Insulin-like Growth Factor 1 Mediates Adrenal Development Dysfunction in Offspring Rats Induced by Prenatal Food Restriction

The changes in adrenal developmental programming and homeostasis in offspring induced by glucocorticoids exposure during pregnancy

Clinically, synthetic glucocorticoids are often used to treat maternal and fetal related diseases, such as preterm birth and autoimmune diseases. Although its clinical efficacy is positive, it will expose the fetus to exogenous glucocorticoids. Adverse environments during pregnancy (e.g., exogenous glucocorticoids exposure, malnutrition, infection, hypoxia, and stress) can lead to fetal overexposure to endogenous maternal glucocorticoids. Basal glucocorticoids levels in utero are crucial in determining fetal tissue maturation and its postnatal fate. As the synthesis and secretion organ of glucocorticoids, the adrenal development is crucial for the growth and development of the body. Studies have found that glucocorticoids exposure during pregnancy could cause abnormal fetal adrenal development, which could last after birth or even adulthood. As the key organ of fetal-originated adult disease, the adrenal developmental programming has a profound impact on the health of offspring, which can lead to many chronic diseases in adulthood. However, the aberrant adrenal development in offspring caused by glucocorticoids exposure during pregnancy and its intrauterine programming mechanism have not been systematically clarified. Therefore, this review summarizes recent research progress on the short and long-term hazards of aberrant adrenal development induced by glucocorticoids exposure during pregnancy, which is of great significance for the analysis of aberrant adrenal development and clarify the intrauterine origin mechanism of fetal-originated adult disease.

Glucocorticoids and intrauterine programming of nonalcoholic fatty liver disease

Accumulating epidemiological and experimental evidence indicates that nonalcoholic fatty liver disease (NAFLD) has an intrauterine origin. Fetuses exposed to adverse prenatal environments (e.g., maternal malnutrition and xenobiotic exposure) are more susceptible to developing NAFLD after birth. Glucocorticoids are crucial triggers of the developmental programming of fetal-origin diseases. Adverse intrauterine environments often lead to fetal overexposure to maternally derived glucocorticoids, which can program fetal hepatic lipid metabolism through epigenetic modifications. Adverse intrauterine environments program the offspring's glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis, which contributes to postnatal catch-up growth and disturbs glucose and lipid metabolism. These glucocorticoid-driven programming alterations increase susceptibility to NAFLD in the offspring. Notably, after delivery, offspring often face an environment distinct from their in utero life. The mismatch between the intrauterine and postnatal environments can serve as a postnatal hit that further disturbs the programmed endocrine axes, accelerating the onset of NAFLD. In this review, we summarize the current epidemiological and experimental evidence demonstrating that NAFLD has an intrauterine origin and discuss the underlying intrauterine programming mechanisms, focusing on the role of overexposure to maternally derived glucocorticoids. We also briefly discuss potential early life interventions that may be beneficial against fetal-originated NAFLD.

H19/let-7 axis mediates caffeine exposure during pregnancy induced adrenal dysfunction and its multi-generation inheritance

Previously, we systemically confirmed that prenatal caffeine exposure (PCE) could cause intrauterine growth retardation (IUGR) and adrenal steroid synthesis dysfunction in offspring rats. However, the multi-generation inheritance of adrenal dysfunction and its epigenetic mechanism has not been reported. In this study, the PCE rat model was established, part of the pregnant rats were executed on gestational day 20, while the others were delivered normally and the fetal rats were reared into adulthood. The PCE female rats of filial generation 1 (F1) were mated with wild males to produce F2 offspring, and the same way to produce F3 offspring. All the adult female rats of three generations were sacrificed for the related detection. Results showed that PCE could decrease fetal weight, increase IUGR rate, and elevate serum corticosterone level. Meanwhile, the expression of fetal adrenal GR, DNMT3a/3b, miRNA let-7c increased while those of CTCF, H19, and StAR decreased, and the total methylation rate of the H19 promoter region was enhanced. We used SW-13 cells to clarify the molecular mechanism and found that cortisol-induced in vitro changes of these indexes were consistent with those in vivo. We confirmed that high level of cortisol through activating GR, on the one hand, promoted let-7 expression and inhibited StAR expression; on the other hand, caused high methylation and low expression of H19 by down-regulating CTCF and up-regulating DNMT3a/3b, then enhanced let-7 inhibitory effect on StAR by "molecular sponge" effect. Finally, in vivo experiments showed that the adrenal steroid synthesis function and H19/let-7 axis presented the glucocorticoid-dependent changes in the adult female F1, F2, and F3. In conclusion, PCE can cause female adrenal dysfunction with matrilineal multi-generation inheritance, which is related to the programming alteration of the H19/let-7 axis. This study provides a novel perspective to explain the multi-generation inheritance of fetal-originated disease in IUGR offspring.

