Prenatal Dexamethasone Exposure Research Articles

Multi-organ developmental toxicity and its characteristics in fetal mice induced by dexamethasone at different doses, stages, and courses during pregnancy.

Dexamethasone is widely used in pregnant women at risk of preterm birth to reduce the occurrence of neonatal respiratory distress syndrome and subsequently reduce neonatal mortality. Studies have suggested that dexamethasone has developmental toxicity, but there is a notable absence of systematic investigations about its characteristics. In this study, we examined the effects of prenatal dexamethasone exposure (PDE) on mother/fetal mice at different doses (0.2, 0.4, or 0.8mg/kg b.i.d), stages (gestational day 14-15 or 16-17) and courses (single- or double-course) based on the clinical practice. Results showed that PDE increased intrauterine growth retardation rate, and disordered the serum glucose, lipid and cholesterol metabolic phenotypes, and sex hormone level of mother/fetal mice. PDE was further discovered to interfere with the development of fetal lung, hippocampus and bone, inhibits steroid synthesis in adrenal and testis, and promotes steroid synthesis in the ovary and lipid synthesis in the liver, with significant effects observed at high dose, early stage and double course. The order of severity might be: ovary > lung > hippocampus/bone > others. Correlation analysis revealed that the decreased serum corticosterone and insulin-like growth factor 1 (IGF1) levels were closely related to PDE-induced low birth weight and abnormal multi-organ development in offspring. In conclusion, this study systematically confirmed PDE-induced multi-organ developmental toxicity, elucidated its characteristics, and proposed the potential "glucocorticoid (GC)-IGF1" axis programming mechanism. This research provided an experimental foundation for a comprehensive understanding of the effect and characteristics of dexamethasone on fetal multi-organ development, thereby guiding the application of "precision medicine" during pregnancy.

Prenatal dexamethasone exposure impairs rat blood-testis barrier function and sperm quality in adult offspring via GR/KDM1B/FSTL3/TGFβ signaling.

Both epidemiological and animal studies suggest that adverse environment during pregnancy can change the offspring development programming, but it is difficult to achieve prenatal early warning. In this study we investigated the impact of prenatal dexamethasone exposure (PDE) on sperm quality and function of blood-testis barrier (BTB) in adult offspring and the underlying mechanisms. Pregnant rats were injected with dexamethasone (0.1, 0.2 and 0.4 mg·kg-1·d-1, s.c.) from GD9 to GD20. After weaning (PW4), the pups were fed with lab chow. At PW12 and PW28, the male offspring were euthanized to collect blood and testes samples. We showed that PDE significantly decreased sperm quality (including quantity and motility) in male offspring, which was associated with impaired BTB and decreased CX43/E-cadherin expression in the testis. We demonstrated that PDE induced morphological abnormalities of fetal testicle and Sertoli cell development originated from intrauterine. By tracing to fetal testicular Sertoli cells, we found that PDE dose-dependently increased expression of histone lysine demethylases (KDM1B), decreasing histone 3 lysine 9 dimethylation (H3K9me2) levels of follistatin-like-3 (FSTL3) promoter region and increased FSTL3 expression, and inhibited TGFβ signaling and CX43/E-cadherin expression in offspring before and after birth. These results were validated in TM4 Sertoli cells following dexamethasone treatment. Meanwhile, the H3K9me2 levels of FSTL3 promoter in maternal peripheral blood mononuclear cell (PBMC) and placenta were decreased and its expression increased, which was positively correlated with the changes in offspring testis. Based on analysis of human samples, we found that the H3K9me2 levels of FSTL3 promoter in maternal blood PBMC and placenta were positively correlated with fetal blood testosterone levels after prenatal dexamethasone exposure. We conclude that PDE can reduce sperm quality in adult offspring rats, which is related to the damage of testis BTB via epigenetic modification and change of FSTL3 expression in Sertoli cells. The H3K9me2 levels of the FSTL3 promoter and its expression in the maternal blood PBMC can be used as a prenatal warning marker for fetal testicular dysplasia.

