Hippocampus Of Offspring Research Articles

Paternal fenvalerate exposure transgenerationally impairs cognition and hippocampus in female offspring

The impairments of maternal fenvalerate exposure have been well documented in previous study, but little was known about the effects of paternal fenvalerate exposure. The current study aimed to assess the effects of paternal fenvalerate exposure on spatial cognition and hippocampus across generations. Adult male mice (F0) were orally administered with fenvalerate (0, 2 or 20 mg/kg) for 5 weeks. F0 males were mated with untreated-females to generate F1 generation. F1 males were mated with F1 control females to generate F2 generation. For F1 and F2 adult offspring, spatial learning and memory were detected by Morris water maze. Results showed that spatial learning and memory were impaired in F1 females but not F1 males derived from F0 males exposed to 20 mg/kg FEN. Furthermore, significant impairment of spatial learning and memory were found in F2 females but not F2 males derived from F0 males exposed to 20 mg/kg FEN. As expected, histopathology showed that neural density in hippocampal CA3 region was reduced in F1 and F2 females but not F1 and F2 males derived from F0 males exposed to 20 mg/kg FEN. Mechanistically, hippocampal thyroid hormone receptor alpha1 (TRα1) was down-regulated in F1 and F2 females derived from F0 males exposed to 20 mg/kg FEN. Correspondingly, hippocampal brain-derived neurotrophic factor, tropomyosin receptor kinase B and p75 neurotrophin receptor, three downstream genes of TR signaling, were down-regulated in F1 and F2 females. Taken together, the present study firstly found that paternal fenvalerate exposure transgenerationally impaired spatial cognition in a gender-dependent manner. Hippocampal TR signaling may, at least partially, contribute to the process of cognitive impairment induced by paternal fenvalerate exposure. Further exploration in the mode of action of fenvalerate is critically important to promote human health and environmental safety.

Lipopolysaccharide-induced maternal immune activation modulates microglial CX3CR1 protein expression and morphological phenotype in the hippocampus and dentate gyrus, resulting in cognitive inflexibility during late adolescence

Inflammation during pregnancy can disturb brain development and lead to disorders in the progeny, including autism spectrum disorder and schizophrenia. However, the mechanism by which a prenatal, short-lived increase of cytokines results in adverse neurodevelopmental outcomes remains largely unknown. Microglia—the brain’s resident immune-cells—stand as fundamental cellular mediators, being highly sensitive and responsive to immune signals, which also play key roles during normal development.The fractalkine signaling axis is a neuron-microglia communication mechanism used to regulate neurogenesis and network formation. Previously, we showed hippocampal reduction of fractalkine receptor (Cx3cr1) mRNA at postnatal day (P) 15 in male offspring exposed to maternal immune activation induced with lipopolysaccharide (LPS) during late gestation, which was concomitant to an increased dendritic spine density in the dentate gyrus, a neurogenic niche. The current study sought to evaluate the origin and impact of this reduced hippocampal Cx3cr1 mRNA expression on microglia and cognition. We found that microglial total cell number and density are not affected in the dorsal hippocampus and dentate gyrus, respectively, but that the microglial CX3CR1 protein is decreased in the hippocampus of LPS-male offspring at P15. Further characterization of microglial morphology in the dentate gyrus identified a more ameboid phenotype in LPS-exposed offspring, predominantly in males, at P15. We thus explored maternal plasma and fetal brain cytokines to understand the mechanism behind microglial priming, showing a robust immune activation in the mother at 2 and 4 hrs after LPS administration, while only IL-10 tended towards upregulation at 2 hrs after LPS in fetal brains. To evaluate the functional long-term consequences, we assessed learning and cognitive flexibility behavior during late adolescence, finding that LPS affects only the latter with a male predominance on perseveration. A CX3CR1 gene variant in humans that results in disrupted fractalkine signaling has been recently associated with an increased risk for neurodevelopmental disorders. We show that an acute immune insult during late gestation can alter fractalkine signaling by reducing the microglial CX3CR1 protein expression, highlighting neuron-microglial fractalkine signaling as a relevant target underlying the outcomes of environmental risk factors on neurodevelopmental disorders.

