Perinatal and neonatal ischemic stroke is a significant cause of cognitive and behavioral impairments. Further research is needed to support models of neonatal ischemic stroke and advance our understanding of the mechanisms of infarction formation following such strokes. We used two different levels of photothrombotic stroke (PTS) models to assess stroke outcomes in neonatal mice. We measured brain damage, dynamic changes in glial cells, and neuronal expression at various time points within two weeks following ischemic injury. Our results from 2,3,5-Triphenyltetrazolium chloride (TTC) staining and immunofluorescence staining showed that in the severe group, a dense border of astrocytes and microglia was observed within 3 days post infarct. This ultimately resulted in the formation of a permanent cortical cavity, accompanied by neuronal loss in the surrounding tissues. In the mild group, a relatively sparse arrangement of glial borders was observed 7 days post infarct. This was accompanied by intact cortical tissue and the restoration of viability in the brain tissue beyond the glial boundary. Additionally, neonatal ischemic injury leads to the altered expression of key molecules such as Aldh1L1 and Olig2 in immature astrocytes. In conclusion, we demonstrated the dynamic changes in glial cells and neuronal expression following different degrees of ischemic injury in a mouse model of PTS. These findings provide new insights for studying the cellular and molecular mechanisms underlying neuroprotection and neural regeneration after neonatal ischemic injury.

OBJECTIVE: To study the protective effect of melatonin (Mel) against oxygen-induced retinopathy (OIR) in neonatal mice and the role of the HMGB1/NF-κB/NLRP3 axis.
METHODS: Neonatal C57BL/6J mice, aged 7 days, were randomly divided into a control group, a model group (OIR group), and a Mel treatment group (OIR+Mel group), with 9 mice in each group. The hyperoxia induction method was used to establish a model of OIR. Hematoxylin and eosin staining and retinal flat-mount preparation were used to observe retinal structure and neovascularization. Immunofluorescent staining was used to measure the expression of proteins and inflammatory factors associated with the HMGB1/NF-κB/NLRP3 axis and lymphocyte antigen 6G. Colorimetry was used to measure the activity of myeloperoxidase.
RESULTS: The OIR group had destruction of retinal structure with a large perfusion-free area and neovascularization, while the OIR+Mel group had improvement in destruction of retinal structure with reductions in neovascularization and perfusion-free area. Compared with the control group, the OIR group had significant increases in the expression of proteins and inflammatory factors associated with the HMGB1/NF-κB/NLRP3 axis, the expression of lymphocyte antigen 6G, and the activity of myeloperoxidase (P<0.05). Compared with the OIR group, the OIR+Mel group had significant reductions in the above indices (P<0.05). Compared with the control group, the OIR group had significant reductions in the expression of melatonin receptors in the retina (P<0.05). Compared with the OIR group, the OIR+Mel group had significant increases in the expression of melatonin receptors (P<0.05).
CONCLUSIONS: Mel can alleviate OIR-induced retinal damage in neonatal mice by inhibiting the HMGB1/NF-κB/NLRP3 axis and may exert an effect through the melatonin receptor pathway.
目的: 观察褪黑素（melatonin，Mel）对新生小鼠氧诱导视网膜病变（oxygen-induced retinopathy，OIR）的保护作用，并探讨HMGB1/NF-κB/NLRP3轴在其中的作用。方法: 7日龄C57BL/6J新生小鼠随机分为对照组、模型组（OIR组）及Mel处理组（OIR+Mel组），各组n=9。采用高氧诱导法制备OIR模型。苏木精-伊红染色和视网膜铺片法检测视网膜结构和新生血管；免疫荧光染色法检测HMGB1/NF-κB/NLRP3轴相关蛋白和炎性因子及淋巴细胞抗原6G表达；比色法检测髓过氧化物酶活性。结果: OIR组视网膜结构被破坏，出现大片无灌注区和新生血管，OIR+Mel组可见破坏的视网膜结构改善，新生血管和无灌注区减少。与对照组相比，OIR组HMGB1/NF-κB/NLRP3轴相关蛋白和炎性因子表达升高（均P<0.05），淋巴细胞抗原6G表达和髓过氧化物酶活性升高（均P<0.05）；Mel处理后，上述各指标降低（均P<0.05）。与对照组相比，OIR组视网膜中褪黑素受体表达降低；Mel处理后，褪黑素受体表达较OIR组升高（均P<0.05）。结论: Mel可能通过抑制HMGB1/NF-κB/NLRP3轴减轻OIR新生小鼠视网膜损伤，且可能通过褪黑素受体途径发挥作用。.