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.

Epigenetic programming mediates abnormal gut microbiota and disease susceptibility in offspring with prenatal dexamethasone exposure

Prenatal dexamethasone exposure (PDE) can lead to increased susceptibility to various diseases in adult offspring, but its effect on gut microbiota composition and the relationship with disease susceptibility remains unclear. In this study, we find sex-differential changes in the gut microbiota of 6-month-old infants with prenatal dexamethasone therapy (PDT) that persisted in female infants up to 2.5 years of age with altered bile acid metabolism. PDE female offspring rats show abnormal colonization and composition of gut microbiota and increased susceptibility to cholestatic liver injury. The aberrant gut microbiota colonization in the PDE offspring can be attributed to the inhibited Muc2 expression caused by decreased CDX2 expression before and after birth. Integrating animal and cell experiments, we further confirm that dexamethasone could inhibit Muc2 expression by activating GR/HDAC11 signaling and regulating CDX2 epigenetic modification. This study interprets abnormal gut microbiota and disease susceptibility in PDT offspring from intrauterine intestinal dysplasia.

Transgenerational inheritance of adrenal steroidogenesis inhibition induced by prenatal dexamethasone exposure and its intrauterine mechanism

BackgroundAdrenal gland is the synthesis and secretion organ of glucocorticoid, which is crucial to fetal development and postnatal fate. Recently, we found that prenatal dexamethasone exposure (PDE) could cause adrenal dysfunction in offspring rats, but its multigenerational genetic effects and related mechanisms have not been reported.MethodsThe PDE rat model was established, and female filial generation 1 (F1) rats mate with wild males to produce the F2, the same way for the F3. Three generation rats were sacrificed for the related detection. SW-13 cells were used to clarify the epigenetic molecular mechanism.ResultsThis study confirmed that PDE could activate fetal adrenal glucocorticoid receptor (GR). The activated GR, on the one hand, up-regulated Let-7b (in human cells) to inhibit steroidogenic acute regulatory protein (StAR) expression directly; on the other hand, down-regulated CCCTC binding factor (CTCF) and up-regulated DNA methyltransferase 3a/3b (Dnmt3a/3b), resulting in H19 hypermethylation and low expression. The decreased interaction of H19 and let-7 can further inhibit adrenal steroidogenesis. Additionally, oocytes transmitted the expression change of H19/let-7c axis to the next generation rats. Due to its genetic stability, F2 generation oocytes indirectly exposed to dexamethasone also inhibited H19 expression, which could be inherited to the F3 generation.ConclusionsThis cascade effect of CTCF/H19/Let-7c ultimately resulted in the transgenerational inheritance of adrenal steroidogenesis inhibition of PDE offspring. This study deepens the understanding of the intrauterine origin of adrenal developmental toxicity, and it will provide evidence for the systematic analysis of the transgenerational inheritance effect of acquired traits induced by PDE.45YfzC5bohQgYTrjifxqYiVideo

Prenatal dexamethasone exposure affects mandibular bone and tooth development in rats

Prenatal dexamethasone exposure affects mandibular bone and tooth development in rats

Gestational dexamethasone exposure impacts hippocampal excitatory synaptic transmission and learning and memory function with transgenerational effects.

The formation of learning and memory is regulated by synaptic plasticity in hippocampal neurons. Here we explored how gestational exposure to dexamethasone, a synthetic glucocorticoid commonly used in clinical practice, has lasting effects on offspring's learning and memory. Adult offspring rats of prenatal dexamethasone exposure (PDE) displayed significant impairments in novelty recognition and spatial learning memory, with some phenotypes maintained transgenerationally. PDE impaired synaptic transmission of hippocampal excitatory neurons in offspring of F1 to F3 generations, and abnormalities of neurotransmitters and receptors would impair synaptic plasticity and lead to impaired learning and memory, but these changes failed to carry over to offspring of F5 and F7 generations. Mechanistically, altered hippocampal miR-133a-3p-SIRT1-CDK5-NR2B signaling axis in PDE multigeneration caused inhibition of excitatory synaptic transmission, which might be related to oocyte-specific high expression and transmission of miR-133a-3p. Together, PDE affects hippocampal excitatory synaptic transmission, with lasting consequences across generations, and CDK5 in offspring's peripheral blood might be used as an early-warning marker for fetal-originated learning and memory impairment.

