Developmental Neuroscience最新文献

Introduction: Hypoxia-inducible factor-1α (HIF-1α) has a wide-ranging role in the cellular responses to hypoxia. We previously found that neuron-specific HIF-1α-deficient mice (HIF-KO) that underwent neonatal hypoxia-ischemia (HI) had increased brain injury suggesting its neuroprotective function. To investigate whether HIF-1α is also involved in the mechanisms of protection by hypothermia (HT), the standard of care for hypoxic-ischemic encephalopathy, we tested the effect of HT on HIF-KO and wild-type (WT) littermates after HI in postnatal day 9 mice.

Methods: Cooling at 32°C began 1 h following HI and lasted for 3.5 h. Mice were perfused 5-7 days later for histological determination of injury severity. For Western blots, mice were killed 4 h or 24 h after HI with HT or HI with normothermia (NT) and ipsilateral cortices and hippocampi were evaluated for expression of HIF-1α, spectrin, ERK1/2, phosphorylated-ERK1/2 (p-ERK), and RNA-binding motif protein 3 (RBM3), one of the main cold-inducible mRNA-binding proteins.

Results: Histological evaluation showed WT mice with HT had less injury than WT with NT, but HIF-KO mice showed no reduction of injury with HT. Regionally, the reduction of injury in WT with HT is greater in the hippocampus than in the cortex. Protein expression of HIF-1α was lower in HIF-KO cortex at 4 h with NT or HT and at 24 h with NT, but HIF-1α was higher in WT with NT at 24 h. Expression of spectrin 145/150 in WT cortex with HT was not different than sham at 4 h, indicating limitation of necrosis with HT. In the HIF-KO cortex at 4 h spectrin 145/150 was higher in both NT and HT, indicating no protection with HT. In the hippocampus at 4 h and 24 h, spectrin 145/150 was elevated in all groups compared to sham. ERK activity, as represented by the ratio of p-ERK/ERK, was upregulated at 24 h in the cortex in WT with NT or HT compared to sham and in HIF-KO mice with NT or HT treatment compared to sham. RBM3 was elevated at 4 h in both WT and HIF-KO cortex with HT, but there was no change in the hippocampus.

Conclusion: These results support a critical role for HIF-1α in the mechanisms of protection with HT.

Background: It is well established that therapeutic hypothermia improves outcomes for infants with moderate-severe hypoxic-ischemic encephalopathy (HIE) in high-income counties. However, ∼29% of the infants treated with therapeutic hypothermia still have adverse outcome. Additionally, therapeutic hypothermia is not recommended as a treatment for infants with HIE in low- and middle-income countries. Therefore, there is an urgent need to develop alternative treatments for infants with HIE in low- and middle-income countries, as well as additive treatments to therapeutic hypothermia in high-income countries. Summary: Caffeine is widely used as an agent to prevent apnea in preterm infants, and more recently, it has been investigated as a potential neuroprotective treatment for perinatal hypoxic-ischemic (HI) brain injury, but the preclinical evidence so far has been mixed. Furthermore, there are concerns that caffeine, which is an adenosine receptor antagonist, could abolish the endogenous neuroprotective effects of adenosine, during and after HI. Key Messages: Further studies using caffeine particularly in large animal translational models of HI brain injury are required to establish the safety and efficacy of caffeine for HIE before conducting large randomized controlled trials.

Background: Healthcare costs are rising at an exponential rate. Given the constraints of limited resources, it is essential to make informed decisions about priorities to ensure the best possible health outcomes globally. The history of medicine illustrates how these priorities have shifted over time - from early focus on infectious diseases to later emphasis on noncommunicable conditions such as metabolic disorders. Today, neurodegenerative diseases and aging brain are the forefront of medical research, as these conditions profoundly affect individuals, families, and society.

