ABSTRACT
Intracerebral hemorrhage (ICH) is a severe stroke subtype caused by the rupture of blood vessels within the brain. Increased levels of S100B protein may contribute to neuroinflammation after ICH through activation of astrocytes and resident microglia, with the consequent production of proinflammatory cytokines and reactive oxygen species (ROS). Inhibition of astrocytic synthesis of S100B by arundic acid (AA) has shown beneficial effects in experimental central nervous system disorders. In present study, we administered AA in a collagenase-induced ICH rodent model in order to evaluate its effects on neurological deficits, S100B levels, astrocytic activation, inflammatory, and oxidative parameters. Rats underwent stereotactic surgery for injection of collagenase in the left striatum and AA (2 µg/µl; weight × 0.005) or vehicle in the left lateral ventricle. Neurological deficits were evaluated by the Ladder rung walking and Grip strength tests. Striatal S100B, astrogliosis, and microglial activation were assessed by immunofluorescence analysis. Striatal levels of interleukin 1ß (IL-1ß) and tumor necrosis factor α (TNF-α) were measured by ELISA, and the ROS production was analyzed by dichlorofluorescein (DCF) oxidation. AA treatment prevented motor dysfunction, reduced S100B levels, astrogliosis, and microglial activation in the damaged striatum, thus decreasing the release of proinflammatory cytokines IL-1ß and TNF-α, as well as ROS production. Taken together, present results suggest that AA could be a pharmacological tool to prevent the harmful effects of increased S100B, attenuating neuroinflammation and secondary brain damage after ICH.
Subject(s)
Motor Disorders , Neuroinflammatory Diseases , Animals , Caprylates/pharmacology , Cerebral Hemorrhage/complications , Cerebral Hemorrhage/drug therapy , Cerebral Hemorrhage/metabolism , Microglia/metabolism , Motor Disorders/complications , RatsABSTRACT
Preterm birth and hypoxia-ischemia (HI) are major causes of neonatal death and neurological disabilities in newborns. The widely used preclinical HI model combines carotid occlusion with hypoxia exposure; however, the relationship between different hypoxia exposure periods with brain tissue loss, astrocyte reactivity and behavioral impairments following HI is lacking. Present study evaluated HI-induced behavioral and morphological consequences in rats exposed to different periods of hypoxia at postnatal day 3. Wistar rats of both sexes were assigned into four groups: control group, HI-120 min, HI-180 min and HI-210 min. Neurodevelopmental reflexes, exploratory abilities and cognitive function were assessed. At adulthood, tissue damage and reactive astrogliosis were measured. Animals exposed to HI-180 and HI-210 min had delayed neurodevelopmental reflexes compared to control group. Histological assessment showed tissue loss that was restricted to the ipsilateral hemisphere in lower periods of hypoxia exposure (120 and 180 min) but affected both hemispheres when 210 min was used. Reactive astrogliosis was increased only after 210 min of hypoxia. Interestingly, cognitive deficits were induced regardless the duration of hypoxia and there were correlations between behavioral parameters and cortex, hippocampus and corpus callosum volumes. These results show the duration of hypoxia has a close relationship with astrocytic response and tissue damage progression. Furthermore, the long-lasting cognitive memory deficit and its association with brain structures beyond the hippocampus suggests that complex anatomical changes should be involved in functional alterations taking place as hypoxia duration is increased, even when the cognitive impairment limit is achieved.
Subject(s)
Astrocytes/physiology , Hypoxia-Ischemia, Brain/physiopathology , Animals , Animals, Newborn , Brain/pathology , Cognitive Dysfunction/physiopathology , Female , Gliosis/physiopathology , Hypoxia-Ischemia, Brain/pathology , Male , Maze Learning/physiology , Memory Disorders/physiopathology , Rats, Wistar , Regression Analysis , Time FactorsABSTRACT
Neonatal hypoxia-ischemia (HI) is an etiologic component of several neurologic pathologies associated to cognitive impairment. The mechanisms involved in HI-induced tissue damage start immediately after HI and extend for days. Acetylcholine is an important neurotransmitter in the central nervous system and exerts a protector effect on tissue damage by modulating inflammation, and cholinesterase inhibitors have shown neuroprotective properties and their action are often attributed to inhibition of the immune response. The administration of Huperzia quadrifariata alkaloid extract (HqAE), with potent and selective cholinesterase inhibitor properties, will reduce the HI induced behavioral deficits and tissue damage. A total of 84 newborn Wistar rat pups at post natal day 7 (PND7) were subjected to right carotid occlusion followed by 1 h of hypoxia (8% of O2) and i.p. injections of saline, vehicle or HqAE (10 mg/kg). Morris Water Maze and inhibitory avoidance tests were used to assess the cognitive function. Flow cytometry was performed at PND11. Histological analysis was performed at PND45. HqAE treatment was able to prevent the HI induced cognitive deficits in both tests and, at PND45, histological analysis showed that HqAE treatment reduced hippocampus tissue damage. Flow cytometry of the injured hippocampus revealed that the treatment was able to reduce cellular death and the number of infiltrating T cells. Altogether, these results show the therapeutic potential of the Huperzia quadrifariata alkaloid extract to prevent cognitive deficits and histological damage caused by neonatal hypoxia-ischemia, probably by reducing cellular death and T cell mobilization.
