 17) showed a significant decrease in femoral trabecular bone mass with decreased trabecular number and thickness. For those newborn mice treated after repeated PDE at different doses (0, 0.2, 0.8, and 1.2 mg/kg/d), the toxic effect of dexamethasone on bone development was observed at 0.8 and 1.2 mg/kg/d. More severe retardation in bone development was observed in the fetal mice after PDE at 0.8 mg/kg/d during GD12-14, compared with that during GD15-17. Interestingly, stronger toxic effects were observed in male newborn mice after PDE than were observed in female newborn mice. In conclusion, PDE with multiple course, higher dose, or exposure at an early stage of pregnancy have stronger toxic effects on bone development of fetal mice.

Insulin-Like Growth Factor (IGF) System in Liver Diseases

Hepatocyte differentiation, proliferation, and apoptosis are affected by growth factors produced in liver. Insulin-like growth factor 1 and 2 (IGF1 and IGF2) act in response to growth hormone (GH). Other IGF family components include at least six binding proteins (IGFBP1 to 6), manifested by both IGFs develop due to interaction through the type 1 receptor (IGF1R). The data based on animal models and/or in vitro studies suggest the role of IGF system components in cellular aspects of hepatocarcinogenesis (cell cycle progression, uncontrolled proliferation, cell survival, migration, inhibition of apoptosis, protein synthesis and cell growth), and show that systemic IGF1 administration can reduce fibrosis and ameliorate general liver function. In epidemiologic and clinicopathological studies on chronic liver disease (CLD), lowered serum levels, decreased tissue expression of IGF1, elevated production of IGF1R and variable IGF2 expression has been noted, from the start of preneoplastic alterations up to the developed hepatocellular carcinoma (HCC) stage. These changes result in well-known clinical symptoms of IGF1 deficiency. This review summarized the current data of the complex role of IGF system components in the most common CLD (nonalcoholic fatty liver disease, cirrhosis, and hepatocellular carcinoma). Better recognition and understanding of this system can contribute to discovery of new and improved versions of current preventive and therapeutic actions in CLD.

Prenatal stress-immune programming of sex differences in comorbidity of depression and obesity/metabolic syndrome

Major depressive disorder (MDD) is the number one cause of disability worldwide and is comorbid with many chronic diseases, including obesity/metabolic syndrome (MetS). Women have twice as much risk for MDD and comorbidity with obesity/MetS as men, although pathways for understanding this association remain unclear. On the basis of clinical and preclinical studies, we argue that prenatal maternal stress (ie, excess glucocorticoid expression and associated immune responses) that occurs during the sexual differentiation of the fetal brain has sex-dependent effects on brain development within highly sexually dimorphic regions that regulate mood, stress, metabolic function, the autonomic nervous system, and the vasculature. Furthermore, these effects have lifelong consequences for shared sex-dependent risk of MDD and obesity/MetS. Thus, we propose that there are shared biologic substrates at the anatomical, molecular, and/or genetic levels that produce the comorbid risk for MDD-MetS through sex-dependent fetal origins.

Prolonged fasting elicits increased hepatic triglyceride accumulation in rats born to dexamethasone-treated mothers

We investigated the effect of dexamethasone during the last week of pregnancy on glucose and lipid metabolism in male offspring. Twelve-week old offspring were evaluated after fasting for 12-hours (physiological) and 60-hours (prolonged). Physiological fasting resulted in glucose intolerance, decreased glucose clearance after pyruvate load and increased PEPCK expression in rats born to dexamethasone-treated mothers (DEX). Prolonged fasting resulted in increased glucose tolerance and increased glucose clearance after pyruvate load in DEX. These modulations were accompanied by accumulation of hepatic triglycerides (TG). Sixty-hour fasted DEX also showed increased citrate synthase (CS) activity, ATP citrate lyase (ACLY) content, and pyruvate kinase 2 (pkm2), glucose transporter 1 (slc2a1) and lactate dehydrogenase-a (ldha) expressions. Hepatic AKT2 was increased in 60-hour fasted DEX, in parallel with reduced miRNAs targeting the AKT2 gene. Altogether, we show that metabolic programming by prenatal dexamethasone is characterized by an unexpected hepatic TG accumulation during prolonged fasting. The underlying mechanism may depend on increased hepatic glycolytic flux due to increased pkm2 expression and consequent conversion of pyruvate to non-esterified fatty acid synthesis due to increased CS activity and ACLY levels. Upregulation of AKT2 due to reduced miRNAs may serve as a permanent mechanism leading to increased pkm2 expression.

