Excitotoxicity and compensatory upregulation of GAD67 in fetal rat hippocampus caused by prenatal nicotine exposure are associated with inhibition of the BDNF pathway

Evidence for Wnt signaling's central involvement in perinatal nicotine exposure-induced offspring lung pathology and its modulation by electroacupuncture

OBJECTIVE

Many factors during pregnancy can induce intrauterine growth restriction (IUGR), resulting in various adverse perinatal outcomes such as low birth weight and multiple organ disorders. Among these factors, prenatal smoke/nicotine exposure is a common cause of IUGR, often associated with altered fetal lung development. The classical Wnt signaling pathway plays a vital role in lung development, and its alterations are commonly associated with developmental lung pathologies. The purpose of this study was to determine whether electroacupuncture (EA) at "Zusanli" (ST 36) points protects perinatal nicotine exposure (PNE)-induced offspring lung dysplasia through Wnt/β-catenin signaling pathway and to identify specific Wnt signaling pathway targets of EA.

METHODS

Following a well-established protocol, nicotine (1 mg/kg/ body weight) was administered subcutaneously to pregnant Sprague Dawley rat dams from gestational day 6 to postnatal day 21. In the EA group, dams were treated with EA at both ST 36 acupoints, while in another experimental group, Wnt/β-catenin signaling pathway agonist was injected subcutaneously (2 mg/kg/ body weight). Offspring body weight (PND 1, 7, 14, and 21), lung weight, Wnt signaling markers, pulmonary function, and lung morphology were determined at sacrifice on PND 21. Specifically, Western blotting and Real-time PCR were used to detect the protein and mRNA levels of critical Wnt signaling markers Wnt2, Wnt7b, FZD4, FZD7, LRP5, and LRP6 in the offspring lung. The protein levels of β-catenin in lung tissue of offspring rats were detected by ELISA that of LEF-1 by Western blotting.

RESULTS

Compared to the control group, the body and lung weights of the offspring rats were significantly decreased in the nicotine-only exposed group. The pulmonary function determined as FVC, PEF, TV, and Cdyn was also significantly decreased, while PIF was significantly increased. The protein levels and mRNA expression of Wnt2, Wnt7b, FZD4, FZD7, LRP5, and LRP6 in the lung tissue of the PNE offspring rats were significantly increased. With EA administration at ST 36 acupoints concomitant with nicotine administration, the body and lung weights, pulmonary function (FVC, PEF, PIF, TV, and Cdyn), protein and mRNA levels Wnt signaling pathway markers (Wnt2, Wnt7b, FZD4, FZD7, LRP5, LRP6, β-catenin, and LEF-1) normalized and were not different from the control group. Notably, Wnt agonists agonist administration blocked the protective effects of EA against PNE-induced lung morphological, molecular, and function changes, highlighting the central significance of Wnt pathway signaling in PNE-induced offspring pulmonary pathology and its modulation by EA at ST 36 acupoints.

CONCLUSION

Concomitant maternal EA at ST 36 acupoints from gestational day 6 to PND 21 protects against offspring PNE-induced lung phenotype. The protective effect is achieved by regulating the expression of Wnt ligand proteins (Wnt2 and Wnt7b) and receptor proteins (FZD4, FZD7, LRP5, and LRP6) upstream of the Wnt/β-catenin signaling pathway intermediates β-catenin, and LEF-1.

Endurance Exercise Training Attenuates the Waterpipe Smoke Inhaling-Induced Learning and Memory Impairment in Rats: Role of Neurotrophic Factors and Apoptotic System

INTRODUCTION

The increasing prevalence of waterpipe tobacco smoking (WTS) and its detrimental effects on memory function have been reported. This study was conducted to investigate the effect of moderate-intensity endurance exercise on the detrimental effects of WTS on learning and spatial memory in rats.

AIMS AND METHODS

Animals were divided into the Control group (CTL), the exercise group (Ex) which trained for 8 weeks, the WTS group (Wp) exposed to smoke inhalation (30 minutes per day, 5 days each week, and for 8 weeks), and the group that did exercise training and received waterpipe smoke together (Ex + Wp). Thereafter, learning and spatial memory were assessed by the Morris water maze test and hippocampal molecular measurements were done.