Triadimefon suppresses fetal adrenal gland development after in utero exposure

Triadimefon is a broad-spectrum antifungal agent, which is widely used in agriculture to control mold and fungal infections. It is considered an endocrine disruptor. Whether triadimefon exposure can inhibit the development of fetal adrenal glands and the underlying mechanism remain unclear. Thirty-two pregnant female Sprague-Dawley rats were randomly divided into four groups. Dams were gavaged triadimefon (0, 25, 50, and 100 mg/kg/day) daily for 10 days from gestational day (GD) 12 to GD 21. Triadimefon significantly reduced the thickness of the zona fasciculata of male fetuses at 100 mg/kg, although it did not change the thickness of the zona glomerulosa. It significantly reduced the serum aldosterone levels of male fetuses at a dose of 100 mg/kg, and significantly reduced serum corticosterone and adrenocorticotropic hormone levels at doses of 50 and 100 mg/kg. Triadimefon significantly down-regulated the expression of Agtr1, Mc2r, Star, Cyp11b1, Cyp11b2, Igf1, Nr5a1, Sod2, Gpx1, and Cat, but did not affect the mRNA levels of Scarb1, Cyp11a1, Cyp21, Hsd3b1, and Hsd11b2. Triadimefon markedly reduced AT1R, CYP11B2, IGF1, NR5A1, and MC2R protein levels. Triadimefon significantly reduced the phosphorylation of AKT1 and ERK1/2 at 100 mg/kg without affecting the phosphorylation of AKT2. In contrast, it significantly increased AMPK phosphorylation at 100 mg/kg. In conclusion, exposure to triadimefon during gestation inhibits the development of fetal adrenal cortex in male fetuses. This inhibition is possibly due to the reduction of several proteins required for the synthesis of steroid hormones, and may be involved in changes in antioxidant contents and the phosphorylation of AKT1, ERK1/2, and AMPK.

Panel of suitable reference genes and its gender differences of fetal rat liver under physiological conditions and exposure to dexamethasone during pregnancy

The panel of suitable reference genes in the fetal liver have not been reported. In this study, five commonly used reference genes (GAPDH, β-actin, Rn18 s, Rpl13a, and Rps29) were firstly selected as candidates. Bestkeeper, GeNorm, and NormFinder software were then used to screen out the panel of suitable reference genes of male and female fetal rat liver under physiological and prenatal dexamethasone exposure (PDE) conditions. Finally, we verified the reliability of the screened panel of reference genes by standardizing sterol regulatory element binding protein 1c (SREBP1c) expression with different reference genes. The results showed that GAPDH + Rn18 s and GAPDH + Rpl13a were respectively the panel of suitable reference genes in male and female rat fetal liver under the physiological model, while Rn18 s + Rps29 and GAPDH + Rn18 s were respectively under the PDE model. The results showed that different reference genes affected the statistical results of SREBP1c expression, and the screened panel of suitable reference genes under the PDE model had smaller intragroup differences, when compared with other reference genes under physiological and PDE models. In conclusion, we screened and determined that the panel of suitable reference genes were GAPDH + Rn18 s and Rn18 s + Rps29 in the male rat fetal liver under physiological and PDE models, while they were GAPDH + Rpl13a and GAPDH + Rn18 s in the females, and confirmed that the selection of the panel of suitable reference genes in the fetal liver had gender differences and pathological model specificity.