Influence of long-term, high-dose dexamethasone administration on proliferation and apoptosis in porcine hepatocytes

The aim of this study was to examine the influence of long-term, high-dose dexamethasone administration on the liver, with particular emphasis on hepatocyte proliferation and apoptosis, using a swine model. The study included 48 large, female Polish breed pigs aged 3months (weighing ca. 30kg) divided into groups I (control; n=24) and II (dexamethasone; n=24) that receiving intra-muscular injections of monosodium phosphate dexamethasone for 29days. The pigs were euthanized on days subsequent to the experiment. Immediately after the euthanasia, the pig livers were sampled, fixed, and processed routinely for histopathology, histochemistry, and immunohistochemistry (for proliferating cell nuclear antigen, Bcl-2, and caspase-3). Apoptosis was visualized by terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL). Dexamethasone administration gradually caused hepatocyte glycogen degeneration and finally lipid degeneration, accompanied by sinusoid and central vein dilatation and nuclear chromatin condensation. The proliferating cell nuclear antigen index, mean number of argyrophilic nucleolar organizer regions and proliferation index of argyrophilic nucleolar organizer regions were lower, while Bcl-2 expression was higher in group II compared with group I. The results from this study suggest that safe high-dose dexamethasone administration time is difficult to establish. Long-term, high-dose dexamethasone administration can cause pronounced morphological changes in hepatocytes by diminishing their transcriptional and proliferation activity but also protects them from apoptosis by potentially affecting Bcl-2 expression.

Early life programming and the risk of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is associated with obesity, insulin resistance, type 2 diabetes and cardiovascular disease and can be considered the hepatic manifestation of the metabolic syndrome. NAFLD represents a spectrum of disease, from the relatively benign simple steatosis to the more serious non-alcoholic steatohepatitis, which can progress to liver cirrhosis, hepatocellular carcinoma and end-stage liver failure, necessitating liver transplantation. Although the increasing prevalence of NAFLD in developed countries has substantial implications for public health, many of the precise mechanisms accounting for the development and progression of NAFLD are unclear. The environment in early life is an important determinant of cardiovascular disease risk in later life and studies suggest this also extends to NAFLD. Here we review data from animal models and human studies which suggest that fetal and early life exposure to maternal under- and overnutrition, excess glucocorticoids and environmental pollutants may confer an increased susceptibility to NAFLD development and progression in offspring and that such effects may be sex-specific. We also consider studies aimed at identifying potential dietary and pharmacological interventions aimed at reducing this risk. We suggest that further human epidemiological studies are needed to ensure that data from animal models are relevant to human health.

Prenatal stress-immune programming of sex differences in comorbidity of depression and obesity/metabolic syndrome

Major depressive disorder (MDD) is the number one cause of disability worldwide and is comorbid with many chronic diseases, including obesity/metabolic syndrome (MetS). Women have twice as much risk for MDD and comorbidity with obesity/MetS as men, although pathways for understanding this association remain unclear. On the basis of clinical and preclinical studies, we argue that prenatal maternal stress (ie, excess glucocorticoid expression and associated immune responses) that occurs during the sexual differentiation of the fetal brain has sex-dependent effects on brain development within highly sexually dimorphic regions that regulate mood, stress, metabolic function, the autonomic nervous system, and the vasculature. Furthermore, these effects have lifelong consequences for shared sex-dependent risk of MDD and obesity/MetS. Thus, we propose that there are shared biologic substrates at the anatomical, molecular, and/or genetic levels that produce the comorbid risk for MDD-MetS through sex-dependent fetal origins.

Prenatal food restriction induces poor-quality articular cartilage in female rat offspring fed a post-weaning high-fat diet and its intra-uterine programming mechanisms

Epidemiological data show that osteoarthritis (OA) is significantly associated with lower birth weight, and that OA may be a type of fetal-originated adult disease. The present study aimed to investigate the prenatal food-restriction (PFR) effect on the quality of articular cartilage in female offspring to explore the underlying mechanisms of fetal-originated OA. Maternal rats were fed a restricted diet from gestational day (GD) 11 to 20 to induce intra-uterine growth retardation. Female fetuses and female adult offspring fed a post-weaning high-fat diet were killed at GD20 and postnatal week 24, respectively. Serum and knee cartilage samples from fetuses and adult female offspring were collected and examined for cholesterol metabolism and histology. Fetal serum corticosterone and insulin-like growth factor-1 (IGF-1) in the PFR group were lower than those of the control, but the serum cholesterol level was not changed. The lower expression of IGF-1 in the PFR group lasted into adulthood. The expression of extracellular matrix (ECM) genes, including type II collagen, aggrecan and cholesterol efflux genes including liver X receptor, were significantly induced, but the ATP-binding-cassette transporter A1 was unchanged. PFR could induce a reduction in ECM synthesis and impaired cholesterol efflux in female offspring, and eventually led to poor quality of articular cartilage and OA.

