Correlation of sLOX-1 and CSF1 with the pathological progression of hypoxic-ischemic encephalopathy in neonatal rats

To provide clinical evidence for the management of hypoxic-ischemic encephalopathy (HIE) by analyzing the role of soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) and colony-stimulating factor-1 (CSF1) in the disease. We purchased 15 Sprague-Dawley (SD) rat pups and randomized them into five groups (n=3), of which one group was untreated as the control group and the other four were modeled by HIE. After modeling, a group was treated as a model group without any treatment, another group was injected with sLOX-1-silencing lentiviral vector (sLOX-1-si group), and the third and fourth were injected with CSF1-silencing lentiviral vector (CSF1-si group) and an equal amount of normal saline (blank group), respectively. After the corresponding intervention, the rat tissue in each group was obtained to observe the pathological injury by HE and TUNEL staining. In addition, sLOX-1, CSF1, 5-hydroxytryptamine (5-HT), dopamine (DA), and norepinephrine (NE) levels in brain tissue of each group were determined. The model group showed more severe pathological damage of the hippocampus and higher neuronal apoptosis than the control group. Besides, higher sLOX-1 and CSF1 levels and lower 5-HT, DA and NE contents were identified in the model group versus the control group (P<0.05). Compared with the blank group, sLOX-1-si and CSF1-si groups showed significantly alleviated hippocampal damage, inhibited neuronal apoptosis, reduced 5-HT, DA, NE, Bax, and cl-caspase-3, and increased Bcl-2 (P<0.05). Silencing sLOX-1 and CSF1 expression ameliorated the pathological injury of HIE and inhibited neuronal apoptosis.

FGF21 modulates hippocampal cold-shock proteins and CA2-subregion proteins in neonatal mice with hypoxia-ischemia

BACKGROUND

Fibroblast growth factor 21 (FGF21) is a neuroprotectant with cognitive enhancing effects but with poorly characterized mechanism(s) of action, particularly in females. Prior studies suggest that FGF21 may regulate cold-shock proteins (CSPs) and CA2-marker proteins in the hippocampus but empirical evidence is lacking.

METHODS

We assessed in normothermic postnatal day (PND) 10 female mice, if hypoxic-ischemic (HI) brain injury (25 min 8% O2/92% N2) altered endogenous levels of FGF21 in serum or in the hippocampus, or its receptor β-klotho. We also tested if systemic administration of FGF21 (1.5 mg/kg) modulated hippocampal CSPs or CA2 proteins. Finally, we measured if FGF21 therapy altered markers of acute hippocampal injury.

RESULTS

HI increased endogenous serum FGF21 (24 h), hippocampal tissue FGF21 (4d), and decreased hippocampal β-klotho levels (4d). Exogenous FGF21 therapy modulated hippocampal CSP levels, and dynamically altered hippocampal CA2 marker expression (24 h and 4d). Finally, FGF21 ameliorated neuronal damage markers at 24 h but did not affect GFAP (astrogliosis) or Iba1 (microgliosis) levels at 4d.

CONCLUSIONS

FGF21 therapy modulates CSP and CA2 protein levels in the injured hippocampus. These proteins serve different biological functions, but our findings suggest that FGF21 administration modulates them in a homeostatic manner after HI.

IMPACT

Hypoxic-ischemic (HI) injury in female post-natal day (PND) 10 mice decreases hippocampal RNA binding motif 3 (RBM3) levels in the normothermic newborn brain. HI injury in normothermic newborn female mice alters serum and hippocampal fibroblast growth factor 21 (FGF21) levels 24 h post-injury. HI injury in normothermic newborn female mice alters hippocampal levels of N-terminal EF-hand calcium binding protein 2 (NECAB2) in a time-dependent manner. Exogenous FGF21 therapy ameliorates the HI-mediated loss of hippocampal cold-induced RNA-binding protein (CIRBP). Exogenous FGF21 therapy modulates hippocampal levels of CA2-marker proteins after HI.

Interleukin-33 improves the neurogenesis of neural stem cells in perinatal brain after hypoxia-ischemia

Perinatal hypoxia-ischemia (HI) insult is an important cause of neonatal encephalopathy, and the effective therapeutic approaches are currently limited. Interleukin (IL)-33 acts as a member of the IL-1 superfamily and has been shown to be neuroprotective following experimental neonatal HI and adult stroke. Here, we explore the effect of IL-33 and its specific receptor ST2 axis on endogenous neurogenesis in neonatal brain after HI. ST2 was found on the surface of NSCs, and the expression of ST2 was further enhanced after HI challenge. Delivery of IL-33 obviously repopulated the size of NSC pool, whereas ST2 deficiency worsened the neurogenesis of NSCs in neonatal brain post HI insult. Further in vivo and in vitro studies showed IL-33 regulates the survival, proliferation and differentiation of NSCs through ST2 signaling pathways. Intriguingly, IL-33 facilitated translocation of Nrf2 from the cytoplasm to the nucleus, which is involved in neural differentiation of NSCs. These data demonstrate a critical role of IL-33/ST2 axis in regulation of endogenous neurogenesis of NSCs via activation of the Nrf2 signaling, which provide a new insight into the effect of IL-33 in neonatal brain following HI injury.

Neuro-Specific and Immuno-Inflammatory Biomarkers in Umbilical Cord Blood in Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVES

The aim of the study was to evaluate neuronal injury and immuno-inflammatory biomarkers in umbilical cord blood (UCB) at birth, in cases with perinatal asphyxia with or without hypoxic-ischemic encephalopathy (HIE), compared with healthy controls and to assess their ability to predict HIE.