Subject(s)
Alkaloids/therapeutic use , Cholinesterase Inhibitors/therapeutic use , Huperzia , Hypoxia-Ischemia, Brain/enzymology , Neuroprotective Agents/therapeutic use , Plant Extracts/therapeutic use , Alkaloids/isolation & purification , Alkaloids/pharmacology , Animals , Animals, Newborn , Cholinesterase Inhibitors/isolation & purification , Cholinesterase Inhibitors/pharmacology , Disease Models, Animal , Female , Hypoxia-Ischemia, Brain/prevention & control , Male , Maze Learning/drug effects , Maze Learning/physiology , Neuroprotective Agents/isolation & purification , Neuroprotective Agents/pharmacology , Plant Components, Aerial , Plant Extracts/isolation & purification , Plant Extracts/pharmacology , Rats , Rats, Wistar , Treatment OutcomeABSTRACT
There is evidence that maternal milieu and changes in environmental factors during the prenatal period may exert a lasting impact on the brain health of the newborn, even in case of neonatal brain hypoxia-ischemia (HI). The present study aimed to investigate the effects of maternal environmental enrichment (EE) on HI-induced energetic and metabolic failure, along with subsequent neural cell responses in the early postnatal period. Male Wistar pups born to dams exposed to maternal EE or standard conditions (SC) were randomly divided into Sham-SC, HI-SC, Sham-EE, and HI-EE groups. Neonatal HI was induced on postnatal day (PND) 3. The Na+,K+-ATPase activity, mitochondrial function and neuroinflammatory related-proteins were assessed at 24 h and 48 h after HI. MicroPET-FDG scans were used to measure glucose uptake at three time points: 24 h post-HI, PND18, and PND24. Moreover, neuronal preservation and glial cell responses were evaluated at PND18. After HI, animals exposed to maternal EE showed an increase in Na+,K+-ATPase activity, preservation of mitochondrial potential/mass ratio, and a reduction in mitochondrial swelling. Glucose uptake was preserved in HI-EE animals from PND18 onwards. Maternal EE attenuated HI-induced cell degeneration, white matter injury, and reduced astrocyte immunofluorescence. Moreover, the HI-EE group exhibited elevated levels of IL-10 and a reduction in Iba-1 positive cells. Data suggested that the regulation of AKT/ERK1/2 signaling pathways could be involved in the effects of maternal EE. This study evidenced that antenatal environmental stimuli could promote bioenergetic and neural resilience in the offspring against early HI damage, supporting the translational value of pregnancy-focused environmental treatments.
Subject(s)
Hypoxia-Ischemia, Brain , Neuromuscular Diseases , Animals , Rats , Female , Male , Pregnancy , Animals, Newborn , Rats, Wistar , Brain/metabolism , Hypoxia-Ischemia, Brain/metabolism , Astrocytes/metabolism , Glucose/metabolism , Adenosine Triphosphatases/metabolismABSTRACT
Sex steroid hormones play an important role in fetal development, brain functioning and neuronal protection. Growing evidence highlights the positive effects of these hormones against brain damage induced by neonatal hypoxia-ischemia (HI). This systematic review with meta-analysis aims to verify the efficacy of sex steroid hormones in preventing HI-induced brain damage in rodent models. The protocol was registered at PROSPERO and a total of 22 articles were included. Moderate to large effects were observed in HI animals treated with sex steroid hormones in reducing cerebral infarction size and cell death, increasing neuronal survival, and mitigating neuroinflammatory responses and astrocyte reactivity. A small effect was evidenced for cognitive function, but no significant effect for motor function; moreover, a high degree of heterogeneity was observed. In summary, data suggest that sex steroid hormones, such as progesterone and 17ß estradiol, improve morphological and cellular outcomes following neonatal HI. Further research is paramount to examine neurological function during HI recovery and standardization of methodological aspects is imperative to reduce the risk of spurious findings.
