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How can short-lived molecules selectively maintain the potentiation of activated synapses to sustain long-term memory? Here, we find kidney and brain expressed adaptor protein (KIBRA), a postsynaptic scaffolding protein genetically linked to human memory performance, complexes with protein kinase Mzeta (PKMζ), anchoring the kinase's potentiating action to maintain late-phase long-term potentiation (late-LTP) at activated synapses. Two structurally distinct antagonists of KIBRA-PKMζ dimerization disrupt established late-LTP and long-term spatial memory, yet neither measurably affects basal synaptic transmission. Neither antagonist affects PKMζ-independent LTP or memory that are maintained by compensating PKCs in ζ-knockout mice; thus, both agents require PKMζ for their effect. KIBRA-PKMζ complexes maintain 1-month-old memory despite PKMζ turnover. Therefore, it is not PKMζ alone, nor KIBRA alone, but the continual interaction between the two that maintains late-LTP and long-term memory.
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Péptidos y Proteínas de Señalización Intracelular , Potenciación a Largo Plazo , Ratones Noqueados , Proteína Quinasa C , Animales , Proteína Quinasa C/metabolismo , Proteína Quinasa C/genética , Ratones , Humanos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Péptidos y Proteínas de Señalización Intracelular/genética , Memoria/fisiología , Memoria a Largo Plazo/fisiología , Sinapsis/metabolismo , Sinapsis/fisiología , Unión Proteica , FosfoproteínasRESUMEN
Traumatic brain injury (TBI) results in both rapid and delayed brain damage. The speed, complexity, and persistence of TBI present large obstacles to drug development. Preclinical studies from multiple laboratories have tested the FDA-approved anti-microbial drug minocycline (MINO) to treat traumatic brain injury. At concentrations greater than needed for anti-microbial action, MINO readily inhibits microglial activation. MINO has additional pleotropic effects including anti-inflammatory, anti-oxidant, and anti-apoptotic activities. MINO inhibits multiple proteins that promote brain injury including metalloproteases, caspases, calpain, and polyADP-ribose-polymerase-1. At these elevated doses, MINO is well tolerated and enters the brain even when the blood-brain barrier is intact. Most preclinical studies with a first dose of MINO at less than 1 h after injury have shown improved multiple outcomes after TBI. Fewer studies with more delayed dosing have yielded similar results. A small number of clinical trials for TBI have established the safety of MINO and suggested some drug efficacy. Studies are also ongoing that either improve MINO pharmacology or combine MINO with other drugs to increase its therapeutic efficacy against TBI. This review builds upon a previous, recent review by some of the authors (Lawless and Bergold, Neural Regen Res 17:2589-92, 2022). The present review includes the additional preclinical studies examining the efficacy of minocycline in preclinical TBI models. This review also includes recommendations for a clinical trial to test MINO to treat TBI.
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Lesiones Traumáticas del Encéfalo , Lesiones Encefálicas , Humanos , Minociclina/uso terapéutico , Lesiones Traumáticas del Encéfalo/tratamiento farmacológico , Lesiones Encefálicas/tratamiento farmacológico , AntioxidantesRESUMEN
Traumatic brain injury (TBI) acutely damages the brain; this injury can evolve into chronic neurodegeneration. While much is known about the chronic effects arising from multiple mild TBIs, far less is known about the long-term effects of a single moderate to severe TBI. We found that a single moderate closed head injury to mice induces diffuse axonal injury within 1-day post-injury (DPI). At 14 DPI, injured animals have atrophy of ipsilesional cortex, thalamus, and corpus callosum, with bilateral atrophy of the dorsal fornix. Atrophy of the ipsilesional corpus callosum is accompanied by decreased fractional anisotropy and increased mean and radial diffusivity that remains unchanged between 14 and 180 DPI. Injured animals show an increased density of phospho-tau immunoreactive (pTau+) cells in the ipsilesional cortex and thalamus, and bilaterally in corpus callosum. Between 14 and 180 DPI, atrophy occurs in the ipsilesional ventral fornix, contralesional corpus callosum, and bilateral internal capsule. Diffusion tensor MRI parameters remain unchanged in white matter regions with delayed atrophy. Between 14 and 180 DPI, pTau+ cell density increases bilaterally in corpus callosum, but decreases in cortex and thalamus. The location of pTau+ cells within the ipsilesional corpus callosum changes between 14 and 180 DPI; density of all cells increases including pTau+ or pTau- cells. >90% of the pTau+ cells are in the oligodendrocyte lineage in both gray and white matter. Density of thioflavin-S+ cells in thalamus increases by 180 DPI. These data suggest a single closed head impact produces multiple forms of chronic neurodegeneration. Gray and white matter regions proximal to the impact site undergo early atrophy. More distal white matter regions undergo chronic, progressive white matter atrophy with an increasing density of oligodendrocytes containing pTau. These data suggest a complex chronic neurodegenerative process arising from a single moderate closed head injury.