Selection and Validation of the Optimal Panel of Reference Genes for RT-qPCR Analysis in the Developing Rat Cartilage

Real-time fluorescence quantitative PCR (RT-qPCR) is widely used to detect gene expression levels, and selection of reference genes is crucial to the accuracy of RT-qPCR results. Minimum Information for Publication of RT-qPCR Experiments (MIQE) proposes that using the panel of reference genes for RT-qPCR is conducive to obtaining accurate experimental results. However, the selection of the panel of reference genes for RT-qPCR in rat developing cartilage has not been well documented. In this study, we selected eight reference genes commonly used in rat cartilage from literature (GAPDH, ACTB, 18S, GUSB, HPRT1, RPL4, RPL5, and SDHA) as candidates. Then, we screened out the optimal panel of reference genes in female and male rat cartilage of fetus (GD20), juvenile (PW6), and puberty (PW12) in physiology with stability analysis software of genes expression. Finally, we verified the reliability of the selected panel of reference genes with the rat model of intrauterine growth retardation (IUGR) induced by prenatal dexamethasone exposure (PDE). The results showed that the optimal panel of reference genes in cartilage at GD20, PW6, and PW12 in physiology was RPL4 + RPL5, which was consistent with the IUGR model, and there was no significant gender difference. Further, the results of standardizing the target genes showed that RPL4 + RPL5 performed smaller intragroup differences than other panels of reference genes or single reference genes. In conclusion, we found that the optimal panel of reference genes in female and male rat developing cartilage was RPL4 + RPL5, and there was no noticeable difference before and after birth.

Long-term triphenyltin exposure disrupts adrenal function in adult male rats

Triphenyltin is an organotin, which is widely used as a fungicide in agriculture. Here, we reported the effects of triphenyltin on adrenal function in adult male rats. Adult male Sprague Dawley rats were daily gavaged with triphenyltin (0, 0.5, 1, and 2 mg/kg body weight) from postnatal day 56-86. Triphenyltin significantly decreased serum corticosterone levels at 1 and 2 mg/kg without affecting serum levels of aldosterone and adrenocorticotropic hormone. Triphenyltin increased thickness of zona glomerulosa without affecting that of zona fasciculata. Triphenyltin did not affect cell number in zona fasciculata and zona glomerulosa. Triphenyltin down-regulated the expression of Scarb1, Star, Cyp11a1, Hsd3b1, Cyp21, Cyp11b1, and Hsd11b1 at 1 and/or 2 mg/kg while it up-regulated the expression of At1, Nr4a2, and Hsd11b2 at 2 mg/kg. Triphenyltin activated the phosphorylation of AMPKα while suppressed the phosphorylation of AKT1 and SIRT1/PGC-1α in rat adrenals in vivo and H295R cells in vitro. In vitro, triphenyltin also induced ROS production in H295R cells at 100 nM, a concentration at which no apoptosis was induced. In conclusion, triphenyltin disrupts glucocorticoid synthesis in rat adrenal cortex via several mechanisms: 1) lowering AKT1 phosphorylation and SIRT1/PGC-1α levels; 2) activating AMPKα; and 3) possibly inducing ROS production.

Prenatal glucocorticoids exposure and fetal adrenal developmental programming

Clinically, we apply synthetic glucocorticoids to treat fetal and maternal diseases, such as premature labor and autoimmune diseases. Although its clinical efficacy is positive, the fetus will be exposed to exogenous synthetic glucocorticoids. Prenatal adverse environments (such as xenobiotics exposure, malnutrition, infection, hypoxia and stress) can cause fetuses overexposure to excessive endogenous maternal glucocorticoids. The level of glucocorticoids is the key to fetal tissue maturation and postnatal fate. A large number of studies have found that prenatal glucocorticoids exposure can lead to fetal adrenal dysplasia and dysfunction, continuing after birth and even into adulthood. As the core organ of fetal-originated adult diseases, fetal adrenal dysplasia is closely related to the susceptibility and occurrence of multiple chronic diseases, and there are also obvious gender differences. However, its intrauterine programming mechanisms have not been fully elucidated. This review summarizes recent advances in prenatal glucocorticoids exposure and fetal adrenal developmental programming alterations, which is of great significance for explaining adrenal developmental toxicity and the intrauterine origin of fetal-originated adult diseases.