Effects of sevoflurane exposure during different stages of pregnancy on the brain development of rat offspring

ObjectiveThis study explored the effects of sevoflurane exposure during different stages of pregnancy on the brain development of offspring.MethodsThirty-six pregnant SD rats were randomly divided into 4 groups: control, sevoflurane exposure in early (S1) pregnancy, sevoflurane exposure in middle (S2) pregnancy, and sevoflurane exposure in late (S3) pregnancy. After natural birth, the learning and memory capacity of offspring rats was analyzed using the Morris water maze experiment. The hippocampi of offspring rats were collected. The levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the hippocampus were measured by ELISA. Additionally, the Nissl bodies in the hippocampus were analyzed using Nissl staining. Immunohistochemistry was used to examine the expression of BDNF and CPEB2 in the hippocampus of offspring. Proteins related to the NR4A1/NF-κB pathway were analyzed using western blotting.ResultsThe memory and learning capacity of offspring rats was significantly reduced in the S1 and S2 groups compared to the control group (p < 0.05), while there was no obvious difference between the control and S3 groups (p > 0.05). The level of IL-1β was significantly increased (p < 0.05) in the S1 group compared with the control group. Sevoflurane anesthesia received in early and middle pregnancy could significantly affect the formation of Nissl bodies in the hippocampi of offspring rats. In addition, the expression of BDNF and CPEB2 in the hippocampi of offspring rats was greatly decreased in the S1 group compared with the control group (p < 0.05). The expression of NR4A1 in the hippocampi of rat offspring was significantly decreased in the S1 and S2 groups compared with the control group (p < 0.05). The expression of proteins related to the NF-κB pathway was increased in the S1 group compared to the control group (p < 0.05).ConclusionsThe neurotoxic effect of maternal sevoflurane anesthesia on the brain development of offspring is higher when the exposure occurs in early pregnancy than in late pregnancy, and its mechanism might involve the NR4A1/NF-κB pathway to increase the secretion of inflammatory cytokines.

P-BN005. Maternal vitamin B12 deficiency is associated with increased oxidative stress and DNA damage in brain regions of C57BL/6 mouse offspring

Introduction . Maternal micronutrient deficiencies are predominant in developing countries. Vitamin B12 deficiency is common in women, especially during child-bearing age. Maternal vitamin B12 deficiency is known to have a profound impact on the developing fetus and programs it to a number of complex adult-onset disorders like cardiovascular diseases, diabetes, neurological disturbances, etc. We hypothesized that increased oxidative stress and reduced activity of antioxidant enzymes along with DNA damage in the brain are associated with the etiology of these complications. As little is known about the effects of maternal vitamin B12 restriction on brain regions of the offspring, we have focused particularly on the cerebral cortex and hippocampus in our study. Methods . Female, weaning C57BL/6 mice received ad libitum for 4 weeks a control diet (American Institute of Nutrition-76A) or the same with restriction of vitamin B12. After confirming the deficiency, the mice were allowed to breed with control males to obtain the F1 generation offspring. The different parameters related to oxidative stress and DNA damage were assessed at 3 months of age of the offspring. Results . Interestingly, offspring born to mice fed on vitamin B12 restricted diet had a significantly higher degree of oxidative stress in both the cerebral cortex and hippocampus as reflected by their increased levels of lipid peroxidation and protein oxidation. Also, the activity of antioxidant enzymes (superoxide dismutase and catalase) was diminished in both the brain regions of offspring born to mice fed on vitamin B12 restricted diet. DNA damage in the form of single and double-stranded DNA breaks were also increased in the cerebral cortex and hippocampus of mice offspring born to vitamin B12 restricted dams. Conclusion . To conclude, maternal vitamin B12 deficiency is associated with increased oxidative stress in the brain of young offspring, which further leads to DNA damage in the brain.

Prenatal dexamethasone exposure induces anxiety- and depressive-like behavior of male offspring rats through intrauterine programming of the activation of NRG1-ErbB4 signaling in hippocampal PV interneurons.

Dexamethasone is a commonly used synthetic glucocorticoid in the clinic. As a compound that can cross the placental barrier to promote fetal lung maturation, dexamethasone is extensively used in pregnant women at risk of premature delivery. However, the use of glucocorticoids during pregnancy increases the risk of neurodevelopmental disorders. In the present study, we observed anxiety- and depressive-like behavior changes and hyperexcitability of hippocampal neurons in adult rat offspring with previous prenatal dexamethasone exposure (PDE); the observed changes were related to in utero damage of parvalbumin interneurons. A programmed change in neuregulin 1 (NRG1)-Erb-b2 receptor tyrosine kinase 4 (ErbB4) signaling was the key to the damage of parvalbumin interneurons in the hippocampus of PDE offspring. Anxiety- and depressive-like behavior, NRG1-ErbB4 signaling activation, and damage of parvalbumin interneurons in PDE offspring were aggravated after chronic stress. The intervention of NRG1-ErbB4 signaling contributed to the improvement in dexamethasone-mediated injury to parvalbumin interneurons. These results suggested that PDE might cause anxiety- and depressive-like behavior changes in male rat offspring through the programmed activation of NRG1-ErbB4 signaling, resulting in damage to parvalbumin interneurons and hyperactivity of the hippocampus. Intrauterine programming of neuregulin 1 (NRG1)-Erb-b2 receptor tyrosine kinase 4 (ERBB4) overactivation by dexamethasone mediates anxiety- and depressive-like behavior in male rat offspring.