Inhibition of miR-6215 rescued low subchondral bone mass caused by maternal exposure to dexamethasone in female offspring rats

Osteoporotic osteoarthritis is primarily associated with low subchondral bone mass. However, the mechanisms and therapeutic targets of osteoporotic osteoarthritis caused by prenatal dexamethasone exposure (PDE) in offspring remain unclear. In this study, pregnant Wistar rats were injected with dexamethasone to obtain bone tissue from fetal and postnatal rat offspring for analysis. Bone marrow mesenchymal stem cells (BMSCs) were isolated in vitro to elucidate the underlying molecular mechanisms. We determined in vivo that PDE reduced subchondral bone mass in adult female rat offspring, which originated from dysplasia of the subchondral bone. PDE led to a continuous increase in miR-6215 expression, accompanied by a decrease in FERM domain-containing protein 6 (FRMD6) expression. In vitro, dexamethasone upregulated miR-6215 expression through the glucocorticoid receptor, thereby inhibiting FRMD6 expression, promoting the translocation of yes-associated protein 1 (YAP1) into the nucleus of BMSCs, and downregulating downstream osteogenic marker genes. Finally, the rAAV-miR-6215 inhibitor rescued the low subchondral bone mass and osteoarthritis susceptibility caused by PDE in rat offspring. In conclusion, increased expression of miR-6215 mediates low subchondral bone mass caused by PDE through FRMD6/YAP1 signaling. Therefore, miR-6215 is a promising therapeutic target for PDE-induced low subchondral bone mass in offspring.

Prenatal dexamethasone exposure impaired vascular reactivity in adult male offspring cerebral arteries

BackgroundCerebrovascular disease is one of the leading causes of death worldwide. Middle cerebral artery (MCA) is the largest and most complex of cerebral arteries. The prenatal period is a critical time for development, which largely determines lifelong health. Clinically, glucocorticoids (GCs) administration to accelerate preterm fetal lung maturation has become standard practice. Prenatal GCs administration increases cardiovascular risks in offspring, but little is known regarding the side effects on offspring MCA function. ObjectiveWe investigated the alterations of MCA reactivity following prenatal GCs administration in postnatal offspring. Method and resultsPregnant Sprague-Dawley rats received synthetic GCs (dexamethasone, DEX) during the last week of pregnancy, and we examined vascular reactivity, cellular electrophysiology, and gene promoter epigenetic modifications in the male offspring MCA. Our results showed that prenatal DEX exposure increased the sensitivity of offspring MCA to Angiotensin II, which was resulted from the increased Cav1.2 (L-type Ca2+ channels subunit alpha1 C). Mechanistically, prenatal DEX exposure resulted in a transcriptionally active chromatin structure at the Cav1.2 gene promoter by altering histone modifications. This activation led to increased expression of vascular Cav1.2 gene, ultimately resulting in increased MCA contractility in offspring. ConclusionThe present study is the first to demonstrate that the adverse effects of prenatal GCs administration on cerebrovascular tone persist into adulthood, providing new insights into developmental origins of cerebrovascular disease.

Autophagy inhibition mediated by intrauterine miR-1912-3p/CTSD programming participated in the susceptibility to osteoarthritis induced by prenatal dexamethasone exposure in male adult offspring rats.

