RESUMO
Neonatal hypoxia-ischemia (HI) is one of the main causes of tissue damage, cell death, and imbalance between neuronal excitation and inhibition and synaptic loss in newborns. GABA, the major inhibitory neurotransmitter of the central nervous system (CNS) in adults, is excitatory at the onset of neurodevelopment and its action depends on the chloride (Cl-) cotransporters NKCC1 (imports Cl-) and KCC2 (exports Cl-) expression. Under basal conditions, the NKCC1/KCC2 ratio decreases over neurodevelopment. Thus, changes in this ratio caused by HI may be related to neurological disorders. The present study evaluated the effects of bumetanide (NKCC cotransporters inhibitor) on HI impairments in two neurodevelopmental periods. Male Wistar rat pups, 3 (PND3) and 11 (PND11) days old, were submitted to the Rice-Vannucci model. Animals were divided into 3 groups: SHAM, HI-SAL, and HI-BUM, considering each age. Bumetanide was administered intraperitoneally at 1, 24, 48, and 72 h after HI. NKCC1, KCC2, PSD-95, and synaptophysin proteins were analyzed after the last injection by western blot. Negative geotaxis, righting reflex, open field, object recognition test, and Morris water maze task were performed to assess neurological reflexes, locomotion, and memory function. Tissue atrophy and cell death were evaluated by histology. Bumetanide prevented neurodevelopmental delay, hyperactivity, and declarative and spatial memory deficits. Furthermore, bumetanide reversed HI-induced brain tissue damage, reduced neuronal death and controlled GABAergic tone, maintained the NKCC1/KCC2 ratio, and synaptogenesis close to normality. Thereby, bumetanide appears to play an important therapeutic role in the CNS, protecting the animals against HI damage and improving functional performance.
Assuntos
Bumetanida , Hipóxia-Isquemia Encefálica , Ratos , Animais , Masculino , Bumetanida/farmacologia , Bumetanida/uso terapêutico , Ratos Wistar , Membro 2 da Família 12 de Carreador de Soluto/metabolismo , Isquemia/tratamento farmacológico , Hipóxia/tratamento farmacológico , Hipóxia-Isquemia Encefálica/complicações , Hipóxia-Isquemia Encefálica/tratamento farmacológico , Encéfalo/metabolismo , Cognição , Animais Recém-NascidosRESUMO
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.
Assuntos
Apoptose/fisiologia , Hipocampo/metabolismo , Hipóxia-Isquemia Encefálica/metabolismo , Mitocôndrias/metabolismo , Estresse Oxidativo/fisiologia , Fatores Etários , Animais , Modelos Animais de Doenças , Feminino , Homeostase/fisiologia , Oxirredução , Consumo de Oxigênio/fisiologia , Ratos , Ratos WistarRESUMO
Prenatal and early postnatal periods are important for brain development and neural function. Neonatal insults such as hypoxia-ischemia (HI) causes prolonged neural and metabolic dysregulation, affecting central nervous system maturation. There is evidence that brain hypometabolism could increase the risk of adult-onset neurodegenerative diseases. However, the impact of non-pharmacologic strategies to attenuate HI-induced brain glucose dysfunction is still underexplored. This study investigated the long-term effects of early environmental enrichment in metabolic, cell, and functional responses after neonatal HI. Thereby, male Wistar rats were divided according to surgical procedure, sham, and HI (performed at postnatal day 3), and the allocation to standard (SC) or enriched condition (EC) during gestation and lactation periods. In-vivo cerebral metabolism was assessed by means of [18 F]-FDG micro-positron emission tomography, and cognitive, biochemical, and histological analyses were performed in adulthood. Our findings reveal that HI causes a reduction in glucose metabolism and glucose transporter levels as well as hyposynchronicity in metabolic brain networks. However, EC during prenatal or early postnatal period attenuated these metabolic disturbances. A positive correlation was observed between [18 F]-FDG values and volume ratios in adulthood, indicating that preserved tissue by EC is metabolically active. EC promotes better cognitive scores, as well as down-regulation of amyloid precursor protein in the parietal cortex and hippocampus of HI animals. Furthermore, growth-associated protein 43 was up-regulated in the cortex of EC animals. Altogether, results presented support that EC during gestation and lactation period can reduce HI-induced impairments that may contribute to functional decline and progressive late neurodegeneration.