Maternal fluoxetine reduces hippocampal inflammation and neurogenesis in adult offspring with sex-specific effects of periadolescent oxytocin

Untreated perinatal depression can have severe consequences for the mother and her children. However, both the efficacy to mothers and safety to exposed infants of pharmacological antidepressants such as selective serotonin reuptake inhibitors (SSRIs), have been questioned. We previously reported that maternal SSRI exposure increased hippocampal IL-1β levels, which may be tied to limited efficacy of SSRIs during the postpartum to the dam but is not yet known whether maternal postpartum SSRIs affect the neuroinflammatory profile of adult offspring. In addition, although controversial, perinatal SSRI exposure has been linked to increased risk of autism spectrum disorder (ASD) in children. Oxytocin (OT) is under investigation as a treatment for ASD, but OT is a large neuropeptide that has difficulty crossing the blood–brain barrier (BBB). TriozanTM is a nanoformulation that can facilitate OT to cross the BBB. Thus, we investigated the impact of maternal postpartum SSRIs and offspring preadolescent OT treatment on adult offspring neuroinflammation, social behavior, and neurogenesis in the hippocampus. Using a model of de novo postpartum depression, corticosterone (CORT) was given in the postpartum to the dam with or without treatment with the SSRI, fluoxetine (FLX) for 21 days postpartum. Offspring were then subsequently treated with either OT, OT + TriozanTM, or vehicle for 10 days prior to adolescence (PD25-34). Maternal FLX decreased hippocampal IL-10 and IL-13 and neurogenesis in both sexes, whereas maternal CORT increased hippocampal IL-13 in both sexes. Maternal CORT treatment shifted the neuroimmune profile towards a more proinflammatory profile in offspring hippocampus, whereas oxytocin, independent of formulation, normalized this profile. OT treatment increased hippocampal neurogenesis in adult males but not in adult females, regardless of maternal treatment. OT treatment increased the time spent with a novel social stimulus animal (social investigation) in both adult male and female offspring, although this effect depended on maternal CORT. These findings underscore that preadolescent exposure to OT can reverse some of the long-lasting effects of postpartum maternal CORT and FLX treatments in the adult offspring. In addition, we found that maternal treatments that reduce (CORT) or increase (FLX) hippocampal inflammation in dams resulted in opposing patterns of hippocampal inflammation in adult offspring.

Maternal fructose consumption downregulates hippocampal catalase expression via DNA methylation in rat offspring

Some studies have demonstrated that excessive fructose consumption negatively impact brain function. Recently, the Developmental Origins of Health and Disease hypothesis - which suggests that maternal nutritional status during gestation and lactation can alter offspring phenotype - has received much attention. In a previous study, we demonstrated that maternal fructose consumption increases levels of lipid peroxides in hippocampi of offspring. The hypothesis in the present study was that maternal fructose intake would affect hippocampal antioxidant enzyme via epigenetic regulation. Upon confirmation of gestation, female rats were assigned to receive either water (control group) or a 20% fructose solution (fructose-fed group). Water or fructose solution were administered to dams from day 1 of gestation to postnatal day 21. Immediately after weaning, hippocampi of offspring were removed for analysis of antioxidant enzyme (Sod1, Sod2, Gpx1, Gpx4, and Cat) messenger RNA transcript levels. Levels of the Cat transcript were significantly lower in the fructose-fed relative to the control group. The Cat protein level was also significantly lower in the fructose-fed relative to the control group as with the messenger RNA transcript levels. Moreover, Cat promoter DNA methylation levels were higher in the fructose-fed group. The present study indicates that maternal fructose consumption may decrease offspring hippocampal Cat transcript levels via altered DNA methylation, which may result in higher levels of oxidative stress due to a decreased ability to neutralize lipid peroxides.