RESULTS

Waterpipe smoke significantly impaired learning and spatial memory, decreased expression of neurotrophic factors IGF-1 and BDNF (p < .01 and p < .05 vs. CTL group, respectively), increased BAX to BCL-2 ratio (p < .001 vs. CTL group) in hippocampal tissue, and increased the percent of damaged neurons in the hippocampal CA1 area (p < .05 vs. CTL group). Combination of exercise training with WTS prevented learning and spatial memory disturbances and recovered expression of neurotrophic factors IGF-1 (p < .05 vs. Wp group), decreased BAX to BCL-2 ratio (p < .001 vs. Wp group), and reduced percentage of damaged neurons (p < .05 vs. Wp group).

CONCLUSIONS

Findings suggest that moderate-intensity endurance exercise training can ameliorate learning and memory impairment caused by waterpipe smoke in rats. This effect partly results from increasing the expression of neurotrophic factors BDNF and IGF-1 and correcting pro/anti-apoptotic proteins balance in the hippocampal tissue.

IMPLICATIONS

The popularity of WTS especially among youth is increasing. We assessed the effect of hookah smoke with/without exercise on learning and memory. Hookah smoke leads to CA1-neural injury and impairs learning and memory in rats. A combination of exercise training with hookah smoke attenuates these complications. This positive effect of exercise is partially mediated by the balancing of brain-derived neurotrophic factor (BDNF) and Insulin-like growth factor-1 (IGF-1) and also the BAX to BCL-2 ratio, a significant predictor of cell susceptibility to apoptosis. Extrapolation of these positive findings to humans needs complementary studies.

Antidepressant effects of cherry leaf decoction on a chronic unpredictable mild stress rat model based on the Glu/GABA-Gln metabolic loop

Cherry leaves (Prunus pseudocerasus Lindl. [Rosaceae]), a traditional Chinese herbal medicine, can regulate the factors closely related to depression including inflammatory cytokines, oxidative stress and blood glucose level. However, the antidepressant effects of cherry leaves and underlying neuromodulatory mechanisms remain relatively have not been elucidated explicitly. The present study investigated the antidepressant effects of cherry leaf decoction (CLD). The underlying neuromodulatory mechanism was explored by examining the glutamate (Glu)/γ-aminobutyric acid (GABA)-glutamine (Gln) metabolic loop. The chronic unpredictable mild stress (CUMS) rodent model was used in this study. The main flavonoids components of CLD were identified using high-performance liquid chromatography (HPLC). The antidepressant effects of CLD were assessed throughout behavioural tests including the bodyweight, sucrose preference test (SPT), forced swimming test (FPT) and tail suspension test (TST). Moreover, The baseline levels of serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were quantified. The expression of proteins integrally involved in the Glu/GABA-Gln metabolic loop were observed and quantified by Western blotting, reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. This study found that CLD ameliorated depressive-like behaviours induced by CUMS. The increase of serum ACTH and CORT baseline levels induced by CUMS was also reversed after CLD intervention. Furthermore, CUMS reduced the expression of GAD65, GAD67, GLT-1, GS and GABA_A and increased NMDAR1 levels in the rat hippocampus, which was normalized by CLD treatment. The findings demonstrated that CLD could ameliorate the depression-like behaviours induced by CUMS, potentially through the inhibition of hypothalamic-pituitary-adrenal (HPA) axis hyperactivity and the regulation of Glu/GABA-Gln metabolic loop.

Prenatal smoke (Nicotine) exposure and offspring's metabolic disease susceptibility in adulthood

Exposure to smoking (nicotine) during pregnancy not only directly affects fetal development, but also increases susceptibility to metabolic diseases in adulthood, but the mechanism of action remains unclear. Here, we review epidemiological and laboratory studies linking these relationships. In addition to the direct effect of nicotine on the fetus, intrauterine neuroendocrine-metabolic programming mediated by maternal glucocorticoid overexposure also plays an important role, involving glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis, hypothalamic-pituitary-adrenal (HPA) axis, renin-angiotensin system (RAS) and other endocrine systems. Epigenetics is involved in intrauterine neuroendocrine-metabolic programming, metabolic disease susceptibility and multigenerational inheritance. There are "two programming" and "two strikes" mechanisms for the occurrence of fetal-originated metabolic diseases in adulthood. These innovative research summaries and academic viewpoints provide experimental and theoretical basis for systematically elucidating the occurrence and development of fetal-originated metabolic diseases.