Autophagy inhibition is known to be involved in the development of adult osteoarthritis. Dexamethasone, as a synthetic glucocorticoid, is widely used for premature delivery and related pregnancy diseases in clinics. We have previously shown that prenatal dexamethasone exposure (PDE) was associated with increased susceptibility to postnatal osteoarthritis in offspring. However, whether the occurrence of fetal-originated adult osteoarthritis induced by PDE is related to autophagy remains unclear. In this study, we first found that PDE could increase the mRNA and protein expression of cartilage matrix-degrading enzymes (MMP3, MMP13, and ADAMTS5) and decrease the cartilage matrix contents in adult offspring, and the in vitro results suggested that this might be related to the autophagy inhibition of chondrocytes. Further, we demonstrated a persistent autophagy inhibition with autolysosome accumulation, low expression of cathepsin D (CTSD), increased H3K9ac level, and expression of miR-1912-3p in the cartilage of PDE offspring from fetus to adulthood. In vitro experiments showed that dexamethasone inhibited autophagy flux and CTSD expression in fetal chondrocytes, while overexpression of CTSD could alleviate the inhibition of autophagic flux induced by dexamethasone. Finally, we confirmed that dexamethasone increased the H3K9ac level and expression of miR-1912-3p through activation of the glucocorticoid receptor (GR), resulting in the decreased expression of CTSD and inhibition of autophagy flux in fetal chondrocytes. In conclusion, intrauterine miR-1912-3p/CTSD programming-mediated autophagy inhibition promoted the susceptibility to osteoarthritis in PDE adult offspring rats. This study provides new ideas for exploring early prevention and therapeutic targets in fetal-originated osteoarthritis.

The role of chondrocyte-to-osteoblast trans-differentiation in fetal bone dysplasia of mice caused by prenatal exposure to dexamethasone.

Maternal exposure to dexamethasone can cause developmental toxicity of long bones in offspring. However, the effect of dexamethasone on the trans-differentiation of growth plate chondrocytes into osteoblasts and its role in bone dysplasia of fetuses caused by prenatal dexamethasone exposure (PDE) remains unclear. In this study, pregnant mice were treated with different doses, stages, and courses of dexamethasone according to clinical practice to reveal the phenomenon. Further, growth plate chondrocytes were treated with dexamethasone in vitro to clarify the phenomenon and mechanism. The results showed that PDE caused dysplasia of fetal long bones in female and male mice, accompanied by the delayed formation of the primary ossification center and the widening hypertrophic zone of growth plate cartilage. Meanwhile, PDE increased the number of hypertrophic chondrocytes at growth plate cartilage and decreased the number of osteoblasts at the primary ossification center. Moreover, PDE significantly decreased the expression of osteogenic transcription factor Runx2 but increased the expression of hypertrophic chondrocytes marker Col10. These above phenomena were more significant in the high dose, early stage, and double courses of dexamethasone exposure groups, and the male fetal mice showed more obvious than the female fetal mice. In vitro, dexamethasone significantly inhibited the trans-differentiation of growth plate chondrocytes into osteoblasts, accompanied by a decrease in Runx2 expression and an increase in Col10 expression. In conclusion, this study revealed the phenomenon and mechanism of fetal bone dysplasia caused by PDE from the new perspective of trans-differentiation disorder of growth plate chondrocytes to osteoblasts.

Epigenetic programming of TBX2/CX43 mediates lower sperm quality in male offspring induced by prenatal dexamethasone exposure.