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Lesiones Traumáticas del Encéfalo , Traumatismos Cerrados de la Cabeza , Sustancia Blanca , Animales , Ratones , Masculino , Sustancia Blanca/diagnóstico por imagen , Sustancia Blanca/patología , Imagen de Difusión Tensora , Lesiones Traumáticas del Encéfalo/patología , Cuerpo Calloso/diagnóstico por imagen , Cuerpo Calloso/patología , Oligodendroglía , Atrofia/patología , Traumatismos Cerrados de la Cabeza/patologíaRESUMEN
Traumatic brain injury has a complex pathophysiology that produces both rapid and delayed brain damage. Rapid damage initiates immediately after injury. Treatment of traumatic brain injury is typically delayed many hours, thus only delayed damage can be targeted with drugs. Delayed traumatic brain injury includes neuroinflammation, oxidative damage, apoptosis, and glutamate toxicity. Both the speed and complexity of traumatic brain injury pathophysiology present large obstacles to drug development. Repurposing of Food and Drug Administration-approved drugs may be a highly efficient approach to get therapeutics to the clinic. This review examines the preclinical outcomes of minocycline and N-acetylcysteine as individual drugs and compares them to the minocycline plus N-acetylcysteine combination. Both minocycline and N-acetylcysteine are Food and Drug Administration-approved drugs with pleiotropic therapeutic effects. As individual drugs, minocycline and N-acetylcysteine are well tolerated, with known pharmacokinetics, and enter the brain through an intact blood-brain barrier. At concentrations greater than needed for anti-microbial action, minocycline is a potent anti-inflammatory minocycline, also acts as an antioxidant and inhibits multiple enzymes that promote brain injury including metalloproteases, caspases, and polyADP-ribose-polymerase-1. N-acetylcysteine alone is also an antioxidant. It increases brain glutathione, prevents lipid oxidation, and protects mitochondria. N-acetylcysteine also acts as an anti-inflammatory as well as increases extracellular glutamate by activating the Xc cystine-glutamate anti-transporter. These multiple actions of minocycline and N-acetylcysteine have made them attractive candidates to treat traumatic brain injury. When first dosed within the one hour after injury, either minocycline or N-acetylcysteine improves a diverse set of therapeutic outcome measures in multiple traumatic brain injury animal models. A small number of clinical trials for traumatic brain injury have established the safety of minocycline or N-acetylcysteine and suggested that either drug has some efficacy. Preclinical studies have shown that minocycline plus N-acetylcysteine have positive synergy resulting in therapeutic effects and a more prolonged therapeutic time window not seen with the individual drugs. This review compares the actions of minocycline and N-acetylcysteine, individually and in combination. Evidence supports that the combination has greater utility to treat traumatic brain injury than the individual drugs.
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Multiple drugs to treat traumatic brain injury (TBI) have failed clinical trials. Most drugs lose efficacy as the time interval increases between injury and treatment onset. Insufficient therapeutic time window is a major reason underlying failure in clinical trials. Few drugs have been developed with therapeutic time windows sufficiently long enough to treat TBI because little is known about which brain functions can be targeted if therapy is delayed hours to days after injury. We identified multiple injury parameters that are improved by first initiating treatment with the drug combination minocycline (MINO) plus N-acetylcysteine (NAC) at 72 h after injury (MN72) in a mouse closed head injury (CHI) experimental TBI model. CHI produces spatial memory deficits resulting in impaired performance on Barnes maze, hippocampal neuronal loss, and bilateral damage to hippocampal neurons, dendrites, spines and synapses. MN72 treatment restores Barnes maze acquisition and retention, protects against hippocampal neuronal loss, limits damage to dendrites, spines and synapses, and accelerates recovery of microtubule associated protein 2 (MAP2) expression, a key protein in maintaining proper dendritic architecture and synapse density. These data show that in addition to the structural integrity of the dendritic arbor, spine and synapse density can be successfully targeted with drugs first dosed days after injury. Retention of substantial drug efficacy even when first dosed 72 h after injury makes MINO plus NAC a promising candidate to treat clinical TBI.