Maternal high-fat diet modifies myelin organization, microglial interactions, and results in social memory and sensorimotor gating deficits in adolescent mouse offspring

Prenatal exposure to maternal high-fat diet (mHFD) acts as a risk factor for various neurodevelopmental alterations in the progeny. Recent studies in mice revealed that mHFD results in both neuroinflammation and hypomyelination in the exposed offspring. Microglia, the brain-resident macrophages, play crucial roles during brain development, notably by modulating oligodendrocyte populations and performing phagocytosis of myelin sheaths. Previously, we reported that mHFD modifies microglial phenotype (i.e., morphology, interactions with their microenvironment, transcripts) in the hippocampus of male and female offspring. In the current study, we further explored whether mHFD may induce myelination changes among the hippocampal-corpus callosum-prefrontal cortex pathway, and result in behavioral outcomes in adolescent offspring of the two sexes. To this end, female mice were fed with control chow or HFD for 4 weeks before mating, during gestation, and until weaning of their litter. Histological and ultrastructural analyses revealed an increased density of myelin associated with a reduced area of cytosolic myelin channels in the corpus callosum of mHFD-exposed male compared to female offspring. Transcripts of myelination-associated genes including Igf1 –a growth factor released by microglia– were also lower, specifically in the hippocampus (without changes in the prefrontal cortex) of adolescent male mouse offspring. These changes in myelin were not related to an altered density, distribution, or maturation of oligodendrocytes, instead we found that microglia within the corpus callosum of mHFD-exposed offspring showed reduced numbers of mature lysosomes and increased synaptic contacts, suggesting microglial implication in the modified myelination. At the behavioral level, both male and female mHFD-exposed adolescent offspring presented loss of social memory and sensorimotor gating deficits. These results together highlight the importance of studying oligodendrocyte-microglia crosstalk and its involvement in the long-term brain alterations that result from prenatal mHFD in offspring across sexes.

Placental endocrine insufficiency programs anxiety, deficits in cognition and atypical social behaviour in offspring.

Abnormally elevated expression of the imprinted PHLDA2 gene has been reported in the placenta of human babies that are growth restricted in utero in several studies. We previously modelled this gene alteration in mice and found that just 2-fold increased expression of Phlda2 resulted in placental endocrine insufficiency. In addition, elevated Phlda2 was found to drive fetal growth restriction (FGR) of transgenic offspring and impaired maternal care by their wildtype mothers. Being born small and being exposed to suboptimal maternal care have both been associated with the increased risk of mental health disorders in human populations. In the current study we probed behavioural consequences of elevated Phlda2 for the offspring. We discovered increased anxiety-like behaviours, deficits in cognition and atypical social behaviours, with the greatest impact on male offspring. Subsequent analysis revealed alterations in the transcriptome of the adult offspring hippocampus, hypothalamus and amygdala, regions consistent with these behavioural observations. The inclusion of a group of fully wildtype controls raised in a normal maternal environment allowed us to attribute behavioural and molecular alterations to the adverse maternal environment induced by placental endocrine insufficiency rather than the specific gene change of elevated Phlda2. Our work demonstrates that a highly common alteration reported in human FGR is associated with negative behavioural outcomes later in life. Importantly, we also establish the experimental paradigm that placental endocrine insufficiency can program atypical behaviour in offspring highlighting the under-appreciated role of placental endocrine insufficiency in driving disorders of later life behaviour.

Perinatal low-dose bisphenol AF exposure impairs synaptic plasticity and cognitive function of adult offspring in a sex-dependent manner

Bisphenol AF (BPAF), a kind of the ideal substitutes of Bisphenol A (BPA), has frequently been detected in environmental media and biological samples. Numerous studies have focused on the reproductive toxicity, cardiotoxicity and endocrine disrupting toxicity of BPAF. However, little evidence is available on neurodevelopmental toxicity of BPAF. Here, our study is to evaluate the effect of perinatal BPAF exposure (0, 0.34, 3.4 and 34 mg/kg body weight/day, correspond to Ctrl, low-, medium- and high-dose groups) on the cognitive function of adult mouse offspring. This study firstly found that perinatal BPAF exposure caused cognitive impairments of mouse offspring, in which male offspring was more sensitive than female offspring in low- and medium-dose BPAF groups. Furthermore, the dendritic arborization and complexity of hippocampal CA1 and DG neurons in male offspring were impaired in all BPAF groups, and these effects were only found in high-dose BPAF group for female offspring. The damage of BPAF to dendritic spines, and the structural basis of learning and memory, was found in male offspring but not in females. Correspondingly, perinatal BPAF exposure significantly downregulated the expressions of hippocampal PSD-95 and Synapsin-1 proteins, and male offspring was more vulnerable than female offspring. Meanwhile, we explored the alteration of hippocampal estrogen receptors (ERs) to explain the sex specific impairment of cognitive function in low- and medium-dose BPAF groups. The results showed that perinatal BPAF exposure significantly decreased the expression of ERα in male offspring in a dose-dependent manner, but not in female offspring. In addition, we found that perinatal BPAF exposure can disordered the balance of oxidation and antioxidation in hippocampus of male offspring. In summary, perinatal low-dose bisphenol AF exposure impairs synaptic plasticity and cognitive function of adult offspring in a sex-dependent manner. The present results provide a pierce of potential mechanism of BPAF-caused neurodevelopmental toxicity.