STUDY DESIGN

In this case-control study, term infants with perinatal asphyxia were recruited at birth. UCB was stored at delivery for batch analysis. HIE was diagnosed by clinical Sarnat staging at 24 h. Glial fibrillary acidic protein (GFAP), the neuronal biomarkers tau and neurofilament light protein (NFL), and a panel of cytokines were analyzed in a total of 150 term neonates: 50 with HIE, 50 with asphyxia without HIE (PA), and 50 controls. GFAP, tau, and NFL concentrations were measured using ultrasensitive single-molecule array (Simoa) assays, and a cytokine screening panel was applied to analyze the immuno-inflammatory and infectious markers.

RESULTS

GFAP, tau, NFL, and several cytokines were significantly higher in newborns with moderate and severe HIE compared to a control group and provided moderate prediction of HIE II/III (AUC: 0.681-0.827). Furthermore, the levels of GFAP, tau, interleukin-6 (IL-6), and interleukin-8 (IL-8) were higher in HIE II/III cases compared with cases with PA/HIE I. IL-6 was also higher in HIE II/III compared with HIE I cases.

CONCLUSIONS

Biomarkers of brain injury and inflammation were increased in umbilical blood in cases with asphyxia. Several biomarkers were higher in HIE II/III versus those with no HIE or HIE I, suggesting that they could assist in the prediction of HIE II/III.

Effect of Leuprolide Acetate, a GnRH Agonist, on Neuroinflammation and Anxiety-Like Behavior after Mild Hypoxic-Ischemic Encephalopathy in Rat Model

BACKGROUND

Mild hypoxic-ischemic encephalopathy (HIE) is a condition that predisposes to negative outcomes such as neuroanatomical injury, mood disorders, and motor or cognitive disabilities. The neuroinflammation plays an important role in the neurological damage; therefore, reducing it could provide neuroprotection. The leuprolide acetate (LA) has shown to have neuroregenerative and immunomodulator properties in other nervous system injuries.

OBJECTIVE

The aim of this study was to evaluate the immunomodulatory effect of LA in the acute phase of mild HIE and its effects in motor activity and behavior in a subacute phase.

METHOD

Forty-five Wistar rats on postnatal day 7 were divided into Sham, HIE treated with saline solution (HIE-SS), and HIE-LA. The HIE was performed cutting of the right carotid artery followed by 60 min of hypoxia. The expression of the inflammatory cytokines interleukin (IL)-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and the chemokine CXCL-1 were evaluated 72 h after HIE by RT-qPCR and the motor activity and behavior were evaluated by open field test at postnatal day 33.

RESULTS

HIE-SS animals showed increased expression of IL-1β, TNF-α, IFN-γ, and CXCL-1 genes in injured tissue. However, the HIE-LA group exhibited similar expression levels of IL-1β and TNF-α to the Sham group, while IFN-γ and CXCL-1 mRNA expression were attenuated with LA treatment. LA treatment also prevented anxiety-like behavior in the open field test.

CONCLUSION

Treatment with LA partially reverses HIE-induced neuroinflammation and prevents anxiety-like behavior in neonatal rats.

[Effect of ligustrazine on hypoxic-ischemic encephalopathy in neonatal rats by regulating autophagy through the PINK1/Parkin pathway]

OBJECTIVES

To study the effect of ligustrazine injection on mitophagy in neonatal rats with hypoxic-ischemic encephalopathy (HIE) and its molecular mechanism.

METHODS

Neonatal Sprague-Dawley rats, aged 7 days, were randomly divided into a sham-operation group with 8 rats, a model group with 12 rats, and a ligustrazine group with 12 rats. The rats in the model group and the ligustrazine group were used to establish a neonatal rat model of HIE by ligation of the left common carotid artery followed by hypoxia treatment, and blood vessels were exposed without any other treatment for the rats in the sham-operation group. The rats in the ligustrazine group were intraperitoneally injected with ligustrazine (20 mg/kg) daily after hypoxia-ischemia, and those in the sham-operation group and the model group were intraperitoneally injected with an equal volume of normal saline daily. Samples were collected after 7 days of treatment. Hematoxylin and eosin staining and Nissl staining were used to observe the pathological changes of neurons in brain tissue; immunohistochemical staining was used to observe the positive expression of PINK1 and Parkin in the hippocampus and cortex; TUNEL staining was used to measure neuronal apoptosis; Western blotting was used to measure the expression levels of the mitophagy pathway proteins PINK1 and Parkin and the autophagy-related proteins Beclin-1, microtubule-associated protein 1 light chain 3 (LC3), and ubiquitin-binding protein (P62).

RESULTS

Compared with the sham-operation group, the model group had a significant reduction in the number of neurons, an increase in intercellular space, loose arrangement, lipid vacuolization, and a reduction in Nissl bodies. The increased positive expression of PINK1 and Parkin, apoptosis rate of neurons, and protein expression levels of PINK1, Parkin, Beclin1 and LC3 (P<0.05) and the decreased protein expression level of P62 in the hippocampus were also observed in the model group (P<0.05). Compared with the model group, the ligustrazine group had a significant increase in the number of neurons with ordered arrangement and an increase in Nissl bodies, significant reductions in the positive expression of PINK1 and Parkin, the apoptosis rate of neurons, and the protein expression levels of PINK1, Parkin, Beclin1, and LC3 (P<0.05), and a significant increase in the protein expression level of P62 (P<0.05).

CONCLUSIONS

Ligustrazine can alleviate hypoxic-ischemic brain damage and inhibit neuronal apoptosis in neonatal rats to a certain extent, possibly by inhibiting PINK1/Parkin-mediated autophagy.