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Acetilcisteína/administración & dosificación , Lesiones Traumáticas del Encéfalo/tratamiento farmacológico , Encéfalo/efectos de los fármacos , Minociclina/administración & dosificación , Fármacos Neuroprotectores/administración & dosificación , Memoria Espacial/efectos de los fármacos , Animales , Encéfalo/metabolismo , Encéfalo/patología , Lesiones Traumáticas del Encéfalo/metabolismo , Lesiones Traumáticas del Encéfalo/patología , Esquema de Medicación , Quimioterapia Combinada , Depuradores de Radicales Libres/administración & dosificación , Masculino , Trastornos de la Memoria/tratamiento farmacológico , Trastornos de la Memoria/metabolismo , Trastornos de la Memoria/patología , Ratones , Ratones Endogámicos C57BL , Enfermedades Neurodegenerativas/tratamiento farmacológico , Enfermedades Neurodegenerativas/metabolismo , Enfermedades Neurodegenerativas/patología , Memoria Espacial/fisiologíaRESUMEN
PKMζ is an autonomously active PKC isoform crucial for the maintenance of synaptic long-term potentiation (LTP) and long-term memory. Unlike other kinases that are transiently stimulated by second messengers, PKMζ is persistently activated through sustained increases in protein expression of the kinase. Therefore, visualizing increases in PKMζ expression during long-term memory storage might reveal the sites of its persistent action and thus the location of memory-associated LTP maintenance in the brain. Using quantitative immunohistochemistry validated by the lack of staining in PKMζ-null mice, we examined the amount and distribution of PKMζ in subregions of the hippocampal formation of wild-type mice during LTP maintenance and spatial long-term memory storage. During LTP maintenance in hippocampal slices, PKMζ increases in the pyramidal cell body and stimulated dendritic layers of CA1 for at least 2 hr. During spatial memory storage, PKMζ increases in CA1 pyramidal cells for at least 1 month, paralleling the persistence of the memory. During the initial expression of the memory, we tagged principal cells with immediate-early gene Arc promoter-driven transcription of fluorescent proteins. The subset of memory-tagged CA1 cells selectively increases expression of PKMζ during memory storage, and the increase persists in dendritic compartments within stratum radiatum for 1 month, indicating long-term storage of information in the CA3-to-CA1 pathway. We conclude that persistent increases in PKMζ trace the molecular mechanism of LTP maintenance and thus the sites of information storage within brain circuitry during long-term memory.
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Potenciación a Largo Plazo , Proteína Quinasa C , Animales , Hipocampo/metabolismo , Memoria a Largo Plazo , Ratones , Neuronas/metabolismo , Proteína Quinasa C/metabolismo , Memoria EspacialRESUMEN
Comorbid post-traumatic stress disorder with traumatic brain injury (TBI) produce more severe affective and cognitive deficits than PTSD or TBI alone. Both PTSD and TBI produce long-lasting neuroinflammation, which may be a key underlying mechanism of the deficits observed in co-morbid TBI/PTSD. We developed a model of co-morbid TBI/PTSD by combining the closed head (CHI) model of TBI with the chronic variable stress (CVS) model of PTSD and examined multiple behavioral and neuroinflammatory outcomes. Male C57/Bl6 mice received sham treatment, CHI, CVS, CHI then CVS (CHI â CVS) or CVS then CHI (CVS â CHI). The CVS â CHI group had deficits in Barnes maze or active place avoidance not seen in the other groups. The CVS â CHI, CVS and CHI â CVS groups displayed increased basal anxiety level, based on performance on elevated plus maze. The CVS â CHI had impaired performance on Barnes Maze, and Active Place Avoidance. These performance deficits were strongly correlated with increased hippocampal Iba-1 level an indication of activated MP/MG. These data suggest that greater cognitive deficits in the CVS â CHI group were due to increased inflammation. The increased deficits and neuroinflammation in the CVS â CHI group suggest that the order by which a subject experiences TBI and PTSD is a major determinant of the outcome of brain injury in co-morbid TBI/PTSD.
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Reacción de Prevención/fisiología , Lesiones Traumáticas del Encéfalo/psicología , Modelos Animales de Enfermedad , Aprendizaje por Laberinto/fisiología , Trastornos por Estrés Postraumático/psicología , Animales , Lesiones Traumáticas del Encéfalo/complicaciones , Lesiones Traumáticas del Encéfalo/patología , Comorbilidad , Inflamación/patología , Inflamación/psicología , Masculino , Ratones , Reflejo de Sobresalto/fisiología , Trastornos por Estrés Postraumático/complicaciones , Trastornos por Estrés Postraumático/patologíaRESUMEN
Traumatic brain injury (TBI) is a major cause of death and disability. Despite its importance in public health, there are presently no drugs to treat TBI. Many reasons underlie why drugs have failed clinical trials, one reason is that most drugs to treat TBI lose much of their efficacy before patients are first treated. This review discusses the importance of therapeutic time window; the time interval between TBI onset and the initiation of treatment. Therapeutic time window is complex, as brain injury is both acute and chronic, resulting in multiple drug targets that appear and disappear with differing kinetics. The speed and increasing complexity of TBI pathophysiology is a major reason why drugs lose efficacy as time to first dose increases. Recent Phase III clinical trials treated moderate to severe TBI patients within 4-8 h after injury, yet they turned away many potential patients who could not be treated within these time windows. Additionally, most head trauma is mild TBI. Unlike moderate to severe TBI, patients with mild TBI often delay treatment until their symptoms do not abate. Thus, drugs to treat moderate to severe TBI likely will need to retain high efficacy for up to 12 h after injury; drugs for mild TBI, however, will likely need even longer windows. Early pathological events following TBI progress with similar kinetics in humans and animal TBI models suggesting that preclinical testing of time windows assists the design of clinical trials. We reviewed preclinical studies of drugs first dosed later than 4 h after injury. This review showed that therapeutic time window can differ depending upon the animal TBI model and the outcome measure. We identify the few drugs (methamphetamine, melanocortin, minocycline plus N-acetylcysteine, and cycloserine) that demonstrated good therapeutic windows with multiple outcome measures. On the basis of their therapeutic window, these drugs appear to be excellent candidates for clinical trials. In addition to further testing of these drugs, we recommend that the assessment of therapeutic time window with multiple outcome measures becomes a standard component of preclinical drug testing.