Subject(s)
Gonadal Steroid Hormones , Hypoxia-Ischemia, Brain , Animals , Animals, Newborn , Brain , Estradiol , Hypoxia-Ischemia, Brain/drug therapy , Hypoxia-Ischemia, Brain/metabolism , Ischemia , Progesterone/pharmacology , Progesterone/therapeutic useABSTRACT
Neonatal hypoxia-ischemia (HI) is a major cause of mortality and morbidity in newborns and, despite recent advances in neonatal intensive care, there is no definitive treatment for this pathology. Once preclinical studies have shown that environmental enrichment (EE) seems to be a promising therapy for children with HI, the present study conducts a systematic review and meta-analysis of articles with EE in HI rodent models focusing on neurodevelopmental reflexes, motor and cognitive function as well as brain damage. The protocol was registered a priori at PROSPERO. The search was conducted in PubMed, Embase and PsycINFO databases, resulting in the inclusion of 22 articles. Interestingly, EE showed a beneficial impact on neurodevelopmental reflexes (SMD= -0.73, CI= [-0.98; -0.47], p< 0.001, I2= 0.0%), motor function (SMD= -0.55, CI= [-0.81; -0.28], p< 0.001, I2= 62.6%), cognitive function (SMD= -0.93, CI= [-1.14; -0.72], p< 0.001, I2= 27.8%) and brain damage (SMD= -0.80, CI= [-1.03; -0.58], p< 0.001, I2= 10.7%). The main factors that potentiate EE positive effects were enhanced study quality, earlier age at injury as well as earlier start and longer duration of EE exposure. Overall, EE was able to counteract the behavioral and histological damage induced by the lesion, being a promising therapeutic strategy for HI.
Subject(s)
Hypoxia-Ischemia, Brain , Animals , Animals, Newborn , Disease Models, Animal , Environment , Hypoxia-Ischemia, Brain/pathology , Ischemia , Rats , Rats, Wistar , RodentiaABSTRACT
INTRODUCTION: Cerebral palsy (CP) is the major cause of motor and cognitive impairments during childhood. CP can result from direct or indirect structural injury to the developing brain. In this study, we aimed to describe brain damage and behavioural alterations during early adult life in a CP model using the combination of maternal inflammation, perinatal anoxia and postnatal sensorimotor restriction. METHODS: Pregnant Wistar rats were injected intraperitoneally with 200 µg/kg LPS at embryonic days E18 and E19. Between 3 and 6 h after birth (postnatal day 0 - PND0), pups of both sexes were exposed to anoxia for 20 min. From postnatal day 2 to 21, hindlimbs of animals were immobilized for 16 h daily during their active phase. From PND40, locomotor and cognitive tests were performed using Rota-Rod, Ladder Walking and Morris water Maze. Ex-vivo MRI Diffusion Tensor Imaging (DTI) and Neurite Orientation Dispersion and Density Imaging (NODDI) were used to assess macro and microstructural damage and brain volume alterations induced by the model. Myelination and expression of neuronal, astroglial and microglial markers, as well as apoptotic cell death were evaluated by immunofluorescence. RESULTS: CP animals showed decreased body weight, deficits in gross (rota-rod) and fine (ladder walking) motor tasks compared to Controls. No cognitive impairments were observed. Ex-vivo MRI showed decreased brain volumes and impaired microstructure in the cingulate gyrus and sensory cortex in CP brains. Histological analysis showed increased cell death, astrocytic reactivity and decreased thickness of the corpus callosum and altered myelination in CP animals. Hindlimb primary motor cortex analysis showed increased apoptosis in CP animals. Despite the increase in NeuN and GFAP, no differences between groups were observed as well as no co-localization with the apoptotic marker. However, an increase in Iba-1+ microglia with co-localization to cleaved caspase 3 was observed. CONCLUSION: Our results suggest that experimental CP induces long-term brain microstructural alterations in myelinated structures, cell death in the hindlimb primary motor cortex and locomotor impairments. Such new evidence of brain damage could help to better understand CP pathophysiological mechanisms and guide further research for neuroprotective and neurorehabilitative strategies for CP patients.
ABSTRACT
Neonatal hypoxia-ischemia (HI) is among the main causes of mortality and morbidity in newborns. Experimental studies show that the immature rat brain is less susceptible to HI injury, suggesting that changes that occur during the first days of life drastically alter its susceptibility. Among the main developmental changes observed is the mitochondrial function, namely, the tricarboxylic acid (TCA) cycle and respiratory complex (RC) activities. Therefore, in the present study, we investigated the influence of neonatal HI on mitochondrial functions, redox homeostasis, and cell damage at different postnatal ages in the hippocampus of neonate rats. For this purpose, animals were divided into four groups: sham postnatal day 3 (ShP3), HIP3, ShP11, and HIP11. We initially observed increased apoptosis in the HIP11 group only, indicating a higher susceptibility of these animals to brain injury. Mitochondrial damage, as determined by flow cytometry showing mitochondrial swelling and loss of mitochondrial membrane potential, was also demonstrated only in the HIP11 group. This was consistent with the decreased mitochondrial oxygen consumption, reduced TCA cycle enzymes, and RC activities and induction of oxidative stress in this group of animals. Considering that HIP3 and the sham animals showed no alteration of mitochondrial functions, redox homeostasis, and showed no apoptosis, our data suggest an age-dependent vulnerability of the hippocampus to hypoxia-ischemia. The present results highlight age-dependent metabolic differences in the brain of neonate rats submitted to HI indicating that different treatments might be needed for HI newborns with different gestational ages.