Prenatal Dexamethasone and Postnatal High-Fat Diet Decrease Interferon Gamma Production through an Age-Dependent Histone Modification in Male Sprague-Dawley Rats

Overexposure to prenatal glucocorticoid (GC) disturbs hypothalamic-pituitary-adrenocortical axis-associated neuroendocrine metabolism and susceptibility to metabolic syndrome. A high-fat (HF) diet is a major environmental factor that can cause metabolic syndrome. We aimed to investigate whether prenatal GC plus a postnatal HF diet could alter immune programming in rat offspring. Pregnant Sprague-Dawley rats were given intraperitoneal injections of dexamethasone or saline at 14-21 days of gestation. Male offspring were then divided into four groups: vehicle, prenatal dexamethasone exposure, postnatal HF diet (VHF), and prenatal dexamethasone exposure plus a postnatal HF diet (DHF). The rats were sacrificed and adaptive immune function was evaluated. Compared to the vehicle, the DHF group had lower interferon gamma (IFN-γ) production by splenocytes at postnatal day 120. Decreases in H3K9 acetylation and H3K36me3 levels at the IFN-γ promoter correlated with decreased IFN-γ production. The impaired IFN-γ production and aberrant site-specific histone modification at the IFN-γ promoter by prenatal dexamethasone treatment plus a postnatal HF diet resulted in resilience at postnatal day 180. Prenatal dexamethasone and a postnatal HF diet decreased IFN-γ production through a site-specific and an age-dependent histone modification. These findings suggest a mechanism by which prenatal exposure to GC and a postnatal environment exert effects on fetal immunity programming.

Mitogen-inducible gene-6 partly mediates the inhibitory effects of prenatal dexamethasone exposure on endochondral ossification in long bones of fetal rats

BACKGROUND AND PURPOSE

Prenatal exposure to dexamethasone slows down fetal linear growth and bone mineralization but the regulatory mechanism remains unknown. Here we assessed how dexamethasone regulates bone development in the fetus.

EXPERIMENTAL APPROACH

Dexamethasone (1 mg·kg(-1) ·day(-1) ) was injected subcutaneously every morning in pregnant rats from gestational day (GD)9 to GD20. Fetal femurs and tibias were harvested at GD20 for histological and gene expression analysis. Femurs of 12-week-old female offspring were harvested for microCT (μCT) measurement. Primary chondrocytes were treated with dexamethasone (10, 50, 250 and 1000 nM).

KEY RESULTS

Prenatal dexamethasone exposure resulted in accumulation of hypertrophic chondrocytes and delayed formation of the primary ossification centre in fetal long bone. The retardation was accompanied by reduced maturation of hypertrophic chondrocytes, decreased osteoclast number and down-regulated expression of osteocalcin and bone sialoprotein in long bone. In addition, the mitogen-inducible gene-6 (Mig6) and osteoprotegerin (OPG) expression were stimulated, and the receptor activator of NF-κB ligand (RANKL) expression was repressed. Moreover, dexamethasone activated OPG and repressed RANKL expression in both primary chondrocytes and primary osteoblasts, and the knockdown of Mig6 abolished the effect of dexamethasone on OPG expression. Further, μCT measurement showed loss of bone mass in femur of 12-week-old offspring with prenatal dexamethasone exposure.

CONCLUSIONS AND IMPLICATIONS

Prenatal dexamethasone exposure delays endochondral ossification by suppressing chondrocyte maturation and osteoclast differentiation, which may be partly mediated by Mig6 activation in bone. Bone development retardation in the fetus may be associated with reduced bone mass in later life.

