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- Ardalan, Maryam, 1979, et al.
(author)
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Dysmaturation of Somatostatin Interneurons Following Umbilical Cord Occlusion in Preterm Fetal Sheep
- 2019
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In: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 10
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Journal article (peer-reviewed)abstract
- Introduction: Cerebral white matter injury is the most common neuropathology observed in preterm infants. However, there is increasing evidence that gray matter development also contributes to neurodevelopmental abnormalities. Fetal cerebral ischemia can lead to both neuronal and non-neuronal structural-functional abnormalities, but less is known about the specific effects on interneurons. Objective: In this study we used a well-established animal model of fetal asphyxia in preterm fetal sheep to study neuropathological outcome. We used comprehensive stereological methods to investigate the total number of oligodendrocytes, neurons and somatostatin (STT) positive interneurons as well as 3D morphological analysis of STT cells 14 days following umbilical cord occlusion (UCO) in fetal sheep. Materials and Methods: Induction of asphyxia was performed by 25 min of complete UCO in five preterm fetal sheep (98-100 days gestational age). Seven, non-occluded twins served as controls. Quantification of the number of neurons (NeuN), STT interneurons and oligodendrocytes (Olig2, CNPase) was performed on fetal brain regions by applying optical fractionator method. A 3D morphological analysis of STT interneurons was performed using IMARIS software. Results: The number of Olig2, NeuN, and STT positive cells were reduced in IGWM, caudate and putamen in UCO animals compared to controls. There were also fewer STT interneurons in the ventral part of the hippocampus, the subiculum and the entorhinal cortex in UCO group, while other parts of cortex were virtually unaffected (p > 0.05). Morphologically, STT positive interneurons showed a markedly immature structure, with shorter dendritic length and fewer dendritic branches in cortex, caudate, putamen, and subiculum in the UCO group compared with control group (p < 0.05). Conclusion: The significant reduction in the total number of neurons and oligodendrocytes in several brain regions confirm previous studies showing susceptibility of both neuronal and non-neuronal cells following fetal asphyxia. However, in the cerebral cortex significant dysmaturation of STT positive neurons occurred in the absence of cell loss. This suggests an abnormal maturation pattern of GABAergic interneurons in the cerebral cortex, which might contribute to neurodevelopmental impairment in preterm infants and could implicate a novel target for neuroprotective therapies.
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- Bay, V., et al.
(author)
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Flinders sensitive line rats are resistant to infarction following transient occlusion of the middle cerebral artery
- 2020
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In: Brain Research. - : Elsevier BV. - 0006-8993. ; 1737
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Journal article (peer-reviewed)abstract
- Background: Depression is a common complication of stroke and increases the risk of mortality and disability. Pre-stroke depression is a possible risk factor for stroke and has also been linked to adverse outcomes. The underlying mechanisms linking depression and stroke remain unclear. Preclinical models may provide novel insights, but models reflecting both conditions are lacking. Methods: In this study, we investigated the effects of a 45-min transient middle cerebral artery occlusion (MCAo) on infarct size in male adult Flinders Sensitive Line rats, a genetic animal model of depression, and their control strains Flinders Resistant Line and Sprague-Dawley rats. Infarct size was assessed by tetrazolium chloride (TTC) and microtubule-associated protein 2 (MAP2) staining after 48 h of reperfusion. Angiograms of the vascular structure of naive animals were produced with a mu-CT scanner. Results: Both Flinders strains had significantly smaller infarcts following MCAo compared to Sprague-Dawley rats. This effect does not appear to be due to changes in cerebrovascular architecture, as indicated by an initial exploration of vascular organization using angiograms, or body temperature regulation. Conclusions: Our study suggests that the rat strain does not influence infarct volumes following MCAo.
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- Dudink, I., et al.