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INTRODUCTION: We hereby report on studies aimed to characterize safety, pharmacokinetics, and bio-distribution of fluorescent nanodiamond particles (NV)-Z~800 (FNDP-(NV)) administered to rats by intravenous infusion in a single high dose. METHODS: Broad scale biological variables were monitored following acute (90 minutes) and subacute (5 or 14 days) exposure to FNDP-(NV). Primary endpoints included morbidity and mortality, while secondary endpoints focused on hematology and clinical biochemistry biomarkers. Particle distribution (liver, spleen, lung, heart, and kidney) was assessed by whole organ near infrared imaging using an in vivo imaging system. This was validated by the quantification of particles extracted from the same organs and visualized by fluorescent and scanning electron microscopy. FNDP-(NV)-treated rats showed no change in morbidity or mortality and preserved normal motor and sensory function, as assessed by six different tests. RESULTS: Blood cell counts and plasma biochemistry remained normal. The particles were principally distributed in the liver and spleen. The liver particle load accounted for 51%, 24%, and 18% at 90 minutes, 5 days, and 14 days, respectively. A pilot study of particle clearance from blood indicated 50% clearance 33 minutes following the end of particle infusion. CONCLUSION: We concluded that systemic exposure of rats to a single high dose of FDNP-(NV)-Z~800 (60 mg/kg) appeared to be safe and well tolerated over at least 2 weeks. These data suggest that FNDP-(NV) should proceed to preclinical development in the near future.
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Materiales Biocompatibles/efectos adversos , Materiales Biocompatibles/farmacocinética , Nanodiamantes/química , Tamaño de la Partícula , Animales , Biomarcadores/metabolismo , Recuento de Células Sanguíneas , Peso Corporal/efectos de los fármacos , Fluorescencia , Infusiones Intravenosas , Masculino , Nanodiamantes/ultraestructura , Tamaño de los Órganos/efectos de los fármacos , Especificidad de Órganos , Proyectos Piloto , Ratas Sprague-Dawley , Solubilidad , Distribución Tisular/efectos de los fármacosRESUMEN
The mouse closed head injury (CHI) model of traumatic brain injury (TBI) produces widespread demyelination. Myelin content is restored by minocycline (MINO) plus n-acetylcysteine (NAC) or MINO alone when first dosed at 12â¯h after CHI. In a rat controlled cortical impact model of TBl, a first dose of MINO plus NAC one h after injury protects resident oligodendrocytes that induce remyelination. In contrast, MINO less effectively protects oligodendrocytes and remyelination is mediated by oligodendrocyte precursor cell proliferation and differentiation. MINO plus NAC or MINO alone is hypothesized to work similarly in the CHI model as in the controlled cortical impact model even when first dosed at 12-h post-CHI. We tested this hypothesis by examining the time course of the changes in the oligodendrocyte antigenic markers CC1, 2',3'-Cyclic-nucleotide 3'-phosphodiesterase and phospholipid protein between 2 and 14 days post-CHI in mice treated with saline, NAC, MINO or MINO plus NAC. CHI produced a long-lasting loss of these markers that was not altered by NAC treatment. In contrast, oligodendrocyte marker expression was maintained by MINO plus NAC between 2 and 14 days post-injury. MINO alone did not prevent the early loss of oligodendrocyte markers, but marker expression significantly increased by 14-days post-injury. These data suggest that MINO plus NAC or MINO alone when first dosed 12â¯h after CHI increase myelin content using similar mechanisms seen when first dosed 1â¯h after closed head injury. These data also suggest that drugs protect oligodendrocytes with a clinically useful therapeutic time window.