Altered hippocampal GR/KCC2 signaling mediates susceptibility to convulsion in male offspring following dexamethasone exposure during pregnancy in rats

Epidemiological research suggests that convulsions may have an intrauterine developmental origin related to the application of dexamethasone, an artificially synthesized glucocorticoid. Here, using a rat animal model of prenatal dexamethasone exposure (PDE) we confirm that PDE can cause susceptibility to convulsions in male offspring and explore the epigenetic programming mechanism underlying this effect related to intrauterine type 2K⁺-Cl^- cotransporter (KCC2). Wistar rats were injected with dexamethasone (0.2mg/kg/d) subcutaneously during the gestational days (GD) 9-20 and part of the offspring was given lithium pilocarpine (LiPC) at postnatal week 10. Our results showed that male offspring of the PDE+LiPC group exhibited convulsions susceptibility, as well as increased hippocampal gamma-aminobutyric acid (GABA) and intracellular chloride ions level and decreased GABA receptor expression. The offspring also showed a decrease of hippocampal KCC2 H3K14ac levels and KCC2 expression. PDE male fetal rats (GD20) showed similar changes to male offspring after birth and exhibited an increased expression of glucocorticoid receptor (GR) and histone deacetylase type 2 (HDAC2). We observed effects consistent with those observed in PDE fetal rats following in vitro dexamethasone treatment of the fetal rat hippocampal neuron H19-7 cell line, and the effects could be reversed by treatment with a GR inhibitor (RU486) or HDAC2 inhibitor (romidepsin). Taken together, this study confirmed that PDE causes a reduction of H3K14ac levels in the KCC2 promoter region caused by activation of fetal hippocampal GR-HDAC2-KCC2 signaling. We proposed that this abnormal epigenetic modification is the mechanism underlying offspring convulsions susceptibility. CATEGORIES: mechanism of toxicity.

DNA methylome perturbations: an epigenetic basis for the emergingly heritable neurodevelopmental abnormalities associated with maternal smoking and maternal nicotine exposure†

Maternal smoking during pregnancy is associated with an ensemble of neurodevelopmental consequences in children and therefore constitutes a pressing public health concern. Adding to this burden, contemporary epidemiological and especially animal model research suggests that grandmaternal smoking is similarly associated with neurodevelopmental abnormalities in grandchildren, indicative of intergenerational transmission of the neurodevelopmental impacts of maternal smoking. Probing the mechanistic bases of neurodevelopmental anomalies in the children of maternal smokers and the intergenerational transmission thereof, emerging research intimates that epigenetic changes, namely DNA methylome perturbations, are key factors. Altogether, these findings warrant future research to fully elucidate the etiology of neurodevelopmental impairments in the children and grandchildren of maternal smokers and underscore the clear potential thereof to benefit public health by informing the development and implementation of preventative measures, prophylactics, and treatments. To this end, the present review aims to encapsulate the burgeoning evidence linking maternal smoking to intergenerational epigenetic inheritance of neurodevelopmental abnormalities, to identify the strengths and weaknesses thereof, and to highlight areas of emphasis for future human and animal model research therein.

Mechanisms Underlying Neurologic Injury in Intrauterine Growth Restriction

Intrauterine growth restriction is a condition that prevents normal fetal development, and previous studies have reported that intrauterine growth restriction is caused by adverse intrauterine factors. This condition affects both short- and long-term neurodevelopmental disorders. Studies have revealed that neurodevelopmental disorders can contribute to gray and white matter damage and decrease the brain volume of affected individuals. Further, these disorders are associated with increased risks of mental retardation, cognitive impairment, and cerebral palsy, which seriously affect the quality of life. Although the mechanisms underlying the neurologic injury associated with intrauterine growth restriction are not completely clear, studies have revealed that neuronal apoptosis, neuroinflammation, oxidative stress, excitatory toxicity, disruption of blood-brain barrier, and epigenetics may be involved in this process. This article reviews the manifestations and possible mechanisms underlying neurologic injury in intrauterine growth restriction and provides a theoretical basis for the effective prevention and treatment of this condition.