(author)
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An Optimized and Detailed Step-by-Step Protocol for the Analysis of Neuronal Morphology in Golgi-Stained Fetal Sheep Brain
- 2022
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In: Developmental neuroscience. - : S. Karger AG. - 0378-5866 .- 1421-9859. ; 44:4-5, s. 344-362
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Journal article (peer-reviewed)abstract
- Antenatal brain development during the final trimester of human pregnancy is a time when mature neurons become increasingly complex in morphology, through axonal and dendritic outgrowth, dendritic branching, and synaptogenesis, together with myelin production. Characterizing neuronal morphological development over time is of interest to developmental neuroscience and provides the framework to measure gray matter pathology in pregnancy compromise. Neuronal microstructure can be assessed with Golgi staining, which selectively stains a small percentage (1-3%) of neurons and their entire dendritic arbor. Advanced imaging processing and analysis tools can then be employed to quantitate neuronal cytoarchitecture. Traditional Golgi-staining protocols have been optimized, and commercial kits are readily available offering improved speed and sensitivity of Golgi staining to produce consistent results. Golgi-stained tissue is then visualized under light microscopy and image analysis may be completed with several software programs for morphological analysis of neurons, including freeware and commercial products. Each program requires optimization, whether semiautomated or automated, requiring different levels of investigator intervention and interpretation, which is a critical consideration for unbiased analysis. Detailed protocols for fetal ovine brain tissue are lacking, and therefore, we provide a step-by-step workflow of computer software analysis for morphometric quantification of Golgi-stained neurons. Here, we utilized the commonly applied FD Rapid GolgiStain kit (FD NeuroTechnologies) on ovine fetal brains collected at 127 days (0.85) of gestational age for the analysis of CA1 pyramidal neurons in the hippocampus. We describe the step-by-step protocol to retrieve neuronal morphometrics using Imaris imaging software to provide quantification of apical and basal dendrites for measures of dendrite length (mu m), branch number, branch order, and Sholl analysis (intersections over radius). We also detail software add-ons for data retrieval of dendritic spines including the number of spines, spine density, and spine classification, which are critical indicators of synaptic function. The assessment of neuronal morphology in the developing brain using Rapid-Golgi and Imaris software is labor-intensive, particularly during the optimization period. The methodology described in this step-by-step description is novel, detailed, and aims to provide a reproducible, working protocol to quantify neuronal cytoarchitecture with simple descriptions that will save time for the next users of these commonly used techniques.
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- Mansouri, M., et al.
(author)
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Autistic-like behaviours and associated brain structural plasticity are modulated by oxytocin in maternally separated rats
- 2020
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In: Behavioural Brain Research. - : Elsevier BV. - 0166-4328. ; 393:September
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Journal article (peer-reviewed)abstract
- Background: Early psycho-social experiences influence the developing brain and possible onset of various neurodevelopmental disorders, such as Autism Spectrum Disorder (ASD). ASD is characterized by a variety of brain abnormalities, including alteration of oxytocin receptors in the brain. Recently, early life adverse experiences, such as maternal separation (MS), have been shown to constitute risk factors for ASD in preclinical studies. Therefore, the main aims of the current study were to i) explore the association between onset of autistic-like behaviours and molecular/structural changes in the brain following MS, and ii) evaluate the possible beneficial effects of oxytocin treatment on the same parameters. Method and Material: Male rats were exposed to the maternal separation from post-natal day (PND) 1 to PND14. After weaning, daily injections of oxytocin (1 mg/kg, ip) were administered (PND 22-30), followed by examination of autism-related behaviours at adolescence (PND 42-50). Brain structural plasticity was examined using stereological methods, and the plasma level of brain derived neurotrophic factor (BDNF) was analysed using ELISA. Results: We found that maternal separation induced autistic-like behaviours, which was associated with increase in the hippocampal CA1 stratum radiatum (CA1.SR) volume. In addition, we observed increase in the infralimbic brain region volume and in the number of the pyramidal neurons in the same brain region. Maternal separation significantly increased the plasma BDNF levels. Treatment with oxytocin improved autistic like behaviours, normalized the number of neurons and the volume of the infralimbic region as well as the plasma BDNF level (p < 0.05). Conclusion: Maternal separation induced autistic-like behaviours, brain structural impairment together with plasma BDNF level abnormally, which could be improved by oxytocin treatment.
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| 10. |
- Mansouri, M., et al.