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Acetilcisteína/administración & dosificación , Traumatismos Cerrados de la Cabeza/tratamiento farmacológico , Minociclina/administración & dosificación , Neuroprotección/efectos de los fármacos , Oligodendroglía/efectos de los fármacos , Animales , Cuerpo Calloso/efectos de los fármacos , Cuerpo Calloso/patología , Quimioterapia Combinada , Depuradores de Radicales Libres/administración & dosificación , Traumatismos Cerrados de la Cabeza/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Neuroprotección/fisiología , Oligodendroglía/patología , Factores de TiempoRESUMEN
Mild traumatic brain injury afflicts over 2 million people annually and little can be done for the underlying injury. The Food and Drug Administration-approved drugs Minocycline plus N-acetylcysteine (MINO plus NAC) synergistically improved cognition and memory in a rat mild controlled cortical impact (mCCI) model of traumatic brain injury.3 The underlying cellular and molecular mechanisms of the drug combination are unknown. This study addressed the effect of the drug combination on white matter damage and neuroinflammation after mCCI. Brain tissue from mCCI rats given either sham-injury, saline, MINO alone, NAC alone, or MINO plus NAC was investigated via histology and qPCR at four time points (2, 4, 7, and 14 days post-injury) for markers of white matter damage and neuroinflammation. MINO plus NAC synergistically protected resident oligodendrocytes and decreased the number of oligodendrocyte precursor cells. Activation of microglia/macrophages (MP/MG) was synergistically increased in white matter two days post-injury after MINO plus NAC treatment. Patterns of M1 and M2 MP/MG were also altered after treatment. The modulation of neuroinflammation is a potential mechanism to promote remyelination and improve cognition and memory. These data also provide new and important insights into how drug treatments can induce repair after traumatic brain injury.
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Acetilcisteína/uso terapéutico , Antiinflamatorios/uso terapéutico , Antioxidantes/uso terapéutico , Lesiones Traumáticas del Encéfalo/tratamiento farmacológico , Minociclina/uso terapéutico , Oligodendroglía/efectos de los fármacos , Remielinización/efectos de los fármacos , Animales , Lesiones Traumáticas del Encéfalo/complicaciones , Lesiones Traumáticas del Encéfalo/patología , Modelos Animales de Enfermedad , Sinergismo Farmacológico , Inflamación/complicaciones , Inflamación/tratamiento farmacológico , Inflamación/patología , Masculino , Oligodendroglía/patología , Ratas , Ratas Sprague-DawleyRESUMEN
There are no drugs to manage traumatic brain injury (TBI) presently. A major problem in developing therapeutics is that drugs to manage TBI lack sufficient potency when dosed within a clinically relevant time window. Previous studies have shown that minocycline (MINO, 45 mg/kg) plus N-acetylcysteine (NAC, 150 mg/kg) synergistically improved cognition and memory, modulated inflammation, and prevented loss of oligodendrocytes that remyelinated damaged white matter when first dosed 1 h after controlled cortical impact (CCI) in rats. We show that MINO (45 mg/kg) plus NAC (150 mg/kg) also prevent brain injury in a mouse closed head injury (CHI) TBI model. Using the CHI model, the concentrations of MINO and NAC were titrated to determine that MINO (22.5 mg/kg) plus NAC (75 mg/kg) was more potent than the original formulation. MINO (22.5 mg/kg) plus NAC (75 mg/kg) also limited injury in the rat CCI model. The therapeutic time window of MINO plus NAC was then tested in the CHI and CCI models. Mice and rats could acquire an active place avoidance task when MINO plus NAC was first dosed at 12 h post-injury. A first dose at 12 h also limited gray matter injury in the hippocampus and preserved myelin in multiple white matter tracts. Mice and rats acquired Barnes maze when MINO plus NAC was first dosed at 24 h post-injury. These data suggest that MINO (22.5 mg/kg) plus NAC (75 mg/kg) remain potent when dosed at clinically useful time windows. Both MINO and NAC are drugs approved by the Food and Drug Administration and have been administered safely to patients in clinical trials at the doses in the new formulation. This suggests that the drug combination of MINO plus NAC may be effective in treating patients with TBI.
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This study examined whether peripheral vision reaction time (PVRT) in patients with mild traumatic brain injury (mTBI) correlated with white matter abnormalities in centroaxial structures and impairments in neuropsychological testing. Within 24 h after mTBI, crossed reaction times (CRT), uncrossed reaction times (URT), and crossed-uncrossed difference (CUD) were measured in 23 patients using a laptop computer that displayed visual stimuli predominantly to either the left or the right visual field of the retina. The CUD is a surrogate marker of the interhemispheric transfer time (ITT). Within 7 days after the injury, patients received a diffusion tensor-MRI (DTI) scan and a battery of neuropsychological tests. Nine uninjured control subjects received similar testing. Patients 18-50 years of age were included if they had a post-resuscitation Glasgow Coma Scale >13 and an injury mechanism compatible with mTBI. Healthy controls were either age- and gender-matched family members of the TBI patients or healthy volunteers. CUD deficits >2 standard deviations (SD) were seen in 40.9% of patients. The CUD of injured patients correlated with mean diffusivity (MD) (p < 0.001, ρ = -0.811) in the posterior corpus callosum. Patients could be stratified on the basis of CUD on the Stroop 1, Controlled Oral Word Association Test (COWAT), and the obsessive-compulsive component of the Basic Symptom Inventory tests. These studies suggest that the PVRT indirectly measures white matter integrity in the posterior corpus callosum, a brain region frequently damaged by mTBI.