Assuntos
Encéfalo/metabolismo , Meio Ambiente , Hipóxia-Isquemia Encefálica/metabolismo , Hipóxia-Isquemia Encefálica/prevenção & controle , Plasticidade Neuronal/fisiologia , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Animais , Animais Recém-Nascidos , Feminino , Hipóxia-Isquemia Encefálica/psicologia , Lactação/metabolismo , Lactação/psicologia , Masculino , Aprendizagem em Labirinto/fisiologia , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/prevenção & controle , Doenças Neurodegenerativas/psicologia , Tomografia por Emissão de Pósitrons/métodos , Gravidez , Efeitos Tardios da Exposição Pré-Natal/psicologia , Ratos , Ratos WistarRESUMO
BACKGROUND AND PURPOSE: Hypoxia and cerebral ischemia (HI) events are capable of triggering important changes in brain metabolism, including glucose metabolism abnormalities, which may be related to the severity of the insult. Using positron emission microtomography (microPET) with [18F]fluorodeoxyglucose (18F-FDG), this study proposes to assess abnormalities of brain glucose metabolism in adult rats previously submitted to the neonatal HI model. We hypothesize that cerebral metabolic outcomes will be associated with cognitive deficits and magnitude of brain injury. METHODS: Seven-day-old rats were subjected to an HI model, induced by permanent occlusion of the right common carotid artery and systemic hypoxia. 18F-FDG-microPET was used to assess regional and whole brain glucose metabolism in rats at 60 postnatal days (PND 60). An interregional cross-correlation matrix was utilized to construct metabolic brain networks (MBN). Rats were also subjected to the Morris Water Maze (MWM) to evaluate spatial memory and their brains were processed for volumetric evaluation. RESULTS: Brain glucose metabolism changes were observed in adult rats after neonatal HI insult, limited to the right brain hemisphere. However, not all HI animals exhibited significant cerebral hypometabolism. Hippocampal glucose metabolism was used to stratify HI animals into HI hypometabolic (HI-h) and HI non-hypometabolic (HI non-h) groups. The HI-h group had drastic MBN disturbance, cognitive deficit, and brain tissue loss, concomitantly. Conversely, HI non-h rats had normal brain glucose metabolism and brain tissue preserved, but also presented MBN changes and spatial memory impairment. Furthermore, data showed that brain glucose metabolism correlated with cognitive deficits and brain volume outcomes. CONCLUSIONS: Our findings demonstrated that long-term changes in MBN drive memory impairments in adult rats subjected to neonatal hypoxic ischemia, using in vivo imaging microPET-FDG. The MBN analyses identified glucose metabolism abnormalities in HI non-h animals, which were not detected by conventional 18F-FDG standardized uptake value (SUVr) measurements. These animals exhibited a metabolic brain signature that may explain the cognitive deficit even with no identifiable brain damage.
Assuntos
Encéfalo/metabolismo , Hipóxia-Isquemia Encefálica/metabolismo , Transtornos da Memória/metabolismo , Rede Nervosa/metabolismo , Animais , Encéfalo/diagnóstico por imagem , Modelos Animais de Doenças , Glucose/metabolismo , Hipóxia-Isquemia Encefálica/complicações , Hipóxia-Isquemia Encefálica/diagnóstico por imagem , Masculino , Transtornos da Memória/diagnóstico por imagem , Transtornos da Memória/etiologia , Rede Nervosa/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Ratos , Ratos WistarRESUMO
INTRODUCTION: Neonatal Hypoxia-Ischemia (HI) is a major cause of morbidity and mortality, and is frequently associated with short and long-term neurologic and cognitive impairments. The HI injury causes mitochondrial damage leading to increased production of reactive oxygen species (ROS). Phytoestrogens are non-steroidal plant substances structurally and functionally similar to estrogen. Coumestrol is a potent isoflavonoid with a protective effect against ischemic brain damage in adult rats. Our aim was to determine if coumestrol treatment following neonatal HI attenuates the long-term cognitive deficits induced by neonatal HI, as well as to investigate one possible mechanism underlying its potential effect. METHODS: On the 7th postnatal day, male Wistar rats were submitted to the Levine-Rice HI model. Intraperitoneal injections of 20â¯mg/kg of coumestrol, or vehicle, were administered immediately pre-hypoxia or 3â¯h post-hypoxia. At 12â¯h after HI the mitochondrial status and ROS levels were determined. At 60th postnatal day the cognitive deficits were revealed in the Morris water maze reference and working spatial memories. Following behavioral analysis, histological assessment was performed and reactive astrogliosis was measured by GFAP expression. RESULTS: Results demonstrate that both pre- and post-HI administration of coumestrol were able to counteract the long-term cognitive and morphological impairments caused by HI, as well as to block the late reactive astrogliosis. The pre-HI administration of coumestrol was able to prevent the early mitochondrial dysfunction in the hippocampus of injured rat pups. CONCLUSION: Present data suggest that coumestrol exerts protection against experimental neonatal brain hypoxia-ischemia through, at least in part, early modulation of mitochondrial function.