Desflurane Post-treatment Reduces Hypoxic-ischemic Brain Injury via Reducing Transient Receptor Potential Ankyrin 1 in Neonatal Rats

Perinatal hypoxic-ischemic (HI) brain injury leads to mortality and morbidity in neonates and children. There are no effective and practical methods to attenuate this brain injury. This study determined whether desflurane, a volatile anesthetic with limited effect on the cardiovascular system, protected against HI-induced brain damage and the role of transient receptor potential ankyrin 1 (TRPA1), a mediator for simulated ischemia-induced myelin damage, in this protection. Seven-day-old male and female Sprague-Dawley rats had brain HI. They were exposed to 4.8%, 7.6% or 11.4% desflurane immediately or 4.8% desflurane at 0.5, 1 or 2 h after the HI. Brain tissue loss was evaluated 7 days later. Neurological functions and brain structures of rats with HI and 4.8% desflurane post-treatment were evaluated 4 weeks after the HI. TRPA1 expression was determined by Western blotting. HC-030031, a TRPA1 inhibitor, was used to determine the role of TRPA1 in the HI-induced brain injury. HI induced brain tissue and neuronal loss, which was attenuated by all tested concentrations of desflurane. Desflurane post-treatment also improved motor function, learning and memory in rats with brain HI. Brain HI increased the expression of TRPA1 and this increase was inhibited by desflurane. TRPA1 inhibition reduced HI-induced brain tissue loss and impairment of learning and memory. However, the combination of TRPA1 inhibition and desflurane post-treatment did not preserve brain tissues, learning and memory better than TRPA1 inhibition or desflurane post-treatment alone. Our results suggest that desflurane post-treatment induces neuroprotection against neonatal HI. This effect may be mediated by inhibiting TRPA1.

Inter-Alpha Inhibitor Proteins Modify the Microvasculature after Exposure to Hypoxia-Ischemia and Hypoxia in Neonatal Rats

Microvasculature develops during early brain development. Hypoxia-ischemia (HI) and hypoxia (H) predispose to brain injury in neonates. Inter-alpha inhibitor proteins (IAIPs) attenuate injury to the neonatal brain after exposure to HI. However, the effects of IAIPs on the brain microvasculature after exposure to HI have not been examined in neonates. Postnatal day-7 rats were exposed to sham treatment or right carotid artery ligation and 8% oxygen for 90 min. HI comprises hypoxia (H) and ischemia to the right hemisphere (HI-right) and hypoxia to the whole body, including the left hemisphere (H-left). Human IAIPs (hIAIPs, 30 mg/kg) or placebo were injected immediately, 24 and 48 h after HI/H. The brains were analyzed 72 h after HI/H to determine the effects of hIAIPs on the microvasculature by laminin immunohistochemistry and calculation of (1) the percentage area stained by laminin, (2) cumulative microvessel length, and (3) density of tunneling nanotubes (TNTs), which are sensitive indicators of the earliest phases of neo-vascularization/collateralization. hIAIPs mainly affected the percent of the laminin-stained area after HI/H, cumulative vessel length after H but not HI, and TNT density in females but not males. hIAIPs modify the effects of HI/H on the microvasculature after brain injury in neonatal rats and exhibit sex-related differential effects. Our findings suggest that treatment with hIAIPs after exposure to H and HI in neonatal rats affects the laminin content of the vessel basal lamina and angiogenic responses in a sex-related fashion.

Neuroprotective effects of oxymatrine on hypoxic-ischemic brain damage in neonatal rats by activating the Wnt/β-catenin pathway

Neuronal apoptosis is a major pathological process associated with neurological dysfunction in neonates after hypoxic-ischemic brain damage (HIBD). Our previous study demonstrated that oxymatrine (OMT) exerts potential neuroprotective effects on neonatal rats subjected to hypoxic-ischemic insult. However, the underlying molecular mechanism remains unclear. In this study, we investigated the effects of OMT-mediated neuroprotection on neonatal HIBD by attempting to determine its effect on the Wnt/β-catenin signaling pathway and explored the underlying mechanism. Both 7-day-old rat pups and primary hippocampus neurons were used to establish the HIBD and oxygen-glucose deprivation (OGD) injury models, respectively. Our results demonstrated that OMT treatment significantly increased cerebral blood flow and reduced S100B concentration, infarct volume, and neuronal apoptosis in neonatal rats. In vitro, OMT markedly increased cell viability and MMP level and decreased DNA damage. Moreover, OMT improved the mRNA and protein levels of Wnt1 and β-catenin, inhibited the expression of DKK1 and GSK-3β, enhanced the nuclear transfer of β-catenin, and promoted the binding activity of β-catenin with Tcf-4; however, it downregulated the expression of cleaved caspase-3 and cleaved caspase-9. Notably, the introduction of XAV-939 (a Wnt/β-catenin signaling inhibitor) reversed the positive effects of OMT both in vivo and in vitro. Collectively, our findings demonstrated that OMT exerted a neuroprotective effect on neonatal HIBD by inhibiting neuronal apoptosis, which was partly via the activation of the Wnt/β-catenin signaling pathway.

Neutrophil Extracellular Traps Release following Hypoxic-Ischemic Brain Injury in Newborn Rats Treated with Therapeutic Hypothermia

The peripheral immune system plays a critical role in neuroinflammation of the central nervous system after an insult. Hypoxic-ischemic encephalopathy (HIE) induces a strong neuroinflammatory response in neonates, which is often associated with exacerbated outcomes. In adult models of ischemic stroke, neutrophils infiltrate injured brain tissue immediately after an ischemic insult and aggravate inflammation via various mechanisms, including neutrophil extracellular trap (NETs) formation. In this study, we used a neonatal model of experimental hypoxic-ischemic (HI) brain injury and demonstrated that circulating neutrophils were rapidly activated in neonatal blood. We observed an increased infiltration of neutrophils in the brain after exposure to HI. After treatment with either normothermia (NT) or therapeutic hypothermia (TH), we observed a significantly enhanced expression level of the NETosis marker Citrullinated H3 (Cit-H3), which was significantly more pronounced in animals treated with TH than in those treated with NT. NETs and NLR family pyrin domain containing 3 (NLRP-3) inflammasome assembly are closely linked in adult models of ischemic brain injury. In this study, we observed an increase in the activation of the NLRP-3 inflammasome at the time points analyzed, particularly immediately after TH, when we observed a significant increase in NETs structures in the brain. Together, these results suggest the important pathological functions of early arriving neutrophils and NETosis following neonatal HI, particularly after TH treatment, which is a promising starting point for the development of potential new therapeutic targets for neonatal HIE.