Decreased sperm quality is the main cause of male infertility. Studies have found that prenatal dexamethasone exposure (PDE) decreases sperm quality in male offspring after birth, but the mechanism is unclear. Wistar pregnant rats were subcutaneously injected with 0.1, 0.2 and 0.4 mg/kg.d dexamethasone at gestational day 9-20. The testes and sperm of first-generation (F1) offspring were collected, and F1 offspring were mated with wild-type female rats to obtain F2. Compared with the control group, F1 offspring in PDE group had lower sperm count and motility after birth, and the deformity rate increased. F2 fetal rats' body length and weight decreased, and the intrauterine growth retardation rate increased. Meanwhile, PDE decreased the expression of connexin 43 (CX43) in offspring testes, while T-box transcription factor 2 (TBX2) promoter region histone 3 lysine 9 acetylation (H3K9ac) level and its expression were increased. Traced back to F1 fetus testes, PDE increased the expression of glucocorticoid receptor (GR) and P300, activated GR protein into the nucleus, and made GR act on the TBX2 promoter region. Further, a series of Sertoli cell interventions confirmed that dexamethasone promoted GR to recruit P300, increased the H3K9ac level of TBX2 promoter region and its expression, and inhibited the expression of CX43. This study confirmed that PDE decreased sperm quality of male offspring, which is related to the epigenetic programming of TBX2/CX43 in the Sertoli cells, provided a theoretical and experimental basis for guiding the rational use of drugs during pregnancy.

Hypermethylation of the Bmp4 promoter dampens binding of HIF-1α and impairs its cardiac protective effects from oxidative stress in prenatally GC-exposed offspring

The exposure to an unhealthy environment in utero can lead to the occurrence of cardiovascular diseases in the offspring. Glucocorticoids (GC) are essential for normal development and maturation of fetal organs and is a first-line treatment for pregnant women affected by autoimmune diseases. However, excess prenatal GC exposure might program the development of fetal organs and cause a number of chronic diseases in later life. Our previous studies indicated that cardiac functions were significantly compromised in rat offspring prenatally exposed to the synthetic glucocorticoid dexamethasone (DEX), only after ischemia–reperfusion. In the present study, we further observed that DNA hypermethylation of bone morphogenetic protein 4 (Bmp4) promoter in cardiomyocytes caused by prenatal DEX exposure substantially dampened the binding activity of transcription factor HIF-1α induced by cardiac ischemia. Therefore, prenatal DEX exposure inhibits the induction of BMP4 upon I/R and attenuates the protective effects of BMP4 in cardiomyocytes, which eventually manifests as malfunction of the adult heart. Moreover, we employed two cardiac-specific Bmp4 knock-in mouse models and found that in vivo BMP4 overexpression could rescue the cardiac dysfunction caused by prenatal GC exposure. In depth mechanistic research revealed that BMP4 protects the cardiomyocytes from mitophagy and apoptosis by attenuating mitochondrial PGC-1α expression in a p-Smad and Parkin-dependent manner. These findings suggest that prenatal GC exposure increases the susceptibility of the offspring’s heart to a “second strike” after birth, due to the failure of hypoxia-induced HIF-1α transactivation of the hypermethylated Bmp4 promoter in cardiomyocytes. Pretreatment with the DNA methylation inhibitor, 5-Aza-2′-deoxycytidine, could be a potential therapeutic method for this programming effect of GC exposure during pregnancy on neonatal cardiac dysfunction.

The Effects of Prenatal Dexamethasone Exposure on Brain Metabolic Homeostasis in Adulthood: Implications for Depression.

Since depression produces a long-term negative impact on quality of life, understanding the pathophysiological changes implicated in this disorder is urgent. There is growing evidence that demonstrates a key role for dysfunctional energy metabolism in driving the onset of depression; thus, bioenergetic alterations should be extensively studied. Brain metabolism is known to be a glucocorticoid-sensitive process, but the long-lasting consequences in adulthood following high levels of glucocorticoids at the early stages of life are unclear. We examined a possible association between brain energetic changes induced by synthetic glucocorticoid-dexamethasone treatment in the prenatal period and depressive-like behavior. The results show a reduction in the oxidative phosphorylation process, Krebs cycle impairment, and a weakening of the connection between the Krebs cycle and glycolysis in the frontal cortex of animals receiving dexamethasone, which leads to ATP reduction. These changes appear to be mainly due to decreased expression of pyruvate dehydrogenase, impairment of lactate transport to neurons, and pyruvate to the mitochondria. Acute stress in adulthood only slightly modified the observed alterations in the frontal cortex, while in the case of the hippocampus, prenatal exposure to dexamethasone made this structure more sensitive to future adverse factors.

