Postnatal Day Research Articles

Retinoic acid antagonizes estrogen signaling to maintain adult uterine cell fate

Classical tissue recombination experiments demonstrate that cell-fate determination along the anterior-posterior axis of the Müllerian duct occurs prior to postnatal day 7 in mice. However, little is known about how these cell types are maintained in adults. In this study, we provide genetic evidence that a balance between antagonistic retinoic acid (RA) and estrogen signaling activity is required to maintain simple columnar cell fate in adult uterine epithelium. Transdifferentiation of simple columnar uterine epithelium into stratified cervicovaginal-like epithelium was observed in three related mouse genetic models, in which RA signaling was perturbed in the postnatal uterus. Single-cell RNA sequencing analysis identified the transformed epithelial cell populations and revealed extensive immune cell infiltration resulting from loss of RA signaling. Surprisingly, disruption of RA signaling led to dysregulated expression of a substantial number of estrogen target genes, suggesting that these two pathways may functionally oppose each other in determining and maintaining uterine epithelial cell fate. Consistent with this model, neonatal exposure to the strong synthetic estrogen, diethylstilbestrol, downregulated expression of a group of RA target genes and led to epithelial stratification and immune cell infiltration in wild-type uterus. Treating RA receptor triple conditional knockout pups with fulvestrant, an estrogen antagonist, reestablished the balance between the two signaling pathways, and effectively prevented the transformation of mutant simple columnar epithelia to metaplastic stratified epithelia. These findings implicate an essential role for RA signaling in maintaining uterine cytodifferentiation by antagonizing estrogen signaling in the postnatal uterus.

Validation of a New Classification for Severe Bronchopulmonary Dysplasia in Extremely Preterm Infants: Insights from a Large Japanese Cohort.

A recent scoping review identified histological chorioamnionitis (HCA), small for gestational age (SGA), and bubbly/cystic appearance on chest X-ray (bubbly/cystic CXR) as risk factors for severe bronchopulmonary dysplasia (BPD). To further validate these results, a large-scale database was analyzed. This retrospective multicenter cohort study included infants born at <28 weeks' gestational age between 2003 and 2016. The validated risk factors identified from the scoping review were analyzed for independent associations with severe BPD using multivariable logistic regression. Additionally, the association of these factors with long-term outcomes at 3 years, including home oxygen therapy (HOT) and neurodevelopmental impairments (NDIs), were analyzed. Among 15,834 extremely preterm infants, HCA, SGA, and bubbly/cystic CXR on postnatal day 28 were significantly and independently associated with severe BPD (adjusted odds ratio, 1.20; 95% confidence interval, 1.06-1.36) (1.73; 1.51-1.98) (1.79; 1.60-2.01), respectively. These three factors were also linked to HOT at 3 years (1.54; 1.14-2.08) (1.70; 1.21-2.39) (2.63; 1.94-3.56), respectively. Their combination significantly increased the prevalence of severe BPD and HOT at 3 years, particularly with bubbly/cystic CXR. Only SGA was independently associated with NDIs in BPD infants (1.55; 1.32-1.83). HCA, SGA, and bubbly/cystic CXR on postnatal day 28 were identified as important risk factors for severe BPD and long-term respiratory outcomes. While further research is needed to validate their role in endotype-specific classification of BPD, these findings may contribute to early prognostic strategies and targeted interventions before 36 weeks' postmenstrual age.

Long-Lasting Auditory and Vestibular Recovery Following Gene Replacement Therapy in a Novel Usher Syndrome Type 1c Mouse Model.

Usher syndrome type 1C (USH1C) is a genetic disorder caused by mutations in the USH1C gene, which encodes harmonin, a key component of the mechanoelectrical transduction complex in auditory and vestibular hair cells. USH1C leads to deafness and vestibular dysfunction in humans. An Ush1c knockout (KO) mouse model displaying these characteristic deficits is generated in our laboratory. To examine gene replacement therapy (GT) in this model, a synthetic adeno-associated viral vector, Anc80L65, driving harmonin expression is administered, to the inner ears of Ush1c KO mice at postnatal day 2 (P2). Remarkably, this single treatment significantly improved auditory brainstem response (ABR) thresholds and balance motor function at 1 month post-injection, with these effects persisting for up to 10 months. At 12 months post-treatment, the vestibular function is assessed using the vestibular-ocular reflexes (VOR) and single vestibular afferent recordings. The GT treatment significantly restored both the canal and otolith VORs and increased vestibular afferent spontaneous firing rates and responses to head rotation and translation. These findings provide the first evidence of long-lasting restoration of both the auditory and vestibular functions by GT in a novel mouse model of Usher syndrome, highlighting the potential of GT for treating deficits associated with USH1C.

