Disruption of the Serotonergic System after Neonatal Hypoxia-Ischemia in a Rodent Model

Identifying which specific neuronal phenotypes are vulnerable to neonatal hypoxia-ischemia, where in the brain they are damaged, and the mechanisms that produce neuronal losses are critical to determine the anatomical substrates responsible for neurological impairments in hypoxic-ischemic brain-injured neonates. Here we describe our current work investigating how the serotonergic network in the brain is disrupted in a rodent model of preterm hypoxia-ischemia. One week after postnatal day 3 hypoxia-ischemia, losses of serotonergic raphé neurons, reductions in serotonin levels in the brain, and reduced serotonin transporter expression are evident. These changes can be prevented using two anti-inflammatory interventions; the postinsult administration of minocycline or ibuprofen. However, each drug has its own limitations and benefits for use in neonates to stem damage to the serotonergic network after hypoxia-ischemia. By understanding the fundamental mechanisms underpinning hypoxia-ischemia-induced serotonergic damage we will hopefully move closer to developing a successful clinical intervention to treat neonatal brain injury.

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Circulating Tight-Junction Proteins Are Potential Biomarkers for Blood-Brain Barrier Function in a Model of Neonatal Hypoxic/Ischemic Brain Injury

10.21203/rs.3.rs-90299/v1 ◽

2020 ◽

Author(s):

Axel Erik Andersson ◽

Carina Mallard ◽

Carl Joakim Ek

Keyword(s):

Brain Injury ◽

Blood Brain Barrier ◽

Brain Injuries ◽

Brain Barrier ◽

Neonatal Brain ◽

Ischemic Brain ◽

Blood Brain ◽

Hypoxia Ischemia ◽

The Brain ◽

Junction Proteins

Abstract BackgroundNeonatal hypoxia-ischemia often leads to lifelong disabilities with limited treatments currently available. The brain vasculature is an important factor in many neonatal brain pathologies but there is a lack of diagnostic tools to evaluate the brain vascular health of neonates in a clinical setting. Measurement of blood-brain barrier tight-junction proteins have shown promise as biomarkers for brain injury in the adult. Here we tested the biomarker potential of tight-junctions in the context of neonatal brain injury.MethodsThe levels of TJ-proteins (occluding, claudin-5, and zonula occludens-1) in both blood plasma and cerebrospinal fluid (CSF) as well as blood-brain barrier function were measured in a clinically relevant hypoxia/ischemia model in neonatal rats.ResultsTemporally acute elevated levels of occludin and claudin-5 could be measured in blood and CSF after hypoxia/ischemia with males generally having higher levels than females. The levels of claudin-5 in CSF correlated with the severity of the brain injury at 24h post- hypoxia/ischemia. Simultaneously, we detected early increase in blood-brain barrier-permeability at 6 and 24h after hypoxia/ischemia.ConclusionsLevels of circulating claudin-5 and occludin are increased after hypoxic/ischemic brain injuries and blood-brain barrier-impairment and have promise as early biomarkers for cerebral vascular health and as a tool for risk assessment of neonatal brain injuries.

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Circulating tight-junction proteins are potential biomarkers for blood–brain barrier function in a model of neonatal hypoxic/ischemic brain injury

Fluids and Barriers of the CNS ◽

10.1186/s12987-021-00240-9 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

E. Axel Andersson ◽

Carina Mallard ◽

C. Joakim Ek

Keyword(s):