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Conmoción Encefálica/diagnóstico por imagen , Conmoción Encefálica/fisiopatología , Disfunción Cognitiva/fisiopatología , Cuerpo Calloso/diagnóstico por imagen , Desempeño Psicomotor/fisiología , Trastornos de la Visión/fisiopatología , Percepción Visual/fisiología , Sustancia Blanca/diagnóstico por imagen , Adolescente , Adulto , Conmoción Encefálica/complicaciones , Disfunción Cognitiva/etiología , Imagen de Difusión Tensora , Femenino , Escala de Coma de Glasgow , Humanos , Masculino , Persona de Mediana Edad , Tiempo de Reacción/fisiología , Trastornos de la Visión/etiología , Pruebas del Campo Visual , Adulto JovenRESUMEN
Blunt impact produces a heterogeneous brain injury in people and in animal models of traumatic brain injury. We report that a single closed head impact to adult C57/BL6 mice produced two injury syndromes (CHI-1 and CHI-2). CHI-1 mice spontaneously reinitiated breathing after injury while CHI-2 mice had prolonged apnea and regained breathing only after cardiopulmonary resuscitation and supplementation of 100% O2. The CHI-1 group significantly regained righting reflex more rapidly than the CHI-2 group. At 7 days post-injury, CHI-1, but not CHI-2 mice, acquired but had no long-term retention of an active place avoidance task. The behavioral deficits of CHI-1 and CHI-2 mice were retained one-month after the injury. CHI-1 mice had loss of hippocampal neurons and localized white matter injury at one month after injury. CHI-2 had a larger loss of hippocampal neurons and more widespread loss of myelin and axons. High-speed videos made during the injury were followed by assessment of breathing and righting reflex. These videos show that CHI-2 mice experienced a larger vertical g-force than CHI-1 mice. Time to regain righting reflex in CHI-2 mice significantly correlated with vertical g-force. Thus, physiological responses occurring immediately after injury can be valuable surrogate markers of subsequent behavioral and histological deficits.
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Traumatic brain injury rapidly induces inflammation. This inflammation is produced both by endogenous brain cells and circulating inflammatory cells that enter from the brain. Together they drive the inflammatory response through a wide variety of bioactive lipids, cytokines and chemokines. A large number of drugs with anti-inflammatory action have been tested in both preclinical studies and in clinical trials. These drugs either have known anti-inflammatory action or inhibit the inflammatory response through unknown mechanisms. The results of these preclinical studies and clinical trials are reviewed. Recommendations are suggested on how to improve preclinical testing of drugs to make them more relevant to evaluate for clinical trials.
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Antiinflamatorios/uso terapéutico , Lesiones Encefálicas/tratamiento farmacológico , Mediadores de Inflamación/antagonistas & inhibidores , Animales , Antiinflamatorios/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Lesiones Encefálicas/metabolismo , Lesiones Encefálicas/patología , Quimiocinas/antagonistas & inhibidores , Quimiocinas/metabolismo , Citocinas/antagonistas & inhibidores , Citocinas/metabolismo , Humanos , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Inflamación/patología , Mediadores de Inflamación/metabolismo , Resultado del TratamientoRESUMEN
Folate is essential for fetal development, and its deficiency during gestation causes behavioural deficits in the offspring. The present study investigated its influence during weaning on brain function in the pups of rats that were put on a folate-deficient (FD) diet on postnatal day (PND) 1. Systemic folate deficiency in pups on the FD diet (n 15) was evident from the dramatically lower hepatic folate concentrations (median 23·7, range 8·1-48·4 ng/mg protein) and higher homocysteine concentrations (median 27·7, range 14·7-45·5 pmol/mg protein), respectively, compared with those of pups on the normal diet (ND; n 9) (median 114·5, range 64·5-158·5 ng/mg protein and median 15·5, range 11·6-18·9 pmol/mg protein) on PND 23. Brain folate concentrations although low were similar in pups on the FD diet (median 10·5, range 5·5-24·5 ng/mg protein) and ND (median 11·1, range 7·1-24·2 ng/mg protein). There was a high accumulation of homocysteine in the brain of FD pups, mostly in the hippocampus (median 58·1, range 40·8-99·7 pmol/mg protein) and cerebellum (median 69·1, range 50·8-126·6 pmol/mg protein), indicating metabolic folate deficiency despite normal brain folate concentrations. Developmental deficits or autistic traits were more frequent in the FD group than in the ND group and repetitive self-grooming occurred, on average, three times (range 1-8) v. once (range 0-3) during 5 min, respectively. Long-term memory or spatial learning and set-shifting deficits affected 12 to 62% of rats in the FD group compared with none in the ND group. Post-weaning folic acid supplementation did not correct these deficits. These observations indicate that folate deficiency during weaning affects postnatal development even when gestational folate supply is normal.
