scholarly journals Synaptic Injury in the Thalamus Accompanies White Matter Injury in Hypoxia/Ischemia-Mediated Brain Injury in Neonatal Rats

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Na Liu ◽  
Xin Tong ◽  
Wanjie Huang ◽  
Jianhua Fu ◽  
Xindong Xue
Keyword(s):  
White Matter ◽  
White Matter Injury ◽  
Neonatal Rat ◽  
Morris Water Maze Test ◽  
Neonatal Rats ◽  
Sprague Dawley ◽  
Artery Ligation ◽  
Compensatory Response ◽  
Significant Difference ◽  
Hypoxia Ischemia

The broad spectrum of disabilities caused by white matter injury (WMI) cannot be explained simply by hypomyelination. Synaptic injury in the thalamus may be related to disabilities in WMI survivors. Neuronal injury in the thalamus has been found most commonly in autopsy cases of preterm WMI. We hypothesized that hypoxia/ischemia (HI) in neonatal rats results in synaptic abnormalities in the thalamus that contribute to disabilities in WMI survivors. We examined changes in synapses in a neonatal rat model of HI-induced WMI. Right common carotid artery ligation and hypoxia (8% oxygen for 2.5 hours (h)) were performed in three-day-old Sprague-Dawley rats. We found HI rats performed worse in the Morris water maze test than sham rats, suggesting long-term cognition impairment after HI injury. A loss of synapses in the thalamus accompanied by hypomyelination and oligodendrocytes (OLs) reduction was observed. At the ultrastructural level, reductions in active zone (AZ) length and postsynaptic density (PSD) thickness were detected at 2 weeks after HI exposure. Furthermore, increased expression of synaptophysin and PSD-95 in both groups was observed from 3 days (d) to 21 d after hypoxic/ischemic (HI) injury. PSD-95 expression was significantly lower in HI rats than in sham rats from 14 d to 21 d after HI injury, and synaptophysin expression was significantly lower in HI rats from 7 d to 14 d after HI injury. However, no significant difference in synaptophysin expression was observed between HI rats and sham rats at 21 d after HI injury. The results demonstrated synaptic abnormalities in the thalamus accompanied by hypomyelination in WMI in response to HI exposure, which may contribute to the diverse neurological defects observed in WMI patients. Although synaptic reorganization occurred as a compensatory response to HI injury, the impairments in synaptic transmission were not reversed.

scholarly journals Pioglitazone Ameliorates Lipopolysaccharide-Induced Behavioral Impairment, Brain Inflammation, White Matter Injury and Mitochondrial Dysfunction in Neonatal Rats

2021 ◽  
Vol 22 (12) ◽  
pp. 6306
Author(s):  
Jiann-Horng Yeh ◽  
Kuo-Ching Wang ◽  
Asuka Kaizaki ◽  
Jonathan W. Lee ◽  
Han-Chi Wei ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
White Matter ◽  
Brain Inflammation ◽  
White Matter Injury ◽  
Neonatal Rat ◽  
Mitochondrial Activity ◽  
Neonatal Rats ◽  
Activated Microglia ◽  
Brain White Matter ◽  
Performance Reduction

Previous studies have demonstrated that pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, inhibits ischemia-induced brain injury. The present study was conducted to examine whether pioglitazone can reduce impairment of behavioral deficits mediated by inflammatory-induced brain white matter injury in neonatal rats. Intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 2 mg/kg) was administered to Sprague–Dawley rat pups on postnatal day 5 (P5), and i.p. administration of pioglitazone (20 mg/kg) or vehicle was performed 5 min after LPS injection. Sensorimotor behavioral tests were performed 24 h after LPS exposure, and changes in biochemistry of the brain was examined after these tests. The results show that systemic LPS exposure resulted in impaired sensorimotor behavioral performance, reduction of oligodendrocytes and mitochondrial activity, and increases in lipid peroxidation and brain inflammation, as indicated by the increment of interleukin-1β (IL-1β) levels and number of activated microglia in the neonatal rat brain. Pioglitazone treatment significantly improved LPS-induced neurobehavioral and physiological disturbances including the loss of body weight, hypothermia, righting reflex, wire-hanging maneuver, negative geotaxis, and hind-limb suspension in neonatal rats. The neuroprotective effect of pioglitazone against the loss of oligodendrocytes and mitochondrial activity was associated with attenuation of LPS-induced increment of thiobarbituric acid reactive substances (TBARS) content, IL-1β levels and number of activated microglia in neonatal rats. Our results show that pioglitazone prevents neurobehavioral disturbances induced by systemic LPS exposure in neonatal rats, and its neuroprotective effects are associated with its impact on microglial activation, IL-1β induction, lipid peroxidation, oligodendrocyte production and mitochondrial activity.

scholarly journals Knockdown of IL-6 Plays a Crucial Role in Protection of Hypoxia-Ischemia in Neonatal Rats via Inhibiting Casp3 and BAX Signaling Pathway

2021 ◽  
Author(s):  
Ting-Hua Wang ◽  
Xue Bai ◽  
Liu-Lin Xiong ◽  
Ting-Ting Li ◽  
Chang-Le Fang ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Neonatal Rat ◽  
Regulation Mechanism ◽  
Sprague Dawley ◽  
Artery Ligation ◽  
Carotid Artery Ligation ◽  
Hypoxia Ischemia ◽  
Neurologic Function ◽  
Underlying Mechanisms ◽  
The Right