From circuits to lifespan: translating mouse and human timelines with neuroimaging based tractography.

Animal models are commonly used to investigate developmental processes and disease risk, but humans and model systems (e.g., mice) differ substantially in the pace of development and aging. The timeline of human developmental circuits is well known, butit is unclear how such timelines compare to those in mice. We lack age alignments across the lifespan of mice and humans. Here, we build upon our Translating Time resource, which is a tool that equates corresponding ages during development. We collected 1,125 observations from age-related changes in body, bone, dental, and brain processes to equate corresponding ages across humans, mice, and rats to boost power for comparison across humans and mice. We acquired high-resolution diffusion MR scans of mouse brains (n=16) of either sex at sequential stages of postnatal development (postnatal day 3, 4, 12, 21, 60) to track brain circuit maturation (e.g., olfactory association, transcallosal pathways). We found heterogeneity in white matter pathway growth. Corpus callosum growth largely ceases days after birth while the olfactory association pathway grows through P60. We found that a P3-4 mouse equates to a human at roughly GW24, and a P60 mouse equates to a human in teenage years. Therefore, white matter pathway maturation is extended in mice as it is in humans, but there are species-specific adaptations. For example, olfactory-related wiring is protracted in mice, which is linked to their reliance on olfaction. Our findings underscore the importance of translational tools to map common and species-specific biological processes from model systems to humans.Significance statement Mice are essential models of human brain development, but we currently lack precise age alignments across their lifespan. Here, we equate corresponding ages across mice and humans. We utilize high-resolution diffusion mouse brain scans to track the growth of brain white matter pathways, and we use our cross-species age alignments to map the timeline of these growth patterns from mouse to humans. In mice, olfactory association pathway growth continues well into the equivalent of human teenage years. The protracted development of olfactory association pathways in mice aligns with their specialized sense of smell. The generation of translational tools bridges the gap between animal models and human biology while enhancing our understanding of developmental processes generating variation across species.

A first morphological and electrophysiological characterization of Fañanas cells of the mouse cerebellum.

Fañanas cells (FCs) are cerebellar glia of unknown function. First described more than a century ago, they have been almost absent from the scientific literature ever since. Here, we combined whole-cell, patch clamp recordings, near-UV laser photolysis, dye-loading and confocal imaging for a first characterization of FCs in terms of their morphology, electrophysiology and glutamate-evoked currents. We identified FCs of the molecular layer in cerebellar slices by their stubby process and small cell bodies. Despite their more compact shape compared to Bergmann glia (BGs), FCs showed similar membrane resistances and basal currents, suggesting that these passive currents are partly a result of electrical coupling between neighbouring glia. Dye filling and pharmacological experiments confirmed both homo- and heterotypic gap-junction coupling among FCs and BGs. Parallel-fibre stimulation evoked TTX-sensitive slow inward currents in FCs that were partially blocked by NBQX but not APV. Occasionally, we observed superimposed fast (milliseconds) current transients. Near-UV flash photolysis of MNI-caged glutamate revealed rapid desensitization of these AMPA-receptor mediated currents, which fully recovered only for stimulation intervals >500ms. We mapped the highest current densities in proximal processes. We conclude that FCs respond with fast AMPA currents to local glutamate release and they integrate ambient glutamate rises to a slow inward current. Interestingly, we found FCs to prevail throughout adulthood at stable but different densities among cerebellar lobules, with the highest cell densities in lobules I-II and X. Our results strongly suggest that FCs are not just displaced BGs, and that they may have lobule-specific functions - both locally and at the circuit level, yet to be uncovered. KEY POINTS: Using whole-cell recordings and near-UV laser photolyisis of caged glutamate, we provide a first characterization of cells of Fañanas (FCs) in mouse cerebellar slices. FCs are present from postnatal day 5 onward throughout adulthood and have a lobule- dependent density. Parallel-fibre stimulation generates biphasic, predominantly AMPA-mediated currents in FCs. Currents induced in FCs by parallel fibre stimulation are not NMDA receptor-dependent and are enhanced upon glutamate-transporter block with TBOA. Local near-UV glutamate uncaging indicates that FCs can detect fast glutamatergic inputs on the millisecond-time scale. FCs functionally integrate into the glial syncytium.