(author)
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Dual Profile of Environmental Enrichment and Autistic-Like Behaviors in the Maternal Separated Model in Rats
- 2021
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In: International Journal of Molecular Sciences. - : MDPI AG. - 1422-0067. ; 22:3
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Journal article (peer-reviewed)abstract
- Background: Environmental Enrichment (EE) has been suggested as a possible therapeutic intervention for neurodevelopmental disorders such as autism. Although the benefits of this therapeutic method have been reported in some animal models and human studies, the unknown pathophysiology of autism as well as number of conflicting results, urge for further examination of the therapeutic potential of EE in autism. Therefore, the aim of this study was to examine the effects of environmental enrichment on autism-related behaviors which were induced in the maternal separation (MS) animal model. Material and Methods: Maternally separated (post-natal day (PND) 1-14, 3 h/day) and control male rats were at weaning (PND21) age equally divided into rats housed in enriched environment and normal environment. At adolescence (PND42-50), the four groups were behaviorally tested for direct social interaction, sociability, repetitive behaviors, anxiety behavior, and locomotion. Following completion of the behavioral tests, the blood and brain tissue samples were harvested in order to assess plasma level of brain derived neurotrophic factor (BDNF) and structural plasticity of brain using ELISA and stereological methods respectively. Results: We found that environmental enrichment reduced repetitive behaviors but failed to improve the impaired sociability and anxiety behaviors which were induced by maternal separation. Indeed, EE exacerbated anxiety and social behaviors deficits in association with increased plasma BDNF level, larger volume of the hippocampus and infra-limbic region and higher number of neurons in the infra-limbic area (p < 0.05). Conclusion: We conclude that environmental enrichment has a significant improvement effect on the repetitive behavior as one of the core autistic-like behaviors induced by maternal separation but has negative effect on the anxiety and social behaviors which might have been modulated by BDNF.
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| 11. |
- Rafati, A. H., et al.
(author)
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Geometrical modelling of neuronal clustering and development
- 2022
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In: Heliyon. - : Elsevier BV. - 2405-8440. ; 8:7
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Journal article (peer-reviewed)abstract
- The dynamic geometry of neuronal development is an essential concept in theoretical neuroscience. We aimed to design a mathematical model which outlines stepwise in an innovative form and designed to model neuronal development geometrically and modelling spatially the neuronal-electrical field interaction. We demonstrated flexibility in forming the cell and its nucleus to show neuronal growth from inside to outside that uses a fractal cylinder to generate neurons (pyramidal/sphere) in form of mathematically called 'surface of revolution'. Furthermore, we verified the effect of the adjacent neurons on a free branch from one-side, by modelling a 'normal vector surface' that represented a group of neurons. Our model also indicated how the geometrical shapes and clustering of the neurons can be transformed mathematically in the form of vector field that is equivalent to the neuronal electromagnetic activity/electric flux. We further simulated neuronal-electrical field interaction that was implemented spatially using Van der Pol oscillator and taking Laplacian vector field as it reflects biophysical mechanism of neuronal activity and geometrical change. In brief, our study would be considered a proper platform and inspiring modelling for next more complicated geometrical and electrical constructions.
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| 12. |
- Singh-Mallah, Gagandeep, et al.
(author)
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N-Acetyl Cysteine Restores Sirtuin-6 and Decreases HMGB1 Release Following Lipopolysaccharide-Sensitized Hypoxic-Ischemic Brain Injury in Neonatal Mice
- 2021
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In: Frontiers in Cellular Neuroscience. - : Frontiers Media SA. - 1662-5102. ; 15
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Journal article (peer-reviewed)abstract
- Inflammation and neonatal hypoxia-ischemia (HI) are important etiological factors of perinatal brain injury. However, underlying mechanisms remain unclear. Sirtuins are a family of nicotinamide adenine dinucleotide (NAD)+-dependent histone deacetylases. Sirtuin-6 is thought to regulate inflammatory and oxidative pathways, such as the extracellular release of the alarmin high mobility group box-1 (HMGB1). The expression and role of sirtuin-6 in neonatal brain injury are unknown. In a well-established model of neonatal brain injury, which encompasses inflammation (lipopolysaccharide, LPS) and hypoxia-ischemia (LPS+HI), we investigated the protein expression of sirtuin-6 and HMGB1, as well as thiol oxidation. Furthermore, we assessed the effect of the antioxidant N-acetyl cysteine (NAC) on sirtuin-6 expression, nuclear to cytoplasmic translocation, and release of HMGB1 in the brain and blood thiol oxidation after LPS+HI. We demonstrate reduced expression of sirtuin-6 and increased release of HMGB1 in injured hippocampus after LPS+HI. NAC treatment restored sirtuin-6 protein levels, which was associated with reduced extracellular HMGB1 release and reduced thiol oxidation in the blood. The study suggests that early reduction in sirtuin-6 is associated with HMGB1 release, which may contribute to neonatal brain injury, and that antioxidant treatment is beneficial for the alleviation of these injurious mechanisms.