Selectively compromised inner retina function following hypoxic-ischemic encephalopathy in mice: A noninvasive measure of severity of the injury

The intricate system of connections between the eye and the brain implies that there are common pathways for the eye and brain that get activated following injury. Hypoxia-ischemia (HI) related encephalopathy is a consequence of brain injury caused by oxygen and blood flow deprivation that may result in visual disturbances and neurodevelopmental disorders in surviving neonates. We have previously shown that the tyrosine receptor kinase B (TrkB) agonist/modulator improves neuronal survival and long-term neuroprotection in a sexually differential way. In this study, we tested the hypotheses that; 1) TrkB agonist therapy improves the visual function in a sexually differential way; 2) Visual function detected by electroretinogram (ERG) correlates with severity of brain injury detected by magnetic resonance (MRI) imaging following neonatal HI in mice. To test our hypotheses, we used C57/BL6 mice at postnatal day (P) 9 and subjected them to either Vannucci's rodent model of neonatal HI or sham surgery. ERG was performed at P 30, 60, and 90. MRI was performed following the completion of the ERG. ERG in these mice showed that the a-wave is normal, but the b-wave amplitude is severely abnormal, reducing the b/a wave amplitude ratio. Inner retina function was found to be perturbed as we detected severely attenuated oscillatory potential after HI. No sex differences were detected in the injury and severity pattern to the retina as well as in response to 7,8-DHF therapy. Strong correlations were detected between the percent change in b/a ratio and percent hemispheric/hippocampal tissue loss obtained by MRI, suggesting that ERG is a valuable noninvasive tool that can predict the long-term severity of brain injury.

Insight into the Neuroprotective Effect of Genistein-3'-Sodium Sulfonate Against Neonatal Hypoxic-Ischaemic Brain Injury in Rats by Bioinformatics

Therapeutic hypothermia (TH) is the only intervention approved for the treatment of neonatal hypoxic-ischaemic encephalopathy (HIE), but its treatment window is narrow (within 6 h after birth), and its efficacy is not ideal. Thus, alternative treatments are urgently needed. Our previous studies showed that genistein-3'-sodium sulfonate (GSS), a derivative of genistein (Gen), has a strong neuroprotective effect in rats with ischaemic stroke, but its role in HIE is unclear. A hypoxia-ischaemia (HI) brain injury model was established in neonatal male Sprague‒Dawley (SD) rats. Twenty-four hours after reperfusion, rats treated with GSS were assessed for cerebral infarction, neurological function, and neuronal damage. RNA-Seq and bioinformatics analysis were used to explore differentially expressed genes (DEGs) and regulated signalling pathways, which were subsequently validated by Western blotting and immunofluorescence. In this study, we found that GSS not only significantly reduced the size of brain infarcts and alleviated nerve damage in rats with HIE but also inhibited neuronal loss and degeneration in neonatal rats with HIE. A total of 2170 DEGs, of which 1102 were upregulated and 1068 were downregulated, were identified in the GSS group compared with the HI group. In an analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) categories, the downregulated DEGs were significantly enriched in the pathways "Phagosome", "NF-κB signalling", and "Complement and coagulation cascades", amongst others. Meanwhile, the upregulated DEGs were significantly enriched in the pathways "Neurodegeneration", "Glutamatergic synapse", and "Calcium signalling pathway", amongst others. These results indicate that GSS intervenes in the process of HIE-induced brain injury by participating in multiple pathways, which suggests potential candidate drugs for the treatment of HIE.

Neuroprotective effect of lipopolysaccharides in a dual-hit rat pup model of preterm hypoxia-ischemia

The combination of lipopolysaccharide (LPS) and hypoxia-ischemia (HI) has been used to model the brain injury sustained by sick pre-term infants in order to study the pathological conditions of diffuse white matter injury, which is a major cause of preterm morbidity. Prior studies have shown that the timing and dose of LPS administration will determine whether the injury is reduced or exacerbated. Here we show that administering a single injection of LPS (0.1 mg/kg) to postnatal-day-2 rat pups 14 h before inducing HI effectively protects the brain from HI-associated damage. We show that the LPS-treated HI rat pups have significantly less histopathology compared to the saline-treated HI rat pups. Apoptotic deaths were dramatically curtailed in both the neocortex and white matter when evaluated at 2 days of recovery. Microglial activation was reduced when the percentage of CD68+/Iba1+ cells was quantified in the neocortex of the LPS-treated vs the saline-treated HI rat pups. One mechanism through which LPS pre-treatment appears to be preventing injury is through the AKT-endothelial nitric oxide synthase (eNOS) pathway as LPS induced an increase in both the expression and phosphorylation of eNOS. Altogether these data show that the neocortex, as well as the white matter sustain damage after HI at this timepoint in forebrain development and that acutely activating the immune system can protect the brain from brain injury.