Programming changes of hippocampal miR-134-5p/SOX2 signal mediate the susceptibility to depression in prenatal dexamethasone-exposed female offspring

Depression is a neuropsychiatric disorder and has intrauterine developmental origins. This study aimed to confirm the depression susceptibility in offspring rats induced by prenatal dexamethasone exposure (PDE) and to further explore the intrauterine programming mechanism. Wistar rats were injected with dexamethasone (0.2 mg/kg·d) subcutaneously during the gestational days 9-20 and part of the offspring was given chronic stress at postnatal weeks 10-12. Behavioral results showed that the adult PDE female offspring was susceptible to depression, accompanied by increased hippocampal miR-134-5p expression and decreased sex-determining region Y-box 2 (SOX2) expression, as well as disorders of neural progenitor cells proliferation and hippocampal neurogenesis. The PDE female fetal rats presented consistent changes with the adult offspring, accompanied by the upregulation of glucocorticoid receptor (GR) expression and decreased sirtuin 1 (SIRT1) expression. We further found that the H3K9ac level of the miR-134-5p promoter was significantly increased in the PDE fetal hippocampus, as well as in adult offspring before and after chronic stress. In vitro, the changes of GR/SIRT1/miR-134-5p/SOX2 signal by dexamethasone were consistent with in vivo experiments, which could be reversed by GR receptor antagonist, SIRT1 agonist, and miR-134-5p inhibitor. This study confirmed that PDE led to an increased expression level as well as H3K9ac level of miR-134-5p by activating the GR/SIRT1 pathway in the fetal hippocampus and then inhibited the SOX2 expression. The programming effect mediated by the abnormal epigenetic modification could last from intrauterine to adulthood, which constitutes the intrauterine programming mechanism leading to hippocampal neurogenesis disorders and depression susceptibility in female offspring. Intrauterine programming mechanism for the increased depressive susceptibility in adult female offspring by prenatal dexamethasone exposure (PDE). GR, glucocorticoid receptor; SIRT1, sirtuin 1; SOX2, sex-determining region Y-box 2; NPCs, neuroprogenitor cells; H3K9ac, histone 3 lysine 9 acetylation; GRE, glucocorticoid response element.

Maternal nicotine exposure during pregnancy and lactation induces brown adipose tissue whitening in female offspring

Maternal nicotine exposure during pregnancy and lactation is associated with obesity in female offspring. Brown adipose tissue (BAT) is related to energy metabolism and obesity. In this study, we explored the mechanism of maternal nicotine exposure on BAT "whitening" in female offspring. Pregnant rats were randomly assigned to nicotine (1.0 mg/kg twice per day, subcutaneous administration) or control groups. The weight, structure, and microvascular density of interscapular BAT (iBAT) and the expression of PGC-1αUCP1 signals, mitochondrial biogenesis-related genes and angiogenesis-related genes were tested in 4- and 26-week-aged female offspring. In vitro, C3H10T1/2 cells were induced to differentiate into mature brown adipocytes, and 0-50 μM nicotine was treated on cells during the differentiation process. Nicotine-exposed females had higher iBAT weight, white-like adipocytes and abnormal mitochondrial structure in iBAT at 26 weeks rather than 4 weeks. The PGC-1αUCP1 signals and brown-like genes were down-regulated at 26 weeks, but the microvascular density and the expression of pro-angiogenic factors reduced more at 4 weeks in the nicotine group. In vitro, 50 μM nicotine significantly decreased the expression of PGC-1αUCP1 signals and angiogenesis-related genes. In conclusion, maternal nicotine exposure during pregnancy and lactation led to the "whitening" of BAT in adult female offspring: nicotine decreased BAT angiogenesis in the early development stage, and then, the impairment of blood vessels programed for the reduction of BAT phenotype through down-regulating the PGC-1αUCP1 signals in adulthood. This impairment of BAT may be a potential mechanism of nicotine-induced obesity in female offspring.

BDNF and nicotine dependence: associations and potential mechanisms

Smoking is the leading preventable cause of death worldwide and tobacco addiction has become a serious public health problem. Nicotine is the main addictive component of tobacco, and the majority of people that smoke regularly develop nicotine dependence. Nicotine addiction is deemed to be a chronic mental disorder. Although it is well known that nicotine binds to the nicotinic acetylcholine receptors (nAChRs) and activates the mesolimbic dopaminergic system (MDS) to generate the pleasant and rewarding effects, the molecular mechanisms of nicotine addiction are not fully understood. Brain-derived neurotrophic factor (BDNF) is the most prevalent growth factor in the brain, which regulates neuron survival, differentiation, and synaptic plasticity, mainly through binding to the high affinity receptor tyrosine kinase receptor B (TrkB). BDNF gene polymorphisms are associated with nicotine dependence and blood BDNF levels are altered in smokers. In this review, we discussed the effects of nicotine on BDNF expression in the brain and summarized the underlying signaling pathways, which further indicated BDNF as a key regulator in nicotine dependence. Further studies that aim to understand the neurobiological mechanism of BDNF in nicotine addcition would provide a valuable reference for quitting smoking and developing the treatment of other addictive substances.