Long-term live-cell imaging of GFAP+ astroglia and laminin+ vessels in organotypic mouse brain slices using microcontact printing

Organotypic brain slices are three-dimensional, 150-μm-thick sections derived from postnatal day 10 mice that can be cultured for several weeks in vitro. However, these slices pose challenges for live-cell imaging due to their thickness, particularly without access to expensive two-photon microscopy. In this study, we present an innovative method to label and visualize specific brain cell populations in living slices. Using microcontact printing, antibodies are applied directly onto the slices in a controlled 400-μm-diameter pattern. Astrocytes are labeled with glial fibrillary acidic protein (GFAP), and vessels are labeled with laminin. Subsequently, slices are incubated with secondary fluorescent antibodies (green fluorescent Alexa-488 or red fluorescent Alexa-546) and visualized using an inverted fluorescence microscope. This approach offers a cost-effective and detailed visualization technique for astroglia and vessels in living brain slices, enabling investigation to be conducted over several weeks.

Maternal exposure to ozone during implantation promotes a feminized transcriptomic profile in the male adolescent liver.

Maternal exposure to ozone during implantation results in reduced fetal weight gain in rats. Offspring from ozone-exposed dams demonstrate sexually dimorphic risks to high-fat diet feeding in adolescence. To better understand the adolescent hepatic metabolic landscape following fetal growth restriction, RNA sequencing was performed to characterize the effects of ozone-induced fetal growth restriction on male and female offspring. Pregnant Long-Evans rats were exposed to filtered air or 0.8 ppm ozone for 4 hours on both gestation days 5 and 6 (n = 6/group). At approximately postnatal day 48, liver tissue was obtained for RNA sequencing from offspring. Peri-implantation exposure to ozone in the dam had greater effects on hepatic gene expression in male offspring than in the females. Interestingly, heatmaps of these DEGs suggested that male offspring from ozone-exposed dams had a transcriptomic pattern like that of female offspring. Using a filtered set of highly female-predominant genes (n = 390), 57% were upregulated in the male offspring from ozone-exposed dams. Upregulated canonical pathways included sirtuin and orexin signaling, estrogen receptor signaling, and integration of energy metabolism. Relatively few genes altered in the male offspring from ozone exposed dams were associated with endpoints of sexual maturity, signifying the likely source of the observed feminization was not attributed to sex hormones. This study provides initial evidence that growth restriction in utero may increase the risk of hepatic feminization in male offspring. Additional work is needed to further understand the relationship between developmental undernutrition and feminization in the male liver.

Memory Decline and Aberration of Synaptic Proteins in X-Linked Moesin Knockout Male Mice

Objective This study aims to investigate may moesin deficiency resulted in neurodevelopmental abnormalities caused by negative impact on synaptic signaling ultimately leading to synaptic structure and plasticity.Methods Behavioral assessments measured neurodevelopment (surface righting, negative geotaxis, cliff avoidance), anxiety (open field test, elevated plus maze test), and memory (passive avoidance test, Y-maze test) in moesin-knockout mice (KO) compared to wild-type mice (WT). Whole exome sequencing (WES) of brain (KO vs. WT) and analysis of synaptic proteins were performed to determine the disruption of signal pathways downstream of moesin. Risperidone, a therapeutic agent, was utilized to reverse the neurodevelopmental aberrance in moesin KO.Results Moesin-KO pups exhibited decrease in the surface righting ability on postnatal day 7 (p&lt;0.05) and increase in time spent in the closed arms (p&lt;0.01), showing increased anxiety-like behavior. WES revealed mutations in pathway aberration in neuron projection, actin filament-based processes, and neuronal migration in KO. Decreased cell viability (p&lt;0.001) and expression of soluble NSF adapter protein 25 (SNAP25) (p&lt;0.001) and postsynaptic density protein 95 (PSD95) (p&lt;0.01) was observed in days in vitro 7 neurons. Downregulation of synaptic proteins, and altered phosphorylation levels of Synapsin I, mammalian uncoordinated 18 (MUNC18), extracellular signal-regulated kinase (ERK), and cAMP response element-binding protein (CREB) was observed in KO cortex and hippocampus. Risperidone reversed the memory impairment in the passive avoidance test and the spontaneous alternation percentage in the Y maze test. Risperidone also restored the reduced expression of PSD95 (p&lt;0.01) and the phosphorylation of Synapsin at Ser605 (p&lt;0.05) and Ser549 (p&lt;0.001) in the cortex of moesin-KO.Conclusion Moesin deficiency leads to neurodevelopmental delay and memory decline, which may be caused through altered regulation in synaptic proteins and function.