Sex-dependent programming effects of prenatal glucocorticoid treatment on the developing serotonin system and stress-related behaviors in adulthood

Prenatal stress and overexposure to glucocorticoids (GC) during development may be associated with an increased susceptibility to a number of diseases in adulthood including neuropsychiatric disorders, such as depression and anxiety. In animal models, prenatal overexposure to GC results in hyper-responsiveness to stress in adulthood, and females appear to be more susceptible than males. Here, we tested the hypothesis that overexposure to GC during fetal development has sex-specific programming effects on the brain, resulting in altered behaviors in adulthood. We examined the effects of dexamethasone (DEX; a synthetic GC) during prenatal life on stress-related behaviors in adulthood and on the tryptophan hydroxylase-2 (TpH2) gene expression in the adult dorsal raphe nucleus (DRN). TpH2 is the rate-limiting enzyme for serotonin (5-HT) synthesis and has been implicated in the etiology of human affective disorders. Timed-pregnant rats were treated with DEX from gestational days 18-22. Male and female offspring were sacrificed on the day of birth (postnatal day 0; P0), P7, and in adulthood (P80-84) and brains were examined for changes in TpH2 mRNA expression. Adult animals were also tested for anxiety- and depressive- like behaviors. In adulthood, prenatal DEX increased anxiety- and depressive- like behaviors selectively in females, as measured by decreased time spent in the center of the open field and increased time spent immobile in the forced swim test, respectively. Prenatal DEX increased TpH2 mRNA selectively in the female caudal DRN at P7, whereas it decreased TpH2 mRNA selectively in the female caudal DRN in adulthood. In animals challenged with restraint stress in adulthood, TpH2 mRNA was significantly lower in rostral DRN of prenatal DEX-treated females compared to vehicle-treated females. These data demonstrated that prenatal overexposure to GC alters the development of TpH2 gene expression and these alterations correlated with lasting behavioral changes found in adult female offspring.

Postnatal High-Fat Diet Increases Liver Steatosis and Apoptosis Threatened by Prenatal Dexamethasone through the Oxidative Effect

The objective of this study was to investigate cellular apoptosis in prenatal glucocorticoid overexposure and a postnatal high fat diet in rats. Pregnant Sprague-Dawley rats at gestational days 14 to 21 were administered saline (vehicle) or dexamethasone and weaned onto either a normal fat diet or a high fat diet for 180 days; in total four experimental groups were designated, i.e., vehicle treated group (VEH), dexamethasone treated group (DEX), vehicle treated plus high-fat diet (VHF), and dexamethasone treated plus high-fat diet (DHF). Chronic effects of prenatal liver programming were assessed at postnatal day 180. The apoptotic pathways involved proteins were analyzed by Western blotting for their expressions. Apoptosis and liver steatosis were also examined by histology. We found that liver steatosis and apoptosis were increased in the DHF, DEX, and VHF treated groups, and that the DHF treated group was increased at higher levels than the DEX and VHF treated groups. The expression of leptin was decreased more in the DHF treated group than in the DEX and VHF treated groups. Decreased peroxisome proliferator-activated receptor-gamma coactivator 1α, phosphoinositide-3-kinase, manganese superoxide dismutase and increased malondialdehyde expression levels were seen in DHF treated group relative to the DEX treated group. The DHF treated group exhibited higher levels of oxidative stress, apoptosis and liver steatosis than the DEX treated group. These results indicate that the environment of high-fat diet plays an important role in the development of liver injury after prenatal stress.

Minireview: the impact of antenatal therapeutic synthetic glucocorticoids on the developing fetal brain

The life-threatening, emotional, and economic burdens of premature birth have been greatly alleviated by antenatal glucocorticoid (GC) treatment. Antenatal GCs accelerate tissue development reducing respiratory distress syndrome and intraventricular hemorrhage in premature infants. However, they can also alter developmental processes in the brain and trigger adverse behavioral and metabolic outcomes later in life. This review summarizes animal model and clinical studies that examined the impact of antenatal GCs on the developing brain. In addition, we describe studies that assess glucocorticoid receptor (GR) action in neural stem/progenitor cells (NSPCs) in vivo and in vitro. We highlight recent work from our group on two GR pathways that impact NSPC proliferation, ie, a nongenomic GR pathway that regulates gap junction intercellular communication between coupled NSPCs through site-specific phosphorylation of connexin 43 and a genomic pathway driven by differential promoter recruitment of a specific GR phosphoisoform.

Prenatal nicotine exposure-induced intrauterine programming alteration increases the susceptibility of high-fat diet-induced non-alcoholic simple fatty liver in female adult offspring rats

“Two intrauterine programming”, involved in the intrauterine origin of high-fat diet-induced NAFL in female offspring rats, induced by prenatal nicotine exposure.