Neuronal excitability is a critical feature of central nervous system development, playing a fundamental role in the functional maturation of brain regions, including the hippocampus, cerebellum, auditory and visual systems. The present study aimed to determine the mechanism by which hypoxia causes brain dysfunction through perturbation of neuronal excitability in a hypoxic neonatal mouse model. Functional brain development was assessed in humans using the Gesell Development Diagnosis Scale. In mice, gene transcription was evaluated via mRNA sequencing and quantitative PCR; furthermore, patch clamp recordings assessed potassium currents. Clinical observations revealed disrupted functional brain development in 6- and 18-month-old hypoxic neonates, and those born with normal hearing screening unexpectedly exhibited impaired central auditory function at 3 months. In model mice, CA1 pyramidal neurons exhibited reduced spontaneous activity, largely induced by excitatory synaptic input suppression, despite the elevated membrane excitability of hypoxic neurons compared to that of control neurons. In hypoxic neurons, Kcnd3 gene transcription was upregulated, confirming upregulated hippocampal Kv 4.3 expression. A-type potassium currents were enhanced, and Kv 4.3 participated in blocking excitatory presynaptic inputs. Elevated Kv 4.3 activity in pyramidal neurons under hypoxic conditions inhibited excitatory presynaptic inputs and further decreased neuronal excitability, disrupting functional brain development in hypoxic neonates.

Enterovirus 71 can cause severe hand, foot, and mouth disease (HFMD) in children. However, little is known about the mechanism of inflammatory disorders caused by EV71 infection and why severe cases are mainly children aged under-three. In current study, using mRNA microarray assay, the differential expression of Placenta-specific 8 (PLAC8) was identified in mice brain. In addition, we found that PLAC8 expression was down-regulated with age in mice lung tissues and human peripheral blood. Then, we further proved that PLAC8 could promote inflammation progress and disturb Th1/Th2/Th17/Treg related cytokines release after EV71 infection using PLAC8 plasmid over-expressed neonatal mouse model. Our data suggest that PLAC8 might play a crucial role in Th cell differentiation and inflammatory damage caused by EV71 infection in infants. Thus, our findings would help understand the causes of severe inflammatory injury in infants during EV71 infection, and provide new insights into the prevention and control of severe HFMD.

The meninges are important for brain development and pathology. Using single-cell RNA sequencing, we have generated the first comprehensive transcriptional atlas of neonatal mouse meningeal leukocytes under normal conditions and after perinatal brain injury. We identified almost all known leukocyte subtypes and found differences between neonatal and adult border-associated macrophages, thus highlighting that neonatal border-associated macrophages are functionally immature with regards to immune responses compared with their adult counterparts. We also identified novel meningeal microglia-like cell populations that may participate in white matter development. Early after the hypoxic-ischemic insult, neutrophil numbers increased and they exhibited increased granulopoiesis, suggesting that the meninges are an important site of immune cell expansion with implications for the initiation of inflammatory cascades after neonatal brain injury. Our study provides a single-cell resolution view of the importance of meningeal leukocytes at the early stage of development in health and disease.

The heart regeneration after apical resection and myocardial infarction in neonatal mice has been studied for years. However, the response of neonatal mouse heart under pressure overload is seldom explored. This study aimed to induce pressure overload in neonatal mice through a transverse aortic constriction (TAC) with different-gauge needles so as to investigate the effect of pressure overload on cardiomyocyte proliferation and hypertrophy in these mice. Myocardial hypertrophy was evaluated by echocardiographic, pathological, and molecular analyses. Cardiomyocyte proliferation was detected by immune-staining of phospho-histone H3, Ki67, and 5-bromo-2-deoxyuridine. Mild pressure overload induced with a 30-gauge needle stimulated cardiomyocyte proliferation, adaptive hypertrophy, and angiogenesis. The heart function was not hampered even 21 days after the surgery. Moderate pressure overload induced with a 32-gauge needle led to pathological myocardial hypertrophy, fibrosis, and heart failure 7 days after the surgery. The gene and protein expression levels of markers of hypertrophy and fibrosis increased in 32-gauge TAC group compared with that in sham and 30-gauge TAC groups. The mice barely survived after severe pressure overload induced with a 34-gauge needle. The findings of this study might provide new insights into cardiomyocyte proliferation and hypertrophy in neonatal mice under pressure overload.