Subject(s)
Apoptosis/physiology , Hippocampus/metabolism , Hypoxia-Ischemia, Brain/metabolism , Mitochondria/metabolism , Oxidative Stress/physiology , Age Factors , Animals , Disease Models, Animal , Female , Homeostasis/physiology , Oxidation-Reduction , Oxygen Consumption/physiology , Rats , Rats, WistarABSTRACT
Neonatal hypoxia-ischemia (HI) is a major cause of cognitive impairments in infants. Antenatal strategies improving the intrauterine environment can have high impact decreasing pregnancy-derived intercurrences. Physical exercise alters the mother-fetus unity and has been shown to prevent the energetic challenge imposed by HI. This study aimed to reveal neuroprotective mechanisms afforded by pregnancy swimming on early metabolic failure and late cognitive damage, considering animals' sex as a variable. Pregnant Wistar rats were submitted to daily swimming exercise (20' in a tank filled with 32 °C water) during pregnancy. Neonatal HI was performed in male and female pups at postnatal day 7. Electron chain transport, mitochondrial mass and function and ROS formation were assessed in the right brain hemisphere 24 h after HI. From PND45, reference and working spatial memory were tested in the Morris water maze. MicroPET-FDG images were acquired 24 h after injury (PND8) and at PND60, following behavioral analysis. HI induced early energetic failure, decreased enzymatic activity in electron transport chain, increased production of ROS in cortex and hippocampus as well as caused brain glucose metabolism dysfunction and late cognitive impairments. Maternal swimming was able to prevent mitochondrial dysfunction and to improve spatial memory. The intergenerational effects of swimming were sex-specific, since male rats were benefited most. In conclusion, maternal swimming was able to affect the mitochondrial response to HI in the offspring's brains, preserving its function and preventing cognitive damage in a sex-dependent manner, adding relevant information on maternal exercise neuroprotection and highlighting the importance of mitochondria as a therapeutic target for HI neuropathology.
Subject(s)
Brain/metabolism , Hypoxia-Ischemia, Brain/metabolism , Hypoxia-Ischemia, Brain/prevention & control , Mitochondria/metabolism , Neuroprotection/physiology , Sex Characteristics , Swimming/physiology , Animals , Animals, Newborn , Brain/pathology , Female , Hypoxia-Ischemia, Brain/pathology , Male , Maze Learning/physiology , Mitochondria/pathology , Pregnancy , Rats , Rats, Wistar , Time FactorsABSTRACT
In the last decade, increased homocysteine levels have been implicated as a risk factor for neurodegenerative and psychiatric disorders. We have developed an experimental model of chronic mild hyperhomocysteinemia (HHcy) in order to observe metabolic impairments in the brain of adult rodents. Besides its known effects on brain metabolism, the present study sought to investigate whether chronic mild HHcy could induce learning/memory impairments associated with biochemical and histological damage to the hippocampus. Adult male Wistar rats received daily subcutaneous injections of homocysteine (0.03 µmol/g of body weight) twice a day, from the 30th to the 60th day of life or saline solution (Controls). After injections, anxiety-like and memory tests were performed. Following behavioral analyses, brains were sliced and hippocampal volumes assessed and homogenized for redox state assessment, antioxidant activity, mitochondrial functioning (chain respiratory enzymes and ATP levels) and DNA damage analyses. Behavioral analyses showed that chronic mild HHcy may induce anxiety-like behavior and impair long-term aversive memory (24 h) that was evaluated by inhibitory avoidance task. Mild HHcy decreased locomotor and/or exploratory activities in elevated plus maze test and caused hippocampal atrophy. Decrease in cytochrome c oxidase, DNA damage and redox state changes were also observed in hippocampus of adult rats subjected to mild HHcy. Our findings show that chronic mild HHcy alters biochemical and histological parameters in the hippocampus, leading to behavioral impairments. These findings might be considered in future studies aiming to search for alternative strategies for treating the behavioral impairments in patients with mild elevations in homocysteine levels.