Summary: One in three people will experience a mental health disorder in their lifetime, yet it is not widely recognized that many of these conditions may have origins in pre-birth experiences and early life influences. Disruptions in progenitor proliferation, neuronal and glial migration, and differentiation during prenatal development can contribute to lifelong neurodevelopmental abnormalities. Despite the fundamental importance of brain development, most of the neuroscience funding is allocated to studying neurodegeneration, such as dementia and Parkinson's disease, while early life influences remain underexplored. Crucially, the impact of developmental factors begins even before conception. Environmental risks extend beyond direct maternal exposures during pregnancy; they include cumulative parental exposure to teratogenic agents affecting both male and female gametes, as well as early life environmental exposures affecting newborns, infants, and children. These influences are complex yet highly relevant to long-term health outcomes.

Key messages: We urge greater recognition of the developmental origins of disease and advocate for increased investment in preventive strategies. These include lifestyle modifications, dietary improvements, targeted supplementation, regular exercise, and minimizing exposure to environmental pollutants. Addressing these factors proactively could yield profound benefits for both individual and public health.

Introduction: Lysophosphatidic acid (LPA) is a bioactive phospholipid that mediates a variety of biological actions through binding to G protein-coupled receptors known as LPA receptors (LPARs). In mammals, six LPAR subtypes (LPAR1-6) have been identified. This study aimed to determine the expression of LPAR4 in the developing mouse brain.

Methods: Brains samples were prepared from mice in various stages of development and biochemical and immunohistochemical analyses were conducted using anti-LPAR4.

Results: Western blot analysis detected two LPAR4-immunoreactive species at ∼50 kDa and ∼42 kDa from embryonic day 16.5 (E16.5). The ∼50 kDa molecule increased during development, reaching a peak at postnatal day 3 (P3), and then gradually decreased through P22. In contrast, the ∼42 kDa molecule continued to increase up to P22. Immunohistochemical analyses demonstrated strong LPAR4 expression in neural cells in the intermediate zone and cortical plate of the E15.5 cerebral cortex, whereas neural progenitors in the ventricular and subventricular zones exhibited weaker expression. At P15, fiber-like staining resembling the apical dendrites of cortical neurons and hippocampal pyramidal cells was also observed.

Conclusion: This study demonstrated dynamic, spatiotemporal changes of LPAR4 expression in the brain from embryonic to postnatal stages. These findings support a potential role for LPAR4 in neural development.

Introduction: The combination of prenatal alcohol exposure (PAE) and placental insufficiency (PI) places infants at an increased risk for preterm birth and may worsen brain injury and neurobehavioral outcomes. In this preclinical study, the effect of PAE + PI on lateral, medial, and ventral prefrontal cortex (PFC), striatum and corpus callosum microstructure were investigated using diffusion tensor imaging (DTI). These brain regions are important for executive and higher cognitive functions, like cognitive flexibility.

Methods: Pregnant Long-Evans rat dams voluntarily drank 5% ethanol in saccharin water or plain saccharin water until embryonic day 18 (E18) to mimic moderate PAE. On E19, an open laparotomy was completed, and the uterine arteries were transiently occluded for 1 h. The dams in the sham group underwent the same procedure, but without uterine artery occlusion. Offspring are delivered normally on E22 and matured with their dams. On postnatal day 35 (P35), tissue was collected from male and female rat offspring from all four prenatal treatment groups (Sham, PAE, PI, and PAE+PI). Fixed brain tissue was then scanned ex vivo on a Bruker 11.7 T magnetic resonance imaging. Fractional anisotropy (FA) and directional diffusion were measured in regions of interest. Two-way analysis of variance with Tukey's correction was used, with p < 0.05 significant.

Results: DTI analyses of the medial PFC (n = 14-30/group) revealed a significant impact of the prenatal exposure/insult on the FA (p < 0.05), with sham having the lowest FA (0.24 ± 0.01) and PI having the highest FA (0.28 ± 0.02) as well as a lower mean diffusivity (MD; 3.32 × 10-4 ± 2.35 × 10-5 mm2/s; p < 0.01) compared to PAE (4.35 × 10-4 ± 1.47 × 10-5 mm2/s). The lateral PFC was significantly impacted by prenatal exposure/insult with sham having the highest radial diffusivity (RD; 4.97 × 10-4 ± 2.20 × 10-5 mm2/s; p < 0.05) and MD (4.41 × 10-4 ± 2.10 × 10-5 mm2/s; p < 0.05) compared to the other groups. The striatum was sensitive to the prenatal exposure/insult, with the axial diffusivity (AD), RD, and MD all significantly increased in the PAE group and decreased in the PI group (p < 0.05). In the corpus callosum, the prenatal exposure/insult significantly decreased the AD (p < 0.05; PAE+PI AD: 5.00 × 10-4 ± 4.60 × 10-5 mm2/s).