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- Yang, Liu, et al.
(author)
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Impact of the 2017 American Academy of Pediatrics Guideline on Hypertension Prevalence Compared With the Fourth Report in an International Cohort.
- 2019
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In: Hypertension. - : American Heart Association. - 0194-911X .- 1524-4563. ; 74:6, s. 1343-1348
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Journal article (peer-reviewed)abstract
- In 2017, the American Academy of Pediatrics (AAP) updated the clinical practice guideline for high blood pressure (BP) in the pediatric population. In this study, we compared the difference in prevalence of elevated and hypertensive BP values defined by the 2017 AAP guideline and the 2004 Fourth Report and estimated the cardiovascular risk associated with the reclassification of BP status defined by the AAP guideline. A total of 47 200 children and adolescents aged 6 to 17 years from 6 countries (China, India, Iran, Korea, Poland, and Tunisia) were included in this study. Elevated BP and hypertension were defined according to 2 guidelines. In addition, 1606 children from China, Iran, and Korea who were reclassified upward by the AAP guideline compared with the Fourth Report and for whom laboratory data were available were 1:1 matched with children from the same countries who were normotensive by both guidelines. Compared with the Fourth Report, the prevalence of elevated BP defined by the AAP guideline was lower (14.9% versus 8.6%), whereas the prevalence of stages 1 and 2 hypertension was higher (stage 1, 6.6% versus 14.5%; stage 2, 0.4% versus 1.7%). Additionally, comparison of laboratory data in the case-control study showed that children who were reclassified upward were more likely to have adverse lipid profiles and high fasting blood glucose compared with normotensive children. In conclusion, the prevalence of elevated BP and hypertension varied significantly between both guidelines. Applying the new AAP guideline could identify more children with hypertension who are at increased cardiovascular risk.
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| 15. |
- Yang, Liu, et al.
(author)
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Impact of the 2017 American Academy of Pediatrics Guideline on Hypertension Prevalence Compared With the Fourth Report in an International Cohort
- 2019
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In: Hypertension. - : Ovid Technologies (Wolters Kluwer Health). - 0194-911X .- 1524-4563. ; 74:6, s. 1343-1348
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Journal article (peer-reviewed)abstract
- In 2017, the American Academy of Pediatrics (AAP) updated the clinical practice guideline for high blood pressure (BP) in the pediatric population. In this study, we compared the difference in prevalence of elevated and hypertensive BP values defined by the 2017 AAP guideline and the 2004 Fourth Report and estimated the cardiovascular risk associated with the reclassification of BP status defined by the AAP guideline. A total of 47 200 children and adolescents aged 6 to 17 years from 6 countries (China, India, Iran, Korea, Poland, and Tunisia) were included in this study. Elevated BP and hypertension were defined according to 2 guidelines. In addition, 1606 children from China, Iran, and Korea who were reclassified upward by the AAP guideline compared with the Fourth Report and for whom laboratory data were available were 1:1 matched with children from the same countries who were normotensive by both guidelines. Compared with the Fourth Report, the prevalence of elevated BP defined by the AAP guideline was lower (14.9% versus 8.6%), whereas the prevalence of stages 1 and 2 hypertension was higher (stage 1, 6.6% versus 14.5%; stage 2, 0.4% versus 1.7%). Additionally, comparison of laboratory data in the case-control study showed that children who were reclassified upward were more likely to have adverse lipid profiles and high fasting blood glucose compared with normotensive children. In conclusion, the prevalence of elevated BP and hypertension varied significantly between both guidelines. Applying the new AAP guideline could identify more children with hypertension who are at increased cardiovascular risk.
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