Subject(s)
Anxiety/etiology , Hippocampus/pathology , Hyperhomocysteinemia/complications , Memory Disorders/etiology , Adenosine Triphosphate/metabolism , Animals , Anxiety/pathology , Atrophy/etiology , Atrophy/pathology , Avoidance Learning , Chronic Disease , DNA Damage/physiology , Electron Transport Complex IV/metabolism , Hippocampus/physiopathology , Homocysteine/blood , Hyperhomocysteinemia/chemically induced , Male , Memory Disorders/physiopathology , Open Field Test , Oxidative Stress/physiology , Rats , Rats, WistarABSTRACT
Neonatal hypoxia-ischemia (HI) is one of the main causes of neurological damage in newborns. Pregnancy swimming (PS) alters brain maturation and has neuroprotective effects following HI; however, variables such as timing play a decisive role in its effects. Prior to mating, we tested if adaptation of female rats to a tank filled with water at 32 °C for 7 days before mating, modulates PS benefits. After mating, rats swam 20 min/day or remained in standard cages. Seven-day-old pups were subjected to HI (right common carotid artery occlusion followed by FiO2 8% for 60 min). Animals were divided into 8 experimental groups, adaptation, swimming and injury. Astrocytic reactivity, apoptosis-related proteins, neurotrophins and cell survival markers expression were assessed in the hippocampus 24 h after HI. From PND45, animals performed behavioral tests followed by histological assessment. Three-way ANOVA showed a significant increase in astrogliosis only in non-adapted HI animals. Swimming decreased apoptotic cell death despite adaptation period in both exercised groups. Cylinder evidenced HI impairments; no effect of swimming or adaptation period were observed. In the open field, only HI animals whose mothers had been adapted had increased locomotion; moreover, swimming reversed HI damage. Hemisphere and hippocampus were preserved only in the HI group whose mothers swam before mating, suggesting a preconditioning effect mediated by the adaptation. In summary, adaptation period plays a major role in the mechanisms involving neuroprotection afforded by PS and needs to be further explored in future studies involving damage to the neonatal brain.
Subject(s)
Adaptation, Physiological , Hippocampus/metabolism , Hypoxia-Ischemia, Brain/metabolism , Neuroprotection , Swimming , Animals , Animals, Newborn , Behavior, Animal , Female , Hypoxia-Ischemia, Brain/prevention & control , Pregnancy , Rats, WistarABSTRACT
Stroke is one of the leading causes of mortality and neurological morbidity. Intracerebral hemorrhage (ICH) has the poorest prognosis among all stroke subtypes and no treatment has been effective in improving outcomes. Following ICH, the observed high levels of S100B protein have been associated with worsening of injury and neurological deficits. Arundic acid (AA) exerts neuroprotective effects through inhibition of astrocytic synthesis of S100B in some models of experimental brain injury; however, it has not been studied in ICH. The aim of this study was to evaluate the effects of intracerebroventricular (ICV) administration of AA in male Wistar rats submitted to ICH model assessing the following variables: reactive astrogliosis, S100B levels, antioxidant defenses, cell death, lesion extension and neurological function. Firstly, AA was injected at different doses (0.02, 0.2, 2 and 20⯵g/µl) in the left lateral ventricle in order to observe which dose would decrease GFAP and S100B striatal levels in non-injured rats. Following determination of the effective dose, ICH damage was induced by IV-S collagenase intrastrial injection and 2⯵g/µl AA was injected through ICV route immediately before injury. AA treatment prevented ICH-induced neurological deficits and tissue damage, inhibited excessive astrocytic activation and cellular apoptosis, reduced peripheral and central S100B levels (in striatum, serum and cerebrospinal fluid), improved neuronal survival and enhanced the antioxidant defences after injury. Altogether, these results suggest that S100B is a viable target for treating ICH and highlight AA as an interesting strategy for improving neurological outcome after experimental brain hemorrhage.