A meta-analysis of sex differences in neonatal rodent ultrasonic vocalizations and the implication for the preclinical maternal immune activation model

As the earliest measure of social communication in rodents, ultrasonic vocalizations (USVs) in response to maternal separation are critical in preclinical research on neurodevelopmental disorders (NDDs). While sex differences in both USV production and behavioral outcomes are reported, many studies overlook sex as a biological variable in preclinical NDD models. We aimed to evaluate sex differences in USV call parameters and determine if USVs are differently impacted based on sex in the preclinical maternal immune activation (MIA) model. Results indicate that sex differences in USVs vary with developmental stage and are more pronounced in MIA offspring. Specifically, developmental stage is a moderator of sex differences in USV call duration, with control females emitting longer calls than males in early development (up to postnatal day [PND] 8), but this pattern reverses after PND8. MIA leads to a reduction in call numbers for females compared to same-sex controls in early development, with a reversal post-PND8. MIA decreased call duration and increased total call duration in males, but unlike females, developmental stage did not influence these differences. In males, MIA effects varied by species, with decreased call numbers in rats but increased call numbers in mice. MIA timing (gestational day ≤ 12.5 vs. > 12.5) did not significantly affect results. Our findings highlight the importance of considering sex, developmental timing, and species in USVs research. We discuss how analyzing USV call types and incorporating sex as a biological variable can enhance our understanding of neonatal ultrasonic communication and its translational value in NDD research.

Investigation of the Roles of the Adenosine A(2A) and Metabotropic Receptor Type 5 (mGlu5) Receptors in Prepulse Inhibition and CREB Signaling in a Heritable Rodent Model of Psychosis

The metabotropic glutamate receptor type 5 (mGlu5) and adenosine A(2A) receptor form a mutually inhibitory heteromer with the dopamine D2 receptor, where the activation of either mGlu5 or A(2A) leads to reduced D2 signaling. This study investigated whether a mGlu5-positive allosteric modulator (PAM) or an A(2A) agonist treatment could mitigate sensorimotor gating deficits and alter cyclic AMP response element-binding protein (CREB) levels in a rodent neonatal quinpirole (NQ) model of psychosis. F0 Sprague–Dawley rats were treated with neonatal saline or quinpirole (1 mg/kg) from postnatal day 1 to 21 and bred to produce an F1 generation. F1 offspring underwent prepulse inhibition (PPI) testing from postnatal day 44 to 48 to assess sensorimotor gating. The rats were treated with mGlu5 PAM 3-Cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl) benzamide (CDPPB) or A(2A) agonist CGS21680. Rats with at least one NQ-treated parent showed PPI deficits, which were alleviated by both CDPPB and CGS21680. Sex differences were noted across groups, with CGS21680 showing greater efficacy than CDPPB. Additionally, CREB levels were elevated in the nucleus accumbens (NAc), and both CDPPB and CGS21680 reduced CREB expression to control levels. These findings suggest that targeting the adenosinergic and glutamatergic systems alleviates sensorimotor gating deficits and abnormal CREB signaling, both of which are associated with psychosis.

Exposure to environmentally relevant levels of DEHP during development modifies the distribution and expression patterns of androgen receptors in the anterior pituitary in a sex-specific manner.