T0901317, a liver X receptor agonist, ameliorates perinatal white matter injury induced by ischemia and hypoxia in neonatal rats

Perinatal white matter injury (PWMI) can lead to permanent neurological damage in preterm infants and bring a huge economic burden to their families and society. Liver X receptors (LXRs) are transcription factors that have been confirmed to mediate the myelination process under physiological conditions and are involved in regulating neurogenesis in adult animal models of acute and chronic cerebral ischemia. However, the role of LXRs in PWMI induced by both ischemic and hypoxic stimulation in the immature brain has not been reported. Herein, we investigated the role of LXRs in a neonatal rat model of white matter loss after hypoxia-ischemia (HI) injury through intraperitoneal injection of the LXR agonist T0901317 (T09) 1 day before and 15 min postinjury. The in vivo data showed that T09 treatment significantly facilitated myelination and ameliorated neurological behavior after PWMI. Moreover, T09 enhanced the proliferation of oligodendrocyte lineage cells and reduced microgliosis and astrogliosis in the microenvironment for oligodendrocytes (OLs), maintaining a healthy microenvironment for myelinating OLs. In vitro data suggested that the expression of the myelin-related genes Plp and Cnpase was increased in OLN-93 cells after T09 intervention compared with OLN-93 cells injured by oxygen and glucose deprivation (OGD). In primary mixed astrocytes/microglia cells, T09 also reduced the expression of Il6, Cox2, Tnfa and Il10 that was induced by OGD. Mechanistically, the mRNA expression level and the protein level of ATP binding cassette subfamily A member 1 (Abca1) decreased after HI injury, and the protective effect of T09 might be related to the activation of the LXRβ-ABCA1 signaling pathway. Our study revealed the protective role of LXRs in myelination and white matter homeostasis, providing a potential therapeutic option for PWMI.

Neuroprotective Mechanism of Icariin on Hypoxic Ischemic Brain Damage in Neonatal Mice

Objective

Our previous results showed that icariin (ICA) could inhibit apoptosis and provide neuroprotection against hypoxic-ischemic brain damage (HIBD) in neonatal mice, but the specific mechanism of its neuroprotective effect remains unknown. This study aims at exploring whether ICA plays a neuroprotective role in apoptosis inhibition by regulating autophagy through the estrogen receptor α (ERα)/estrogen receptor β (ERβ) pathway in neonatal mice with HIBD.

Methods

A neonatal mouse model of HIBD was constructed in vivo, and an oxygen and glucose deprivation (OGD) model in HT22 cells from the hippocampal neuronal system was constructed in vitro. The effects of ICA pretreatment on autophagy and the expression of ERα and ERβ were detected in vitro and in vivo, respectively. ICA pretreatment was also supplemented with the autophagy inhibitor 3-methyladenine (3-MA), ERα inhibitor methylpiperidino pyrazole (MPP), and ERβ inhibitor 4-(2-phenyl-5,7-bis (trifluoromethyl) pyrazolo [1,5-a] pyramidin-3-yl) phenol (PHTPP) to further detect whether ICA pretreatment can activate the ERα/ERβ pathway to promote autophagy and reduce HIBD-induced apoptosis to play a neuroprotective role against HIBD in neonatal mice.

Results

ICA pretreatment significantly promoted autophagy in HIBD mice. Treatment with 3-MA significantly inhibited the increase in autophagy induced by ICA pretreatment, reversed the neuroprotective effect of ICA pretreatment, and promoted apoptosis. Moreover, ICA pretreatment significantly increased the expression levels of the ERα and ERβ proteins in HIBD newborn mice. Both MPP and PHTPP administration significantly inhibited the expression levels of the ERα and ERβ proteins activated by ICA pretreatment, reversed the neuroprotective effects of ICA pretreatment, inhibited the increase in autophagy induced by ICA pretreatment, and promoted apoptosis.

Conclusion

ICA pretreatment may promote autophagy by activating the ERα and ERβ pathways, thus reducing the apoptosis induced by HIBD and exerting a neuroprotective effect on neonatal mice with HIBD.

[The TXNIP/Trx-1/GPX4 pathway promotes ferroptosis in hippocampal neurons after hypoxia-ischemia in neonatal rats]

OBJECTIVES

To observe the change in ferroptosis in hippocampal neurons after hypoxia-ischemia (HI) in neonatal rats and investigate the related mechanism based on the TXNIP/Trx-1/GPX4 signaling pathway.

METHODS

Healthy neonatal Sprague-Dawley rats, aged 7 days, were randomly divided into three groups: sham-operation (n=30), hypoxic-ischemic brain damage (HIBD) (n=30) and siRNA (TXNIP siRNA) (n=12). The classic Rice-Vannucci method was used to establish a neonatal rat model of HIBD. At 6 hours, 24 hours, 72 hours, and 7 days after modeling, Western blot was used to measure the protein expression of GPX4 in the hippocampal tissue at the injured side; at 24 hours after modeling, laser speckle imaging combined with hematoxylin-eosin staining was used to determine whether the model was established successfully; NeuN/GPX4 and GFAP/GPX4 immunofluorescence staining combined with Western blot and other methods was used to measure the protein expression of GPX4 and the signal molecules TXNIP and Trx-1 in the hippocampal tissue at the injured side; the kits for determining the content of serum iron and tissue iron were used to measure the change in iron content; quantitative real-time PCR was used to measure the mRNA expression of TXNIP, Trx-1, and GPX4.

RESULTS

At 6 hours, 24 hours, 72 hours, and 7 days after modeling, the HIBD group had a significantly lower protein expression level of GPX4 than the sham-operation group (P<0.05). At 24 hours after modeling, the HIBD group had a significantly lower cerebral blood flow of the injured side than the sham-operation group (P<0.05), with loose and disordered arrangement and irregular morphology of hippocampal CA1 neurons at the injured side. Compared with the sham-operation group, the HIBD group had a significantly higher number of TXNIP+ cells and significantly lower numbers of Trx-1+ cells and NeuN+GPX4+/NeuN+ cells in the hippocampal CA1 region at the injured side (P<0.05), with almost no GFAP+GPX4+ cells in the hippocampal CA1 region. Compared with the sham-operation group, the HIBD group and the siRNA group had significantly higher levels of serum iron and tissue iron in the hippocampus at the injured side (P<0.05). Compared with the HIBD group, the siRNA group had significantly lower levels of serum iron and tissue iron in the hippocampus at the injured side (P<0.05). The HIBD group and the siRNA group had significantly higher mRNA and protein expression levels of TXNIP than the sham-operation group (P<0.05), and the siRNA group had significantly lower expression levels than the HIBD group (P<0.05). The HIBD group and the siRNA group had significantly lower mRNA and protein expression levels of Trx-1 and GPX4 in the hippocampus at the injured side than the sham-operation group (P<0.05), and the siRNA group had significantly higher expression levels than the HIBD group (P<0.05).