Maternal Interleukin-6 Hampers Hippocampal Neurogenesis in Adult Rat Offspring in a Sex-Dependent Manner

Maternal immune activation (MIA) during pregnancy leads to long-lasting effects on brain development and function. Several lines of evidence suggest that the maternal inflammatory cytokine interleukin (IL)-6 plays a crucial role in the long-lasting effects of MIA on adult offspring. IL-6 is naturally produced during pregnancy in the absence of any underlying immune activation. The objective of this study was to assess whether this naturally occurring IL-6 has long-lasting effects on brain plasticity and function. Therefore, pregnant rats were given either an IL-6-neutralizing antibody (IL-6Ab) or vehicle during the third week of pregnancy. Newly born (doublecortin) and mature neurons (NeuN) were monitored in the hippocampus of adult male and female offspring. Prenatal IL-6Ab led to an enhanced number of newly born and mature neurons in the dentate gyrus of the hippocampus of male but not female adult offspring. This enhanced neurogenesis was associated with an increased propensity in memory acquisition in male offspring. Blunting the naturally occurring IL-6 during pregnancy did not have a significant long-lasting impact on astrocyte cell density (GFAP), or on anxiety-like behavior as assessed with elevated plus maze and open field tests. Taken together, these data suggest that maternal IL-6 contributes, at least in part, to the programming of the brain’s development in a sex-dependent manner.

Maternal Nicotine Exposure Alters Hippocampal Microglia Polarization and Promotes Anti-inflammatory Signaling in Juvenile Offspring in Mice.

Accumulating evidence reveal that maternal smoking or perinatal nicotine replacement therapy impairs hippocampal neurogenesis, neural development, and cognitive behaviors in the offspring. Microglia is a source of non-neural regulation of neuronal development and postnatal neurogenesis. In this study, we explored the impact of nicotine on the microglia during the development of hippocampus. Developmental nicotine exposure in a mouse model was conducted by supplementing nicotine in the drinking water to mother mice during gestation and lactation period. We found that juvenile offspring with maternal nicotine exposure presented physical and neurobehavioral development delay and an increase in anxiety-like behavior in the open field test on postnatal day (PND) 20. To further detect possible developmental neurotoxic effects of nicotine in offspring and underlying mechanism, whole genome microarray analysis of the expression profile of the hippocampus was performed on postnatal day 20. Significant alterations in the expression of genes related to inflammatory, neurotransmitter, and synapsis were observed in the hippocampus after maternal nicotine exposure, as compared to the vehicle control. Concurrently, an increase in microglial markers and the presence of M2 polarity state in the hippocampus of the nicotine offspring were observed by histological analysis and confocal z-stacking scanning. The M2 microglial polarization state was further confirmed with in vitro primary microglia culture by cytokine array, and double-positive expression of BDNF/Iba1 in microglia by immunohistochemical staining in the juvenile offspring hippocampus was visualized. We also found that nicotine offspring showed an increase of neurite length in the molecular layer and CA1 by Tuj1 staining, as well as an increase in the expression of synapse associated protein, PSD95, but the expression of NeuroD1 in CA1 and CA3 reduced. In summary, maternal nicotine exposure dysregulates immune-related genes expression by skewing the polarity of M2 microglia in the hippocampus, which may cause abnormal cognitive and behavioral performance in the offspring.

Alterations in Tau Protein Level and Phosphorylation State in the Brain of the Autistic-Like Rats Induced by Prenatal Exposure to Valproic Acid.