Intrauterine RAS programming alteration-mediated susceptibility and heritability of temporal lobe epilepsy in male offspring rats induced by prenatal dexamethasone exposure

Partial temporal lobe epilepsy (TLE) has an intrauterine developmental origin. This study was aimed at elucidating the heritable effects and programming mechanism of TLE in offspring rats induced by prenatal dexamethasone exposure (PDE). Pregnant Wistar rats were injected subcutaneously with dexamethasone (0.2 mg/kg day) from gestational day 9 to 20. The F1 and F2 generations of male offspring were administered lithium pilocarpine (LiPC) for electroencephalography and video monitoring in epilepsy or behavioral tests. Results showed that the PDE + LiPC group exhibited TLE susceptibility, which continued throughout F2 generation. Expression of hippocampal glucocorticoid receptor (GR), CCAAT enhancer-binding protein α (C/EBPα), intrauterine renin-angiotensin system (RAS) classical pathway related genes, the H3K27ac level in angiotensin-converting enzyme (ACE) promoter, as well as high mobility group box 1 (HMGB1) and toll-like receptor 4 (TLR4) were increased, but glutamate dehydrogenase (GLUD) 1/2 expression were decreased, accompanied by increased glutamate levels in PDE fetal and adult rats, as well as in F1 and F2 offspring of the PDE + LiPC group. These consistent changes were also observed by treating the H19-7 fetal hippocampal cell line with dexamethasone and were reversed by GR inhibitor (RU486) and ACE inhibitor (enalaprilat). Our results confirmed that PDE-induced H3K27ac enrichment in the ACE promoter and enhanced the RAS classic pathway via activating GR-C/EBPα-p300 in utero, which caused changes of the HMGB1 pathway and glutamate excitatory damage. Intrauterine programming mediated by abnormal histone modification of hippocampal ACE could continue to adulthood and even F2 generation, which induced the heritability of TLE in male offspring rats.

Effect of electronic cigarette aerosol exposure during gestation and lactation on learning and memory of adult male offspring rats

INTRODUCTION

Electronic cigarette (ECIG) use has increased worldwide, including among pregnant and breastfeeding women. In this study, we examined the effect of ECIG aerosol exposure during gestation and lactation on learning and memory of adult male offspring rats.

METHODS

Rats were exposed to either fresh air or ECIG aerosol for one hour daily during gestational period as well as days 4-21 of lactation. Male offspring were followed through 19 weeks and then spatial learning and memory were tested by radial arm water maze (RAWM). The hippocampus was examined for biomarkers of harm, including oxidative stress, superoxide dismutase, catalase, glutathione peroxidase and thiobarbituric acid reactive substances and brain derived neurotrophic factor (BDNF).

RESULTS

Relative to exposure to fresh air, exposure to ECIG aerosol during gestation/lactation impaired long-term memory in adult offspring (P < 0.05). This impairment was associated with increased activity of superoxide dismutase in the hippocampus (P < 0.05). BDNF and the other tested oxidative stress biomarkers were not affected by ECIG aerosol exposure (p > 0.05).

CONCLUSIONS

In conclusion, ECIG aerosol exposure during gestation and lactation impaired long-term memory and increased the activity of superoxide dismutase in the hippocampus of offspring adult rats. These results support the development of strategies to enhance ECIG cessation during pregnancy and breastfeeding.

Developmental nicotine exposure engenders intergenerational downregulation and aberrant posttranslational modification of cardinal epigenetic factors in the frontal cortices, striata, and hippocampi of adolescent mice

BACKGROUND

Maternal smoking of traditional or electronic cigarettes during pregnancy, which constitutes developmental nicotine exposure (DNE), heightens the risk of neurodevelopmental disorders including ADHD, autism, and schizophrenia in children. Modeling the intergenerationally transmissible impacts of smoking during pregnancy, we previously demonstrated that both the first- and second-generation adolescent offspring of nicotine-exposed female mice exhibit enhanced nicotine preference, hyperactivity and risk-taking behaviors, aberrant rhythmicity of home cage activity, nicotinic acetylcholine receptor and dopamine transporter dysfunction, impaired furin-mediated proBDNF proteolysis, hypocorticosteronemia-related glucocorticoid receptor hypoactivity, and global DNA hypomethylation in the frontal cortices and striata. This ensemble of multigenerational DNE-induced behavioral, neuropharmacological, neurotrophic, neuroendocrine, and DNA methylomic anomalies recapitulates the pathosymptomatology of neurodevelopmental disorders such as ADHD, autism, and schizophrenia. Further probing the epigenetic bases of DNE-induced multigenerational phenotypic aberrations, the present study examined the expression and phosphorylation of key epigenetic factors via an array of immunoblot experiments.