Disruption of fetal hormonal programming (prenatal stress) implicates shared risk for sex differences in depression and cardiovascular disease

Comorbidity of major depressive disorder (MDD) and cardiovascular disease (CVD) represents the fourth leading cause of morbidity and mortality worldwide, and women have a two times greater risk than men. Thus understanding the pathophysiology has widespread implications for attenuation and prevention of disease burden. We suggest that sex-dependent MDD-CVD comorbidity may result from alterations in fetal programming consequent to the prenatal maternal environments that produce excess glucocorticoids, which then drive sex-dependent developmental alterations of the fetal hypothalamic-pituitary-adrenal (HPA) axis circuitry impacting mood, stress regulation, autonomic nervous system (ANS), and the vasculature in adulthood. Evidence is consistent with the hypothesis that disruptions of pathways associated with gamma aminobutyric acid (GABA) in neuronal and vascular development and growth factors have critical roles in key developmental periods and adult responses to injury in heart and brain. Understanding the potential fetal origins of these sex differences will contribute to development of novel sex-dependent therapeutics.

Prenatal ethanol exposure programs an increased susceptibility of non-alcoholic fatty liver disease in female adult offspring rats

Prenatal ethanol exposure (PEE) induces dyslipidemia and hyperglycemia in fetus and adult offspring. However, whether PEE increases the susceptibility to non-alcoholic fatty liver disease (NAFLD) in offspring and its underlying mechanism remain unknown. This study aimed to demonstrate an increased susceptibility to high-fat diet (HFD)-induced NAFLD and its intrauterine programming mechanisms in female rat offspring with PEE. Rat model of intrauterine growth retardation (IUGR) was established by PEE, the female fetus and adult offspring that fed normal diet (ND) or HFD were sacrificed. The results showed that, in PEE+ND group, serum corticosterone (CORT) slightly decreased and insulin-like growth factor-1 (IGF-1) and glucose increased with partial catch-up growth; In PEE+HFD group, serum CORT decreased, while serum IGF-1, glucose and triglyceride (TG) increased, with notable catch-up growth, higher metabolic status and NAFLD formation. Enhanced liver expression of the IGF-1 pathway, gluconeogenesis, and lipid synthesis as well as reduced expression of lipid output were accompanied in PEE+HFD group. In PEE fetus, serum CORT increased while IGF-1 decreased, with low body weight, hyperglycemia, and hepatocyte ultrastructural changes. Hepatic IGF-1 expression as well as lipid output was down-regulated, while lipid synthesis significantly increased. Based on these findings, we propose a "two-programming" hypothesis for an increased susceptibility to HFD-induced NAFLD in female offspring of PEE. That is, the intrauterine programming of liver glucose and lipid metabolic function is "the first programming", and postnatal adaptive catch-up growth triggered by intrauterine programming of GC-IGF1 axis acts as "the second programming".

The androgen metabolite, 5α-androstane-3β,17β-diol (3β-diol), activates the oxytocin promoter through an estrogen receptor-β pathway

Testosterone has been shown to suppress the acute stress-induced activation of the hypothalamic-pituitary-adrenal axis; however, the mechanisms underlying this response remain unclear. The hypothalamic-pituitary-adrenal axis is regulated by a neuroendocrine subpopulation of medial parvocellular neurons in the paraventricular nucleus of the hypothalamus (PVN). These neurons are devoid of androgen receptors (ARs). Therefore, a possibility is that the PVN target neurons respond to a metabolite in the testosterone catabolic pathway via an AR-independent mechanism. The dihydrotestosterone metabolite, 5α-androstane-3β,17β-diol (3β-diol), binds and activates estrogen receptor-β (ER-β), the predominant ER in the PVN. In the PVN, ER-β is coexpressed with oxytocin (OT). Therefore, we tested the hypothesis that 3β-diol regulates OT expression through ER-β activation. Treatment of ovariectomized rats with estradiol benzoate or 3β-diol for 4 days increased OT mRNA selectively in the midcaudal, but not rostral PVN compared with vehicle-treated controls. 3β-Diol treatment also increased OT mRNA in the hypothalamic N38 cell line in vitro. The functional interactions between 3β-diol and ER-β with the human OT promoter were examined using an OT promoter-luciferase reporter construct (OT-luc). In a dose-dependent manner, 3β-diol treatment increased OT-luc activity when cells were cotransfected with ER-β, but not ER-α. The 3β-diol-induced OT-luc activity was reduced by deletion of the promoter region containing the composite hormone response element (cHRE). Point mutations of the cHRE also prevented OT-luc activation by 3β-diol. These results indicate that 3β-diol induces OT promoter activity via ER-β-cHRE interactions.