CONCLUSIONS

HI induces ferroptosis of hippocampal neurons in neonatal rats by activating the TXNIP/Trx-1/GPX4 pathway, thereby resulting in HIBD.

Human-rat integrated microRNAs profiling identified a new neonatal cerebral hypoxic-ischemic pathway melatonin-sensitive

Neonatal encephalopathy (NE) is a pathological condition affecting long-term neurodevelopmental outcomes. Hypothermia is the only therapeutic option, but does not always improve outcomes; hence, researchers continue to hunt for pharmaceutical compounds. Melatonin treatment has benefitted neonates with hypoxic-ischemic (HI) brain injury. However, unlike animal models that enable the study of the brain and the pathophysiologic cascade, only blood is available from human subjects. Therefore, due to the unavailability of neonatal brain tissue, assumptions about the pathophysiology in pathways and cascades are made in human subjects with NE. We analyzed animal and human specimens to improve our understanding of the pathophysiology in human neonates. A neonate with NE who underwent hypothermia and enrolled in a melatonin pharmacokinetic study was compared to HI rats treated/untreated with melatonin. MicroRNA (miRNA) analyses provided profiles of the neonate's plasma, rat plasma, and rat brain cortexes. We compared these profiles through a bioinformatics tool, identifying Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways common to HI brain injury and melatonin treatment. After evaluating the resulting pathways and the literature, to validate the method, the key proteins expressed in HI brain injury were investigated using cerebral cortexes. The upregulated miRNAs in human neonate and rat plasma helped identify two KEGG pathways, glioma and long-term potentiation, common to HI injury and melatonin treatment. A unified neonatal cerebral melatonin-sensitive HI pathway was designed and validated by assessing the expression of protein kinase Cα (PKCα), phospho (p)-Akt, and p-ERK proteins in rat brain cortexes. PKCα increased in HI-injured rats and further increased with melatonin. p-Akt and p-ERK returned phosphorylated to their basal level with melatonin treatment after HI injury. The bioinformatics analyses validated by key protein expression identified pathways common to HI brain injury and melatonin treatment. This approach helped complete pathways in neonates with NE by integrating information from animal models of HI brain injury.

The Regulatory Role of H19/miR-181a/ATG5 Signaling in Perinatal Nicotine Exposure-Induced Development of Neonatal Brain Hypoxic-Ischemic Sensitive Phenotype

Nicotine exposure either from maternal cigarette smoking or e-cigarette vaping is one of the most common risk factors for neurodevelopmental disease in offspring. Previous studies revealed that perinatal nicotine exposure programs a sensitive phenotype to neonatal hypoxic-ischemic encephalopathy (HIE) in postnatal life, yet the underlying mechanisms remain undetermined. The goal of the present study was to determine the regulatory role of H19/miR-181a/ATG5 signaling in perinatal nicotine exposure-induced development of neonatal brain hypoxic-ischemic sensitive phenotype. Nicotine was administered to pregnant rats via subcutaneous osmotic minipumps. All experiments were conducted in offspring pups at postnatal day 9 (P9). Perinatal nicotine exposure significantly enhanced expression of miR-181a but attenuated autophagy-related protein 5 (ATG5) mRNA and protein levels in neonatal brains. Of interest, miR-181a mimicking administration in the absence of nicotine exposure also produced dose-dependent increased hypoxia/ischemia (H/I)-induced brain injury associated with a decreased ATG5 expression, closely resembling perinatal nicotine exposure-mediated effects. Locked nucleic acid (LNA)-miR-181a antisense reversed perinatal nicotine-mediated increase in H/I-induced brain injury and normalized aberrant ATG5 expression. In addition, nicotine exposure attenuated a long non-coding RNA (lncRNA) H19 expression level. Knockdown of H19 via siRNA increased the miR-181a level and enhanced H/I-induced neonatal brain injury. In conclusion, the present findings provide a novel mechanism that aberrant alteration of the H19/miR-181a/AGT5 axis plays a vital role in perinatal nicotine exposure-mediated ischemia-sensitive phenotype in offspring and suggests promising molecular targets for intervention and rescuing nicotine-induced adverse programming effects in offspring.

Dexmedetomidine alleviates the hypoxic-ischemic brain damage via miR-20a-5p/methionine adenosyltransferase 2B axis in rat pups

OBJECTIVE

The neuroprotective effect of dexmedetomidine (DEX) has been demonstrated in hypoxic-ischemic brain damage (HIBD) animal models, the mechanism of which will be the foothold in this work.

METHODS

After establishment of HIBD rat model, the rats were treated with DEX, miR-20a-5p agomir and adenoviral methionine adenosyltransferase 2B (MAT2B) overexpression vector, and then their brain tissues were harvested. The infarction volume and pathological changes of these brain tissues were measured using the triphenyl tetrazolium chloride (TTC), Nissl and hematoxylin-eosin (HE) stainings. The levels of miR-20a-5p, Bcl-2, Bax and MAT2B in these brain tissues were detected by Real-Time PCR (RT-PCR) and western blot. The binding sites of MAT2B and miR-20a-5p were predicted using the TargetScan and verified using the dual-luciferase reporter assay. The memory deficits and spatial learning of rat pups were assessed by Morris water maze test.

RESULTS

MiR-20a-5p expression was upregulated, while MAT2B expression was downregulated in rats with HIBD. MAT2B was targeted by miR-20a-5p. DEX treatment improved the neurons and hippocampal tissue damage and decreased miR-20a-5p level in brain tissues of rats with HIBD. MiR-20a-5p overexpression overturned the protective effect of DEX on brain tissues and learning and memory abilities in rats with HIBD. Moreover, DEX promoted Bcl-2 level while inhibiting Bax level in HIBD rats' brain tissues. Besides, overexpressed MAT2B reversed the effect of overexpressed miR-20a-5p on the levels of MAT2B, Bcl-2 and Bax, brain tissue damage, as well as the learning and memory abilities in rats with HIBD.