Asunto(s)
Encéfalo/metabolismo , Dieta/efectos adversos , Deficiencia de Ácido Fólico/fisiopatología , Ácido Fólico/metabolismo , Discapacidades para el Aprendizaje/etiología , Trastornos de la Memoria/etiología , Neuronas/metabolismo , Animales , Conducta Animal , Encéfalo/patología , Cerebelo/metabolismo , Cerebelo/patología , Susceptibilidad a Enfermedades , Femenino , Ácido Fólico/uso terapéutico , Deficiencia de Ácido Fólico/dietoterapia , Deficiencia de Ácido Fólico/etiología , Deficiencia de Ácido Fólico/metabolismo , Hipocampo/metabolismo , Hipocampo/patología , Homocisteína/metabolismo , Lactancia , Discapacidades para el Aprendizaje/prevención & control , Hígado/metabolismo , Hígado/patología , Masculino , Fenómenos Fisiologicos Nutricionales Maternos , Trastornos de la Memoria/prevención & control , Memoria a Largo Plazo , Ratas Long-Evans , Aprendizaje Espacial , DesteteRESUMEN
Traumatic brain injury (TBI) differs in severity from severe to mild. This study examined whether a combination of the drugs minocycline (MINO) plus N-acetylcysteine (NAC) produces behavioral and histological improvements in a mild version of the controlled cortical impact model of TBI (mCCI). Following mCCI, rats acquired an active place avoidance task by learning the location of a stationary shock zone on a rotating arena. Rats acquired this task with a training protocol using a 10-minute intertrial interval. Mildly injured rats had an apparent deficit in long-term memory since they did not acquire the task when the intertrial interval was increased to 24 h. Mildly injured rats also had an apparent deficit in set shifting since, after successfully learning one shock zone location they did not learn the location of a second shock zone. MINO plus NAC synergistically limited these behavioral deficits in long-term memory and set shifting. mCCI also produced neuroinflammation at the impact site and at distal white matter tracts including the corpus callosum. At the impact site, MINO plus NAC attenuated CD68-expressing phagocytic microglia without altering neutrophil infiltration or astrocyte activation. The drugs had no effect on astrocyte activation in the corpus callosum or hippocampus. In the corpus callosum, MINO plus NAC decreased CD68 expression yet increased overall microglial activation as measured by Iba-1. MINO plus NAC acted synergistically to increase Iba-1 expression since MINO alone suppressed expression and NAC alone had no effect. Despite the known anti-inflammatory actions of the individual drugs, MINO plus NAC appeared to modulate, rather than suppress neuroinflammation. This modulation of neuroinflammation may underlie the synergistic improvement in memory and set-shifting by the drug combination after mCCI.
Asunto(s)
Acetilcisteína/administración & dosificación , Lesiones Encefálicas/prevención & control , Trastornos del Conocimiento/prevención & control , Modelos Animales de Enfermedad , Trastornos de la Memoria/prevención & control , Minociclina/administración & dosificación , Animales , Reacción de Prevención/efectos de los fármacos , Reacción de Prevención/fisiología , Lesiones Encefálicas/patología , Lesiones Encefálicas/fisiopatología , Trastornos del Conocimiento/patología , Trastornos del Conocimiento/fisiopatología , Sinergismo Farmacológico , Quimioterapia Combinada , Inflamación/patología , Inflamación/prevención & control , Trastornos de la Memoria/patología , Trastornos de la Memoria/fisiopatología , Fármacos Neuroprotectores/administración & dosificación , Ratas , Ratas Sprague-DawleyRESUMEN
Traumatic brain injury (TBI) selectively damages white matter. White matter damage does not produce deficits in many behavioral tests used to analyze experimental TBI. Rats were impaired on an active place avoidance task following inactivation of one hippocampal injection of tetrodotoxin. The need for both hippocampi suggests that acquisition of the active place avoidance task may require interhippocampal communication. The controlled cortical impact model of TBI demyelinates midline white matter and impairs rats on the active place avoidance task. One white matter region that is demyelinated is the fimbria that contains hippocampal commissural fibers. We therefore tested whether demyelination of the fimbria produces deficits in active place avoidance. Lysophosphatidylcholine (LPC) was injected stereotaxically to produce a cycle of demyelination-remyelination of the fimbria. At 4 days, myelin loss was observed in the fimbria of LPC-, but not saline-injected rats. Fourteen days after injection, myelin content increased in LPC-, but not saline-injected rats. Three days after injection, both saline- and LPC-injected rats had similar performance on an open field and passive place avoidance task in which the rat avoided a stationary shock zone on a stationary arena. The following day, on the active place avoidance task, LPC-injected rats had a significantly higher number of shock zone entrances suggesting learning was impaired. At 14 days after injection, saline- and LPC-injected rats had similar performance on open field and passive place avoidance. On active place avoidance, however, saline- and LPC-injected rats had a similar number of total entrances suggesting that the impairment seen at 4 days was no longer present at 14 days. These data suggest that active place avoidance is highly sensitive to white matter injury.