Conclusion: While all areas analyzed were impacted by the prenatal insults, the striatum, which consists primarily of efferent pathways, appears more vulnerable to injury compared to the PFC. Additional studies are needed to characterize the impact this may have on function related to these critical brain regions.

Introduction: Innervation of the paraventricular nucleus of the hypothalamus (PVN) by the orexigenic agouti-related protein (AgRP) and anorexigenic α-melanocyte-stimulating hormone (α-MSH) neurons of the arcuate nucleus (ARC) is a key element in the appetite-regulating neuronal circuitry whose development is influenced by circulating metabolic signals. In the present work, we studied if PVN innervation by the AgRP and α-MSH fibers is influenced by gut microbiota.

Methods: To this aim, we compared, using immunohistochemistry, the innervation of PVN by AgRP and α-MSH fibers between germ-free and specific pathogen-free 7-week-old female mice.

Results: We found that germ-free mice display an increased innervation of the PVN by both AgRP and α-MSH fibers, but also that the increase in AgRP fiber density was about twice as pronounced as that of α-MSH.

Conclusion: These data reveal that gut microbiota plays a modulatory role in the development of the ARC/PVN axonal projections. An imbalance between AgRP and α-MSH innervation in germ-free mice may contribute to their metabolic and behavioral alterations.

Background: Small for gestational age (SGA) infants face a heightened risk of motor delays that can persist into childhood, affecting cognitive and language development. Early identification and intervention are critical for better long-term outcomes.

Summary: This narrative review highlights evidence on motor development in SGA children, focusing on risk factors, neurobiological mechanisms, and early interventions. Motor delays in SGA infants correlate with lower birth weight, shorter gestation, adverse intrauterine conditions, and perinatal complications. Structural brain changes, especially in white matter and cerebellum, along with prenatal and postnatal inflammation, contribute to these deficits. Nutritional support, physical therapy, and family-based stimulation initiated in the first 2 years show promise for improving motor outcomes.

Key messages: SGA children are at high risk for motor developmental disorders. A comprehensive early intervention approach targeting nutrition, neurodevelopment, and family support is essential. Future research should aim to clarify mechanisms and optimize intervention timing and strategies to enhance long-term outcomes.

Introduction: Neurodevelopmental disorders (NDDs) are chronic conditions marked by abnormal brain development, presenting with significant clinical heterogeneity. Early diagnosis is crucial but challenging due to the complex symptoms. Genetic factors play a dominant role in NDD etiology. This study was to evaluate the diagnostic utility of dual-dimension whole-exome sequencing (WES) analysis in Chinese patients with NDDs and to deepen the understanding of genotype-phenotype correlations.

Methods: This study retrospectively analyzed WES data of 128 Chinese NDD patients from Hubei Maternal and Child Health Hospital (July 2020-March 2024) for single-nucleotide variants (SNVs)/small insertions-deletions (Indels) and copy number variants (CNVs). Pathway enrichment, tissue-expression analyses, and functional experiments were conducted to interpret pathogenic genes and variants of uncertain significance.

Results: The overall diagnostic rate for NDDs was 35.9% (46/128), with 28 cases confirmed by SNV/Indel analysis (30 variants in 29 genes) and 18 by CNV analysis (22 variants). Dual-dimension analysis markedly improved the diagnostic rate compared to conventional SNV/Indel analysis (35.9% vs. 21.9%). Patients with multisystem abnormalities had a higher diagnostic rate (63.2% vs. 31.2%). Among the 30 SNV/Indel variants, 86.7% (26) were de novo, and 70.0% (21) were novel. Recurrent pathogenic variants in ASXL3, SHANK3, and EHMT1 genes were identified. Most pathogenic genes were enriched in transcription-regulation pathways and highly expressed in the cerebellum and cerebral cortex. Functional experiments showed that the NLGN3 c.562G>A (p.G188R) hemizygous variant affects protein stability and is deleterious, aiding prenatal diagnosis and the birth of a healthy offspring.