CONCLUSION

DEX alleviated HIBD via the miR-20a-5p/MAT2B axis in rats.

Ferroptosis is involved in hypoxic-ischemic brain damage in neonatal rats

Ferroptosis is an iron-dependent form of regulated cell death, which is driven by loss of activity of the lipid repair enzyme glutathione peroxidase 4 (GPX4) and subsequent accumulation of lipid peroxidation. Ferroptosis is implicated in various diseases involving neuronal injury. However, the role of ferroptosis in hypoxic-ischemic brain damage (HIBD) has not been elucidated. The objectives of this study were to evaluate whether ferroptosis is involved in hypoxic-ischemic brain damage and its mechanisms through the HIBD model. A 7-day-old male Sprague-Dawley neonatal rat HIBD model was established by blocking the left common carotid artery. Laser speckle contrast imaging, immunohistochemical staining, transmission electron microscopy were used to measure the effects of ferroptosis on HIBD. Brain tissue on the damaged side in the HIBD group showed atrophied, even liquefied, glial cells increased, and blood perfusion was significantly reduced. The HIBD group insult significantly increased reactive oxygen species levels, as well as the protein levels of iron metabolism-related proteins transferrin receptor (TFRC), ferritin heavy chain (FHC), and ferritin light chain (FLC), while reducing the levels of Solute Carrier Family 7 Member 11 (SLC7A11), glutathione (GSH), and GPX4. These changes resulted in diminished cellular antioxidant capacity and mitochondrial damage, causing neuronal ferroptosis in the cerebral cortex. We conclude that ferroptosis plays a role in HIBD in neonatal rats. Ferroptosis-related mechanisms such as abnormalities in iron metabolism, amino acid metabolism, and lipid peroxidation regulation play important roles in HIBD.

Vitamin E Decreases Cytotoxicity and Mitigates Inflammatory and Oxidative Stress Responses in a Ferret Organotypic Brain Slice Model of Neonatal Hypoxia-Ischemia

The gyrencephalic ferret brain is an excellent model in which to study hypoxia-ischemia (HI), a significant contributor to neurological injury in neonates. Vitamin E, an essential fat-soluble antioxidant, reduces oxidative stress and inflammation in both animal models and neonates. The aim of this study was to assess the effects of Vitamin E after oxygen glucose deprivation (OGD) in an organotypic ferret brain slice model of neonatal HI. We hypothesized that Vitamin E would decrease cytotoxicity, inflammation, and oxidative stress in OGD-exposed brain slices. Term-equivalent ferrets were sacrificed at postnatal (P) day 21-23 and 300µM whole hemisphere brain slices were obtained. During a 24h rest period, slices were cultured in either non-treated control conditions or with Erastin, a promotor of oxidative stress. Slices were then exposed to 2h of OGD followed by Vitamin E (25-100 IU/kg), Erastin (10µM) or Ferrostatin (1µM), an inhibitor of ferroptosis. Relative cytotoxicity was determined using an LDH assay, cell death was quantified via nuclear propidium iodide (PI) staining, oxidative stress was quantified via cellular GSH (glutathione) levels and target genes responsive to oxidative stress and inflammation were evaluated by qRT-PCR. OGD increased cytotoxicity, which was significantly reduced by treatment with Vitamin E. Vitamin E also preserved GSH after OGD and decreased amplification of certain markers of oxidative stress (CHAC1, SLC7A11) and inflammation (TNF-alpha, IL-8). Vitamin E remained protective after pretreatment with Erastin and was more protective than Ferrostatin, presumably due to its added anti-inflammatory properties. Results from the ferret whole hemisphere OGD model support the premise that Vitamin E neuroprotection is mediated by restoring GSH and acutely decreasing inflammation and oxidative stress after neonatal HI brain injury.

Down-Regulated microRNA-192-5p Protects Against Hypoxic-Ischemic Brain Damage via Regulation of YAP1-Mediated Hippo Signaling Pathway

Hypoxic-ischemic brain damage (HIBD) is a familiar neurological disorder. Emerging reports manifest that microRNAs (miRs) are related to the progression of HIBD. The goal of this study is to explore the mechanism of miR-192-5p in HIBD via regulation of Yes-associated protein 1 (YAP1)-mediated Hippo signaling pathway. The miR-192-5p, YAP1, and Hippo pathway-related factors Phospho (p)-Triaminoguanidinium azide (TAZ) in hippocampal tissues and neurons were detected. The regulatory relationship between miR-192-5p and YAP1 was verified. Neonatal hypoxic ischemia and oxygen-glucose deprivation (OGD) were used to simulate HIBD in vivo and in vitro. The neurobehavioral impairment, neuronal damage and vascular endothelial growth factor (VEGF) expression of neonatal rats in each group were detected. The viability, apoptosis and VEGF expression of hippocampal neurons in each group were also examined. MiR-192-5p expression was elevated while YAP1 expression was reduced in hippocampal tissues of HIBD rats in vivo and OGD neurons in vitro. MiR-192-5p had a targeting relation with YAP1. Suppressed miR-192-5p or overexpressed YAP1 in HIBD rats alleviated neurobehavioral impairment and neuronal damage, and decreased the expression levels of p-TAZ and VEGF expression in vivo. Reduced miR-192-5p or augmented YAP1 decelerated the neuron apoptosis, decreased the p-TAZ level and VEGF level and promoted cell viability of OGD hippocampal neurons in vitro. The study highlights that inhibited miR-192-5p protects against HIBD via regulation of YAP1 and Hippo signaling pathway, which is beneficial for HIBD treatment.