RESULTS

Data indicate that DNE confers intergenerational deficits in corticostriatal DNA methyltransferase 3A (DNMT3A) expression accompanied by downregulation of methyl-CpG-binding protein 2 (MeCP2) and histone deacetylase 2 (HDAC2) in the frontal cortices and hippocampi, while the expression of ten-eleven translocase methylcytosine dioxygenase 2 (TET2) is unaltered. Moreover, DNE evokes multigenerational abnormalities in HDAC2 (Ser394) but not MeCP2 (Ser421) phosphorylation in the frontal cortices, striata, and hippocampi.

CONCLUSIONS

In light of the extensive gene regulatory roles of DNMT3A, MeCP2, and HDAC2, the findings of this study that DNE elicits downregulation and aberrant posttranslational modification of these factors in both first- and second-generation DNE mice suggest that epigenetic perturbations may constitute a mechanistic hub for the intergenerational transmission of DNE-induced neurodevelopmental disorder-like phenotypes.

Role of neurotrophins in pregnancy, delivery and postpartum

Neurotrophins (NTs) are a family of polypeptides whose functions have been extensively studied in the past two decades. In particular, Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor (BDNF) play a major role in the development, nutrition and growth of the central and peripheral nervous system and in the pathogenesis of neurodegenerative, cardiometabolic and (auto)immune diseases. However, NGF and BDNF have subtle functions for follicular development, implantation, and placentation. This short narrative review summarizes the existing evidence, published between 2000 and 2019, about the role of NTs in many different conditions that might affect women during and after pregnancy such as preeclampsia, gestational diabetes, obesity, depression, anxiety, smoking and alcohol abuse. Literature suggests that the dysregulation of synthesis and release of NTs may lead to decisive effects on both maternal and fetal health. Some piece of evidences was found about a possible association between NGF/BDNF and breastfeeding. Additional studies on human models are necessary to further characterize the role of NTs in life-changing experiences like labor and delivery.

Effects of Xiaoyaosan on Depressive-Like Behaviors in Rats With Chronic Unpredictable Mild Stress Through HPA Axis Induced Astrocytic Activities

ABSTRACT

Astrocytes in the hippocampus are immediately relevant to depressive-like behavior. By regulating their activities, Xiaoyaosan (XYS), a traditional Chinese medicine compound, works in the treatment of depression.

OBJECTIVE

Chronic unpredictable mild stress (CUMS) rat model was established to observe the regulation of XYS. We investigated the behavioral changes of CUMS, the expression of corticosterone (CORT) of the hypothalamo-pituitary-adrenal (HPA) axis, the expression of Glu-NMDA receptor and astrocytes glial fibrillary acidic protein (GFAP) in the hippocampus. We also investigated whether these changes were linked to XYS.

METHODS

80 adult SD rats were randomly divided into four groups, control group, CUMS group, XYS group, and fluoxetine group. The rats in the control group and the CUMS group received 0.5 ml of deionized water once a day by intragastrically administration. Rats in the two treatment groups received XYS (2.224g/kg/d) and fluoxetine (2.0mg/kg/d) once a day, respectively. Rat hippocampus GFAP and Glu-NMDA receptor were respectively detected by real-time fluorescent quantitative PCR and western blot. The CORT of HPA axis was detected by Elisa. Body weight, food intake, and behavioral tests, such as open field tests, the sucrose preference test, and exhaustive swimming test, were used to assess depressive-like behavior in rats.

RESULTS

In this work, significant behavioral changes and differences in expression of the CORT of HPA axis and hippocampal GFAP and Glu-NMDA receptor were presented in CUMS-exposed rats. Like fluoxetine, XYS improved CUMS-induced rat's body weight, food intake, and depressive-like behavior. The study also proved that XYS could reverse the CUMS-induced changes of the CORT of HPA axis and affect the astrocytic activities and down-regulate the NR2B subunit of NMDA receptor (NR2B) level in the hippocampus.