Subject(s)
Brain Injuries , Neuroprotective Agents , Animals , Caprylates , Cerebral Hemorrhage/complications , Cerebral Hemorrhage/drug therapy , Disease Models, Animal , Male , Neuroprotective Agents/pharmacology , Rats , Rats, Wistar , S100 Calcium Binding Protein beta SubunitABSTRACT
Neonatal hypoxia ischemia (HI) is the main cause of newborn mortality and morbidity. Preclinical studies have shown that the immature rat brain is more resilient to HI injury, suggesting innate mechanisms of neuroprotection. During neonatal period brain metabolism experience changes that might greatly affect the outcome of HI injury. Therefore, the aim of the present study was to investigate how changes in brain metabolism interfere with HI outcome in different stages of CNS development. For this purpose, animals were divided into 6 groups: HIP3, HIP7 and HIP11 (HI performed at postnatal days 3, 7 and 11, respectively), and their respective shams. In vivo [18F]FDG micro positron emission tomography (microPET) imaging was performed 24 and 72 h after HI, as well as ex-vivo assessments of glucose and beta-hydroxybutyrate (BHB) oxidation. At adulthood behavioral tests and histology were performed. Behavioral and histological analysis showed greater impairments in HIP11 animals, while HIP3 rats were not affected. Changes in [18F]FDG metabolism were found only in the lesion area of HIP11, where a substantial hypometabolism was detected. Furthermore, [18F]FDG hypometabolism predicted impaired cognition and worst histological outcomes at adulthood. Finally, substrate oxidation assessments showed that glucose oxidation remained unaltered and higher level of BHB oxidation found in P3 animals, suggesting a more resilient metabolism. Overall, present results show [18F]FDG microPET predicts long-term injury outcome and suggests that higher BHB utilization is one of the mechanisms that confer the intrinsic neuroprotection to the immature brain and should be explored as a therapeutic target for treatment of HI.
Subject(s)
3-Hydroxybutyric Acid/metabolism , Glucose/metabolism , Hypoxia-Ischemia, Brain/metabolism , Neuroprotection/physiology , Animals , Animals, Newborn , Disease Models, Animal , Male , Rats , Rats, WistarABSTRACT
Perinatal cerebral hypoxia-ischemia (HI) is an important cause of mortality and neurological disabilities such as cerebral palsy, epilepsy, and mental retardation. The potential for neuroprotection in HI can be achieved mainly during the recovery period. In previous work, we demonstrated that guanosine (Guo) prevented the decrease of glutamate uptake by hippocampal slices of neonatal rats exposed to a hypoxic-ischemic (HI) insult in vivo when administrated before and after insult. In the present study, we compared the effect of Guo administration only after HI using various protocols. When compared with the control, a decrease of [(3)H] glutamate uptake was avoided only when three doses of Guo were administered immediately, 24 h and 48 h after insult, or at 3 h, 24 h, and 48 h after injury or at 6 h, 24 h, and 48 h after HI. These findings indicate that early Guo administration (until 6 h) after HI, in three doses may enhance glutamate uptake into brain slices after hypoxia/ischemia, probably resulting in decreased excitotoxicity.
Subject(s)
Drug Administration Schedule , Guanosine , Hypoxia-Ischemia, Brain , Reperfusion Injury , Animals , Guanosine/administration & dosage , Guanosine/therapeutic use , Hypoxia-Ischemia, Brain/metabolism , Hypoxia-Ischemia, Brain/pathology , Male , Neuroprotective Agents/administration & dosage , Neuroprotective Agents/therapeutic use , Rats , Rats, Wistar , Reperfusion Injury/drug therapy , Reperfusion Injury/metabolism , Reperfusion Injury/pathology , Treatment OutcomeABSTRACT
Neonatal hypoxia-ischemia (HI) is responsible for movement disorders in preterm infants. Non-pharmacological strategies, such as environmental enrichment (EE) during adulthood, have shown positive effects on promoting sensorimotor recovery after HI. However, little is known about the effects of perinatal EE on sensorimotor function following HI. In present study we investigated the hypothesis that enriched experiences during pregnancy and lactation would reduce motor impairments caused by a model of neonatal HI in rats. At postnatal day (PND) 3, Wistar pups of both sexes were subject to the modified Rice-Vannucci model. Motor function was evaluated from PND 60 to PND 64. HI caused a reduction in the forepaws strength and worsening of movement quality in the right forepaw. These effects were attenuated in animals receiving prenatal or lactational EE, which showed better performance when compared to the control group. Moreover, enriched experiences during lactation reversed HI-induced asymmetric use of the forepaws and the trend to increased paw errors in a walking test. Lower scores were found in the contralateral forepaw placement in HI animals, except when EE was provided at both stages of neurodevelopment. These results indicate that enriched experiences reduce motor impairments, i.e, measured in force, asymmetry and coordination domains, and that EE during lactation is more effective in promoting post-injury recovery. These data support that early therapeutic interventions might enhance functional reorganization at a period of high brain plasticity and that enriched-like experience might be encouraged in pediatric rehabilitation programs, in order to reduce long-term movement disorders after neonatal brain insults.