Assuntos
Encéfalo/efeitos dos fármacos , Cognição/efeitos dos fármacos , Disfunção Cognitiva/tratamento farmacológico , Cumestrol/farmacologia , Hipóxia-Isquemia Encefálica/tratamento farmacológico , Mitocôndrias/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Animais , Encéfalo/metabolismo , Disfunção Cognitiva/metabolismo , Cumestrol/uso terapêutico , Hipóxia-Isquemia Encefálica/metabolismo , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Mitocôndrias/metabolismo , Fármacos Neuroprotetores/uso terapêutico , Fitoestrógenos/farmacologia , Fitoestrógenos/uso terapêutico , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismoRESUMO
The authors hereby declare that the Figure 4 in page eight of the paper "Stem cells from human exfoliated deciduous teeth modulate early astrocyte response after spinal cord contusion" authored by Fabrício Nicola and colleagues (DOI: 10.1007/s12035-018-1127-4) was mistakenly included.
RESUMO
The transplantation of stem cells from human exfoliated deciduous teeth (SHED) has been studied as a possible treatment strategy for spinal cord injuries (SCIs) due to its potential for promoting tissue protection and functional recovery. The aim of the present study was to investigate the effects of the early transplantation of SHED on glial scar formation and astrocytic reaction after an experimental model of SCI. Wistar rats were spinalized using the NYU Impactor. Animals were randomly distributed into three groups: control (naive) (animal with no manipulation); SCI (receiving laminectomy followed by SCI and treated with vehicle), and SHED (SCI rat treated with intraspinal SHED transplantation, 1 h after SCI). In vitro investigation demonstrated that SHED were able to express mesenchymal stem cells, vimentin and S100B markers, related with neural progenitor and glial cells, respectively. The acute SHED transplantation promoted functional recovery, measured as from the first week after spinal cord contusion by Basso, Beattie, and Bresnahan scale. Twenty-four and 48 h after lesion, flow cytometry revealed a spinal cord vimentin+ cells increment in the SHED group. The increase of vimentin+ cells was confirmed by immunofluorescence. Moreover, the bioavailability of astrocytic proteins such as S100B and Kir4.1 shown to be increased in the spinal cord of SHED group, whereas there was a glial scar reduction, as indicated by ELISA and Western blot techniques. The presented results support that SHED act as a neuroprotector agent after transplantation, probably through paracrine signaling to reduce glial scar formation, inducing tissue plasticity and functional recovery.
Assuntos
Astrócitos/patologia , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Traumatismos da Medula Espinal/patologia , Traumatismos da Medula Espinal/terapia , Esfoliação de Dente/patologia , Dente Decíduo/citologia , Animais , Aquaporina 4/metabolismo , Astrócitos/metabolismo , Células Cultivadas , Proteína Glial Fibrilar Ácida/metabolismo , Membro Posterior/fisiopatologia , Humanos , Masculino , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , Traumatismos da Medula Espinal/metabolismo , Vimentina/metabolismoRESUMO
Neonatal hypoxia-ischemia (HI) is associated to cognitive and motor impairments and until the moment there is no proven treatment. The underlying neuroprotective mechanisms of stem cells are partially understood and include decrease in excitotoxicity, apoptosis and inflammation suppression. This study was conducted in order to test the effects of intracardiac transplantation of human dental pulp stem cells (hDPSCs) for treating HI damage. Seven-day-old Wistar rats were divided into four groups: sham-saline, sham-hDPSCs, HI-saline, and HI-hDPSCs. Motor and cognitive tasks were performed from postnatal day 30. HI-induced cognitive deficits in the novel-object recognition test and in spatial reference memory impairment which were prevented by hDPSCs. No motor impairments were observed in HI animals. Immunofluorescence analysis showed human-positive nuclei in hDPSC-treated animals closely associated with anti-GFAP staining in the lesion scar tissue, suggesting that these cells were able to migrate to the injury site and could be providing support to CNS cells. Our study evidence novel evidence that hDPSC can contribute to the recovery following hypoxia-ischemia and highlight the need of further investigation in order to better understand the exact mechanisms underlying its neuroprotective effects.