Asunto(s)
Conducta Animal/fisiología , Enfermedades Desmielinizantes/fisiopatología , Fórnix/fisiología , Fórnix/fisiopatología , Vaina de Mielina/fisiología , Animales , Reacción de Prevención/efectos de los fármacos , Reacción de Prevención/fisiología , Conducta Animal/efectos de los fármacos , Enfermedades Desmielinizantes/inducido químicamente , Fórnix/efectos de los fármacos , Lisofosfatidilcolinas/farmacología , Vaina de Mielina/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Factores de TiempoRESUMEN
BACKGROUND: There are no drugs presently available to treat traumatic brain injury (TBI). A variety of single drugs have failed clinical trials suggesting a role for drug combinations. Drug combinations acting synergistically often provide the greatest combination of potency and safety. The drugs examined (minocycline (MINO), N-acetylcysteine (NAC), simvastatin, cyclosporine A, and progesterone) had FDA-approval for uses other than TBI and limited brain injury in experimental TBI models. METHODOLOGY/PRINCIPAL FINDINGS: Drugs were dosed one hour after injury using the controlled cortical impact (CCI) TBI model in adult rats. One week later, drugs were tested for efficacy and drug combinations tested for synergy on a hierarchy of behavioral tests that included active place avoidance testing. As monotherapy, only MINO improved acquisition of the massed version of active place avoidance that required memory lasting less than two hours. MINO-treated animals, however, were impaired during the spaced version of the same avoidance task that required 24-hour memory retention. Co-administration of NAC with MINO synergistically improved spaced learning. Examination of brain histology 2 weeks after injury suggested that MINO plus NAC preserved white, but not grey matter, since lesion volume was unaffected, yet myelin loss was attenuated. When dosed 3 hours before injury, MINO plus NAC as single drugs had no effect on interleukin-1 formation; together they synergistically lowered interleukin-1 levels. This effect on interleukin-1 was not observed when the drugs were dosed one hour after injury. CONCLUSIONS/SIGNIFICANCE: These observations suggest a potentially valuable role for MINO plus NAC to treat TBI.
Asunto(s)
Acetilcisteína/farmacología , Lesiones Encefálicas/fisiopatología , Cognición/efectos de los fármacos , Memoria/efectos de los fármacos , Minociclina/farmacología , Animales , Reacción de Prevención/efectos de los fármacos , Lesiones Encefálicas/metabolismo , Lesiones Encefálicas/patología , Condicionamiento Psicológico , Sinergismo Farmacológico , Interleucina-1beta/biosíntesis , Vaina de Mielina/metabolismo , Percepción/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Análisis y Desempeño de Tareas , Factores de TiempoRESUMEN
The sodium-potassium ATPase (Na/K ATPase) is a major ionic transporter in the brain and is responsible for the maintenance of the Na(+) and K(+) gradients across the cell membrane. Cardiotonic steroids such as ouabain, digoxin and marinobufagenin are well-characterized inhibitors of the Na/K ATPase. Recently, cardiotonic steroids have been shown to have additional effects at concentrations below their IC(50) for pumping. The cardiotonic steroids ouabain, digoxin, and marinobufagenin all show an inverted U-shaped dose-response curve with inhibition of pumping at concentrations near their IC(50), while increasing Na/K ATPase activity at doses below their IC(50). This stimulatory effect of cardiotonic steroids was observed in vitro in hippocampal slice cultures as well as in the hippocampus in vivo. Increased Na/K ATPase activity has been shown to protect slice culture neurons from hypoxia-hypoglycemia. Ouabain protected slice culture neurons from experimental ischemia at concentrations that increased Na/K ATPase. This protective effect was observed when ouabain was dosed 30min before, or 2h following experimental ischemia. Ouabain no longer protected against experimental ischemia if the increase of Na/K ATPase was blocked. These data suggest that the protective effect of ouabain was due to increased Na/K ATPase activity. The demonstration of a neuroprotective effect of cardiotonic steroids could potentially assist in the treatment of stroke since digoxin, one of the cardiotonic steroids examined in this study, has approval by the Food and Drug Administration and can be safely administered at the concentrations that increase Na/K ATPase activity.