Subject(s)
Forelimb/physiopathology , Hypoxia-Ischemia, Brain/complications , Hypoxia-Ischemia, Brain/physiopathology , Movement Disorders/prevention & control , Movement Disorders/physiopathology , Neuronal Plasticity/physiology , Social Environment , Animals , Disease Models, Animal , Female , Male , Movement Disorders/etiology , Pregnancy , Rats , Rats, WistarABSTRACT
INTRODUCTION: Perinatal hypoxia-ischemia (HI) is one of the main causes of mortality and chronic neurological morbidity in infants and children. Astrocytes play a key role in HI progression, becoming reactive in response to the injury, releasing S100 calcium binding protein B (S100B). Since S100B inhibition seems to have neuroprotective effects on central nervous system injury models, here we evaluated the neuroprotective effects of an S100B inhibitor, arundic acid (AA) in a HI model. METHODS: On the 7th postnatal day, animals were submitted to the combination of common carotid artery occlusion and hypoxic atmosphere (8% O2) for 60â¯min. Three experiments were performed in order to: (1) define AA dose (0.1, 1 or 10â¯mg/kg, pre-hypoxia i.p. injection), (2) test if repeated AA administrations (10â¯mg/kg at 3 time points: Pre-hypoxia, 24â¯h and 48â¯h after HI) would improve the response and (3) investigate biochemical mechanisms involved in AA protection two days after HI. RESULTS: AA at a dose of 10â¯mg/kg applied before and after hypoxia, was the only treatment protocol that was able to improve HI-induced memory deficits, to reduce tissue damage, to promote astrocytic survival in the hippocampus and to reduced extracellular release of S100B in the cerebrospinal fluid. CONCLUSION: Overall, AA treatment showed beneficial effects on memory deficits, tissue damage, promoting astrocyte survival likely by reducing S100B release. Protection aided to astrocytes by AA treatment against HI lesion may lead to development of new therapeutic strategies that target these particular cells.
Subject(s)
Astrocytes/drug effects , Caprylates/pharmacology , Hypoxia-Ischemia, Brain/complications , Memory Disorders/prevention & control , Neuroprotective Agents/pharmacology , Animals , Animals, Newborn , Astrocytes/pathology , Brain/pathology , Cell Survival/drug effects , Glial Fibrillary Acidic Protein/metabolism , Glutamate-Ammonia Ligase/metabolism , Hypoxia-Ischemia, Brain/pathology , Maze Learning/drug effects , Memory Disorders/etiology , Rats , S100 Calcium Binding Protein beta Subunit/antagonists & inhibitors , S100 Calcium Binding Protein beta Subunit/metabolismABSTRACT
Environmental enrichment (EE) at early stages of neurodevelopment attenuates HI-induced behavioral, histological and cellular damage. However, the effects of EE exposure during gestational or early postnatal period and the possible influence of sexual dimorphism on EE protection are not fully understood. Present study evaluated the effects of pre-natal and postnatal EE, as well as their combination, in male and female rats submitted to neonatal HI at postnatal day (PND) 3. Wistar rats were housed in EE or in standard condition (SC) during all pregnancy. At PND1, the litters were randomly allocated to the same prenatal environment during lactation (SC + SC or EE + EE) or housed in a new environment until weaning (SC + EE or EE + SC). Behavioral tasks were performed from PND 60-75. Then, animals were euthanized for biochemical and histological analysis. Prenatal and early postnatal EE alone improved performance of HI males in the Water Maze spatial memory task, while HI females were most benefited from early postnatal stimulation. Moreover, EE attenuated HI-induced lower anxiety-like behavior in rats of both sexes and decreased hyperlocomotion in HI females. Hippocampus tissue preservation and higher VEGF and TrkB levels were observed in all HI groups exposed to EE. Interestingly, HI males exposed to prenatal or postnatal EE alone exhibited higher GFAP levels and additional tissue preservation. Therefore, both prenatal and early postnatal environmental enrichment cause attenuation of HI-induced impairments, revealing their preventive and therapeutic actions, possibly due to VEGF and astrocyte activity; some of these effects are sex-specific.
Subject(s)
Environment , Housing, Animal , Hypoxia-Ischemia, Brain/prevention & control , Hypoxia-Ischemia, Brain/therapy , Animals , Animals, Newborn , Astrocytes/metabolism , Astrocytes/pathology , Brain/growth & development , Brain/metabolism , Brain/pathology , Disease Models, Animal , Female , Glial Fibrillary Acidic Protein/metabolism , Hypoxia-Ischemia, Brain/metabolism , Hypoxia-Ischemia, Brain/pathology , Male , Maze Learning , Motor Activity , Random Allocation , Rats, Wistar , Spatial MemoryABSTRACT
Neonatal brain Hypoxia-Ischemia (HI) is one of the major causes of infant mortality and lifelong neurological disabilities. The knowledge about the physiopathological mechanisms involved in HI lesion have increased in recent years, however these findings have not been translated into clinical practice. Current therapeutic approaches remain limited; hypothermia, used only in term or near-term infants, is the golden standard. Epidemiological evidence shows a link between adverse prenatal conditions and increased risk for diseases, health problems, and psychological outcomes later in life, what makes pregnancy a relevant period for preventing future brain injury. Here, we review experimental literature regarding preventive interventions used during pregnancy, i.e., previous to the HI injury, encompassing pharmacological, nutritional and/or behavioral strategies. Literature review used PubMed database. A total of forty one studies reported protective properties of maternal treatments preventing perinatal hypoxia-ischemia injury in rodents. Pharmacological agents and dietary supplementation showed mainly anti-excitotoxicity, anti-oxidant or anti-apoptotic properties. Interestingly, maternal preconditioning, physical exercise and environmental enrichment seem to engage the same referred mechanisms in order to protect neonatal brain against injury. This construct must be challenged by further studies to clearly define the main mechanisms responsible for neuroprotection to be explored in experimental context, as well as to test their potential in clinical settings.