Sex and stress hormone influences on the expression and activity of brain-derived neurotrophic factor

The neurotrophin, brain-derived neurotrophic factor (BDNF), is recognized as a key component in the regulation of CNS ontogeny, homeostasis and adult neuroplasticity. The importance of BDNF in CNS development and function is well documented by numerous reports from animal studies linking abnormal BDNF signaling to metabolic disturbances and anxiety or depressive-like behavior. Despite the diverse roles for BDNF in nearly all aspects of CNS physiology, the regulation of BDNF expression, as well as our understanding of the signaling mechanisms associated with this neurotrophin, remains incomplete. However, links between sex hormones such as estradiol and testosterone, as well as endogenous and synthetic glucocorticoids (GCs), have emerged as important mediators of BDNF expression and function. Examples of such regulation include brain region-specific induction of Bdnf mRNA in response to estradiol. Additional studies have also documented regulation of the expression of the high-affinity BDNF receptor Tropomyosin-Related Kinase B by estradiol, thus implicating sex steroids not only in the regulation of BDNF expression, but also in mechanisms of signaling associated with it. In addition to gonadal steroids, further evidence also suggests functional interaction between BDNF and GCs, such as in the regulation of corticotrophin-releasing hormone and other important neuropeptides. In this review, we provide an overview of the roles played by selected sex or stress hormones in the regulation of BDNF expression and signaling in the CNS.

Prepro-thyrotropin releasing hormone expressing neurons in the juxtaparaventricular region of the lateral hypothalamus are activated by leptin and altered by prenatal glucocorticoid exposure

The neuropeptide thyrotropin-releasing hormone (TRH) is recognized to play an important role in controlling energy balance through direct effects on the CNS, although mechanisms explaining the phenomenon are poorly understood. To begin to understand the effects of TRH on CNS control of energy balance, we first mapped neurons expressing the TRH precursor peptide, prepro-TRH (ppTRH) in the paraventricular nucleus of the rat hypothalamus and the surrounding regions. We identified a population of ppTRH-expressing neurons in the juxtaparaventricular region of the lateral hypothalamus (LHAjp) which were stimulated by the satiety signal leptin (2.5μg/kg, IP). Using a model of fetal glucocorticoid (GC) exposure in which pregnant rats were treated with the synthetic GC dexamethasone (DEX) during gestational days 18-21, it was observed that such exposure resulted in reduced numbers of ppTRH-ir neurons in the LHAjp in adult male and female rats, and was accompanied by increased food intake. Our data provide further insight into the biological role of the LHAjp, as well as the potential involvement of TRH neurons within this region in metabolic disease associated with fetal glucocorticoid exposure.

Exposure to dexamethasone during late gestation causes female-specific decreases in core body temperature and prepro-thyrotropin-releasing hormone expression in the paraventricular nucleus of the hypothalamus in rats

Synthetic glucocorticoids (GC) have been used to promote lung development in preterm infants, thereby decreasing respiratory distress syndrome and mortality, yet, concern has arisen from reports that such treatment predisposes individuals to disease in adulthood. Given the variety of preclinical studies that show metabolic and behavioral abnormalities in adulthood following fetal exposure to synthetic GC, we examined the effect of in utero exposure to the synthetic GC, dexamethasone (DEX), on hypothalamic expression of thyrotropin-releasing hormone (TRH) a central neuropeptide involved in mediating behavior and metabolic balance. Pregnant Sprague-Dawley rats were administered 0.4mg/kg DEX on gestational days 18-21. As adults (postnatal day (PD) 60), the offspring were fitted with temperature sensing transmitters allowing real-time monitoring of core body temperature (CBT) across the 24h light dark period. This revealed a significant decrease in CBT throughout the day in prenatal DEX-treated females on estrus and diestrus, but not in male offspring. The reduction in CBT by prenatal DEX exposure was accompanied by a significant decrease in the expression of Trh transcript in the paraventricular nucleus of the hypothalamus (PVN) of female rats at PD 60 and this effect was also present on PD7. There was also a female-specific reduction in the number of preproTRH-immunoreactive (ir) neurons in the PVN, with ppTRH-ir nerve fibers decreases that were present in both male and female offspring. No changes in thyroid hormone (triiodothyronine, T3; thyroxine, T4) were observed in adult offspring, but during development, both males and females (PD14) had lower T3 and T4 levels. These data indicate abnormal expression of TRH results from fetal DEX exposure during late gestation, possibly explaining the decreased CBT observed in the female offspring.