DEHP is a prevalent phthalate with wide industrial applications and well-documented endocrine-disrupting effects, including the potential disruption of AR signaling in different tissues. The present study aimed to investigate the effects of gestational and lactational exposure to environmentally relevant DEHP concentrations on AR expression and subcellular localization in the pituitary gland, the master endocrine organ, with a focus on gonadotroph cells by in vivo and in vitro approaches. After DEHP exposure during gestation and lactation, a sex-specific modulation was detected in AR-positive pituitary cells and AR protein expression as assessed through flow cytometry and western blot. In male rats, DEHP increased AR-positive cells at postnatal day (PND) 21, with this effect persisting at PND75. In females, DEHP elevated AR-expressing cells at PND21, but this increase was followed by a reduction in adulthood. Furthermore, DEHP altered AR subcellular localization by reducing nuclear AR expression and increasing its cytoplasmic expression in gonadotrophs, and modified LH content in secretory granules, indicating enhanced secretory activity. In primary pituitary cell cultures DEHP exposure regulated AR subcellular localization by decreasing nuclear AR levels, and disrupting the testosterone effect on AR cytoplasmic-nuclear shuttling in a dose-dependent manner. In conclusion, our study shows alteration of pituitary AR expression and subcellular localization following gestational and lactational DEHP exposure in a sex specific manner, and indicates that DEHP retains AR in the cytoplasm, interfering with testosterone activity in pituitary cells.

Single, double, and triple-hit strategies to establish a long-term premature rabbit model of bronchopulmonary dysplasia

BackgroundBronchopulmonary dysplasia (BPD) is a chronic lung condition of premature neonates, yet without an established pharmacological treatment. The BPD rabbit model exposed to 95% oxygen has been used in recent years for drug testing. However, the toxicity of the strong hyperoxic hit precludes a longer-term follow-up due to high mortality after the first week of life. This study aimed to extend the preterm rabbit model to postnatal day (PND) 14 to mimic the evolving phase of BPD and enable the investigation of therapeutic interventions at later and more relevant time points.MethodsPreterm rabbit pups delivered on the 28th day of gestation were either exposed to room air or different degrees of hyperoxia (50% and 70% O2) for 14 days. Single (immediately after birth) or double (at birth and at PND5) intratracheal lipopolysaccharide (LPS) administrations were also tested in combination with 50% O2. Age-matched rabbits delivered vaginally at term were used as controls. Survival, weight gain, lung function, pulmonary artery micro-ultrasound Doppler analysis, lung histology (alveolarization, lung injury score, and design-based stereology), and longitudinal micro-CT imaging were used to compare the outcomes at PND14.ResultsPremature birth itself, without any other BPD hit, was associated with lung function deficits, delayed lung development, and cardiovascular abnormalities. The BPD-like lung phenotype was enhanced by 70% O2 but not by 50% O2 hyperoxia. Intratracheal LPS delivered immediately after birth was associated with significantly higher lung injury scores at PND14 and increased tissue damping, a marker of parenchymal air resistance.ConclusionSeveral strategies are feasible to extend the preterm rabbit model of BPD to PND14. Preterm birth at the saccular phase itself, even in the absence of other postnatal BPD hits, was associated with lung function deficits, delayed lung development, and cardiovascular abnormalities compared with age-matched term rabbit pups. Enhanced BPD-like phenotypes can be further achieved by continued exposure to moderate hyperoxia (70% O2) and the intratracheal administration of LPS.