Brain Injury ◽

Blood Brain Barrier ◽

Brain Injuries ◽

Vascular Dysfunction ◽

Brain Barrier ◽

Neonatal Brain ◽

Ischemic Brain ◽

Blood Brain ◽

Hypoxia Ischemia ◽

The Brain

Abstract Background Neonatal encephalopathy often leads to lifelong disabilities with limited treatments currently available. The brain vasculature is an important factor in many neonatal neurological disorders but there is a lack of diagnostic tools to evaluate the brain vascular dysfunction of neonates in the clinical setting. Measurement of blood–brain barrier tight-junction (TJ) proteins have shown promise as biomarkers for brain injury in the adult. Here we tested the biomarker potential of tight-junctions in the context of neonatal brain injury. Methods The levels of TJ-proteins (occluding, claudin-5, and zonula occludens protein 1) in both blood plasma and cerebrospinal fluid (CSF) as well as blood–brain barrier function via 14C-sucrose (342 Da) and Evans blue extravasation were measured in a hypoxia/ischemia brain-injury model in neonatal rats. Results Time-dependent changes of occludin and claudin-5 levels could be measured in blood and CSF after hypoxia/ischemia with males generally having higher levels than females. The levels of claudin-5 in CSF correlated with the severity of the brain injury at 24 h post- hypoxia/ischemia. Simultaneously, we detected early increase in blood–brain barrier-permeability at 6 and 24 h after hypoxia/ischemia. Conclusions Levels of circulating claudin-5 and occludin are increased after hypoxic/ischemic brain injuries and blood–brain barrier-impairment and have promise as early biomarkers for cerebral vascular dysfunction and as a tool for risk assessment of neonatal brain injuries.

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Sex differences in behavioral outcome following neonatal hypoxia ischemia: Insights from a clinical meta-analysis and a rodent model of induced hypoxic ischemic brain injury

Experimental Neurology ◽

10.1016/j.expneurol.2014.01.003 ◽

2014 ◽

Vol 254 ◽

pp. 54-67 ◽

Cited By ~ 81

Author(s):

Amanda L. Smith ◽

Michelle Alexander ◽

Ted S. Rosenkrantz ◽

Mona Lisa Sadek ◽

R. Holly Fitch

Keyword(s):

Sex Differences ◽

Brain Injury ◽

Meta Analysis ◽

Rodent Model ◽

Ischemic Brain Injury ◽

Behavioral Outcome ◽

Ischemic Brain ◽

Neonatal Hypoxia ◽

Hypoxia Ischemia ◽

Hypoxic Ischemic Brain Injury

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Neuroprotective Effects of Mitochondria-Targeted Plastoquinone in a Rat Model of Neonatal Hypoxic–Ischemic Brain Injury

Molecules ◽

10.3390/molecules23081871 ◽

2018 ◽

Vol 23 (8) ◽

pp. 1871 ◽

Cited By ~ 14

Author(s):

Denis Silachev ◽

Egor Plotnikov ◽

Irina Pevzner ◽

Ljubava Zorova ◽

Anastasia Balakireva ◽

...

Keyword(s):

Oxidative Stress ◽

Targeted Delivery ◽

Cell Damage ◽

Brain Cell ◽

Neuroprotective Effects ◽

Neonatal Hypoxia ◽

Hypoxia Ischemia ◽

Causes Of Mortality ◽

High Production ◽

The Brain

Neonatal hypoxia–ischemia is one of the main causes of mortality and disability of newborns. To study the mechanisms of neonatal brain cell damage, we used a model of neonatal hypoxia–ischemia in seven-day-old rats, by annealing of the common carotid artery with subsequent hypoxia of 8% oxygen. We demonstrate that neonatal hypoxia–ischemia causes mitochondrial dysfunction associated with high production of reactive oxygen species, which leads to oxidative stress. Targeted delivery of antioxidants to the mitochondria can be an effective therapeutic approach to treat the deleterious effects of brain hypoxia–ischemia. We explored the neuroprotective properties of the mitochondria-targeted antioxidant SkQR1, which is the conjugate of a plant plastoquinone and a penetrating cation, rhodamine 19. Being introduced before or immediately after hypoxia–ischemia, SkQR1 affords neuroprotection as judged by the diminished brain damage and recovery of long-term neurological functions. Using vital sections of the brain, SkQR1 has been shown to reduce the development of oxidative stress. Thus, the mitochondrial-targeted antioxidant derived from plant plastoquinone can effectively protect the brain of newborns both in pre-ischemic and post-stroke conditions, making it a promising candidate for further clinical studies.