MiR-133a-3p/Sirt1 epigenetic programming mediates hypercholesterolemia susceptibility in female offspring induced by prenatal dexamethasone exposure

Mounting evidence indicates that adverse intrauterine conditions increase offspring’s hypercholesterolemia susceptibility in adulthood. This study aimed to confirm prenatal dexamethasone exposure (PDE)-induced hypercholesterolemia susceptibility in female adult offspring rats, and elucidate its intrauterine programming mechanism. Pregnant Wistar rats were injected with dexamethasone subcutaneously (0, 0.1 and 0.2 mg/kg·d) from gestational day (GD) 9 to 20. Serum and liver of the female offspring were collected at GD21 and postnatal week (PW) 12 and 28. PDE offspring showed elevated serum total cholesterol (TCH) levels and a cholesterol phenotype of high cardiovascular disease risk at PW12 and PW28. The histone acetylation levels of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (Hmgcr) and its expression were consistently increased in the PDE offspring both in utero and after birth. Moreover, PDE promoted glucocorticoid receptor (GR) nuclear translocation and miR-133a-3p expression and inhibited sirtuin-1 (Sirt1) expression in the fetal liver. In vitro, dexamethasone increased intracellular and supernatant TCH levels and miR-133a-3p expression, decreased SIRT1 expression, and promoted HMGCR histone acetylation and expression in bone marrow mesenchymal stem cells (BMSCs) hepatoid differentiated cells and HepG2 cell line. GR siRNA, miR-133a-3p inhibitor or SIRT1 overexpression reversed dexamethasone-induced downstream molecular and phenotypic changes. Furthermore, elevated TCH levels in umbilical cord blood and increased HMGCR expression in peripheral blood mononuclear cells (PBMCs) were observed in human female neonates who had received dexamethasone treatment during pregnancy. In conclusion, PDE can cause persistent enhancement of hepatic cholesterol synthesis function before and after birth through GR/miR-133a-3p/Sirt1 pathway, eventually leading to increased hypercholesterolemia susceptibility in female offspring rats.

Prenatal Dexamethasone Exposure in Male Rats Alters Gene Expression Patterns of Epigenetic Enzymes in Hippocampus and Cortex

Objective: This study aimed to examine the effects of prenatal stress (PS) induced by dexamethasone exposure on gene expression levels of epigenetic enzymes in hippocampus and cerebral cortex of male rats through relative mRNA levels of histone acetyltransferases (activating transcription factor 2, P300), histone deacetylases (HDAC1, HDAC2), and DNA methyltransferases (DNMT1, DNMT3a, DNMT3b). Methods: Pregnant rats were daily injected subcutaneously with dexamethasone (0.2 mg/kg) or saline during the third week of gestation. After birth, male rats were killed at 90 days of age (n = 5 for control and dexamethasone groups). Hippocampal and cortical tissues were used for gene expression analyses. The effects of dexamethasone on epigenetic mechanisms were investigated by real-time polymerase chain reaction through relative mRNA levels of DNMT1, DNMT3a, DNMT3b, activating transcription factor 2, P300, HDAC1, and HDAC2. Statistical comparisons were performed with Student’s t-test. Results: Prenatal dexamethasone exposure (PDE) caused increased DNMT1, DNMT3a, DNMT3b, activating transcription factor 2 and decreased P300 mRNA levels in hippocampus while increased DNMT3a, DNMT3b, activating transcription factor 2, P300, HDAC1, and HDAC2 mRNA levels were achieved in cortex. Furthermore, no significant differences were obtained in cortical DNMT1 and hippocampal HDAC1 and HDAC2 gene expression levels between control and prenatally stressed rats. Conclusion: Our results emphasize the effect of prenatal dexamethasone exposure on gene expression levels of epigenetic enzymes involved in histone acety latio n/dea cetyl ation and DNA methylation in male rats and suggest that prenatal stress may lead to epigenetic dysregulation through alterations in hippocampal and cortical gene expression patterns of DNMT1, DNMT3a, DNMT3b, activating transcription factor 2, P300, HDAC1, and HDAC2.