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by deficient social interaction and communication besides repetitive, stereotyped behaviours. A characteristic feature of ASD is altered dendritic spine density and morphology associated with synaptic plasticity disturbances. Since microtubules (MTs) regulate dendritic spine morphology and play an important role in spine development and plasticity the aim of the present study was to investigate the alterations in the content of neuronal α/β-tubulin and Tau protein level as well as phosphorylation state in the valproic acid (VPA)-induced rat model of autism. Our results indicated that maternal exposure to VPA induces: (1) decrease the level of α/β-tubulin along with Tau accumulation in the hippocampus and cerebral cortex; (2) excessive Tau phosphorylation and activation of Tau-kinases: CDK5, ERK1/2, and p70S6K in the cerebral cortex; (3) up-regulation of mTOR kinase-dependent signalling in the hippocampus and cerebral cortex of adolescent rat offspring. Moreover, immunohistochemical staining showed histopathological changes in neurons (chromatolysis) in both analysed brain structures of rats prenatally exposed to VPA. The observed changes in Tau protein together with an excessive decrease in α/β-tubulin level may suggest destabilization and thus dysfunction of the MT cytoskeleton network, which in consequence may lead to the disturbance in synaptic plasticity and the development of autistic-like behaviours.

Supplementation of milk polar lipids to obese dams improves neurodevelopment and cognitive function in male offspring.

Milk contains about 4% fat globules with its surface covered by polar lipids. Despite the abundant consumption of dairy products, the biological effects of dietary milk polar lipids on metabolic health have only been sparsely examined. Maternal obesity results in neurodevelopmental disorders and cognitive impairment in offspring. Considering the importance of maternal nutrition, the effects of polar lipids-enriched milk fat globule membrane (MFGM-PL) supplementation to dams during pregnancy and lactation on neurodevelopment and its long-term programming effects on offspring cognition were examined. Female Sprague-Dawley rats consumed 8-week control diet (CON) or high-fat diet (HFD) to induce obesity before mating. Then, female rats were fed CON or HFD with or without the supplementation of 400mg/kg body weight MFGM-PL during pregnancy and lactation. The offspring were fed 11-week HFD after weaning. MFGM-PL supplementation to obese dams suppressed body weight gain and hyperinsulinemia in both dams and offspring. Offspring born to obese dams displayed delayed neurological reflexes development, impaired neurogenesis before weaning, and cognitive impairment in adulthood, which were recovered by maternal MFGM-PL supplementation. Insulin resistance and aberrant brain-derived neurotrophic factor signaling were induced in the hippocampus of neonatal and adult offspring due to maternal and progeny HFD, but recovered by maternal MFGM-PL administration. This study demonstrates that maternal MFGM-PL supplementation can promote neurodevelopment and exert long-term effects against HFD-induced cognitive impairment in offspring via alleviating hippocampal insulin resistance. Hence, MFGM-PL is a promising ingredient for exerting beneficial programming effects on the brain health of offspring.

Maternal exposure to a human based mixture of persistent organic pollutants (POPs) affect gene expression related to brain function in mice offspring hippocampus

Male and female mice pups were exposed to a low and high dose of a human relevant mixture of persistent organic pollutants (POPs) during pregnancy and lactation. Most compounds detected in the dams were found in offspring brains. The mice offspring exhibited changed expression of hippocampal genes involved in cognitive function (Adora2a, Auts2, Crlf1, Chrnb2, Gdnf, Gnal, Kcnh3), neuroinflammation (Cd47, Il1a), circadian rhythm (Per1, Clock), redox signalling (Hmox2) and aryl hydrocarbon receptor activation (Cyp1b1). A few genes were differentially expressed in males versus females. Mostly, similar patterns of gene expression changes were observed between the low and high dose groups. Effects on learning and memory function measured in the Barnes maze (not moving, escape latency) were found in the high dose group when combined with moderate stress exposure (air flow from a fan). Mediation analysis indicated adaptation to the effects of exposure since gene expression compensated for learning disabilities (escape latency, walking distance and time spent not moving in the maze). Additionally, random forest analysis indicated that Kcnh3, Gnal, and Crlf1 were the most important genes for escape latency, while Hip1, Gnal and the low exposure level were the most important explanatory factors for passive behaviour (not moving). Altogether, this study showed transfer of POPs to the offspring brains after maternal exposure, modulating the expression level of genes involved in brain function.