Neonatal Nutrition and Brain Structure at 7 Years in Children Born Very Preterm

Neonatal protein intake following very preterm birth has long lasting effects on brain development. However, it is uncertain whether these effects are associated with improved or impaired brain maturation. To assess the association of neonatal protein intake following very preterm birth with brain structure at 7 years of age. This cohort study involved children born very preterm before or after a change in neonatal intensive care unit nutritional protocol that increased protein intake at the National Women's Hospital in Auckland, New Zealand. The children completed magnetic resonance imaging (MRI) scanning at 7 years. There were 128 children who were initially eligible. MRI data were ineligible for analysis if excessive head motion or clinical brain abnormalities were present. Data were collected from July 2012 to January 2016, and data analysis took place from January 2017 to March 2024. Neonatal intensive care unit nutritional protocol. Those who were born before the protocol change took place (July 2005 to December 2006) were in the old protocol group, while those who were born after the protocol change (January 2007 to October 2008) were in the new protocol group. Observers were blind to participant grouping. All actual enteral and parenteral intakes of protein, fat, energy, and breast milk for days 1 to 7 and days 1 to 14, and growth velocity to postnatal day 28 were calculated for each infant. Preplanned outcomes were group comparisons between regional brain volumes and diffusion parameters of major white matter tracts along with analyses with both groups combined exploring associations of nutrition with brain metrics. Data from 99 children were analyzed, including 42 in the old protocol group (26 female [55%]; mean [SD] gestational age at birth, 27 [2] weeks) and 57 in the new protocol group (27 female [47%]; mean [SD] gestational age at birth, 26 [2] weeks). Protein intake differed between the groups at both 7 days (old protocol: mean [SD] intake, 17 [2] g/kg-1; new protocol: mean [SD] intake, 21 [2] g/kg-1) and 14 days after birth (old protocol: mean [SD] intake, 41 [6] g/kg-1; new protocol: mean [SD] intake, 45 [7] g/kg-1). The new protocol group had smaller brain volume as a percentage of intercranial volume than the old protocol group (mean [SD], 80% [4%] vs 86% [7%]) but absolute brain volumes were similar. The new protocol group had significantly thinner lateral occipital and lateral parietal cortices than the old protocol group. With both groups combined, those with greater protein, fat, energy, and breast milk intake had more mature diffusion tensor metrics (higher fractional anisotropy and less diffusion) across multiple tracts, although this finding did not reach statistical significance for every tract. In this cohort of children born very preterm, children with greater neonatal protein intake had a more mature profile of brain metrics assessed with MRI at 7 years of age. These results contribute to the ongoing evaluation of optimal nutrition for infants born very preterm and suggest that the protein intake experienced by the new protocol group may promote brain maturation in a way that is still observable at 7 years of age.

Paracetamol, its metabolites, and their transfer between maternal circulation and fetal brain in mono- and combination therapies.

Due to its availability and perceived safety, paracetamol is recommended even during pregnancy and for neonates. It is used frequently alone or in combination with other drugs required for the treatment of various chronic conditions. The aim of this study was to investigate potential effects of drug interactions on paracetamol metabolism and its placental transfer and entry into the developing brain. Sprague Dawley rats at postnatal day P4, pregnant embryonic day E19 dams, and non-pregnant adult females were administered paracetamol (15mg/kg) either as monotherapy or in combination with one of seven other drugs: cimetidine, digoxin, fluvoxamine, lamotrigine, lithium, olanzapine, valproate. Concentrations of parent paracetamol and its metabolites (paracetamol-glucuronide, paracetamol-glutathione, and paracetamol-sulfate) in plasma, cerebrospinal fluid (CSF) and brain were measured by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and their entry into the brain, CSF and transfer across the placenta were estimated. In monotherapy, concentration of parent paracetamol in plasma, CSF, and brain remained similar and at all ages brain entry was unrestricted. In combination therapies, CSF entry of paracetamol increased following co-treatment with olanzapine. Placental transfer of parent paracetamol remained unchanged, however, transfer of paracetamol-sulfate increased with lamotrigine co-administration. Acutely administered paracetamol was more extensively metabolized in adults compared to younger ages resulting in increased concentration of its metabolites with age. Developmental changes in the apparent brain and CSF entry of paracetamol appear to be determined more by its metabolism, rather than by cellular control of its transfer across brain and placental barriers.

The effects of early-life whisker deprivation on adolescent behavior in C57BL/6J mice.

Whisker deprivation at different stages of early development results in varied behavioral outcomes. However, there is a notable lack of systematic studies evaluating the specific effects of whisker deprivation from postnatal day 0 (P0) to P14 on adolescent behavioral performance in mice. To investigate these effects, C57BL/6J mice underwent whisker deprivation from P0 to P14 and were subsequently assessed at 5 weeks of age using a battery of tests: motor skills were evaluated using open field test; emotional behavior was evaluated using a series of anxiety- and depression-related behavioral tests; cognitive function was examined via novel location and object recognition tests; and social interactions were analyzed using three-chamber social interaction test. Results show that early-life whisker deprivation impairs social discrimination, as evidenced by reduced interaction preference for novel mice, while not impacting general motor abilities, cognitive performance in novel object and location recognition, or anxiety- and depression-related behaviors during adolescence. The treatment effects were consistent across sexes, with no significant differences observed between control and experimental groups within each sex. These findings contribute to a comprehensive understanding of the behavioral impacts during adolescence resulting from early-life whisker deprivation and provide valuable criteria for selecting appropriate whisker deprivation models in future research.