Positive programming of the GC-IGF1 axis mediates adult osteoporosis susceptibility in male offspring rats induced by prenatal dexamethasone exposure

Prenatal dexamethasone exposure (PDE) can lead to offspring long bone dysplasia and continue to postnatal, and this is an important cause of fetal-derived osteoporosis. Studies have confirmed that intrauterine endogenous GC overexposure mediates multiple organ dysplasia and adult-related disease susceptibility in offspring through the glucocorticoid-insulin-like growth factor1 (GC-IGF1) axis. However, it remains unknown if exogenous dexamethasone can regulate bone development in offspring through the GC-IGF1 axis. We determined that the PDE fetal rats exhibited poor osteogenic differentiation, decreased bone mass that continued to adolescence, and increased susceptibility to osteoporosis in adulthood. Concurrently, PDE decreased the serum corticosterone concentration and IGF1 expression in offspring before and after birth, while the increased serum corticosterone concentration induced by chronic stress reversed the inhibition of IGF1 expression induced by PDE. Furthermore, PDE decreased the expression of GRα and miR-130a-5p, increased HDAC4, and decreased H3K27 acetylation in the IGF1 promoter region in bone tissue, and the above changes were negatively compensated after chronic stress. In vitro, a low concentration of corticosterone inhibited the expression of GRα and miR130a-5p, upregulated the expression of HDAC4, inhibited the promoter region H3K27 acetylation, and expression of IGF1 in bone marrow mesenchymal stem cell (BMSCs) osteoblast differentiated cells and inhibited osteogenic differentiation of BMSCs. GRα overexpression, miR-130a-5p mimic treatment, or HDAC4 siRNA exposure reversed the downstream molecular alterations caused by low corticosterone concentrations. In conclusion, PDE-induced intrauterine hypoglucocorticoid exposure could positively program IGF1 expression in bone tissue through the GRα/miR-130a-5p/HDAC4 pathways, thus mediating osteogenic dysdifferentiation and adult osteoporosis susceptibility in male offspring rats.

Prenatal dexamethasone exposure alters effort decision making and triggers nucleus accumbens and anterior cingulate cortex functional changes in male rats

Daily, individuals select actions based on cost-benefit to allocate resources into goal-directed actions. Different brain regions coordinate this complex decision, including the nucleus accumbens (NAc), anterior cingulate cortex (ACC), and ventral tegmental area (VTA). In utero exposure to synthetic glucocorticoids (iuGC), such as dexamethasone, triggers prominent motivation deficits but the impact of this exposure in the ACC-NAc and/or ACC-VTA circuits is unknown. Here, we show that iuGC exposure causes decreased motivation for natural rewards (food) and impaired effort-based decision-making. Importantly, reduced neuronal activation (number of c-fos+ neurons) was observed in the NAc core and ACC of iuGC rats in comparison to CTR rats after performing the effort-based decision-making task. In addition, iuGC treatment led to increased NAc and ACC basal neuronal activity. Electrophysiological recordings during optogenetic modulation of ACC terminals in the NAc revealed that the ACC-NAc circuit is dysfunctional in iuGC animals. These data suggest that iuGC animals present motivational and effort-based decision-making deficits that can be associated with the observed ACC-NAc dysfunction.