Interaction of maternal immune activation and genetic interneuronal inhibition

Genes and environment interact during intrauterine life, and potentially alter the developmental trajectory of the brain. This can result in life-long consequences on brain function. We have previously developed two transgenic mouse lines that suppress Gad1 expression in parvalbumin (PVALB) and neuropeptide Y (NPY) expressing interneuron populations using a bacterial artificial chromosome (BAC)-driven miRNA-based silencing technology. We were interested to assess if maternal immune activation (MIA), genetic interneuronal inhibition, and the combination of these two factors disrupt and result in long-term changes in neuroinflammatory gene expression, sterol biosynthesis, and acylcarnitine levels in the brain of maternally exposed offspring. Pregnant female WT mice were given a single intraperitoneal injection of saline or polyinosinic–polycytidilic acid [poly(I:C)] at E12.5. Brains of offspring were analyzed at postnatal day 90. We identified complex and persistent neuroinflammatory gene expression changes in the hippocampi of MIA-exposed offspring, as well in the hippocampi of Npy/Gad1 and Pvalb/Gad1 mice. In addition, both MIA and genetic inhibition altered the post-lanosterol sterol biosynthesis in the neocortex and disrupted the typical acylcarnitine profile. In conclusion, our findings suggest that both MIA and inhibition of interneuronal function have long-term consequences on critical homeostatic mechanisms of the brain, including immune function, sterol levels, and energy metabolism.

Effects of repetitive transcranial magnetic and deep brain stimulation on long-range synchrony of oscillatory activity in a rat model of developmental schizophrenia.

Aberrant neuronal network activity likely resulting from disturbed interactions of excitatory and inhibitory systems may be a major cause of cognitive deficits in neuropsychiatric diseases, like within the spectrum of schizophrenic phenotypes. In particular, the synchrony and pattern of oscillatory brain activity appears to be disturbed within limbic networks, e.g. between prefrontal cortex and hippocampus. In a rat model of maternal immune activation (MIA), we compared the acute effects of deep brain stimulation within either medial prefrontal cortex or ventral hippocampus with the effects of repetitive transcranial magnetic stimulation (rTMS), using the intermittent theta-burst protocol (iTBS), on oscillatory activity within limbic structures. Simultaneous local field potential recordings were made from medial prefrontal cortex, ventral hippocampus, nucleus accumbens and rostral part of ventral tegmental area before and after deep brain stimulation in anaesthetized rats previously (~3h) treated with sham or verum rTMS. We found a waxing and waning pattern of theta and gamma activity in all structures which was less synchronous in particular between medial prefrontal cortex and ventral hippocampus in MIA offspring. Deep brain stimulation in medial prefrontal cortex and pre-treatment with iTBS-rTMS partly improved this pattern. Gamma-theta cross-frequency coupling was stronger in MIA offspring and could partly be reduced by deep brain stimulation in medial prefrontal cortex. We can confirm aberrant limbic network activity in a rat MIA model, and at least acute normalizing effects of the neuromodulatory methods. It has to be proven whether these procedures can have chronic effects suitable for therapeutic purposes.

Influence of progestational stress on BDNF and NMDARs in the hippocampus of male offspring and amelioration by Chaihu Shugan San

BackgroundProgestational stress has been proven to be a risk for the neural development of offspring, especially in the hippocampus. However, whether Chaihu Shugan San (CSS) can ameliorate hippocampal neural development via the regulation of brain-derived neurotrophic factor (BDNF), and N-methyl-D-aspartate receptors (NMDAR) 2A (NR2A) and 2B (NR2B), and the mechanism of such action remains unclear. MethodsThirty-six female rats were randomly allocated into control, chronic immobilization stress (CIS) and CSS groups according to the random number table, respectively. The male offspring were fed for 21 days after birth then randomly divided into the same three groups (6 rats/group) as the female rats. Female rats, except for the control group, underwent 21-day CIS to established a progestational stress anxiety-like model which was evaluated by body weight, the elevated plus-maze (EPM) test and serum dopamine (DA) measured using an enzyme-linked immunosorbent assay (ELISA). The expression levels of estrogen receptors (ERα/ERβ) and progesterone receptor (PR) in female rat ovaries were quantified by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. The hippocampal tissue in the 21-day offspring was observed by hematoxylin-eosin (HE) staining. The concentration of BDNF, NR2A, and NR2B were measured by RT-qPCR and immunohistochemistry in the CA3 and dentate gyrus (DG) regions of offsprings’ hippocampus. ResultsCompared with the female control group, significant differences in body weight, EPM test and DA concentration were observed in the CIS group, meanwhile, the concentration of ERα (P < 0.05), PR (P < 0.05) and ERβ in the ovaries were decreased. In the offsprings’ hippocampus of the CIS group, the chromatin of the nucleus was edge set and with condensed and irregular morphology nucleus, and the cytoplasm was unevenly stained with spaces around the cells, moreover, the expression levels of BDNF, NR2A, and NR2B were also declined (P < 0.05). However, Chaihu Shugan San reversed these changes, especially the BDNF in the DG region (P < 0.05), and NR2A and NR2B in the CA3 and DG region (P < 0.05). ConclusionsCSS could ameliorate the neural development of the hippocampus in offspring damaged by anxiety-like progestational stress in female rats via regulating the expression levels of ERα, ERβ, and PR in female rat ovaries and BDNF, NR2A, and NR2B in the hippocampus of their offspring.