CONCLUSION

Changes in the hippocampus GFAP and Glu-NMDA receptor may be an essential mechanism of depression. Besides, XYS may be critical to the treatment of depression by intervention the HPA axis, GFAP and Glu-NMDA receptor.

Developmental nicotine exposure elicits multigenerational disequilibria in proBDNF proteolysis and glucocorticoid signaling in the frontal cortices, striata, and hippocampi of adolescent mice

Maternal smoking of conventional or vapor cigarettes during pregnancy, a form of developmental nicotine exposure (DNE), enhances the risk of neurodevelopmental disorders such as ADHD, autism, and schizophrenia in children. Modeling the multigenerational effects of smoking during pregnancy and nursing in the first- (F1) and second- (F2) generation adolescent offspring of oral nicotine-treated female C57BL/6J mice, we have previously reported that DNE precipitates intergenerational transmission of nicotine preference, hyperactivity and impulsivity-like behaviors, altered rhythmicity of home cage activity, corticostriatal nicotinic acetylcholine receptor and dopamine transporter dysfunction, and corticostriatal global DNA methylome deficits. In aggregate, these DNE-evoked behavioral, neuropharmacological, and epigenomic anomalies mirror fundamental etiological aspects of neurodevelopmental disorders including ADHD, autism, and schizophrenia. Expanding this line of research, the current study profiled the multigenerational neurotrophic and neuroendocrine consequences of DNE. Results reveal impaired proBDNF proteolysis as indicated by proBDNF-BDNF imbalance, downregulation of the proBDNF processing enzyme furin, atypical glucocorticoid receptor (GR) activity as implied by decreased relative nuclear GR localization, and deficient basal plasma corticosterone (CORT) levels in adolescent DNE offspring and grandoffspring. Collectively, these data recapitulate the BDNF deficits and HPA axis dysregulation characteristic of neurodevelopmental disorders such as ADHD, autism, and schizophrenia as well as the children of maternal smokers. Notably, as BDNF is a quintessential mediator of neurodevelopment, our prior findings of multigenerational DNE-induced behavioral and neuropharmacological abnormalities may stem from neurodevelopmental insults conferred by the proBDNF-BDNF imbalance detected in DNE mice. Similarly, our findings of multigenerational GR hypoactivity may contribute to the increased risk-taking behaviors and aberrant circadian rhythmicity of home cage activity that we previously documented in first- and second-generation DNE mice.

Prenatal Dexamethasone Exposure Induced Alterations in Neurobehavior and Hippocampal Glutamatergic System Balance in Female Rat Offspring

Epidemiological investigations have suggested that periodic use of dexamethasone during pregnancy is a risk factor for abnormal behavior in offspring, but the potential mechanism remains unclear. In this study, we investigated the changes in the glutamatergic system and neurobehavior in female offspring with prenatal dexamethasone exposure (PDE) to explore intrauterine programing mechanisms. Compared with the control group, rat offspring with PDE exhibited spatial memory deficits and anxiety-like behavior. The expression of hippocampal glucocorticoid receptors (GR) and histone deacetylase 2 (HDAC2) increased, whereas histone H3 lysine 14 acetylation (H3K14ac) of brain-derived neurotrophic factor (BDNF) exon IV (BDNF IV) and expression of BDNF decreased. The glutamatergic system also changed. We further observed that changes in the fetal hippocampus were consistent with those in adult offspring. In vitro, the administration of 0.5 μM dexamethasone to the H19-7 fetal hippocampal neuron cells directly led to a cascade of changes in the GR/HDAC2/BDNF pathway, whereas the GR antagonist RU486 and the HDAC2 inhibitor romidepsin (Rom) reversed changes caused by dexamethasone to the H3K14ac level of BDNF IV and to the expression of BDNF. The increase in HDAC2 can be reversed by RU486, and the changes in the glutamatergic system can be partially reversed after supplementation with BDNF. It is suggested that PDE increases the expression of HDAC2 by activating GR, reducing the H3K14ac level of BDNF IV, inducing alterations in neurobehavior and hippocampal glutamatergic system balance. The findings suggest that BDNF supplementation and glutamatergic system improvement are potential therapeutic targets for the fetal origins of abnormal neurobehavior.