Subject(s)
Hypoxia-Ischemia, Brain/prevention & control , Pregnancy/physiology , Adult , Animals , Animals, Newborn , Female , Humans , Infant, Newborn , Prenatal CareABSTRACT
Environmental enrichment (EE) is an experimental strategy to attenuate the negative effects of different neurological conditions including neonatal hypoxia ischemia encephalopathy (HIE). The aim of the present study was to investigate the influence of prenatal and early postnatal EE in animals submitted to neonatal HIE model at postnatal day (PND) 3. Wistar rats were housed in EE or standard conditions (SC) during pregnancy and lactation periods. Pups of both sexes were assigned to one of four experimental groups, considering the early environmental conditions and the injury: SC-Sham, SC-HIE, EE-sham, and EE-HIE. The offspring were euthanized at two different time points: 48 h after HIE for biochemical analyses or at PND 67 for histological analyses. Behavioral tests were performed at PND 7, 14, 21, and 60. Offspring from EE mothers had better performance in neurodevelopmental and spatial memory tests when compared to the SC groups. HIE animals showed a reduction of IGF-1 and VEGF in the parietal cortex, but no differences in BDNF and TrkB levels were found. EE-HIE animals showed reduction in cell death, lower astrocyte reactivity, and an increase in AKTp levels in the hippocampus and parietal cortex. In addition, the EE was also able to prevent the hippocampus tissue loss. Altogether, present findings point to the protective potential of the prenatal and early postnatal EE in attenuating molecular and histological damage, as well as the neurodevelopmental impairments and the cognitive deficit, caused by HIE insult at PND 3.
Subject(s)
Cell Death/physiology , Hippocampus/metabolism , Hypoxia-Ischemia, Brain/complications , Memory Disorders/prevention & control , Parietal Lobe/metabolism , Animals , Animals, Newborn , Behavior, Animal , Environment , Female , Housing, Animal , Hypoxia-Ischemia, Brain/metabolism , Insulin-Like Growth Factor I/metabolism , Male , Memory Disorders/etiology , Memory Disorders/metabolism , Rats , Rats, Wistar , Receptor, trkB/metabolism , Spatial Memory/physiology , Vascular Endothelial Growth Factor A/metabolismABSTRACT
Glial glutamate transporters (EAAT1 and EAAT2), glutamate uptake, and oxidative stress are important players in the pathogenesis of ischemic brain injury. However, the changes in EAAT1 and EAAT2 expression, glutamate uptake and the oxidative profile during intracerebral hemorrhage (ICH) development have not been described. The present study sought to investigate the changes of the above-mentioned variables, as well as the Na+/K+-ATPase and glutamine synthetase activities (as important contributors of glutamate homeostasis) and the percentage of neuronal cells after 6 h, 24 h, 72 h and 7 days of ICH. An injection of 0.2U of bacterial collagenase in the ipsilateral striatum was used to induce ICH in male Wistar rats; naïve animals were used as controls. EAAT1 and EAAT2 expression and glutamate uptake in the ipsilateral striatum were assessed. Additionally, the percentage of MAP2+ cells, Na+/K+-ATPase and GS activities, as well as the oxidative profile were analyzed. It is shown a decrease of EAAT1 expression and glutamate uptake 6â¯h post-ICH, whereas EAAT2 decreased 72â¯h after the event; conversely EAAT2 and glutamate uptake were increased after 7 days. The oxidative stress and endogenous defense system exhibited a remarkable response at 72â¯h of injury. ICH also increased Na+/K+-ATPase activity and selectively decreased GS activity, variables known to be important contributors of glial glutamate transporters activities. Altogether, present findings indicate that ICH induces different temporal EAAT1 and EAAT2 responses, culminating with an imbalance of glutamate uptake capacity, increased oxidative stress and sustained neuronal loss.