LncRNA GAS5/miR-137 Is a Hypoxia-Responsive Axis Involved in Cardiac Arrest and Cardiopulmonary Cerebral Resuscitation

Background

Cardiac arrest/cardiopulmonary resuscitation (CA/CPR) represents one of the devastating medical emergencies and is associated with high mortality and neuro-disability. Post-cardiac arrest syndrome (PCAS) is mechanistically ascribed to acute systemic ischemia/reperfusion(I/R) injury. The lncRNA/microRNA/mRNA networks have been found to play crucial roles in the pathogenesis of the hypoxia-responsive diseases. Nonetheless, the precise molecular mechanisms by which lncRNA/miRNA/mRNA axes are involved in the astrocyte-microglia crosstalk in CA/CPR have not been fully elucidated.

Methods

We collected and purified the exosomes from the blood of CA/CPR patients and supernatant of OGD/R-stimulated astrocytes. On the basis of microarray analysis, bioinformatic study, and luciferase activity determination, we speculated that lncRNA GAS5/miR-137 is implicated in the astrocyte-microglia crosstalk under the insult of systemic I/R injury. The regulation of lncRNA GAS5/miR-137 on INPP4B was examined by cellular transfection in OGD/R cell culture and by lateral ventricle injection with miR-137 agomir in CA/CPR mice model. Flow cytometry and immunofluorescence staining were performed to detect the microglial apoptosis, M1/M2 phenotype transformation, and neuroinflammation. Neurological scoring and behavior tests were conducted in CA/CPR group, with miR-137 agomir lateral-ventricle infusion and in their controls.

Results

In all the micRNAs, miR-137 was among the top 10 micRNAs that experienced greatest changes, in both the blood of CA/CPR patients and supernatant of OGD/R-stimulated astrocytes. Bioinformatic analysis revealed that miR-137 was sponged by lncRNA GAS5, targeting INPP4B, and the result was confirmed by Luciferase activity assay. qRT-PCR and Western blotting showed that lncRNA GAS5 and INPP4B were over-expressed whereas miR-137 was downregulated in the blood of CA/CPR patients, OGD/R-stimulated astrocytes, and brain tissue of CA/CPR mice. Silencing lncRNA GAS5 suppressed INPP4B expression, but over-expression of miR-137 negatively modulated its expression. Western blotting exhibited that PI3K and Akt phosphorylation was increased when lncRNA GAS5 was silenced or miR-137 was over-expressed. However, PI3K and Akt phosphorylation was notably suppressed in the absence of miR-137, almost reversing their phosphorylation in the silencing lncRNA GAS5 group. Then we found that GAS5 siRNA or miR-137 mimic significantly increased cell viability and alleviated apoptosis after OGD/R injury. Furthermore, over-expression of miR-137 attenuated microglial apoptosis and neuroinflammation in CA/CPR mice model, exhibiting significantly better behavioral tests after CA/CPR.

Conclusion

LncRNA GAS5/miR-137 may be involved in the astrocyte-microglia communication that inhibits PI3K/Akt signaling activation via regulation of INPP4B during CA/CPR.

Nutritional Supplementation Reduces Lesion Size and Neuroinflammation in a Sex-Dependent Manner in a Mouse Model of Perinatal Hypoxic-Ischemic Brain Injury

Perinatal hypoxia-ischemia (HI) is a major cause of neonatal brain injury, leading to long-term neurological impairments. Medical nutrition can be rapidly implemented in the clinic, making it a viable intervention to improve neurodevelopment after injury. The omega-3 (n-3) fatty acids docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3), uridine monophosphate (UMP) and choline have previously been shown in rodents to synergistically enhance brain phospholipids, synaptic components and cognitive performance. The objective of this study was to test the efficacy of an experimental diet containing DHA, EPA, UMP, choline, iodide, zinc, and vitamin B12 in a mouse model of perinatal HI. Male and female C57Bl/6 mice received the experimental diet or an isocaloric control diet from birth. Hypoxic ischemic encephalopathy was induced on postnatal day 9 by ligation of the right common carotid artery and systemic hypoxia. To assess the effects of the experimental diet on long-term motor and cognitive outcome, mice were subjected to a behavioral test battery. Lesion size, neuroinflammation, brain fatty acids and phospholipids were analyzed at 15 weeks after HI. The experimental diet reduced lesion size and neuroinflammation specifically in males. In both sexes, brain n-3 fatty acids were increased after receiving the experimental diet. The experimental diet also improved novel object recognition, but no significant effects on motor performance were observed. Current data indicates that early life nutritional supplementation with a combination of DHA, EPA, UMP, choline, iodide, zinc, and vitamin B12 may provide neuroprotection after perinatal HI.

The Protective Mechanism of Deuterated Linoleic Acid Involves the Activation of the Ca2+ Signaling System of Astrocytes in Ischemia In Vitro

Ischemia-like (oxygen-glucose deprivation, OGD) conditions followed by reoxygenation (OGD/R) cause massive death of cerebral cortex cells in culture as a result of the induction of necrosis and apoptosis. Cell death occurs as a result of an OGD-induced increase in Ca²⁺ ions in the cytosol of neurons and astrocytes, an increase in the expression of genes encoding proapoptotic and inflammatory genes with suppression of protective genes. The deuterated form of linoleic polyunsaturated fatty acid (D4-Lnn) completely inhibits necrosis and greatly reduces apoptotic cell death with an increase in the concentration of fatty acid in the medium. It was shown for the first time that D4-Lnn, through the activation of the phosphoinositide calcium system of astrocytes, causes their reactivation, which correlates with the general cytoprotective effect on the cortical neurons and astrocytes in vitro. The mechanism of the cytoprotective action of D4-Lnn involves the inhibition of the OGD-induced calcium ions, increase in the cytosolic and reactive oxygen species (ROS) overproduction, the enhancement of the expression of protective genes, and the suppression of damaging proteins.