Assuntos
Disfunção Cognitiva/prevenção & controle , Polpa Dentária/transplante , Hipóxia-Isquemia Encefálica/terapia , Transplante de Células-Tronco/métodos , Animais , Animais Recém-Nascidos , Células Cultivadas , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/patologia , Polpa Dentária/citologia , Polpa Dentária/fisiologia , Feminino , Ventrículos do Coração , Humanos , Hipóxia-Isquemia Encefálica/complicações , Hipóxia-Isquemia Encefálica/patologia , Injeções , Masculino , Aprendizagem em Labirinto/fisiologia , Gravidez , Distribuição Aleatória , Ratos , Ratos Wistar , Células-Tronco/fisiologiaRESUMO
Regular physical activity has shown to improve the quality of life and to prevent age-related memory deficits. Memory processing requires proper regulation of several enzymes such as sodium-potassium adenosine triphosphatase (Na+, K+-ATPase) and acetylcholinesterase (AChE), which have a pivotal role in neuronal transmission. The present study investigated the effects of a treadmill running protocol in young (3 months), mature (6 months) and aged (22 months) Wistar rats, on: (a) cognitive function, as assessed in the Water maze spatial tasks; (b) Na+, K+-ATPase and AChE activities in the hippocampus following cognitive training alone or treadmill running combined with cognitive training. Animals of all ages were assigned to naïve (with no behavioral or exercise training), sedentary (non-exercised, with cognitive training) and exercised (20 min of daily running sessions, 3 times per week for 4 weeks and with cognitive training) groups. Cognition was assessed by reference and working memory tasks run in the Morris Water maze; 24 h after last session of behavioral testing, hippocampi were collected for biochemical analysis. Results demonstrated that: (a) a moderate treadmill running exercise prevented spatial learning and memory deficits in aged rats; (b) training in the Water maze increased both Na+, K+-ATPase and AChE activities in the hippocampus of mature and aged rats; (c) aged exercised rats displayed an even further increase of Na+, K+-ATPase activity in the hippocampus, (d) enzyme activity correlated with memory performance in aged rats. It is suggested that exercise prevents spatial memory deficits in aged rats probably through the activation of Na+, K+-ATPase in the hippocampus.
Assuntos
Envelhecimento/metabolismo , Hipocampo/enzimologia , Transtornos da Memória/enzimologia , Condicionamento Físico Animal/fisiologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Memória Espacial/fisiologia , Animais , Ativação Enzimática/fisiologia , Teste de Esforço/métodos , Teste de Esforço/psicologia , Masculino , Aprendizagem em Labirinto/fisiologia , Transtornos da Memória/prevenção & controle , Condicionamento Físico Animal/métodos , Condicionamento Físico Animal/psicologia , Distribuição Aleatória , Ratos , Ratos WistarRESUMO
Neonatal hypoxia-ischemia (HI) is an important cause of neurological deficits in humans, and the Levine-Rice model of experimental HI in the rat mimics the human brain lesion and the following sensory motor deficits and cognitive disabilities. With the growing evidence that sex influences all levels of brain functions, this Mini-Review highlights studies in which sex was a controlled variable and that provided evidence of sexual dimorphism in behavioral outcome, extension of brain damage, mechanisms of lesion, and treatment efficacy in the rat neonatal HI model. It was shown that 1) females have greater memory deficits; 2) cell death is dependent mainly on caspase activation in females; 3) males are more susceptible to oxidative stress; and 4) treatments acting on distinct cell death pathways afford sex-dependent neuroprotection. These tentative conclusions, along with growing evidence from other fields of neurobiology, support the need for scientists to design their experiments considering sex as an important variable; otherwise, important knowledge will continue to be missed. It is conceivable that sex can influence the development of efficacious therapeutic tools to treat neonates suffering from brain HI. © 2016 Wiley Periodicals, Inc.