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Sex differences in behavioral outcome following neonatal hypoxia ischemia: Insights from a clinical meta-analysis and a rodent model of induced hypoxic ischemic injury

Experimental Neurology ◽

10.1016/j.expneurol.2014.03.018 ◽

2014 ◽

Vol 256 ◽

pp. 70-73 ◽

Cited By ~ 16

Author(s):

Susan S. Cohen ◽

Barbara S. Stonestreet

Keyword(s):

Sex Differences ◽

Meta Analysis ◽

Ischemic Injury ◽

Rodent Model ◽

Behavioral Outcome ◽

Neonatal Hypoxia ◽

Hypoxia Ischemia ◽

Hypoxic Ischemic Injury

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Lack of the brain-specific isoform of apoptosis-inducing factor aggravates cerebral damage in a model of neonatal hypoxia–ischemia

Cell Death and Disease ◽

10.1038/s41419-018-1250-1 ◽

2018 ◽

Vol 10 (1) ◽

Cited By ~ 8

Author(s):

Juan Rodriguez ◽

Yaodong Zhang ◽

Tao Li ◽

Cuicui Xie ◽

Yanyan Sun ◽

...

Keyword(s):

Cerebral Damage ◽

Neonatal Hypoxia ◽

Hypoxia Ischemia ◽

Apoptosis Inducing Factor ◽

The Brain

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Unbiased Quantification of Subplate Neuron Loss following Neonatal Hypoxia-Ischemia in a Rat Model

Developmental Neuroscience ◽

10.1159/000460815 ◽

2017 ◽

Vol 39 (1-4) ◽

pp. 171-181 ◽

Cited By ~ 8

Author(s):

Alexandra Mikhailova ◽

Naveena Sunkara ◽

Patrick S. McQuillen

Keyword(s):

Brain Injury ◽

Lower Layer ◽

Cell Number ◽

Cortical Layer ◽

Rodent Model ◽

Cortical Layers ◽

Cortical Injury ◽

Neonatal Hypoxia ◽

Subplate Neurons ◽

Hypoxia Ischemia

Background: Cellular targets of neonatal hypoxia-ischemia (HI) include both oligodendrocyte and neuronal lineages with differences in the patterns of vulnerable cells depending upon the developmental stage at which the injury occurs. Injury to the developing white matter is a characteristic feature of human preterm brain injury. Data are accumulating, however, for neuronal injury in the developing cerebral cortex. In the most widely used rodent model of preterm HI brain injury, conflicting data have been reported regarding the sensitivity of subplate neurons to early neonatal HI, with some reports of selective vulnerability and others that find no increased loss of subplate neurons in comparison with other cortical layers. Methods used to identify subplate neurons and quantify their numbers vary across studies. Objective: To use recently developed cortical layer-specific markers quantified with definitive stereologic methods to determine the magnitude and specificity of subplate neuron cell loss following neonatal HI in a rodent model. Methods: Postnatal day 2 (P2) rats underwent right common carotid artery coagulation followed by 2-3 h of hypoxia (5.6% oxygen). Categorically moderately injured brains were stained with subplate and cortical layer III-V markers (Complexin3 and Foxp1, respectively) at P8 and P21 (Foxp1 only). An Optical Fractionator was used to quantify subplate and middle/lower cortical neuronal numbers and these were compared across groups (naive control, hypoxia hemisphere, and HI hemisphere). Results: Following HI at P2 in rats, the total Complexin3-expressing subplate neuron number decreases significantly in the HI hemisphere compared with naive controls or hypoxia alone (HI vs. control 26,747 ± 7,952 vs. 35,468 ± 8,029, p = 0.04; HI vs. hypoxia, 26,747 ± 7,952 vs. 40,439 ± 7,363, p = 0.003). In contrast, the total Foxp1-expressing layer III-V cell number did not differ across the 3 conditions at P8 (HI vs. control 1,195,085 ± 436,609 vs. 1,234,640 ± 178,540, p = 0.19; HI vs. hypoxia, 1,195,085 ± 436,609 vs. 1,289,195 ± 468,941, p = 0.35) and at P21 (HI vs. control 1,265,190 ± 48,089 vs. 1,195,632 ± 26,912, p = 0.19; HI vs. hypoxia, 1,265,190 ± 48,089 vs. 1,309,563 ± 41,669, p = 0.49). Conclusions: There is significant biological variability inherent in both the subplate neuron cell number and the pattern and severity of cortical injury following HI at P2 in rats. Despite this variability, the subplate neuron cell number is lower following P2 HI in animals with mild or moderate cortical injury, whereas the middle-to-lower-layer cortical neuronal number is unchanged. In more severe cases, neurons are lost from the lower cortical layers, suggesting a relative vulnerability of subplate neurons.