Neonatal but not Juvenile Gene Therapy Reduces Seizures and Prolongs Lifespan in SCN1B-Dravet Syndrome Mice.

Dravet syndrome (DS) is a developmental and epileptic encephalopathy (DEE) that begins in the first year of life. While most cases of DS are caused by variants in SCN1A, variants in SCN1B, encoding voltage-gated sodium channel β1 subunits, are also linked to DS or to the more severe early infantile DEE. Both disorders fall under the OMIM term DEE52. Scn1b null mice model DEE52, with spontaneous generalized seizures and death in 100% of animals in the third postnatal week. Scn1b null cortical parvalbumin-positive interneurons and pyramidal neurons are hypoexcitable. The goal of this study was to develop a proof-of-principle gene replacement strategy for DEE52. We tested an adeno-associated viral vector encoding β1 subunit cDNA (AAV-Navβ1) in Scn1b null mice. We demonstrated that AAV-Navβ1 drives β1 protein expression in excitatory and inhibitory neurons in mouse brain. Bilateral intracerebroventricular administration of AAV-Navβ1 in Scn1b null mice at postnatal day (P) 2, but not at P10, reduced spontaneous seizure severity and duration, prolonged life span, prevented hyperthermia-induced seizures, and restored cortical neuron excitability. AAV-Navβ1 administration to WT mice resulted in β1 overexpression in brain but no obvious adverse effects. This work lays the foundation for future development of a gene therapeutic strategy for SCN1B-linked DEE patients. .

Histone lysine crotonylation associated epigenetic mechanism dynamically regulates prenatal stress induced anxiety-related behaviour in adolescent offspring.

This study designed to examine whether social/ environmental experiences can induce the epigenetic modification, and influence the associated physiology and behaviour. To test this, we have used social stress [prenatal stress (PNS)] model and then housed at environmental enrichment (EE) condition to evaluate the interaction between specific epigenetic modification and its influence on behaviour. Pregnant rats were randomly divided into a control group, PNS group, and PNS+EE group. PNS and PNS+EE animals were subjected to social defeat (SD) stress during their gestational day (GD) 16-18. PNS animals and their offspring were always housed in standard laboratory condition, PNS+EE animal was housed in EE cage during GD-10 to the pup's age of postnatal day (PND) 30. Animals were tested for anxiety-like behaviour using Open-Field Test (OFT) and memory was examined by passive avoidance test. Western blotting was used to detect the expression pattern of molecules associated with histone crotonylation. We observed anxiety-like behaviour, memory deficit in the animals experienced PNS. Further, level of Methyl-CpG Binding Protein 2 (MeCP2), repressor element-1 silencing transcription factor (REST), Sirtuin 1(SIRT1), Chromodomain Y-like (CDYL) and Enhancer of Zeste 2 Polycomb Repressive Complex 2 Subunit (EZH2) and histone methylation (H3K27me3) was elevated. Where as, the expression of p300, histone crotonylation (H3K18Cr) and neuropeptide VGF were suppressed. Notably, EE restore the normal expression pattern of MeCP2, REST, P300, SIRT1, CYDL, EZH2, H3K27me3, H3K18Cr and VGF. EE reverse the PNS induced alterations, including suppression of histone crotonylation (H3K18Cr), which possibly involved in the regulation of expression of VGF and behaviour.