Transforming growth factor-β receptor 1: An intervention target for genetic poor cartilage quality induced by prenatal dexamethasone exposure

IntroductionFetal-originated osteoarthritis is relative to poor cartilage quality and may exhibit transgenerational genetic effects. Previous findings revealed prenatal dexamethasone exposure (PDE) induced poor cartilage quality in offspring. ObjectivesThis study focused on further exploring molecular mechanism, heritability, and early intervention of fetal-originated osteoarthritis. MethodsPregnant rats (F0) were segregated into control and PDE groups depending upon whether dexamethasone was administered on gestational days (GDs) 9–20. Some female offspring were bred with healthy males during postnatal week (PW) 8 to attain the F2 and F3 generations. The F3-generation rats were administrated with glucosamine intragastrically at PW12 for 6 weeks. The knee cartilages of male and female rats at different time points were harvested to assay their morphologies and functions. Furthermore, primary chondrocytes from the F3-generation rats were isolated to confirm the mechanism and intervention target of glucosamine. ResultsCompared with the control, female and male rats in each generation of PDE group showed thinner cartilage thicknesses; shallower and uneven staining; fewer chondrocytes; higher Osteoarthritis Research Society International scores; and lower mRNA and protein expression of SP1, TGFβR1, Smad2, SOX9, ACAN and COL2A1. After F3-generation rats were treated with glucosamine, all of the above changes could be reversed. In primary chondrocytes isolated from the F3-generation rats of PDE group, glucosamine promoted SP1 expression and binding to TGFβR1 promoter to increase the expression of TGFβR1, p-Smad2, SOX9, ACAN and COL2A1, but these were prevented by SB431542 (a potent and selective inhibitor of TGFβR1). ConclusionsPDE induced chondrodysplasia in offspring and stably inherited in F3-generation rats, which was related to decreased expression of SP1/TGFβR1/Smad2/SOX9 pathway to reduce the cartilage matrix synthesis, without major sex-based variations. Glucosamine could alleviate the poor genetic cartilage quality in offspring induced by PDE by up-regulating SP1/TGFβR1 signaling, which was prevented by a TGFβR1 inhibitor. This study elucidated the molecular mechanism and therapeutic target (TGFβR1) of genetic chondrodysplasia caused by PDE, which provides a research basis for precisely treating fetal-originated osteoarthritis.

Low miR-92a-3p in oocytes mediates the multigenerational and transgenerational inheritance of poor cartilage quality in rat induced by prenatal dexamethasone exposure

An adverse environment during pregnancy leads to intrauterine programming changes in multiple generations, resulting in the multigenerational inheritance of abnormal phenotype. Here, we reported the multigenerational inheritance of poor articular cartilage quality induced by prenatal dexamethasone exposure (PDE) with 0.2 mg/kg·d dexamethasone from gestational day (GD) 9 to GD20 in Wistar rats and investigated its intrauterine epigenetic programming mechanism. For the F1 female offspring at GD20, we found that the matrix synthesis of cartilage was suppressed, the histone 3 lysine 9 acetylation (H3K9ac) level and mRNA expression of the TGFβ signaling pathway were decreased, and the expression of histone deacetylase (HDAC) 2 was increased in the cartilage. Meaningfully, the similar changes were also found in the F1-F3 female adult offspring. Furthermore, PDE decreased the expression of miR-92a-3p in the oocytes of the F1-F2 offspring and in the cartilage of the F1-F3 generations. In vitro, the effect of dexamethasone on chondrocytes revealed that it inhibited the expression of miR-92a-3p through activating and binding glucocorticoid receptor, and reduced the H3K9ac level in the promoter of the TGFβ signaling pathway through the increased HDAC2. In conclusion, PDE induces the multigenerational inheritance of poor articular cartilage quality in female adult offspring; the potential mechanism involves the intergenerational effect of low miR-92a-3p expression in oocytes and low functional programming of TGFβ signaling pathway induced by decreased H3K9ac level via upregulating HDAC2. This study provides a new perspective to explain the multi-generation inheritance of PDE-induced organ dysplasia in adult offspring.