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Effects of Allopurinol and Deferoxamine on Reperfusion Injury of the Brain in Newborn Piglets after Neonatal Hypoxia-Ischemia

Pediatric Research ◽

10.1203/01.pdr.0000081297.53793.c6 ◽

2003 ◽

Vol 54 (4) ◽

pp. 516-522 ◽

Cited By ~ 74

Author(s):

Cacha Peeters-Scholte ◽

Kees Braun ◽

Johanna Koster ◽

Nicole Kops ◽

Klas Blomgren ◽

...

Keyword(s):

Reperfusion Injury ◽

Neonatal Hypoxia ◽

Newborn Piglets ◽

Hypoxia Ischemia ◽

The Brain

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Neuronal apoptosis can be prevented by the combined therapy with melatonin and hypothermia in a neonatal rat model of hypoxic-ischemic encephalopathy

Medicine and Pharmacy Reports ◽

10.15386/mpr-1903 ◽

2021 ◽

Author(s):

Alina Mihaela Toader ◽

Oana Hoteiuc ◽

Cristina Bidian ◽

Dan-Daniel Oltean ◽

Flaviu Tabaran ◽

...

Keyword(s):

Cell Death ◽

Neuroprotective Effect ◽

Ischemic Injury ◽

Brain Regions ◽

Hypoxic Ischemic Encephalopathy ◽

Newborn Rats ◽

Neonatal Hypoxia ◽

Hypoxia Ischemia ◽

The Brain ◽

Ischemic Encephalopathy

Introduction. Birth hypoxia is a leading cause of perinatal mortality and neurological morbidity, resulting in central nervous system injury. Cerebral hypoxia and ischemia can produce a severe brain damage following a typical pattern, defined by selective vulnerability of the brain regions. The neonates are most prone to hypoxic-ischemic injuries due to the lack of efficient antioxidant defense. Neonatal hypoxia–ischemia (HI) in a 7-day-old rat HI model can produce cell death by apoptotic or necrotic mechanisms. The degree of apoptotic or necrotic mechanisms responsible for cell death in neonatal hypoxia–ischemia are not very clear as yet. The form of neuronal death may also depend on the severity of ischemic injury. Necrosis predominates in more severe cases, whereas apoptosis occurs in areas with milder ischemic injury. A human study demonstrated apoptotic and necrotic forms of cell death after hypoxic injury, whereas in some brains from stillbirths, only apoptotic figures were observed. The expression of activated caspase-3 reflects the role of apoptosis in neonatal hypoxic ischemic brain injury. Objectives. The aim of this study was to evaluate the possible neuroprotective effect of melatonin and hypothermia in hypoxic-ischemic encephalopathy in newborn rats. Local damages induced by hypoxia and ischemia were assessed by evaluating the changes in terms of histology and apoptosis. Methods. The experiment was conducted on 20 newborn Wistar rats premedicated for seven days with melatonin in a dose of 20 mg/kg/day. On the 7th postnatal day (P7), the newborn rats were exposed to ischemia (by clamping the right carotid artery) and hypobaric hypoxia (8% O2 for 90 minutes) and some groups to hypothermia. Results. In this experimental model of neonatal encephalopathy, melatonin, in a dose of 20 mg/kg/day has neuroprotective effect by reducing the number of cells expressing apoptosis in Cornu Ammonis (CA) (Ammon’s Horn) CA1, CA2, CA3 and dentate gyrus of the hippocampus when combined with hypothermia. Conclusion. The results of this study prove that melatonin is protective in ischemic-hypoxic brain injuries, but the protection is conditioned in most of the brain regions (excepting cerebral cortex) by conjugation with post-injury hypothermia treatment.

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