Conclusion: Integrating CNV analysis into routine WES workflows effectively clarifies the genetic heterogeneity of NDDs, expands the gene variant spectrum, and provides a basis for NDD prognosis assessment and precision diagnosis and treatment.

Introduction: The developing brain exhibits rostro-caudal gradients that align with the maturation of functionally organized circuits. The barrel cortex, a spatially precise sensory structure, serves as an ideal model to examine such gradients within a confined functional domain. GABAergic interneurons, characterized by subtype-specific developmental trajectories and pivotal roles in early cortical dynamics, provide a strategic cellular entry point for this investigation.

Methods: To explore cellular and functional gradients in the developing barrel cortex, we combined transgenic mouse lines, immunohistochemical analyses with in vivo electrophysiological recordings of whisker-evoked activity during early postnatal stages. We also employed a model of ethanol exposure to assess potential differences in apoptotic vulnerability along the rostro-caudal axis.

Results: Immunohistochemistry revealed distinct layer- and subtype-specific gradients of GABAergic neurons. Notably, we observed a widespread rostro-caudal gradient in 5-HT3AR-expressing cells and a localized gradient of somatostatin-positive (SST+) interneurons in the deep layers. These gradients diminished in a subtype-specific manner from postnatal day (P)5 to P10, indicating transient developmental features. In vivo recordings showed that caudal whisker stimulation elicited stronger responses, while rostral stimulation produced a broader spatial spread of activity, suggesting region-specific functional properties. Furthermore, rostral regions exhibited higher expression of the maturation marker KCC2, supporting the notion of more advanced maturation in the rostral barrel cortex. Ethanol exposure induced greater apoptosis in caudal layer 5 compared to its rostral counterpart, revealing layer- and region-specific vulnerabilities.

Conclusions: These findings highlight spatially regulated trajectories of cortical maturation and underscore how regional differences in development may influence sensory processing and contribute to the heterogeneity of symptoms observed in neurodevelopmental disorders.

Introduction: Single-cell transcriptomic analyses in adult mice show that cortical projection neuron subclasses exhibit heterogenous gene expression profiles that reflect their projection targets and laminar and areal positions. Further analyses revealed that projection neurons within the same subclass also exhibit transcriptomic heterogeneity. Recent evidence suggests that differences in maturation state reflect one source of this heterogeneity. The MET receptor tyrosine kinase, a regulator of synapse maturation, is expressed in a subpopulation within cortical projection neuron subclasses, providing an experimental model to address transcriptomic heterogeneity within developing projection neuron subclasses.

Methods: Single-cell RNA sequencing and smFISH were used to identify transcriptomic differences between Met+ and Met- projection neuron populations in the mouse visual and frontal cortices during the early phase of synapse formation and dendritic growth.

Results: Analyses confirmed enrichment of Met in select projection neuron subclasses and further identified astrocytes as the major source of its ligand, Hgf. No genes were expressed uniquely in Met+ or Met- projection neurons within a subclass; rather, there were graded differences in gene expression between the populations. While the identity of differentially expressed genes varied between subclass and cortical area, there was a consistent overrepresentation of genes associated with axon growth, as well as synapse structure, development, and function, with a subset associated with the MET interactome. Further, compared to Met- projection neurons, expression differences in genes associated with maturation indicate less mature excitatory synapses and spines in the Met+ population at this age.

Conclusion: The current findings provide support for the hypothesis that Met+ projection neurons are in a less mature state than Met- projection neurons within the same subclass. Further, the data are consistent with converging lines of biochemical and electrophysiological evidence that MET contributes to asynchronous maturation of developing cortical circuits.