Sex-specific effects of prenatal bisphenol A exposure on transcriptome-interactome profiles of autism candidate genes in neural stem cells from offspring hippocampus

Bisphenol A (BPA), an endocrine-disrupting chemical, is increasingly linked to the pathogenesis of autism spectrum disorder (ASD). This study investigates the effects of prenatal BPA exposure on neural stem cells (NSCs) from the hippocampi of rat offspring, a brain region critical for neurodevelopment and implicated in ASD. Pregnant rats were administered with BPA or vehicle control once daily via oral gavage from gestational day 1 until parturition. NSCs were isolated from the offspring’s hippocampi on postnatal day 1, and RNA sequencing was performed to examine transcriptomic alterations. Differentially expressed genes (DEGs) were identified through RNA-seq and further analyzed using Ingenuity Pathway Analysis (IPA) to explore disrupted pathways. In addition, in vitro proliferation assays were conducted, utilizing immunofluorescence staining for Sox2, a stem cell marker, and BrdU to quantify proliferating NSCs. Our results revealed that prenatal BPA exposure induced sex-specific alterations in NSC gene expression, with ASD-related genes such as Atp1a3, Nefl, and Grin1 being particularly dysregulated in male offspring. Moreover, sex-specific changes in NSC proliferation were observed. The study underscores BPA’s potential as an environmental risk factor for ASD, emphasizing the need for further research into its role in sex-specific neurodevelopmental effects.

Inhaling arsenic aggravates airway hyperreactivity by upregulating PNEC-sourced 5-HT in OVA-induced allergic asthma.

Increasing epidemiological evidence has proved that early-life exposure to inorganic arsenic (As) elevates the risks of childhood asthma. The present research aimed to explore susceptibility of respiratory As exposure to allergic asthma in a mouse model. BALB/c mice on postnatal day (PND) 28 were exposed to ddH2O or NaAsO2 aerosol for 4 hours daily over 5 consecutive weeks via respiratory tract. Mice were sensitized by intraperitoneal injection of ovalbumin (OVA) combined with Alum Adjuvant on PND42 and PND56. Subsequently, mice were challenged with ddH2O or 1 %OVA through a nebulizer for 3 days starting from PND63. In As-exposed mice, OVA-sensitized goblet cell hyperplasia and airway mucosal secretion did not worsen. OVA-induced inflammatory cell infiltration and upregulation of Th2 cytokines, including IL-4, IL-5, and IL-13, were not aggravated in As-exposed mice. Interestingly, airway hyperreactivity was intensified in As-exposed asthmatic mice. Mechanistically, OVA-induced elevation of 5-hydroxytryptamine (5-HT), probably secreted by pulmonary neuroendocrine cells (PNECs), was exacerbated in As-exposed mice. OVA-induced upregulation of tryptophan hydroxylase (TPH)1 and TPH2, two 5-HT synthases, was aggravated in As-exposed mouse lungs. LX1032, a specific TPH inhibitor, suppressed As-induced elevation of pulmonary 5-HT content in asthmatic mice. Moreover, LX1032 alleviated As-evoked airway hyperreactivity in asthmatic mice. These results suggest that respiratory As exposure elevates airway hyperreactivity partially through upregulating PNEC-sourced 5-HT in OVA-induced allergic asthma, which provides significant insight about the hazards of environmental As exposure.

Postnatal undernutrition increases estradiol plasma levels and sexual receptivity and disrupts the kisspeptin-GnRH pathway in adult female rats.

Undernutrition has increased worldwide in recent years and it is known that environmental factors to which individuals are exposed in early life can result in metabolic and reproductive changes that remain in adult life. In this context, the litter size expansion is a classic model used to induce undernutrition early in development. Thus, this study aimed to evaluate the effects of neonatal undernutrition induced by the litter size expansion on metabolic and reproductive parameters of female rats. At birth, litter size was adjusted to large (LL - 16 pups) and normal (NL - 10 pups) litters. After weaning, the feed was offered ad libitum and the animals were euthanized from postnatal day 90, when in proestrus. Neonatal undernutrition resulted in lower body weight from weaning to adulthood, although food intake remained higher in the LL group in this period. These animals exhibited a delayed onset of puberty, demonstrated by a late first estrus, increased values of circulating estradiol, luteinizing hormone, follicle-stimulating hormone, and number of antral follicles in the ovaries, associated with higher sexual receptivity, without differences in maternal behavior. The LL group also exhibited decreased messenger RNA (mRNA) expression of kisspeptin and gonadotropin-releasing hormone (GnRH) in the preoptic area, without changes in the mRNA expression of GnRH receptor in the pituitary. These results demonstrate that moderate undernutrition in the lactational period promotes metabolic changes associated with impairments in the kisspeptin-GnRH pathway, without compromising maternal behavior and peripheral reproductive functions such as estrous cyclicity, sexual receptivity, and fertility.