Abstract Background: The effect of interleukin-6 (IL-6) knockdown on hypoxia-ischemia (HI) of neonatal rat models was investigated to explore the underlying molecular regulation mechanism. Methods: To establish the HI model, we treated 7days postnatal Sprague-Dawley (SD) rats with the right carotid artery ligation and had them exposed to the environment of 8% oxygen and 92% nitrogen for 2 h, respectively. Then, the neurologic function and morphology changes were assessed. Subsequently, IL-6 siRNA lentivirus was injected into cerebral cortex motor area 2 days before HI; meanwhile, the interference efficiency was detected by quantitative real-time polymerase chain reaction (QRT-PCR) and Western blot. Immunofluorescence staining of Glial fibrillary acidic protein (GFAP), Hexaribonucleotide Binding Protein-3 (NeuN) and IL-6 were used to identify the location and interference effect of IL-6. In order to further research the underlying mechanisms, the expressions of downstream molecular including Bcl-2-associated X protein (BAX) and Casp3 were examined following IL-6 up-regulation by QRT-PCR.Results: It was found that both the growth of cortical neurons and the length of axon were promoted after IL-6 interference, and the cell apoptosis was decreased. In addition, the expression of BAX and Casp3 were closely associated with IL-6. Conclusions: The present findings confirmed that the decreased IL-6 improves the deficiencies in neurologic function and morphology induced by HI, and the potential mechanism may be closely related with the regulation of Casp3 and BAX.

scholarly journals Activin A Improves White Matter Injury in Neonatal Rats via Noggin/bmp4/id2 Signaling

2021 ◽  
Author(s):  
Xiaojuan Su ◽  
Jun Tang ◽  
Lingyi Huang ◽  
Dongqiong Xiao ◽  
Xia Qiu ◽  
...  
Keyword(s):  
White Matter ◽  
Rat Model ◽  
Myelin Sheath ◽  
Immunofluorescence Staining ◽  
White Matter Injury ◽  
Morris Water Maze Test ◽  
Oligodendrocyte Progenitor Cells ◽  
Protective Effects ◽  
Neonatal Rats

Abstract BackgroundActivin A (Act A) has been revealed to enhance the differentiation of oligodendrocyte progenitor cells (OPCs) in vitro. Here we aim to elucidate its roles and mechanisms in a rat model of white matter injury (WMI). MethodsAct A was injected into the lateral ventricle of a hypoxia-ischemia induced WMI rat model. Hematoxylin & eosin staining was used to detect pathological changes. Immunofluorescence staining was used to assess OPC proliferation, migration, apoptosis, and differentiation. Myelin sheath and axon formation were detected via immunofluorescence staining, Western blotting, and electron microscopy. Behavioral assessment of rats was performed with the Morris water maze test. ResultsAct A attenuated the pathological damages, enhanced the formation of myelin sheath and myelinated axons and improved the behavior of WMI rats by promoting OPC proliferation and differentiation. However, Act A showed no significant effects on OPC migration or apoptosis. Interestingly, we found that Act A could enhance Noggin expression, which in turn inhibited the expression of bone morphogenetic protein 4 (BMP4) and inhibitor of DNA binding 2 (Id2). Furthermore, upregulation of Id2 completely abolished the protective effects of Act A in WMI. ConclusionsAct A improves WMI in neonatal rats via Noggin/BMP4/Id2 signalling.

scholarly journals The Synthetic Cannabinoid URB447 Reduces Brain Injury and the Associated White Matter Demyelination after Hypoxia-Ischemia in Neonatal Rats

2020 ◽  
Vol 11 (9) ◽  
pp. 1291-1299 ◽  
Author(s):  
Silvia Carloni ◽  
Rita Crinelli ◽  
Linda Palma ◽  
Francisco J. Álvarez ◽  
Daniele Piomelli ◽  
...  
Keyword(s):  
Brain Injury ◽  
White Matter ◽  
Synthetic Cannabinoid ◽  
Neonatal Rats ◽  
Hypoxia Ischemia

scholarly journals Regional Alterations of ATP and Heat-Shock Protein-72 mRNA following Hypoxia—Ischemia in Neonatal Rat Brain

1995 ◽  
Vol 15 (6) ◽  
pp. 1047-1056 ◽  
Author(s):  
Shuichi Kobayashi ◽  
Frank A. Welsh
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Cell Injury ◽  
Surface Expression ◽  
Subcortical White Matter ◽  
Neonatal Rat ◽  
Heat Shock Protein 72 ◽  
Artery Ligation ◽  
Ipsilateral Hemisphere ◽  
Hypoxia Ischemia

Neonatal rats, 7 days of age, underwent unilateral carotid artery ligation followed by exposure to hypoxia (8% O2) for 80 min. At the end of the period of hypoxia, and after recovery for 2 or 24 h, regional levels of ATP and heat-shock protein-72 (hsp72) mRNA were measured in adjacent brain sections using ATP-luminescence histochemistry and in situ hybridization, respectively. At the end of hypoxia, ATP levels were decreased in a patchy pattern within the hemisphere ipsilateral to the carotid ligation. In the parietal cortex, the reduction of ATP often occurred in columns oriented perpendicular to the cortical surface. Expression of hsp72 mRNA was not detected prior to recovery, except in the ventricular lining of the ipsilateral hemisphere. However, by 2 h of recovery, hsp72 mRNA was expressed in a diffuse pattern in the ipsilateral hemisphere, even in regions in which the distribution of ATP remained patchy. Although the regional extent of expression varied in different animals, hsp72 mRNA was expressed consistently in the subcortical white matter, which, in some animals, was the only region showing expression. In contrast to the diffuse pattern of expression at 2 h of recovery, expression of hsp72 mRNA at 24 h was highly localized in the superficial layers of cerebral cortex and the pyramidal cell layer of hippocampus. The present results demonstrate that hypoxia–ischemia causes regionally distinct alterations in ATP and hsp72 mRNA that may be related to cell injury in this model.

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