Role of Polyinosinic:Polycytidylic Acid-Induced Maternal Immune Activation and Subsequent Immune Challenge in the Behaviour and Microglial Cell Trajectory in Adult Offspring: A Study of the Neurodevelopmental Model of Schizophrenia.

Multiple lines of evidence support the pathogenic role of maternal immune activation (MIA) in the occurrence of the schizophrenia-like disturbances in offspring. While in the brain the homeostatic role of neuron-microglia protein systems is well documented, the participation of the CX3CL1-CX3CR1 and CD200-CD200R dyads in the adverse impact of MIA often goes under-recognized. Therefore, in the present study, we examined the effect of MIA induced by polyinosinic:polycytidylic acid (Poly I:C) on the CX3CL1-CX3CR1 and CD200-CD200R axes, microglial trajectory (MhcII, Cd40, iNos, Il-1β, Tnf-α, Il-6, Arg1, Igf-1, Tgf-β and Il-4), and schizophrenia-like behaviour in adult male offspring of Sprague-Dawley rats. Additionally, according to the “two-hit” hypothesis of schizophrenia, we evaluated the influence of acute challenge with Poly I:C in adult prenatally MIA-exposed animals on the above parameters. In the present study, MIA evoked by Poly I:C injection in the late period of gestation led to the appearance of schizophrenia-like disturbances in adult offspring. Our results revealed the deficits manifested as a diminished number of aggressive interactions, presence of depressive-like episodes, and increase of exploratory activity, as well as a dichotomy in the sensorimotor gating in the prepulse inhibition (PPI) test expressed as two behavioural phenotypes (MIAPPI-low and MIAPPI-high). Furthermore, in the offspring rats subjected to a prenatal challenge (i.e., MIA) we noticed the lack of modulation of behavioural changes after the additional acute immune stimulus (Poly I:C) in adulthood. The important finding reported in this article is that MIA affects the expression and levels of the neuron-microglia proteins in the frontal cortex and hippocampus of adult offspring. We found that the changes in the CX3CL1-CX3CR1 axis could affect microglial trajectory, including decreased hippocampal mRNA level of MhcII and elevated cortical expression of Igf-1 in the MIAPPI-high animals and/or could cause the up-regulation of an inflammatory response (Il-6, Tnf-α, iNos) after the “second hit” in both examined brain regions and, at least in part, might differentiate behavioural disturbances in adult offspring. Consequently, the future effort to identify the biological background of these interactions in the Poly I:C-induced MIA model in Sprague-Dawley rats is desirable to unequivocally clarify this issue.

DNA methylome signatures of prenatal exposure to synthetic glucocorticoids in hippocampus and peripheral whole blood of female guinea pigs in early life

Synthetic glucocorticoids (sGC) are administered to women at risk of preterm delivery, approximately 10% of all pregnancies. In animal models, offspring exposed to elevated glucocorticoids, either by administration of sGC or endogenous glucocorticoids as a result of maternal stress, show increased risk of developing behavioral, endocrine, and metabolic dysregulation. DNA methylation may play a critical role in long-lasting programming of gene regulation underlying these phenotypes. However, peripheral tissues such as blood are often the only accessible source of DNA for epigenetic analyses in humans. Here, we examined the hypothesis that prenatal sGC administration alters DNA methylation signatures in guinea pig offspring hippocampus and whole blood. We compared these signatures across the two tissue types to assess epigenetic biomarkers of common molecular pathways affected by sGC exposure. Guinea pigs were treated with sGC or saline in late gestation. Genome-wide modifications of DNA methylation were analyzed at single nucleotide resolution using reduced representation bisulfite sequencing in juvenile female offspring. Results indicate that there are tissue-specific as well as common methylation signatures of prenatal sGC exposure. Over 90% of the common methylation signatures associated with sGC exposure showed the same directionality of change in methylation. Among differentially methylated genes, 134 were modified in both hippocampus and blood, of which 61 showed methylation changes at identical CpG sites. Gene pathway analyses indicated that prenatal sGC exposure alters the methylation status of gene clusters involved in brain development. These data indicate concordance across tissues of epigenetic programming in response to alterations in glucocorticoid signaling.