Microwave-induced thermoacoustic tomography (TAT) has potential for detecting germinal matrix hemorrhage (GMH). However, it has not been demonstrated in vivo.
To demonstrate the feasibility of TAT for in vivo detecting GMH by using neonatal mouse.
A cylindrical-scanning TAT system was developed with optimized microwave irradiation and ultrasound detection for neonatal mouse imaging. Neonatal mice were used to develop GMH model by injection of autologous blood into the periventricular region. After TAT experiments, the animals were sacrificed, frozen and excised to validate the TAT findings. The detailed comparative analyses of the TAT images and corresponding photographs of the excised brain tissues were conducted.
Satisfactory matches are identified between the TAT images and corresponding histological sections, in terms of the shape and size of the brain tissues. Some organs and tissues were also identified. Particularly, comparing to the corresponding histological sections, using TAT enables to more accurately detect the hematoma region at different depths in the neonatal mouse brain.
This study demonstrates for the first time that TAT can detect GMH in neonatal mouse cerebrum in vivo. This represents the first important step towards the in vivo diagnosis and grading of hemorrhage in the infant human brain.

The regeneration capacity of neonatal mouse heart is controversial. In addition, whether epicardial cells provide a progenitor pool for de novo heart regeneration is incompletely defined. Following apical resection of the neonatal mouse heart, we observed limited regeneration potential. Fate-mapping of Tbx18MerCreMer mice revealed that newly formed coronary vessels and a limited number of cardiomyocytes were derived from the T-box transcription factor 18 (Tbx18) lineage. However, further lineage tracing with SM-MHCCreERT2 and Nfactc1Cre mice revealed that the new smooth muscle and endothelial cells are in fact derivatives of pre-existing coronary vessels. Our data show that neonatal mouse heart can regenerate but that its potential is limited. Moreover, although epicardial cells are multipotent during embryogenesis, their contribution to heart repair through \"stem\" or \"progenitor\" cell conversion is minimal after birth. These observations suggest that early embryonic heart development and postnatal heart regeneration are distinct biological processes. Multipotency of epicardial cells is significantly decreased after birth.

The present study aimed to evaluate the renoprotective effects of chelerythrine (CHE), a protein kinase C inhibitor, on neonatal rats after partial unilateral ureteral obstruction (UUO) surgery. New born Sprague Dawley rats were subjected to partial UUO 48 h after birth and received a daily intraperitoneal injection of 5 mg/kg CHE. At 21-day age, the rats were scarified and the kidneys were collected for analysis. Results showed that CHE treatment significantly increased kidney weight and restored renal function in the obstructed kidney. Histological examination demonstrated that CHE attenuated renal injury by reducing renal parenchymal loss and preventing glomerular and tubular degeneration. In addition, CHE inhibited partial UUO-induced upregulated kidney injury molecule-1 expression and apoptosis and renal fibrosis. Moreover, as a PKC inhibitor, CHE significantly inhibited PKCα and PKCβ membrane translocation. This action may be associated with its effects of anti-apoptosis and anti-fibrosis and contribute to the renoprotection. This short-term study suggests that CHE is beneficial for obstructive nephropathy in neonatal rats and provides foundation for further studies to reveal the long-term effects of CHE on obstructive nephropathy in children and infants.

Zika virus (ZIKV) has been defined as a teratogenic pathogen behind the increased number of cases of microcephaly in French Polynesia, Brazil, Puerto Rico, and other South American countries. Experimental studies using animal models have achieved tremendous insight into understanding the viral pathogenesis, transmission, teratogenic mechanisms, and virus-host interactions. However, the animals used in published investigations are mostly interferon (IFN)-compromised, either genetically or via antibody treatment. Herein, we studied ZIKV infection in IFN-competent mice using African (MR766) and Asian strains (PRVABC59 and SZ-WIV01). After testing four different species of mice, we found that BALB/c neonatal mice were resistant to ZIKV infection, that Kunming, ICR and C57BL/6 neonatal mice were fatally susceptible to ZIKV infection, and that the fatality of C57BL/6 neonates from 1 to 3 days old were in a viral dose-dependent manner. The size and weight of the brain were significantly reduced, and the ZIKV-infected mice showed neuronal symptoms such as hind-limb paralysis, tremor, and poor balance during walking. Pathologic and immunofluorescent experiments revealed that ZIKV infected different areas of the central nervous system (CNS) including gray matter, hippocampus, cerebral cortex, and spinal cord, but not olfactory bulb. Interestingly, ZIKV replicated in multiple organs and resulted in pathogenesis in liver and testis, implying that ZIKV infection may engender a high health risk in neonates by postnatal infection. In summary, we investigated ZIKV pathogenesis using an animal model that is not IFN-compromised.